Java IO 之BIO讲解

短命女 2021-11-19 13:28 230阅读 0赞

### nio介绍 ###

Java BIO是java1.4之前唯一的IO逻辑,在客户端通过socket向服务端传输数据,服务端监听端口,由于传统io读数据的时候,如果数据没有传达,IO会一直等待输入传入,当有请求过来的时候,新起一条线程对数据进行等待,处理.导致每一个链接都对应着服务器的一个线程。在1.4之后出现了NIO，但是不是很稳定，到jdk1.8官方说明已经稳定了，在这一章节主要讲BIO，下面博客会讲解NIO，AIO

### 代码实现 ###

package com.zrkj.admin.api.vo;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.net.ServerSocket;
    import java.net.Socket;
    
    /**
     * @author hawk
     */
    public class BIO {
    
    
        public static void main(String[] args) throws IOException, InterruptedException {
            ServerSocket serverSocket = new ServerSocket(1111);
            new Thread(new Runnable() {
                @Override
                public void run() {
                    while (true) {
                        try {
                            Socket socket = serverSocket.accept();//BIO:服务端接收到链接,新起线程等待读数据并处理数据
                            new Thread(new Runnable() {
                                @Override
                                public void run() {
                                    try {
                                        InputStream inputStream = socket.getInputStream();
                                        System.out.println("开始等待...." + "当前线程:" + Thread.currentThread().getName() + Thread.currentThread().getId());
                                        int count = 0;
                                        while (count == 0) {
                                            count = inputStream.available();
                                        }
                                        byte[] a = new byte[count];
                                        while (inputStream.read(a) > 0) {
                                            System.out.println("receive:" + new String(a) + "当前线程:" + Thread.currentThread().getName() + Thread.currentThread().getId());
                                        }
                                        inputStream.close();
                                    } catch (Exception e) {
                                        e.printStackTrace();
                                    }
                                }
                            }, "接收到消息新起线程-").start();
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                }
            }, "服务器接收线程").start();
            Socket socketClient = new Socket("127.0.0.1", 1111);
            Thread.sleep(3000);
            Socket socketClient2 = new Socket("127.0.0.1", 1111);
            new Thread(new Runnable() {//新起线程标识客户端
                @Override
                public void run() {
                    try {
                        String a = "message";
                        OutputStream outputStream = socketClient.getOutputStream();
                        System.out.println("send:" + a + "当前线程:" + Thread.currentThread().getName() + Thread.currentThread().getId());
                        outputStream.write(a.getBytes());
                        outputStream.flush();
                        outputStream.close();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }, "客户端发送线程1-").start();
            Thread.sleep(3000);
            new Thread(new Runnable() {//新起线程标识客户端
                @Override
                public void run() {
                    try {
                        String a = "message";
                        OutputStream outputStream = socketClient2.getOutputStream();
                        System.out.println("send:" + a + "当前线程:" + Thread.currentThread().getName() + Thread.currentThread().getId());
                        outputStream.write(a.getBytes());
                        outputStream.flush();
                        outputStream.close();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }, "客户端发送线程2-").start();
        }
    }

运行效果：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQ0OTI2NjU_size_16_color_FFFFFF_t_70]

### 结论 ###

每次一个客户端连接，都会新建立一个线程处理数据，线程是非常宝贵的资源，多了可能造成线程创建失败等现象，效率低下

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQ0OTI2NjU_size_16_color_FFFFFF_t_70]: /images/20211119/969779e423db4086bfb3a04472294235.png