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);

详情可以看这里

(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);

详情可以看这里

(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".