Netty之传输POJO(使用Java自带的序列化方式)

小灰灰 2022-07-12 23:16 260阅读 0赞

1、**使用Netty传输POJO对象，重点在于对象的序列化。**序列化的对象通过TCP进行网络传输，结合Netty提供的对象编解码器，可以做到远程传输对象。**首先Java需要序列化的对象，需要实现java.io.Serializable接口.**

2、工程目录

2.1 项目的目录结构

![20161215162945574][]

2.2  关于Request和Response的讲解

Request是对于，客户端向服务端的请求信息的封装；Response是对于，服务端向客户端响应信息的封装。

3、使用Netty提供的对象编解码器

3.1 服务端编解码器的配置

![20161215165714805][]

3.2 客户端编解码器的配置

![20161215165729059][]

3.3 加入对象编解码后，可以直接发送对象

![20161215170216987][]

4、服务端代码

import io.netty.bootstrap.ServerBootstrap;
    import io.netty.channel.ChannelFuture;
    import io.netty.channel.ChannelInitializer;
    import io.netty.channel.ChannelOption;
    import io.netty.channel.EventLoopGroup;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.SocketChannel;
    import io.netty.channel.socket.nio.NioServerSocketChannel;
    import io.netty.handler.codec.serialization.ClassResolvers;
    import io.netty.handler.codec.serialization.ObjectDecoder;
    import io.netty.handler.codec.serialization.ObjectEncoder;
    import io.netty.handler.logging.LogLevel;
    import io.netty.handler.logging.LoggingHandler;
    
    public class Server {
    
    	public Server() {
    	}
    
    	public void bind(int port) throws Exception {
    		// 配置NIO线程组
    		EventLoopGroup bossGroup = new NioEventLoopGroup();
    		EventLoopGroup workerGroup = new NioEventLoopGroup();
    		try {
    			// 服务器辅助启动类配置
    			ServerBootstrap b = new ServerBootstrap();
    			b.group(bossGroup, workerGroup)
    					.channel(NioServerSocketChannel.class)
    					.handler(new LoggingHandler(LogLevel.INFO))
    					.childHandler(new ChildChannelHandler())//
    					.option(ChannelOption.SO_BACKLOG, 1024) // 设置tcp缓冲区 // (5)
    					.childOption(ChannelOption.SO_KEEPALIVE, true); // (6)
    			// 绑定端口 同步等待绑定成功
    			ChannelFuture f = b.bind(port).sync(); // (7)
    			// 等到服务端监听端口关闭
    			f.channel().closeFuture().sync();
    		} finally {
    			// 优雅释放线程资源
    			workerGroup.shutdownGracefully();
    			bossGroup.shutdownGracefully();
    		}
    	}
    
    	/**
    	 * 网络事件处理器
    	 */
    	private class ChildChannelHandler extends ChannelInitializer<SocketChannel> {
    		@Override
    		protected void initChannel(SocketChannel ch) throws Exception {
    			// 添加对象解码器 负责对序列化POJO对象进行解码 设置对象序列化最大长度为1M 防止内存溢出
    			// 设置线程安全的WeakReferenceMap对类加载器进行缓存 支持多线程并发访问 防止内存溢出
    			ch.pipeline().addLast(
    					new ObjectDecoder(1024 * 1024, ClassResolvers
    							.weakCachingConcurrentResolver(this.getClass()
    									.getClassLoader())));
    			// 添加对象编码器 在服务器对外发送消息的时候自动将实现序列化的POJO对象编码
    			ch.pipeline().addLast(new ObjectEncoder());
    			// 处理网络IO
    			ch.pipeline().addLast(new ServerHandler());
    		}
    	}
    
    	public static void main(String[] args) throws Exception {
    		new Server().bind(9999);
    	}
    }

5、服务端处理器代码

import io.netty.channel.ChannelHandlerAdapter;
    import io.netty.channel.ChannelHandlerContext;
    
    public class ServerHandler extends ChannelHandlerAdapter {
    	// 用于获取客户端发送的信息
    	@Override
    	public void channelRead(ChannelHandlerContext ctx, Object msg)
    			throws Exception {
    		// 用于获取客户端发来的数据信息
    		Request body = (Request) msg;
    		System.out.println("Server接受的客户端的信息 :" + body.toString());
    
    		// 会写数据给客户端
    		Response response = new Response(Integer.parseInt(body.getUrl()),
    				"xiaoming");
    		// 当服务端完成写操作后，关闭与客户端的连接
    		ctx.writeAndFlush(response);
    		// .addListener(ChannelFutureListener.CLOSE);
    
    		// 当有写操作时，不需要手动释放msg的引用
    		// 当只有读操作时，才需要手动释放msg的引用
    	}
    
    	@Override
    	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
    			throws Exception {
    		// cause.printStackTrace();
    		ctx.close();
    	}
    }

6、客户端代码

import io.netty.bootstrap.Bootstrap;
    import io.netty.channel.ChannelFuture;
    import io.netty.channel.ChannelInitializer;
    import io.netty.channel.ChannelOption;
    import io.netty.channel.EventLoopGroup;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.SocketChannel;
    import io.netty.channel.socket.nio.NioSocketChannel;
    import io.netty.handler.codec.serialization.ClassResolvers;
    import io.netty.handler.codec.serialization.ObjectDecoder;
    import io.netty.handler.codec.serialization.ObjectEncoder;
    
    public class Client {
    
    	/**
    	 * 连接服务器
    	 * 
    	 * @param port
    	 * @param host
    	 * @throws Exception
    	 */
    	public void connect(int port, String host) throws Exception {
    		// 配置客户端NIO线程组
    		EventLoopGroup group = new NioEventLoopGroup();
    		try {
    			// 客户端辅助启动类 对客户端配置
    			Bootstrap b = new Bootstrap();
    			b.group(group)//
    					.channel(NioSocketChannel.class)//
    					.option(ChannelOption.TCP_NODELAY, true)//
    					.handler(new MyChannelHandler());//
    			// 异步链接服务器 同步等待链接成功
    			ChannelFuture f = b.connect(host, port).sync();
    
    			// 等待链接关闭
    			f.channel().closeFuture().sync();
    
    		} finally {
    			group.shutdownGracefully();
    			System.out.println("客户端优雅的释放了线程资源...");
    		}
    
    	}
    
    	/**
    	 * 网络事件处理器
    	 */
    	private class MyChannelHandler extends ChannelInitializer<SocketChannel> {
    		@Override
    		protected void initChannel(SocketChannel ch) throws Exception {
    			// 添加自定义的编码器和解码器
    			// 添加POJO对象解码器 禁止缓存类加载器
    			ch.pipeline().addLast(
    					new ObjectDecoder(1024, ClassResolvers.cacheDisabled(this
    							.getClass().getClassLoader())));
    			// 设置发送消息编码器
    			ch.pipeline().addLast(new ObjectEncoder());
    			// 处理网络IO
    			ch.pipeline().addLast(new ClientHandler());// 处理网络IO
    		}
    
    	}
    
    	public static void main(String[] args) throws Exception {
    		new Client().connect(9999, "127.0.0.1");
    
    	}
    
    }

7、客户端处理器代码

import io.netty.channel.ChannelHandlerAdapter;
    import io.netty.channel.ChannelHandlerContext;
    import io.netty.util.ReferenceCountUtil;
    
    //用于读取客户端发来的信息
    public class ClientHandler extends ChannelHandlerAdapter {
    
    	// 客户端与服务端，连接成功的售后
    	@Override
    	public void channelActive(ChannelHandlerContext ctx) throws Exception {
    		// 发送消息
    		Request request1 = new Request("666");
    		Request request2 = new Request("777");
    		Request request3 = new Request("888");
    		ctx.writeAndFlush(request1);
    		ctx.writeAndFlush(request2);
    		Thread.sleep(2000);
    		ctx.writeAndFlush(request3);
    	}
    
    	// 只是读数据，没有写数据的话
    	// 需要自己手动的释放的消息
    	@Override
    	public void channelRead(ChannelHandlerContext ctx, Object msg)
    			throws Exception {
    		try {
    			Response response = (Response) msg;
    			System.out.println(response);
    
    		} finally {
    			ReferenceCountUtil.release(msg);
    		}
    	}
    
    	@Override
    	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
    			throws Exception {
    		ctx.close();
    	}
    
    }

8、Request请求信息(要实现 Serializable 接口)

import java.io.Serializable;
    
    public class Request implements Serializable {
    	/**
    	 * 
    	 */
    	private static final long serialVersionUID = -7033707301911915196L;
    	private String url;
    
    	public Request() {
    	}
    
    	public Request(String url) {
    		this.url = url;
    	}
    
    	public String getUrl() {
    		return url;
    	}
    
    	public void setUrl(String url) {
    		this.url = url;
    	}
    
    	@Override
    	public String toString() {
    		return "Request [url=" + url + "]";
    	}
    
    }

9、Response请求信息(要实现 Serializable 接口)

import java.io.Serializable;
    
    public class Response implements Serializable {
    	/**
    	 * 
    	 */
    	private static final long serialVersionUID = -6236340795725143988L;
    	private int age;
    	private String name;
    
    	public Response() {
    	}
    
    	public Response(int age, String name) {
    		this.age = age;
    		this.name = name;
    	}
    
    	public int getAge() {
    		return age;
    	}
    
    	public void setAge(int age) {
    		this.age = age;
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		this.name = name;
    	}
    
    	@Override
    	public String toString() {
    		return "Response [age=" + age + ", name=" + name + "]";
    	}
    
    }

[20161215162945574]: /images/20220713/372bcc2759854e9f9d99e3c3fc9da8be.png
[20161215165714805]: /images/20220713/40dd70892adb4e7a949be42802cb693d.png
[20161215165729059]: /images/20220713/334b285a1ab14033835f21b06a1a0c4b.png
[20161215170216987]: /images/20220713/852de871338a40eca37028e129ca35dd.png