java 实现 tcp_java实现TCP通信

1.概述

通过ServerSocket与Socket实现的TCP的通信,这个例子配合了swing使用,其实作者之前发过一篇ServerSocker与Socket的通信,在这里,这边文章就是在这个例子上修改而成的.

其实原理很简单的,就是一个服务端一个客户端,服务端这边创建好ServerSocket后,使用accept()堵塞一直等待客户端发送socket.

好吧,不废话了.进正题.

2.服务端

swing的部分就不说了,说一下主要操作.

(1)新建ServerSocket

ServerSocket serverSocket = null;

serverSocket = new ServerSocket(12345);//一个不被占用的端口即可

构造方法的参数是端口,默认使用本地ip. ServerSocket有三个构造方法.

ServerSocket(int port);

ServerSocket(int port,int backlog);

ServerSocker(int poer,int backlog,InetAddress ip);

(2)接收socket

Socket socket = serverSocket.accept();

返回一个Socket(),会一直等待,处于阻塞状态. 一般设置一个while(true)循环接收.

(3)数据处理

使用DataInputStream与DataOutputStream:

DataInputStream inputStream = new DataInputStream(socket.getInputStream());

DataOutputStram outputStream = new DataOutputStream(socket.getOutputStream());

然后使用read与write方法即可. 注意关闭的时候要等输入输出完成后再一起关闭,就是说,不能这样:

DataInputStream inputStream = new DataInputStream(socket.getInputStream());

String data = inputStream.readUTF();

inputStream.close();

DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());

outputStream.writeUTF("ok");

outputStream.close();

这样的话getInputStream()没有问题,但是到了getOutputStream()的时候就有问题了,会提示异常:

Socket is closed. 所以解决办法就是等输出完之后再一起关闭:

DataInputStream inputStream = new DataInputStream(socket.getInputStream());

String data = inputStream.readUTF();

DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());

outputStream.writeUTF("ok");

inputStream.close();//等输出完成后再关闭

outputStream.close();

(4)完整代码Server.java

import java.io.DataInputStream;

import java.io.DataOutputStream;

import java.io.IOException;

import java.net.InetAddress;

import java.net.ServerSocket;

import java.net.Socket;

import javax.swing.*;

public class Server {

public static void main(String[] args)

{

JFrame frame = new JFrame("Server");

JPanel panel = new JPanel();

JTextArea text = new JTextArea();

panel.add(text);

frame.setContentPane(panel);

frame.setSize(600, 300);

frame.setLocationRelativeTo(null);

frame.setVisible(true);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

ServerSocket serverSocket = null;

try

{

serverSocket = new ServerSocket(12345);

while (true)

{

Socket socket = serverSocket.accept();

DataInputStream inputStream = new DataInputStream(socket.getInputStream());

text.setText(inputStream.readUTF());

DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());

outputStream.writeUTF("ok");

inputStream.close();

outputStream.close();

socket.close();

}

}

catch (IOException e)

{

e.printStackTrace();

}

finally

{

try

{

serverSocket.close();

}

catch (IOException e)

{

e.printStackTrace();

}

}

}

}

3.客户端

客户端的操作就是开启一个Socket,再通过这个socket获取对应的输入输出流就可以了.

(1)新建一个Socket

Socket socket = new Socket("127.0.0.1",12345);//这个端口与服务端的端口对应

Socket有三个构造方法:

Socket(InetAddress ip,int port);

Socket(String ip,int port);

Socket(InetAddress ip,int port,InetAddress localIp,int localPort);

Socket(String ip,int port,InetAddress localIp,int localPort);

(2)输入输出

同样使用DataInputStream与DataOutputStream:

DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());

DataInputStream inputStream = new DataInputStream(socket.getInputStream());

(3)完整代码Client.java

import java.io.DataInputStream;

import java.io.DataOutputStream;

import java.io.IOException;

import java.net.Socket;

import javax.swing.*;

import java.awt.GridLayout;

public class Client

{

public static void main(String[] args) {

JFrame frame = new JFrame();

JTextArea text = new JTextArea();

JButton send = new JButton();

GridLayout layout = new GridLayout(2, 1, 0, 5);

frame.setTitle("Client");

frame.setVisible(true);

frame.setLocationRelativeTo(null);

frame.setSize(600, 300);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.setLayout(layout);

frame.add(text);

frame.add(send);

send.setText("send");

send.addActionListener(v ->

{

try

{

String host = "127.0.0.1";

int port = 12345;

Socket socket = new Socket(host, port);

DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());

outputStream.writeUTF(text.getText());

DataInputStream inputStream = new DataInputStream(socket.getInputStream());

text.setText(inputStream.readUTF());

outputStream.close();

inputStream.close();

socket.close();

}

catch (IOException e)

{

e.printStackTrace();

}

});

}

}

4.测试

先开启服务端,再开启客户端,这里设置了服务端返回给客户端的信息为"ok".