java--网络编程
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
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(); } } }
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
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(); } } }
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
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; } @Override public String toString() { return "Test{" + "num=" + num + ", name='" + name + '\'' + '}'; } }
- 客户端代码
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(); } } }
- 服务端代码
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(); } } }
- 输出结果:
服务端:我是服务器,客户端说:Test{num=123, name=’deng’}
客户端:我是客户端,服务器端说:服务端应答