实现多人聊天

服务器端代码

package Zn200611wzyfb;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;

public class ServerThread extends Thread{
static final Map <String,Socket> mp = new HashMap<String,Socket>();

static final List<Socket> li = new ArrayList<Socket>();
OutputStream output;//输出流
InputStream input;//输入流
Socket socket;//定义一个socket接收对象的属性
//线程创建方法


public void addUser(Socket ss) {
li.add(ss);
}

Scanner sca = new Scanner(System.in);
public synchronized void run() {
try {
System.out.println("已启动一个线程来处理~");

System.out.println("增加用户成功");

System.out.println("当前用户"+li.size());




//为输入输出流赋值
output=socket.getOutputStream();
input=socket.getInputStream();

PrintWriter pw = new PrintWriter(socket.getOutputStream());
BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));

//接收
Thread t1 = new Thread(new Runnable() {
PrintWriter pw;
@Override
public synchronized void run() {
while(true){
try {
String st = br.readLine();
System.out.println(st); //这里不会造成死循环，这个readline会等待接受


for (int i = 0; i < li.size(); i++) {

if(socket.equals(li.get(i))) {
li.remove(i);
}

}
for (Socket socket : li) {

// System.out.println("当前用户为"+socket);
PrintWriter pw = new PrintWriter(socket.getOutputStream());
//stt = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
pw.println(st);
pw.flush();
}

} catch (IOException e) {
e.printStackTrace();
}
}

}
});

t1.start();


} catch (IOException e) {
e.printStackTrace();
}
}

//定义一个建立服务器的方法

private void setUpServer(int port) throws IOException {
//将输入的端口设置为服务器
ServerSocket server=new ServerSocket(port);
//输出当前服务器的端口号
System.out.println("服务器创建成功，端口号："+server.getLocalPort());

while(true) {
ServerThread ts=new ServerThread();
//为对象的socket属性赋值。 server.accept(); 进入阻塞状态，可以在控制台写入
Socket sk = server.accept();
// mp.put("eee",sk);

addUser(sk);

ts.socket= sk;

//启动线程
ts.start();

}

}

//主函数入口
public static void main(String[] args) throws IOException {

//创建一个通信类的对象
ServerThread server=new ServerThread();

server.setUpServer(9013);

}
}

客户端代码（每执行一下客户端，增加一个人聊天）

package Zn200611wzyfb;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;

public class Clils {

public static void main(String[] args) throws Exception {

//张三客户端
Scanner sca = new Scanner(System.in);
System.out.println("----------这里是客户端，请输入用户名------------");

String name = sca.next();

System.out.println("欢迎"+name);

Socket sc = new Socket("127.0.0.1",9013);

PrintWriter pw = new PrintWriter(sc.getOutputStream());
BufferedReader br = new BufferedReader(new InputStreamReader(sc.getInputStream()));

//接收
Thread t1 = new Thread(new Runnable() {
@Override
public void run() {
while(true){
try {
System.out.println(br.readLine()); //这里不会造成死循环，这个readline会等待接受
} catch (IOException e) {
e.printStackTrace();
}
}

}
});

t1.start();

//写

Thread t2 = new Thread(new Runnable() {

Scanner sca = new Scanner(System.in);
@Override
public void run() {
while(true) {
String speak = Thread.currentThread().getName();
pw.println(speak+"说："+sca.next());
pw.flush();
}

}
});
t2.setName(name);
t2.start();
}

}