Java网络编程案例---聊天室

　　网络编程是指编写运行在多个设备（计算机）的程序，这些设备都通过网络连接起来。

　　java.net包中JavaSE的API包含有类和接口，它们提供低层次的通信细节。你可以直接使用这些类和接口，来专注于解决问题，而不用关注通信细节。

　　java.net包中提供了两种常见的网络协议的支持：

　　TCP：TCP是传输控制协议的缩写，它保障了两个应用程序之间的可靠通信。通常用于互联网协议，被称TCP/IP。

　　UDP:UDP是用户数据报协议的缩写，一个无连接的协议。提供了应用程序之间要发送的数据的数据报。

　　本案例以TCP协议为例，结合多线程，实现一个多人同时聊天的聊天室。

　　释放资源：

　　Utils.java

 package com.bjwyj.chat;

 import java.io.Closeable;

 public class Utils {
     /**
      * 释放资源
      */
     public static void close(Closeable... targets) {
         for(Closeable target:targets) {
             try {
                 if(target!=null) {
                     target.close();
                 }
             }catch(Exception e) {
                 e.printStackTrace();
             }
         }
     }
 }

　　服务器端：

　　Chat.java

 package com.bjwyj.chat;

 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.net.ServerSocket;
 import java.net.Socket;
 import java.util.concurrent.CopyOnWriteArrayList;

 /**
  * 在线聊天室：服务端
  * 目标：加入容器实现群聊和私聊
  *
  * @author 吴永吉
  *
  */
 public class Chat {
     private static CopyOnWriteArrayList<Channel> all = new CopyOnWriteArrayList<>();
     public static void main(String[] args) throws IOException {
         System.out.println("------server------");
         //1.指定端口：使用ServerSocket创建服务器
         ServerSocket server = new ServerSocket(9999);
         //2.阻塞式等待连接accept
         while(true) {
             Socket client = server.accept();
             System.out.println("一个客户端建立了连接");
             Channel c = new Channel(client);
             all.add(c); //管理所有的成员
             new Thread(c).start();
         }
     }
     //一个客户代表一个Channel
     static class Channel implements Runnable{
         private DataInputStream dis;
         private DataOutputStream dos;
         private Socket client;
         private boolean isRunning;
         private String name;

         public Channel(Socket client) {
             isRunning = true;
             this.client = client;
             try {
                 dis = new DataInputStream(client.getInputStream());
                 dos = new DataOutputStream(client.getOutputStream());
                 //获取名称
                 this.name = receive();
                 //欢迎你的到来
                 this.send("欢迎上线");
                 this.sendOthers(this.name+"上线啦！",true);
             }catch(Exception e) {
                 release();
             }
         }

         //接收消息
         public String receive() {
             String msg = "";
             try {
                 msg = dis.readUTF();
             } catch (IOException e) {
                 System.out.println("-------Chat receive------");
                 release();
             }
             return msg;
         }
         //发送消息
         public void send(String msg) {
             try {
                 dos.writeUTF(msg);
                 dos.flush();
             } catch (IOException e) {
                 System.out.println("--------Chat send-------");
                 release();
             }
         }
         /**
          * 群聊：获取自己的消息，发给其他人
          * 私聊：约定数据格式：@xxx:msg
          * @param msg
          */
         public void sendOthers(String msg,boolean isSys) {
             boolean isPrivate = msg.startsWith("@");
             if(isPrivate) { //私聊
                 int idx = msg.indexOf(":");
                 //获取目标和数据
                 String targetName = msg.substring(1,idx);
                 msg = msg.substring(idx+1);
                 for(Channel other:all) {
                     if(other.name.equals(targetName)) { //目标
                         other.send(this.name+"悄悄的对你说："+msg);
                         break;
                     }
                 }
             }else { //群聊
                 for(Channel other:all) {
                     if(this==other) { //自己
                         continue;
                     }
                     if(!isSys) {
                         other.send(this.name+"对所有人说："+msg); //群聊消息
                     }else {
                         other.send(msg); //系统消息
                     }
                 }
             }
         }
         //关闭资源
         public void release() {
             this.isRunning = false;
             Utils.close(dis,dos,client);
             //退出
             all.remove(this);
             sendOthers(this.name+"下线了！",true);
         }

         @Override
         public void run() {
             while(isRunning) {
                 String msg = receive();
                 if(!msg.equals("")) {
                     //send(msg);
                     sendOthers(msg,false);
                 }
             }
         }
     }
 }

　　客户端：

　　Send.java

 package com.bjwyj.chat;

 import java.io.BufferedReader;
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.net.Socket;

 /**
  * 使用多线程封装了客户发送端：
  * 1.发送消息
  * 2.从控制台获取消息
  * 3.释放资源
  * 4.重写run
  * @author 吴永吉
  *
  */
 public class Send implements Runnable{
     private BufferedReader console;
     private DataOutputStream dos;
     private Socket client;
     private boolean isRunning;
     private String name;

     public Send(Socket client,String name) {
         isRunning = true;
         this.client = client;
         this.name = name;
         console = new BufferedReader(new InputStreamReader(System.in));
         try {
             dos = new DataOutputStream(client.getOutputStream());
             //发送名称
             send(name);
         } catch (IOException e) {
             System.out.println("------Client Send------");
             this.release();
         }
     }

     @Override
     public void run() {
         while(isRunning) {
             String msg = this.getStringFromConsole();
             if(!msg.equals("")) {
                 this.send(msg);
             }
         }
     }

     /**
      * 发送消息
      */
     private void send(String msg) {
         try {
             dos.writeUTF(msg);
             dos.flush();
         } catch (IOException e) {
             System.out.println("------Client send------");
             release();
         }
     }

     /**
      * 从控制台获取消息
      */
     private String getStringFromConsole() {
         try {
             return console.readLine();
         } catch (IOException e) {
             System.out.println("------Client console------");
             release();
         }
         return "";
     }

     //释放资源
     private void release() {
         this.isRunning = false;
         Utils.close(dos,client);
     }
 }

　　Receive.java

 package com.bjwyj.chat;

 import java.io.DataInputStream;
 import java.io.IOException;
 import java.net.Socket;

 /**
  * 使用多线程封装了客户接收端
  * 1.接收消息
  * 2.释放资源
  * 3.重写run
  * @author 吴永吉
  *
  */
 public class Receive implements Runnable{
     private DataInputStream dis;
     private Socket client;
     private boolean isRunning;

     public Receive(Socket client) {
         this.isRunning = true;
         this.client = client;
         try {
             dis = new DataInputStream(client.getInputStream());
         } catch (IOException e) {
             System.out.println("------Client Receive------");
             this.release();
         }
     }

     //接收消息
     public String receive() {
         String msg = "";
         try {
             msg = dis.readUTF();
         } catch (IOException e) {
             System.out.println("-------Receive receive------");
             release();
         }
         return msg;
     }

     @Override
     public void run() {
         while(isRunning) {
             String msg = this.receive();
             if(!msg.equals("")) {
                 System.out.println(msg);
             }
         }
     }

     //释放资源
     private void release() {
         this.isRunning = false;
         Utils.close(dis,client);
     }
 }

　　Client.java

 package com.bjwyj.chat;

 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.net.Socket;
 import java.net.UnknownHostException;

 /**
  * 在线聊天室：客户端
  *
  * @author 吴永吉
  *
  */
 public class Client {
     public static void main(String[] args) throws UnknownHostException, IOException {
         System.out.println("------client------");
         BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
         System.out.println("请输入名称：");
         String name = br.readLine();
         //建立连接：使用Socket创建客户端+服务器的地址和端口号
         Socket client = new Socket("localhost",9999);
         //客户端发送消息
         new Thread(new Send(client,name)).start();
         //获取消息
         new Thread(new Receive(client)).start();
     }
 }

　　运行结果：