Java網絡編程案例---聊天室

　　網絡編程是指編寫運行在多個設備（計算機）的程序，這些設備都通過網絡連接起來。

　　java.net包中JavaSE的API包含有類和接口，它們提供低層次的通信細節。你可以直接使用這些類和接口，來專注於解決問題，而不用關注通信細節。

　　java.net包中提供了兩種常見的網絡協議的支持：

　　TCP：TCP是傳輸控制協議的縮寫，它保障了兩個應用程序之間的可靠通信。通常用於互聯網協議，被稱TCP/IP。

　　UDP:UDP是用戶數據報協議的縮寫，一個無連接的協議。提供了應用程序之間要發送的數據的數據報。

　　本案例以TCP協議為例，結合多線程，實現一個多人同時聊天的聊天室。

　　釋放資源：

　　Utils.java

package com.bjwyj.chat;

import java.io.Closeable;

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

　　服務器端：

　　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;

/**
 * 在線聊天室：服務端
 * 目標：加入容器實現群聊和私聊
 * 
 * @author 吳永吉
 *
 */
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創建服務器
        ServerSocket server = new ServerSocket(9999);
        //2.阻塞式等待連接accept
        while(true) {
            Socket client = server.accept();
            System.out.println("一個客戶端建立了連接");
            Channel c = new Channel(client);
            all.add(c); //管理所有的成員
            new Thread(c).start();
        }
    }
    //一個客戶代表一個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());
                //獲取名稱
                this.name = receive();
                //歡迎你的到來
                this.send("歡迎上線");
                this.sendOthers(this.name+"上線啦！",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;
        }
        //發送消息
        public void send(String msg) {
            try {
                dos.writeUTF(msg);
                dos.flush();
            } catch (IOException e) {
                System.out.println("--------Chat send-------");
                release();
            }
        }
        /**
         * 群聊：獲取自己的消息，發給其他人
         * 私聊：約定數據格式：@xxx:msg
         * @param msg
         */
        public void sendOthers(String msg,boolean isSys) {
            boolean isPrivate = msg.startsWith("@");
            if(isPrivate) { //私聊
                int idx = msg.indexOf(":");
                //獲取目標和數據
                String targetName = msg.substring(1,idx);
                msg = msg.substring(idx+1);
                for(Channel other:all) {
                    if(other.name.equals(targetName)) { //目標
                        other.send(this.name+"悄悄的對你說："+msg);
                        break;
                    }
                }
            }else { //群聊
                for(Channel other:all) {
                    if(this==other) { //自己
                        continue;
                    }
                    if(!isSys) {
                        other.send(this.name+"對所有人說："+msg); //群聊消息
                    }else {
                        other.send(msg); //系統消息
                    }
                }
            }
        }
        //關閉資源
        public void release() {
            this.isRunning = false;
            Utils.close(dis,dos,client);
            //退出
            all.remove(this);
            sendOthers(this.name+"下線了！",true);
        }

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

　　客戶端：

　　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;

/**
 * 使用多線程封裝了客戶發送端：
 * 1.發送消息
 * 2.從控制台獲取消息
 * 3.釋放資源
 * 4.重寫run
 * @author 吳永吉
 *
 */
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());
            //發送名稱
            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);
            }
        }
    }
    
    /**
     * 發送消息
     */
    private void send(String msg) {
        try {
            dos.writeUTF(msg);
            dos.flush();
        } catch (IOException e) {
            System.out.println("------Client send------");
            release();
        }
    }
    
    /**
     * 從控制台獲取消息
     */
    private String getStringFromConsole() {
        try {
            return console.readLine();
        } catch (IOException e) {
            System.out.println("------Client console------");
            release();
        }
        return "";
    }
    
    //釋放資源
    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;

/**
 * 使用多線程封裝了客戶接收端
 * 1.接收消息
 * 2.釋放資源
 * 3.重寫run
 * @author 吳永吉
 *
 */
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);
            }
        }
    }
    
    //釋放資源
    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;

/**
 * 在線聊天室：客戶端
 * 
 * @author 吳永吉
 *
 */
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("請輸入名稱：");
        String name = br.readLine();
        //建立連接：使用Socket創建客戶端+服務器的地址和端口號
        Socket client = new Socket("localhost",9999);
        //客戶端發送消息
        new Thread(new Send(client,name)).start();
        //獲取消息
        new Thread(new Receive(client)).start();
    }
}

　　運行結果：