1、Java支持基于流的通信和基于包的通信

基于流的通信使用TCP协议（传输控制协议）进行数据传输，传输是无损可靠的

基于包的通信使用UDP协议（用户数据报协议）进行数据传输，不能保证传输没有丢失

2、服务端和客户端套接字--基于流的通信

客户端代码

复制代码package com.wangluo;

import java.io.*;

import java.net.Socket;import java.net.UnknownHostException;

public class Client {

public static void main(String[] args) {    try {        //1.创建客户端Socket,指定服务器端地址和端口        Socket socket = new Socket("localhost",8888);        //2.获取输出流，向服务器端发送信息        OutputStream os = socket.getOutputStream();//字节输出流        PrintWriter pw = new PrintWriter(os);//将输出流包装为打印流        pw.write("用户名：admin;密码：123");        pw.write("用户名：admin2;密码：456");        pw.flush();        socket.shutdownOutput();//关闭输出流，对于 TCP 套接字，任何以前写入的数据都将被发送        //3.获取输入流，并读取服务器的响应信息        InputStream is = socket.getInputStream();        BufferedReader br = new BufferedReader(new InputStreamReader(is));        String info = null;        while((info = br.readLine()) != null) {            System.out.println("我是客户端，服务器端说："+info);        }        //4.关闭资源        br.close();        is.close();        pw.close();        os.close();        socket.close();    } catch (UnknownHostException e) {        e.printStackTrace();    } catch (IOException e) {        e.printStackTrace();    }}

}

复制代码如果服务端的端口服务没有起来，运行客户端的程序会抛异常

java.net.ConnectException: Connection refused: connect

服务端代码--服务多个客户复制代码package com.wangluo;

import java.io.*;

import java.net.ServerSocket;import java.net.Socket;

public class Server {

public static void main(String[] args) {    try {        //1.创建一个服务器端Socket,即ServerSocket,指定绑定的端口        ServerSocket serverSocket = new ServerSocket(8888);        //2.调用accept()方法开始监听，等待客户端 的连接        System.out.println("***服务器即将启动，等待客户端的连接***");        while (true) {            //监听端口            Socket socket = serverSocket.accept();            new MyThread(socket).start();        }    } catch (IOException e) {        e.printStackTrace();    }}static class MyThread extends Thread{    private Socket socket;    public MyThread(Socket socket){        this.socket=socket;    }    @Override    public void run() {        try {            server(socket);        } catch (IOException e) {            e.printStackTrace();        }    }    private void server(Socket socket) throws IOException {        //3.获取输入流，并读取客户端信息        InputStream is = socket.getInputStream();//字节输入流        InputStreamReader isr = new InputStreamReader(is);//将字节输入流转换为字符流        BufferedReader br = new BufferedReader(isr);//为输入流添加缓冲        String info = null;        while((info=br.readLine())!=null) {//循环读取客户端的信息            System.out.println("我是服务器，客户端说："+info);        }        OutputStream os = socket.getOutputStream();//字节输出流        PrintWriter pw = new PrintWriter(os);//将输出流包装为打印流        pw.write("我是服务端");        pw.flush();        socket.shutdownInput();//关闭输入流         //4.关闭资源        br.close();        isr.close();        is.close();        socket.close();    }}

}

复制代码如果服务端监听的端口已经被使用了，在启动服务端的服务时候会抛异常

java.net.BindException

输出结果：（先启动服务端，再启动客户端）服务端输出：我是服务器，客户端说：用户名：admin;密码：123用户名：admin2;密码：456

客户端输出：我是客户端，服务器端说：我是服务端

3、套接字发送和接受对象

对象必须实现Serializable接口

复制代码package com.wangluo;

import java.io.Serializable;

public class Test implements Serializable{

private static long serialVersionUID=1L;private int num;private String name;public Test(int num, String name){    this.num=num;    this.name=name;}public int getNum() {    return num;}public void setNum(int num) {    this.num = num;}public String getName() {    return name;}public void setName(String name) {    this.name = name;}@Overridepublic String toString() {    return "Test{" +            "num=" + num +            ", name='" + name + '\'' +            '}';}

}

复制代码客户端代码复制代码package com.wangluo;

import java.io.*;

import java.net.Socket;import java.net.UnknownHostException;

public class Client {

public static void main(String[] args) {    try {        //1.创建客户端Socket,指定服务器端地址和端口        Socket socket = new Socket("localhost",8888);        //2.获取输出流，向服务器端发送信息        OutputStream os = socket.getOutputStream();//字节输出流

// PrintWriter pw = new PrintWriter(os);//将输出流包装为打印流

// pw.write("用户名：admin;密码：123");// pw.write("用户名：admin2;密码：456");// pw.flush();ObjectOutputStream objectOutputStream=new ObjectOutputStream(os);objectOutputStream.writeObject(new Test(123,"deng"));objectOutputStream.flush();socket.shutdownOutput();//关闭输出流//3.获取输入流，并读取服务器的响应信息InputStream is = socket.getInputStream();BufferedReader br = new BufferedReader(new InputStreamReader(is));String info = null;while((info = br.readLine()) != null) { System.out.println("我是客户端，服务器端说："+info);}//4.关闭资源br.close();is.close();// pw.close();objectOutputStream.close();os.close();socket.close();

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

}

复制代码服务端代码复制代码package com.wangluo;

import java.io.*;

import java.net.ServerSocket;import java.net.Socket;

public class Server {

public static void main(String[] args) {    try {        //1.创建一个服务器端Socket,即ServerSocket,指定绑定的端口        ServerSocket serverSocket = new ServerSocket(8888);        //2.调用accept()方法开始监听，等待客户端 的连接        System.out.println("***服务器即将启动，等待客户端的连接***");        while (true) {            //监听端口            Socket socket = serverSocket.accept();            new MyThread(socket).start();        }    } catch (IOException e) {        e.printStackTrace();    }}static class MyThread extends Thread{    private Socket socket;    public MyThread(Socket socket){        this.socket=socket;    }    @Override    public void run() {        try {            server(socket);        } catch (Exception e) {            e.printStackTrace();        }    }    private void server(Socket socket) throws Exception {        //3.获取输入流，并读取客户端信息        InputStream is = socket.getInputStream();//字节输入流

// InputStreamReader isr = new InputStreamReader(is);//将字节输入流转换为字符流

// BufferedReader br = new BufferedReader(isr);//为输入流添加缓冲// String info = null;// while((info=br.readLine())!=null) {//循环读取客户端的信息// System.out.println("我是服务器，客户端说："+info);// }

ObjectInputStream objectInputStream=new ObjectInputStream(is);        Object test=objectInputStream.readObject();        System.out.println("我是服务器，客户端说："+test);        OutputStream os = socket.getOutputStream();//字节输出流        PrintWriter pw = new PrintWriter(os);//将输出流包装为打印流        pw.write("服务端应答");        pw.flush();        socket.shutdownInput();//关闭输入流         //4.关闭资源

// br.close();

// isr.close();objectInputStream.close();is.close();socket.close();