四、网络

骑猪看日落 2022-01-07 01:21 194阅读 0赞

**目录**

4.1 连接到服务器

4.1.1 使用telnet

4.1.2 用Java连接服务器

4.1.3 套接字超时

4.1.1 因特网地址

4.2 实现服务器

4.2.1 服务器套接字

4.2.2 为多个客户提供服务

4.2.3 半关闭

4.3 可中断套接字

4.4 获取Web数

4.4.1 URL和URI

4.4.2 使用URLConnection获取信息

4.4.3 提交表单数据

4.5 发送Mail

--------------------

# 4.1 连接到服务器 #

## 4.1.1 使用telnet ##

![20190625092049342.png][]

telnet time-a.nist.gov 13

当你开始使用time-a.nost.gov在端口13上建立telnet对话时，网络软件中有一段代码非常清楚的知道应该将字符串“time-a.nist.gov"转换为正确的IP地址129.6.15.28

![2019062509213449.png][]

## 4.1.2 用Java连接服务器 ##

package Section4;
    
    import java.net.*;
    import java.util.Scanner;
    import java.io.*;
    public class test1 {
    	public static void main(String []args) throws IOException {
    		try(Socket s= new Socket("time-a.nist.gov",13)){
    			Scanner in = new Scanner(s.getInputStream(),"UTF-8");
    			{
    				while(in.hasNextLine()) {
    					String line=in.nextLine();
    					System.out.println(line);
    				}
    			}
    		}
    	}
    }

UnkownHostException是IOException的一个子类。

实际上，java.net包提供的编程接口与操作文件时所用的接口基本相同

**java.net.Socket:**

* * <table> 
 <tbody> 
 <tr> 
 <th>Modifier and Type</th> 
 <th>Method and Description</th> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">bind</a>(<a rel="nofollow">SocketAddress</a>&nbsp;bindpoint)</code> 将套接字绑定到本地地址。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">close</a>()</code> 关闭此套接字。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">connect</a>(<a rel="nofollow">SocketAddress</a>&nbsp;endpoint)</code> 将此套接字连接到服务器。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">connect</a>(<a rel="nofollow">SocketAddress</a>&nbsp;endpoint, int&nbsp;timeout)</code> 将此套接字连接到具有指定超时值的服务器。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">SocketChannel</a></code></td> 
 <td><code><a rel="nofollow">getChannel</a>()</code> 返回与此套接字相关联的唯一的<a rel="nofollow"><code>SocketChannel</code></a>对象（如果有）。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">InetAddress</a></code></td> 
 <td><code><a rel="nofollow">getInetAddress</a>()</code> 返回套接字所连接的地址。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">InputStream</a></code></td> 
 <td><code><a rel="nofollow">getInputStream</a>()</code> 返回此套接字的输入流。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getKeepAlive</a>()</code> 测试是否启用了 <a rel="nofollow"><code>SO_KEEPALIVE</code></a> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">InetAddress</a></code></td> 
 <td><code><a rel="nofollow">getLocalAddress</a>()</code> 获取套接字所绑定的本地地址。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getLocalPort</a>()</code> 返回此套接字绑定到的本地端口号。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">SocketAddress</a></code></td> 
 <td><code><a rel="nofollow">getLocalSocketAddress</a>()</code> 返回此套接字绑定到的端点的地址。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getOOBInline</a>()</code> 测试是否启用了 <a rel="nofollow"><code>SO_OOBINLINE</code></a> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">OutputStream</a></code></td> 
 <td><code><a rel="nofollow">getOutputStream</a>()</code> 返回此套接字的输出流。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getPort</a>()</code> 返回此套接字连接到的远程端口号。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getReceiveBufferSize</a>()</code> 获取这个 <code>Socket</code>的 <a rel="nofollow"><code>SO_RCVBUF</code></a>选项的值，即平台在此 <code>Socket</code>上输入的缓冲区大小。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">SocketAddress</a></code></td> 
 <td><code><a rel="nofollow">getRemoteSocketAddress</a>()</code> 返回此套接字连接，或端点的地址 <code>null</code>如果是未连接。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getReuseAddress</a>()</code> 测试是否启用了 <a rel="nofollow"><code>SO_REUSEADDR</code></a> 。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getSendBufferSize</a>()</code> 获取此 <code>Socket</code>的 <a rel="nofollow"><code>SO_SNDBUF</code></a>选项的值，即该平台在此 <code>Socket</code>上输出使用的缓冲区大小。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getSoLinger</a>()</code> <a rel="nofollow"><code>SO_LINGER</code>的</a>退货设置。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getSoTimeout</a>()</code> <a rel="nofollow"><code>SO_TIMEOUT</code>的</a>退货设置。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getTcpNoDelay</a>()</code> 测试是否启用了 <a rel="nofollow"><code>TCP_NODELAY</code></a> 。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getTrafficClass</a>()</code> 在从此Socket发送的数据包的IP头中获取流量类或服务类型 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isBound</a>()</code> 返回套接字的绑定状态。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isClosed</a>()</code> 返回套接字的关闭状态。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isConnected</a>()</code> 返回套接字的连接状态。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isInputShutdown</a>()</code> 返回套接字连接的一半是否关闭。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isOutputShutdown</a>()</code> 返回套接字连接的写半是否关闭。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">sendUrgentData</a>(int&nbsp;data)</code> 在套接字上发送一个字节的紧急数据。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setKeepAlive</a>(boolean&nbsp;on)</code> 启用/禁用 <a rel="nofollow"><code>SO_KEEPALIVE</code></a> 。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setOOBInline</a>(boolean&nbsp;on)</code> 启用/禁用 <a rel="nofollow"><code>SO_OOBINLINE</code></a> （接收TCP紧急数据）默认情况下，此选项被禁用，并且在套接字上接收的TCP紧急数据被静默地丢弃。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setPerformancePreferences</a>(int&nbsp;connectionTime, int&nbsp;latency, int&nbsp;bandwidth)</code> 设置此套接字的性能首选项。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setReceiveBufferSize</a>(int&nbsp;size)</code> 设置 <a rel="nofollow"><code>SO_RCVBUF</code></a>选项为这个指定的值 <code>Socket</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setReuseAddress</a>(boolean&nbsp;on)</code> 启用/禁用 <a rel="nofollow"><code>SO_REUSEADDR</code></a>套接字选项。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setSendBufferSize</a>(int&nbsp;size)</code> 设置 <a rel="nofollow"><code>SO_SNDBUF</code></a>选项为这个指定的值 <code>Socket</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code>static void</code></td> 
 <td><code><a rel="nofollow">setSocketImplFactory</a>(<a rel="nofollow">SocketImplFactory</a>&nbsp;fac)</code> 设置应用程序的客户端套接字实现工厂。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setSoLinger</a>(boolean&nbsp;on, int&nbsp;linger)</code> 启用/禁用 <a rel="nofollow"><code>SO_LINGER</code></a> ，具有指定的逗留时间（以秒为单位）。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setSoTimeout</a>(int&nbsp;timeout)</code> 启用/禁用 <a rel="nofollow">指定</a>超时的 <code>SO_TIMEOUT</code>（以毫秒为单位）。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setTcpNoDelay</a>(boolean&nbsp;on)</code> 启用/禁用 <a rel="nofollow"><code>TCP_NODELAY</code></a> （禁用/启用Nagle的算法）。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setTrafficClass</a>(int&nbsp;tc)</code> 在从此Socket发送的数据包的IP头中设置流量类或服务类型字节。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">shutdownInput</a>()</code> 将此套接字的输入流放置在“流的末尾”。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">shutdownOutput</a>()</code> 禁用此套接字的输出流。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">toString</a>()</code> 将此套接字转换为 <code>String</code> 。 </td> 
 </tr> 
 </tbody> 
 </table>

## 4.1.3 套接字超时 ##

![20190625092614836.png][]

对于不同的应用，应该确认合理的超时值。

package Section4;
    
    import java.io.IOException;
    import java.net.InetSocketAddress;
    import java.net.Socket;
    import java.util.Scanner;
    
    public class test2 {
    
    	public static void main(String []args) throws IOException {
    		try{
    			Socket s= new Socket("time-a.nist.gov",13);//会一直阻塞到连接到服务器，
    			//添加超时这样做
    			Socket s1=new Socket();
    			s1.connect(new InetSocketAddress("time-a.nist.gov",13),10);
    			s.setSoTimeout(10000);  //10s超时
    			//这些操作会在超时时抛出SocketTimeoutException异常
    			Scanner in = new Scanner(s.getInputStream(),"UTF-8");
    			{
    				while(in.hasNextLine()) {
    					String line=in.nextLine();
    					System.out.println(line);
    				}
    			}
    		}finally {
    			
    		}
    	}
    
    }

## 4.1.1 因特网地址 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MzI2NDcy_size_16_color_FFFFFF_t_70][]

package Section4;
    
    import java.net.InetAddress;
    import java.net.UnknownHostException;
    
    public class test3 {
    	public static void main(String []args) throws UnknownHostException{
    		if(args.length>0) {
    			String host=args[0];
    			InetAddress[] addressed=InetAddress.getAllByName(host);
    			for(InetAddress a:addressed) {
    				System.out.println(a);
    			}
    		}else {
    			InetAddress addressed=InetAddress.getLocalHost();
    			System.out.println(addressed);
    		}
    	}
    }

[命令行执行java][java]

**java.net.InetAddress:**

* * <table> 
 <tbody> 
 <tr> 
 <th>Modifier and Type</th> 
 <th>Method and Description</th> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">equals</a>(<a rel="nofollow">Object</a>&nbsp;obj)</code> 将此对象与指定对象进行比较。 </td> 
 </tr> 
 <tr> 
 <td><code>byte[]</code></td> 
 <td><code><a rel="nofollow">getAddress</a>()</code> 返回此 <code>InetAddress</code>对象的原始IP地址。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">InetAddress</a>[]</code></td> 
 <td><code><a rel="nofollow">getAllByName</a>(<a rel="nofollow">String</a>&nbsp;host)</code> 给定主机的名称，根据系统上配置的名称服务返回其IP地址数组。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">InetAddress</a></code></td> 
 <td><code><a rel="nofollow">getByAddress</a>(byte[]&nbsp;addr)</code> 给出原始IP地址的 <code>InetAddress</code>对象。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">InetAddress</a></code></td> 
 <td><code><a rel="nofollow">getByAddress</a>(<a rel="nofollow">String</a>&nbsp;host, byte[]&nbsp;addr)</code> 根据提供的主机名和IP地址创建InetAddress。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">InetAddress</a></code></td> 
 <td><code><a rel="nofollow">getByName</a>(<a rel="nofollow">String</a>&nbsp;host)</code> 确定主机名称的IP地址。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getCanonicalHostName</a>()</code> 获取此IP地址的完全限定域名。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getHostAddress</a>()</code> 返回文本显示中的IP地址字符串。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getHostName</a>()</code> 获取此IP地址的主机名。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">InetAddress</a></code></td> 
 <td><code><a rel="nofollow">getLocalHost</a>()</code> 返回本地主机的地址。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">InetAddress</a></code></td> 
 <td><code><a rel="nofollow">getLoopbackAddress</a>()</code> 返回回送地址。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">hashCode</a>()</code> 返回此IP地址的哈希码。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isAnyLocalAddress</a>()</code> 检查通配符地址中的InetAddress的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isLinkLocalAddress</a>()</code> 检查InetAddress是否是链接本地地址的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isLoopbackAddress</a>()</code> 检查InetAddress是否是一个环回地址的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isMCGlobal</a>()</code> 检查多播地址是否具有全局范围的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isMCLinkLocal</a>()</code> 检查组播地址是否具有链路范围的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isMCNodeLocal</a>()</code> 检查多播地址是否具有节点范围的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isMCOrgLocal</a>()</code> 检查组播地址是否具有组织范围的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isMCSiteLocal</a>()</code> 检查多播地址是否具有站点范围的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isMulticastAddress</a>()</code> 检查InetAddress是否是IP组播地址的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isReachable</a>(int&nbsp;timeout)</code> 测试该地址是否可达。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isReachable</a>(<a rel="nofollow">NetworkInterface</a>&nbsp;netif, int&nbsp;ttl, int&nbsp;timeout)</code> 测试该地址是否可达。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isSiteLocalAddress</a>()</code> 检查InetAddress是否是站点本地地址的实用程序。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">toString</a>()</code> 将此IP地址转换为 <code>String</code> 。 </td> 
 </tr> 
 </tbody> 
 </table>

# 4.2 实现服务器 #

## 4.2.1 服务器套接字 ##

package Section4;
    
    import java.io.*;
    import java.util.*;
    import java.net.*;
    
    public class test4 {
    
    	public static void main(String[] args) throws IOException{
    		// TODO Auto-generated method stub
    		//建立服务器套接字,建立一个负责监控端口8189的服务器
    		try(ServerSocket s = new ServerSocket(8189)){
    			//等待客户连接。直到有人通过网络发送了正确的连接请求，并以此连接到了端口上。该方法返回一个已经建立的Socket对象
    			try(Socket incoming = s.accept()){
    				InputStream inStream = incoming.getInputStream();
    				OutputStream outStream = incoming.getOutputStream();
    				//本章中，通过套接字发送文本，所以将流转换成扫描器和写入?
    				try(Scanner in = new Scanner(inStream,"UTF-8")){
    					PrintWriter out= new PrintWriter(new OutputStreamWriter(outStream,"UTF-8"),true);
    					out.println("Hello,Welcom to Roe Wang。Enter BYE to Exit");
    					//客户输入
    					boolean done=false;
    					while(!done&&in.hasNextLine()) {
    						String line = in.nextLine();
    						out.println("Echo: "+line);
    						if(line.trim().equals("BYE")) done = true;
    					}
    				}
    			}
    		}
    	}
    
    }

编译运行程序。在命令行界面中执行

telnet localhost 8189

**java.net.ServerSocket:**

* * <table> 
 <tbody> 
 <tr> 
 <th>Modifier and Type</th> 
 <th>Method and Description</th> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">Socket</a></code></td> 
 <td><code><a rel="nofollow">accept</a>()</code> 侦听要连接到此套接字并接受它。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">bind</a>(<a rel="nofollow">SocketAddress</a>&nbsp;endpoint)</code> 将 <code>ServerSocket</code>绑定到特定地址（IP地址和端口号）。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">bind</a>(<a rel="nofollow">SocketAddress</a>&nbsp;endpoint, int&nbsp;backlog)</code> 将 <code>ServerSocket</code>绑定到特定地址（IP地址和端口号）。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">close</a>()</code> 关闭此套接字。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">ServerSocketChannel</a></code></td> 
 <td><code><a rel="nofollow">getChannel</a>()</code> 返回与此套接字相关联的唯一的<a rel="nofollow"><code>ServerSocketChannel</code></a>对象（如果有）。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">InetAddress</a></code></td> 
 <td><code><a rel="nofollow">getInetAddress</a>()</code> 返回此服务器套接字的本地地址。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getLocalPort</a>()</code> 返回此套接字正在侦听的端口号。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">SocketAddress</a></code></td> 
 <td><code><a rel="nofollow">getLocalSocketAddress</a>()</code> 返回此套接字绑定到的端点的地址。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getReceiveBufferSize</a>()</code> 获取此 <code>ServerSocket</code>的 <a rel="nofollow"><code>SO_RCVBUF</code></a>选项的值，即将用于从该 <code>ServerSocket</code>接受的套接字的建议缓冲区大小。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getReuseAddress</a>()</code> 测试是否启用了 <a rel="nofollow"><code>SO_REUSEADDR</code></a> 。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getSoTimeout</a>()</code> 检索 <a rel="nofollow"><code>SO_TIMEOUT</code>的</a>设置。 </td> 
 </tr> 
 <tr> 
 <td><code>protected void</code></td> 
 <td><code><a rel="nofollow">implAccept</a>(<a rel="nofollow">Socket</a>&nbsp;s)</code> ServerSocket的子类使用这个方法来覆盖accept（）来返回自己的套接字子类。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isBound</a>()</code> 返回ServerSocket的绑定状态。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isClosed</a>()</code> 返回ServerSocket的关闭状态。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setPerformancePreferences</a>(int&nbsp;connectionTime, int&nbsp;latency, int&nbsp;bandwidth)</code> 设置此ServerSocket的性能首选项。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setReceiveBufferSize</a>(int&nbsp;size)</code> 设置从 <code>ServerSocket</code>接受的套接字的 <a rel="nofollow"><code>SO_RCVBUF</code></a>选项的默认建议值。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setReuseAddress</a>(boolean&nbsp;on)</code> 启用/禁用 <a rel="nofollow"><code>SO_REUSEADDR</code></a>套接字选项。 </td> 
 </tr> 
 <tr> 
 <td><code>static void</code></td> 
 <td><code><a rel="nofollow">setSocketFactory</a>(<a rel="nofollow">SocketImplFactory</a>&nbsp;fac)</code> 设置应用程序的服务器套接字实现工厂。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setSoTimeout</a>(int&nbsp;timeout)</code> 启用/禁用 <a rel="nofollow"><code>SO_TIMEOUT</code></a>带有指定超时，以毫秒为单位。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">toString</a>()</code> 将该套接字的实现地址和实现端口返回为 <code>String</code> 。 </td> 
 </tr> 
 </tbody> 
 </table>

## 4.2.2 为多个客户提供服务 ##

![20190625130224295.png][]

package Section4;
    
    import java.io.*;
    import java.net.*;
    import java.util.*;
    /**
    * 使用多线程
    */
    public class test5 {
    
    	public static void main(String[] args) throws IOException{
    		// TODO Auto-generated method stub
    		try(ServerSocket s=new ServerSocket(8189)){
    			int i=1;
    			while(true) {
    				Socket incoming = s.accept();
    				System.out.println("Spawing:"+i);
    				Runnable r= new ThreadedEchoHandler(incoming);
    				Thread t= new Thread(r);
    				t.start();
    				i++;
    			}
    		}
    	}
    
    }
    class ThreadedEchoHandler implements Runnable{
    	private Socket incoming;
    	public ThreadedEchoHandler(Socket incoming) {
    		this.incoming=incoming;
    	}
    
    	@Override
    	public void run() {
    		try(InputStream inStream=incoming.getInputStream();
    				OutputStream outStream=incoming.getOutputStream()){
    			Scanner in =new Scanner(inStream,"UTF-8");
    			PrintWriter out=new PrintWriter(new OutputStreamWriter(outStream,"UTF-8"),true);
    			out.println("Hello");
    			//客户输入
    			boolean done=false;
    			while(!done&&in.hasNextLine()) {
    				String line = in.nextLine();
    				out.println("Echo: "+line);
    				if(line.trim().equals("BYE")) done = true;
    			}
    		}catch( IOException e) {
    			e.printStackTrace();
    		}
    		
    	}
    }

## 4.2.3 半关闭 ##

半关闭提供了这样一种能力：套接字连接的一端可以终止其输出，同时仍旧可以接收来自另一端的数据。

package Section4;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.io.OutputStreamWriter;
    import java.io.PrintWriter;
    import java.net.ServerSocket;
    import java.net.Socket;
    import java.util.Scanner;
    
    public class test6 {
    	public static void main(String[] args) throws IOException{
    		try(ServerSocket s = new ServerSocket(8189)){
    			//等待客户连接。直到有人通过网络发送了正确的连接请求，并以此连接到了端口上。该方法返回一个已经建立的Socket对象
    			try(Socket incoming = s.accept()){
    				InputStream inStream = incoming.getInputStream();
    				OutputStream outStream = incoming.getOutputStream();
    				//本章中，通过套接字发送文本，所以将流转换成扫描器和写入?
    				try(Scanner in = new Scanner(inStream,"UTF-8")){
    					PrintWriter out= new PrintWriter(new OutputStreamWriter(outStream,"UTF-8"),true);
    					out.println("Hello,Enter BYE to Exit");
    					out.println("YiLing Song is a hundan");
    					
    					//关闭输出流
    					incoming.shutdownOutput();
    					//仍有输入流
    					while(in.hasNextLine()) {
    						//...
    					}
    				}
    			}
    		}
    	}
    }

# 4.3 可中断套接字 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MzI2NDcy_size_16_color_FFFFFF_t_70 1][]

package Section4;
 
 import java.awt.*;
 import java.awt.event.*;
 import java.util.*;
 import java.net.*;
 import java.io.*;
 import java.nio.channels.*;
 import javax.swing.*;
 
 /**
 * This program shows how to interrupt a socket channel.
 * @author Cay Horstmann
 * @version 1.04 2016-04-27
 */
 public class InterruptibleSocketTest
 {
 public static void main(String[] args)
 {
 EventQueue.invokeLater(() ->
 {
 JFrame frame = new InterruptibleSocketFrame();
 frame.setTitle("InterruptibleSocketTest");
 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 frame.setVisible(true);
 });
 }
 }
 
 class InterruptibleSocketFrame extends JFrame
 {
 private Scanner in;
 private JButton interruptibleButton;
 private JButton blockingButton;
 private JButton cancelButton;
 private JTextArea messages;
 private TestServer server;
 private Thread connectThread;
 
 public InterruptibleSocketFrame()
 {
 JPanel northPanel = new JPanel();
 add(northPanel, BorderLayout.NORTH);
 
 final int TEXT_ROWS = 20;
 final int TEXT_COLUMNS = 60;
 messages = new JTextArea(TEXT_ROWS, TEXT_COLUMNS);
 add(new JScrollPane(messages));
 
 interruptibleButton = new JButton("Interruptible");
 blockingButton = new JButton("Blocking");
 
 northPanel.add(interruptibleButton);
 northPanel.add(blockingButton);
 
 interruptibleButton.addActionListener(event ->
 {
 interruptibleButton.setEnabled(false);
 blockingButton.setEnabled(false);
 cancelButton.setEnabled(true);
 connectThread = new Thread(() ->
 {
 try
 {
 connectInterruptibly();
 }
 catch (IOException e)
 {
 messages.append("\nInterruptibleSocketTest.connectInterruptibly: " + e);
 }
 });
 connectThread.start();
 });
 
 blockingButton.addActionListener(event ->
 {
 interruptibleButton.setEnabled(false);
 blockingButton.setEnabled(false);
 cancelButton.setEnabled(true);
 connectThread = new Thread(() ->
 {
 try
 {
 connectBlocking();
 }
 catch (IOException e)
 {
 messages.append("\nInterruptibleSocketTest.connectBlocking: " + e);
 }
 });
 connectThread.start();
 });
 
 cancelButton = new JButton("Cancel");
 cancelButton.setEnabled(false);
 northPanel.add(cancelButton);
 cancelButton.addActionListener(event -> 
 {
 connectThread.interrupt();
 cancelButton.setEnabled(false);
 });
 server = new TestServer();
 new Thread(server).start();
 pack();
 }
 
 /**
 * Connects to the test server, using interruptible I/O
 */
 public void connectInterruptibly() throws IOException
 {
 messages.append("Interruptible:\n");
 try (SocketChannel channel = SocketChannel.open(new InetSocketAddress("localhost", 8189)))
 {
 in = new Scanner(channel, "UTF-8");
 while (!Thread.currentThread().isInterrupted())
 {
 messages.append("Reading ");
 if (in.hasNextLine())
 {
 String line = in.nextLine();
 messages.append(line);
 messages.append("\n");
 }
 }
 }
 finally
 {
 EventQueue.invokeLater(() ->
 {
 messages.append("Channel closed\n");
 interruptibleButton.setEnabled(true);
 blockingButton.setEnabled(true);
 });
 }
 }
 
 /**
 * Connects to the test server, using blocking I/O
 */
 public void connectBlocking() throws IOException
 {
 messages.append("Blocking:\n");
 try (Socket sock = new Socket("localhost", 8189))
 {
 in = new Scanner(sock.getInputStream(), "UTF-8");
 while (!Thread.currentThread().isInterrupted())
 {
 messages.append("Reading ");
 if (in.hasNextLine())
 {
 String line = in.nextLine();
 messages.append(line);
 messages.append("\n");
 }
 }
 }
 finally
 {
 EventQueue.invokeLater(() ->
 {
 messages.append("Socket closed\n");
 interruptibleButton.setEnabled(true);
 blockingButton.setEnabled(true);
 }); 
 }
 }
 
 /**
 * A multithreaded server that listens to port 8189 and sends numbers to the client, simulating
 * a hanging server after 10 numbers.
 */
 class TestServer implements Runnable
 {
 public void run()
 {
 try (ServerSocket s = new ServerSocket(8189))
 {
 while (true)
 {
 Socket incoming = s.accept();
 Runnable r = new TestServerHandler(incoming);
 Thread t = new Thread(r);
 t.start();
 }
 }
 catch (IOException e)
 {
 messages.append("\nTestServer.run: " + e);
 }
 }
 }
 
 /**
 * This class handles the client input for one server socket connection.
 */
 class TestServerHandler implements Runnable
 {
 private Socket incoming;
 private int counter;
 
 /**
 * Constructs a handler.
 * @param i the incoming socket
 */
 public TestServerHandler(Socket i)
 {
 incoming = i;
 }
 
 public void run()
 {
 try 
 {
 try
 {
 OutputStream outStream = incoming.getOutputStream();
 PrintWriter out = new PrintWriter(
 new OutputStreamWriter(outStream, "UTF-8"),
 true /* autoFlush */);
 while (counter < 100)
 {
 counter++;
 if (counter <= 10) out.println(counter);
 Thread.sleep(100);
 }
 }
 finally
 {
 incoming.close();
 messages.append("Closing server\n");
 }
 }
 catch (Exception e)
 {
 messages.append("\nTestServerHandler.run: " + e);
 }
 }
 }
 }

**java.net.InetSocketAddress:**

* * <table> 
 <tbody> 
 <tr> 
 <th>Modifier and Type</th> 
 <th>Method and Description</th> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">InetSocketAddress</a></code></td> 
 <td><code><a rel="nofollow">createUnresolved</a>(<a rel="nofollow">String</a>&nbsp;host, int&nbsp;port)</code> 从主机名和端口号创建未解析的套接字地址。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">equals</a>(<a rel="nofollow">Object</a>&nbsp;obj)</code> 将此对象与指定对象进行比较。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">InetAddress</a></code></td> 
 <td><code><a rel="nofollow">getAddress</a>()</code> 获得 <code>InetAddress</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getHostName</a>()</code> 获得 <code>hostname</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getHostString</a>()</code> 如果没有主机名（使用文字创建），则返回主机名或地址的String形式。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getPort</a>()</code> 获取端口号。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">hashCode</a>()</code> 返回该套接字地址的哈希码。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">isUnresolved</a>()</code> 检查地址是否已解决。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">toString</a>()</code> 构造此InetSocketAddress的字符串表示形式。 </td> 
 </tr> 
 </tbody> 
 </table>

**java.nio.channels.SocketChannel:**

* * <table> 
 <tbody> 
 <tr> 
 <th>Modifier and Type</th> 
 <th>Method and Description</th> 
 </tr> 
 <tr> 
 <td><code>abstract <a rel="nofollow">SocketChannel</a></code></td> 
 <td><code><a rel="nofollow">bind</a>(<a rel="nofollow">SocketAddress</a>&nbsp;local)</code> 将通道的套接字绑定到本地地址。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract boolean</code></td> 
 <td><code><a rel="nofollow">connect</a>(<a rel="nofollow">SocketAddress</a>&nbsp;remote)</code> 连接此通道的插座。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract boolean</code></td> 
 <td><code><a rel="nofollow">finishConnect</a>()</code> 完成连接插座通道的过程。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract <a rel="nofollow">SocketAddress</a></code></td> 
 <td><code><a rel="nofollow">getLocalAddress</a>()</code> 返回此通道的套接字所绑定的套接字地址。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract <a rel="nofollow">SocketAddress</a></code></td> 
 <td><code><a rel="nofollow">getRemoteAddress</a>()</code> 返回此通道的插座所连接的远程地址。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract boolean</code></td> 
 <td><code><a rel="nofollow">isConnected</a>()</code> 告知本频道的网络插座是否连接。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract boolean</code></td> 
 <td><code><a rel="nofollow">isConnectionPending</a>()</code> 告知此频道是否正在进行连接操作。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">SocketChannel</a></code></td> 
 <td><code><a rel="nofollow">open</a>()</code> 打开套接字通道。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">SocketChannel</a></code></td> 
 <td><code><a rel="nofollow">open</a>(<a rel="nofollow">SocketAddress</a>&nbsp;remote)</code> 打开套接字通道并将其连接到远程地址。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract int</code></td> 
 <td><code><a rel="nofollow">read</a>(<a rel="nofollow">ByteBuffer</a>&nbsp;dst)</code> 从该通道读取到给定缓冲区的字节序列。 </td> 
 </tr> 
 <tr> 
 <td><code>long</code></td> 
 <td><code><a rel="nofollow">read</a>(<a rel="nofollow">ByteBuffer</a>[]&nbsp;dsts)</code> 从该通道读取到给定缓冲区的字节序列。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract long</code></td> 
 <td><code><a rel="nofollow">read</a>(<a rel="nofollow">ByteBuffer</a>[]&nbsp;dsts, int&nbsp;offset, int&nbsp;length)</code> 从该通道读取字节序列到给定缓冲区的子序列中。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract &lt;T&gt;&nbsp;<a rel="nofollow">SocketChannel</a></code></td> 
 <td><code><a rel="nofollow">setOption</a>(<a rel="nofollow">SocketOption</a>&lt;T&gt;&nbsp;name, T&nbsp;value)</code> 设置套接字选项的值。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract <a rel="nofollow">SocketChannel</a></code></td> 
 <td><code><a rel="nofollow">shutdownInput</a>()</code> 关闭连接进行阅读，不关闭频道。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract <a rel="nofollow">SocketChannel</a></code></td> 
 <td><code><a rel="nofollow">shutdownOutput</a>()</code> 关闭连接以进行写入，而不关闭通道。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract <a rel="nofollow">Socket</a></code></td> 
 <td><code><a rel="nofollow">socket</a>()</code> 检索与此通道相关联的套接字。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">validOps</a>()</code> 返回确定此频道支持的操作的操作集。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract int</code></td> 
 <td><code><a rel="nofollow">write</a>(<a rel="nofollow">ByteBuffer</a>&nbsp;src)</code> 从给定的缓冲区向该通道写入一个字节序列。 </td> 
 </tr> 
 <tr> 
 <td><code>long</code></td> 
 <td><code><a rel="nofollow">write</a>(<a rel="nofollow">ByteBuffer</a>[]&nbsp;srcs)</code> 从给定的缓冲区向该通道写入一系列字节。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract long</code></td> 
 <td><code><a rel="nofollow">write</a>(<a rel="nofollow">ByteBuffer</a>[]&nbsp;srcs, int&nbsp;offset, int&nbsp;length)</code> 从给定缓冲区的子序列将一个字节序列写入该通道。 </td> 
 </tr> 
 </tbody> 
 </table>

# 4.4 获取Web数 #

![20190625205736229.png][]

## 4.4.1 URL和URI ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MzI2NDcy_size_16_color_FFFFFF_t_70 2][]

## ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MzI2NDcy_size_16_color_FFFFFF_t_70 3][] ##

## ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MzI2NDcy_size_16_color_FFFFFF_t_70 4][] ##

## 4.4.2 使用URLConnection获取信息 ##

如果想从某个Web资源获取更多的信息，那么应该使用URLConnection类，通过它能够得到比基本的URL更多的控制功能

![20190625191839104.png][]

## ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MzI2NDcy_size_16_color_FFFFFF_t_70 5][] ##

![20190625192007676.png][]

JAVA提供了6个常用的方法用来访问常用的信息头类型的值，并在需要的时候把他们转换为数字类型

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MzI2NDcy_size_16_color_FFFFFF_t_70 6][]

package Section4;
 
 import java.util.*;
 import java.nio.*;
 import java.nio.charset.StandardCharsets;
 import java.net.*;
 import java.io.*;
 
 public class test8 {
 
 	public static void main(String[] args) {
 		// TODO Auto-generated method stub
 		try {
 			String urlName;
 			urlName="http://horst.com";
 			URL url=new URL(urlName);
 			//获得URLConnection对象
 			URLConnection connection = url.openConnection();
 			//set方法设置请求属性
 			/*
 			 * 访问一个有密码保护的Web页，这样做。
 			String name="a";
 			String password="b";
 			String input =name+":"+password;
 			Base64.Encoder encoder = Base64.getEncoder();
 			String encoding =encoder.encodeToString(input.getBytes(StandardCharsets.UTF_8));
 			connection.setRequestProperty("Authorization", "Basic"+encoding);
 			*/
 			//连接远程资源
 			connection.connect();
 			//查询头信息，还有其它的函数
 			Map<String,List<String>> headers = connection.getHeaderFields();
 			for(Map.Entry<String, List<String>> entry:headers.entrySet()) {
 				String key=entry.getKey();
 				for(String value:entry.getValue()) {
 					System.out.println(key+": "+value);
 				}
 			}
 			//没有哪种方法可以返回字段的数量，必须反复调用下列函数知道返回null为止
 			String value=connection.getHeaderField(3); //n从1开始，第三个值，没有返回null
 			String key=connection.getHeaderFieldKey(3); //n从一开始，第三个值，没有返回null
 			System.out.println("()()"+value+" "+key);	
 			//查询各标准字段
 			System.out.println("----------");
 	 System.out.println("getContentType: " + connection.getContentType());
 	 System.out.println("getContentLength: " + connection.getContentLength());
 	 System.out.println("getContentEncoding: " + connection.getContentEncoding());
 	 System.out.println("getDate: " + connection.getDate());
 	 System.out.println("getExpiration: " + connection.getExpiration());
 	 System.out.println("getLastModifed: " + connection.getLastModified());
 	 System.out.println("----------");
 	 //访问资源数据
 	 String encoding = connection.getContentEncoding();
 	 if(encoding==null) encoding="UTF-8";
 	 try(Scanner in = new Scanner(connection.getInputStream(),encoding)){
 	 	for(int n=1;in.hasNextLine()&&n<=10;n++) {
 	 		System.out.println(in.nextLine());
 	 	}
 	 }
 			
 		}catch(Exception e) {
 			e.printStackTrace();
 		}
 	}
 
 }

**java.net.URL:**

* * <table> 
 <tbody> 
 <tr> 
 <th>Modifier and Type</th> 
 <th>Method and Description</th> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">equals</a>(<a rel="nofollow">Object</a>&nbsp;obj)</code> 将此URL与其他对象进行比较。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getAuthority</a>()</code> 获取此的授权部分 <code>URL</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">Object</a></code></td> 
 <td><code><a rel="nofollow">getContent</a>()</code> 获取此URL的内容。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">Object</a></code></td> 
 <td><code><a rel="nofollow">getContent</a>(<a rel="nofollow">类</a>[]&nbsp;classes)</code> 获取此URL的内容。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getDefaultPort</a>()</code> 获取与此 <code>URL</code>的协议的默认端口号。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getFile</a>()</code> 获取此 <code>URL</code>的文件名。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getHost</a>()</code> 获取此 <code>URL</code>的主机名（如适用）。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getPath</a>()</code> 获取此 <code>URL</code>的路径部分。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getPort</a>()</code> 获取此 <code>URL</code>的端口号。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getProtocol</a>()</code> 获取此 <code>URL</code>的协议名称。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getQuery</a>()</code> 获取此 <code>URL</code>的查询部分。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getRef</a>()</code> 获取此的锚定（也称为“参考”） <code>URL</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getUserInfo</a>()</code> 获取该 <code>URL</code>的userInfo部分。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">hashCode</a>()</code> 创建适合哈希表索引的整数。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">URLConnection</a></code></td> 
 <td><code><a rel="nofollow">openConnection</a>()</code> 返回一个<a rel="nofollow"><code>URLConnection</code></a>实例，表示与URL引用的远程对象的<code>URL</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">URLConnection</a></code></td> 
 <td><code><a rel="nofollow">openConnection</a>(<a rel="nofollow">Proxy</a>&nbsp;proxy)</code> 与<a rel="nofollow"><code>openConnection()</code></a>相同，但连接将通过指定的代理进行; 不支持代理的协议处理程序将忽略代理参数并进行正常连接。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">InputStream</a></code></td> 
 <td><code><a rel="nofollow">openStream</a>()</code> 打开与此 <code>URL</code> ，并返回一个 <code>InputStream</code> ，以便从该连接读取。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">sameFile</a>(<a rel="nofollow">URL</a>&nbsp;other)</code> 比较两个URL，不包括片段组件。 </td> 
 </tr> 
 <tr> 
 <td><code>static void</code></td> 
 <td><code><a rel="nofollow">setURLStreamHandlerFactory</a>(<a rel="nofollow">URLStreamHandlerFactory</a>&nbsp;fac)</code> 设置应用程序的 <code>URLStreamHandlerFactory</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">toExternalForm</a>()</code> 构造这个 <code>URL</code>的字符串 <code>URL</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">toString</a>()</code> 构造此 <code>URL</code>的字符串表示 <code>URL</code> 。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">URI</a></code></td> 
 <td><code><a rel="nofollow">toURI</a>()</code> 返回<a rel="nofollow">相当于</a>此URL的<a rel="nofollow"><code>URI</code></a> 。 </td> 
 </tr> 
 </tbody> 
 </table>

**java.net.URLConnection:**

* * <table> 
 <tbody> 
 <tr> 
 <th>Modifier and Type</th> 
 <th>Method and Description</th> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">addRequestProperty</a>(<a rel="nofollow">String</a>&nbsp;key, <a rel="nofollow">String</a>&nbsp;value)</code> 添加由键值对指定的一般请求属性。 </td> 
 </tr> 
 <tr> 
 <td><code>abstract void</code></td> 
 <td><code><a rel="nofollow">connect</a>()</code> 打开与此URL引用的资源的通信链接，如果此类连接尚未建立。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getAllowUserInteraction</a>()</code> 返回此对象的 <code>allowUserInteraction</code>字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getConnectTimeout</a>()</code> 返回连接超时的设置。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">Object</a></code></td> 
 <td><code><a rel="nofollow">getContent</a>()</code> 检索此URL连接的内容。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">Object</a></code></td> 
 <td><code><a rel="nofollow">getContent</a>(<a rel="nofollow">类</a>[]&nbsp;classes)</code> 检索此URL连接的内容。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getContentEncoding</a>()</code> 返回 <code>content-encoding</code>标题字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getContentLength</a>()</code> 返回 <code>content-length</code>标题字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>long</code></td> 
 <td><code><a rel="nofollow">getContentLengthLong</a>()</code> 返回 <code>content-length</code>标头字段的值为long。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getContentType</a>()</code> 返回 <code>content-type</code>标题字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>long</code></td> 
 <td><code><a rel="nofollow">getDate</a>()</code> 返回 <code>date</code>标题字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>static boolean</code></td> 
 <td><code><a rel="nofollow">getDefaultAllowUserInteraction</a>()</code> 返回 <code>allowUserInteraction</code>字段的默认值。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getDefaultRequestProperty</a>(<a rel="nofollow">String</a>&nbsp;key)</code>已弃用 在获得适当的URLConnection实例之后，应该使用实例特定的getRequestProperty方法。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getDefaultUseCaches</a>()</code> 返回默认值为 <code>URLConnection</code>的 <code>useCaches</code>标志。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getDoInput</a>()</code> 返回此 <code>URLConnection</code>的 <code>doInput</code>标志的值。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getDoOutput</a>()</code> 返回此 <code>URLConnection</code>的 <code>doOutput</code>标志的值。 </td> 
 </tr> 
 <tr> 
 <td><code>long</code></td> 
 <td><code><a rel="nofollow">getExpiration</a>()</code> 返回 <code>expires</code>标题字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">FileNameMap</a></code></td> 
 <td><code><a rel="nofollow">getFileNameMap</a>()</code> 从数据文件加载文件名映射（模拟）。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getHeaderField</a>(int&nbsp;n)</code> 返回的值 <code>n</code> th头字段。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getHeaderField</a>(<a rel="nofollow">String</a>&nbsp;name)</code> 返回命名头字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>long</code></td> 
 <td><code><a rel="nofollow">getHeaderFieldDate</a>(<a rel="nofollow">String</a>&nbsp;name, long&nbsp;Default)</code> 返回以日期解析的命名字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getHeaderFieldInt</a>(<a rel="nofollow">String</a>&nbsp;name, int&nbsp;Default)</code> 返回被解析为命名字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getHeaderFieldKey</a>(int&nbsp;n)</code> 返回的关键 <code>n</code> th头字段。 </td> 
 </tr> 
 <tr> 
 <td><code>long</code></td> 
 <td><code><a rel="nofollow">getHeaderFieldLong</a>(<a rel="nofollow">String</a>&nbsp;name, long&nbsp;Default)</code> 返回被解析为命名字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">Map</a>&lt;<a rel="nofollow">String</a>,<a rel="nofollow">List</a>&lt;<a rel="nofollow">String</a>&gt;&gt;</code></td> 
 <td><code><a rel="nofollow">getHeaderFields</a>()</code> 返回不可修改的标题字段的映射。 </td> 
 </tr> 
 <tr> 
 <td><code>long</code></td> 
 <td><code><a rel="nofollow">getIfModifiedSince</a>()</code> 返回此对象的 <code>ifModifiedSince</code>字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">InputStream</a></code></td> 
 <td><code><a rel="nofollow">getInputStream</a>()</code> 返回从此打开的连接读取的输入流。 </td> 
 </tr> 
 <tr> 
 <td><code>long</code></td> 
 <td><code><a rel="nofollow">getLastModified</a>()</code> 返回 <code>last-modified</code>标题字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">OutputStream</a></code></td> 
 <td><code><a rel="nofollow">getOutputStream</a>()</code> 返回写入此连接的输出流。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">Permission</a></code></td> 
 <td><code><a rel="nofollow">getPermission</a>()</code> 返回一个权限对象，该对象表示创建此对象所表示的连接所需的权限。 </td> 
 </tr> 
 <tr> 
 <td><code>int</code></td> 
 <td><code><a rel="nofollow">getReadTimeout</a>()</code> 返回读取超时的设置。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">Map</a>&lt;<a rel="nofollow">String</a>,<a rel="nofollow">List</a>&lt;<a rel="nofollow">String</a>&gt;&gt;</code></td> 
 <td><code><a rel="nofollow">getRequestProperties</a>()</code> 返回此连接的一般请求属性的不可修改映射。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">getRequestProperty</a>(<a rel="nofollow">String</a>&nbsp;key)</code> 返回此连接的命名的常规请求属性的值。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">URL</a></code></td> 
 <td><code><a rel="nofollow">getURL</a>()</code> 返回此 <code>URLConnection</code>的 <code>URL</code>字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>boolean</code></td> 
 <td><code><a rel="nofollow">getUseCaches</a>()</code> 返回此 <code>URLConnection</code>的 <code>useCaches</code>字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">guessContentTypeFromName</a>(<a rel="nofollow">String</a>&nbsp;fname)</code> 根据URL的指定“文件”组件，尝试确定对象的内容类型。 </td> 
 </tr> 
 <tr> 
 <td><code>static <a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">guessContentTypeFromStream</a>(<a rel="nofollow">InputStream</a>&nbsp;is)</code> 根据输入流开头的字符，尝试确定输入流的类型。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setAllowUserInteraction</a>(boolean&nbsp;allowuserinteraction)</code> 设置这个 <code>URLConnection</code>的 <code>allowUserInteraction</code>字段的值。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setConnectTimeout</a>(int&nbsp;timeout)</code> 设置打开与此URLConnection引用的资源的通信链接时使用的指定超时值（以毫秒为单位）。 </td> 
 </tr> 
 <tr> 
 <td><code>static void</code></td> 
 <td><code><a rel="nofollow">setContentHandlerFactory</a>(<a rel="nofollow">ContentHandlerFactory</a>&nbsp;fac)</code> 设置应用 <code>ContentHandlerFactory</code>的ContentHandlerFactory。 </td> 
 </tr> 
 <tr> 
 <td><code>static void</code></td> 
 <td><code><a rel="nofollow">setDefaultAllowUserInteraction</a>(boolean&nbsp;defaultallowuserinteraction)</code> 将所有将来的 <code>URLConnection</code>对象的 <code>allowUserInteraction</code>字段的默认值设置为指定的值。 </td> 
 </tr> 
 <tr> 
 <td><code>static void</code></td> 
 <td><code><a rel="nofollow">setDefaultRequestProperty</a>(<a rel="nofollow">String</a>&nbsp;key, <a rel="nofollow">String</a>&nbsp;value)</code>已弃用 在获得适当的URLConnection实例之后，应该使用实例特定的setRequestProperty方法。 调用此方法将不起作用。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setDefaultUseCaches</a>(boolean&nbsp;defaultusecaches)</code> 将 <code>useCaches</code>字段的默认值设置为指定值。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setDoInput</a>(boolean&nbsp;doinput)</code> 设置的值 <code>doInput</code>领域本 <code>URLConnection</code>指定值。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setDoOutput</a>(boolean&nbsp;dooutput)</code> 设置的值 <code>doOutput</code>领域本 <code>URLConnection</code>指定值。 </td> 
 </tr> 
 <tr> 
 <td><code>static void</code></td> 
 <td><code><a rel="nofollow">setFileNameMap</a>(<a rel="nofollow">FileNameMap</a>&nbsp;map)</code> 设置FileNameMap。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setIfModifiedSince</a>(long&nbsp;ifmodifiedsince)</code> 设置的值 <code>ifModifiedSince</code>这个领域 <code>URLConnection</code>到指定值。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setReadTimeout</a>(int&nbsp;timeout)</code> 将读取超时设置为指定的超时时间，以毫秒为单位。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setRequestProperty</a>(<a rel="nofollow">String</a>&nbsp;key, <a rel="nofollow">String</a>&nbsp;value)</code> 设置一般请求属性。 </td> 
 </tr> 
 <tr> 
 <td><code>void</code></td> 
 <td><code><a rel="nofollow">setUseCaches</a>(boolean&nbsp;usecaches)</code> 设置的值 <code>useCaches</code>这个领域 <code>URLConnection</code>到指定值。 </td> 
 </tr> 
 <tr> 
 <td><code><a rel="nofollow">String</a></code></td> 
 <td><code><a rel="nofollow">toString</a>()</code> 返回 <code>String</code>此URL连接的表示。 </td> 
 </tr> 
 </tbody> 
 </table>

## 4.4.3 提交表单数据 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5MzI2NDcy_size_16_color_FFFFFF_t_70 7][]

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![20190625205158999.png][]

![2019062520523283.png][]

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package post;
 
 import java.io.*;
 import java.net.*;
 import java.nio.file.*;
 import java.util.*;
 
 /**
 * This program demonstrates how to use the URLConnection class for a POST request.
 * @version 1.40 2016-04-24
 * @author Cay Horstmann
 */
 public class PostTest
 {
 public static void main(String[] args) throws IOException
 {
 String propsFilename = args.length > 0 ? args[0] : "post/post.properties"; 
 Properties props = new Properties();
 try (InputStream in = Files.newInputStream(Paths.get(propsFilename)))
 {
 props.load(in);
 }
 String urlString = props.remove("url").toString();
 Object userAgent = props.remove("User-Agent");
 Object redirects = props.remove("redirects");
 CookieHandler.setDefault(new CookieManager(null, CookiePolicy.ACCEPT_ALL));
 String result = doPost(new URL(urlString), props, 
 userAgent == null ? null : userAgent.toString(), 
 redirects == null ? -1 : Integer.parseInt(redirects.toString()));
 System.out.println(result);
 } 
 
 /**
 * Do an HTTP POST.
 * @param url the URL to post to
 * @param nameValuePairs the query parameters
 * @param userAgent the user agent to use, or null for the default user agent
 * @param redirects the number of redirects to follow manually, or -1 for automatic redirects
 * @return the data returned from the server
 */
 public static String doPost(URL url, Map<Object, Object> nameValuePairs, String userAgent, int redirects)
 throws IOException
 { 
 HttpURLConnection connection = (HttpURLConnection) url.openConnection();
 if (userAgent != null)
 connection.setRequestProperty("User-Agent", userAgent);
 
 if (redirects >= 0)
 connection.setInstanceFollowRedirects(false);
 
 connection.setDoOutput(true);
 
 try (PrintWriter out = new PrintWriter(connection.getOutputStream()))
 {
 boolean first = true;
 for (Map.Entry<Object, Object> pair : nameValuePairs.entrySet())
 {
 if (first) first = false;
 else out.print('&');
 String name = pair.getKey().toString();
 String value = pair.getValue().toString();
 out.print(name);
 out.print('=');
 out.print(URLEncoder.encode(value, "UTF-8"));
 }
 } 
 String encoding = connection.getContentEncoding();
 if (encoding == null) encoding = "UTF-8";
 
 if (redirects > 0)
 {
 int responseCode = connection.getResponseCode();
 if (responseCode == HttpURLConnection.HTTP_MOVED_PERM 
 || responseCode == HttpURLConnection.HTTP_MOVED_TEMP
 || responseCode == HttpURLConnection.HTTP_SEE_OTHER) 
 {
 String location = connection.getHeaderField("Location");
 if (location != null)
 {
 URL base = connection.getURL();
 connection.disconnect();
 return doPost(new URL(base, location), nameValuePairs, userAgent, redirects - 1);
 }
 
 }
 }
 else if (redirects == 0)
 {
 throw new IOException("Too many redirects");
 }
 
 StringBuilder response = new StringBuilder();
 try (Scanner in = new Scanner(connection.getInputStream(), encoding))
 {
 while (in.hasNextLine())
 {
 response.append(in.nextLine());
 response.append("\n");
 } 
 }
 catch (IOException e)
 {
 InputStream err = connection.getErrorStream();
 if (err == null) throw e;
 try (Scanner in = new Scanner(err))
 {
 response.append(in.nextLine());
 response.append("\n");
 }
 }
 
 return response.toString();
 }
 }

# 4.5 发送Mail #

一旦连接到服务器，就可以发送一个邮件报头（采用SMTP格式，该格式很容易生成）。紧随其后的是邮件信息

package Section4;
    
    import java.io.IOException;
    import java.net.*;
    import java.io.*;
    
    public class test7 {
    	public static void main(String []args) throws UnknownHostException, IOException{
    		Socket s = new Socket("mail.qq.com",25);
    		PrintWriter out= new PrintWriter(s.getOutputStream());
    		String message =                   "HELO sending host\r\n"
    				+ "MAIL FROM: 1984852655@qq.com\r\n"
    				+ "RCPT TO: 2872718690@qq.com\r\n"
    				+ "DATA\r\n"
    				+ "Subject: Hello World\r\n"
    				+ "\r\n"
    				+"Hello May.do you get this?Please call me later.\r\n"
    				+ ".\r\n"
    				+ "QUIT\r\n";
    		out.print(message);
    		
    	}
    }

许多服务器都内置了检查功能，并且只接收来自授信用户的请求。所以，上面代码会

Exception in thread "main" java.net.ConnectException: Connection timed out: connect

使用下方代码可以顺利发送邮件：

package Section4;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.Properties;
    
    
    import javax.mail.*;
    import javax.mail.internet.*;
    import javax.activation.*;
    
    /**
     * Servlet implementation class SendEmail
     */
    
    public class MailTest {
    	private static final long serialVersionUID = 1L;
           
       
    	public static void main(String[] args){
    		// TODO Auto-generated method stub
    	
    	
            Properties props = new Properties();
            // 表示SMTP发送邮件，必须进行身份验证
            props.put("mail.smtp.auth", "true");
            //此处填写SMTP服务器
            props.put("mail.smtp.host", "smtp.qq.com");
            //端口号，QQ邮箱给出了两个端口，但是另一个我一直使用不了，所以就给出这一个587
            props.put("mail.smtp.port", "25");
            // 此处填写你的账号
            props.put("mail.user","1984852655@qq.com");
            // 此处的密码就是前面说的16位STMP口令
            props.put("mail.password","segpcfwwzsuugjjc");
    
            // 构建授权信息，用于进行SMTP进行身份验证
            Authenticator authenticator = new Authenticator() {
    
                protected PasswordAuthentication getPasswordAuthentication() {
                    // 用户名、密码
                    String userName = props.getProperty("mail.user");
                    String password = props.getProperty("mail.password");
                    return new PasswordAuthentication(userName, password);
                }
            };
            // 使用环境属性和授权信息，创建邮件会话
            Session mailSession = Session.getInstance(props, authenticator);
            // 创建邮件消息
            MimeMessage message = new MimeMessage(mailSession);
            // 设置发件人
            InternetAddress form;
    		try {
    			form = new InternetAddress(
    			        props.getProperty("mail.user"));
    		
    			message.setFrom(form);
    		
    
            // 设置收件人的邮箱
            InternetAddress to = new InternetAddress("2872718690@qq.com");
            message.setRecipient(Message.RecipientType.TO, to);
    
            // 设置邮件标题
            message.setSubject("测试邮件");
    
            // 设置邮件的内容体
            message.setContent("这是一封测试邮件", "text/html;charset=UTF-8");
    
            // 最后当然就是发送邮件啦
            Transport.send(message);
    	} catch (AddressException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}catch (MessagingException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}	
    	}
    
    	
    
    }

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[java]: https://www.cnblogs.com/liushuncheng/p/6528501.html
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