Java的TCP/IP编程学习--简单的TCP/IP应用程序和回馈服务器

一、简单的TCP服务器

指定ServerSocket 本地(localhost或者127.0.0.1或者其他)端口(8888或其他)，接收端口请求。循环等待客户端Socket连接。读取客户端发送的数据并写回客户端Socket，让客户端接收

package main;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketAddress;

/**
 * @ClassName TCPEchoServer
 * @Description TODO
 * @Author Cays
 * @Date 2019/3/15 11:01
 * @Version 1.0
 **/
public class TCPEchoServer {
    private static final int BUFSIZE=32;//size of receive buffer

    public static void main(String[] args) throws IOException {
        //指定本地端口
        int servPort=8888;
        //创建服务器端套接字，监听特定端口的客户端请求
        ServerSocket serverSocket=new ServerSocket(servPort);
        //size of received message
        int recvMsgSize;
        //要接受的字符的缓冲区
        byte []receiveBuf=new byte[BUFSIZE];
        //永久循环，迭代处理新的连接
        while (true){
            //阻塞等待，直到有向serverSocket监听端口新的连接请求
            Socket clntSock=serverSocket.accept();
            SocketAddress clientAddress=clntSock.getRemoteSocketAddress();
            //输出客户端地址/端口号
            System.out.println("Handling client at "+clientAddress);
            InputStream in=clntSock.getInputStream();
            OutputStream out=clntSock.getOutputStream();
            //receive until client closes connectoion,
            while ((recvMsgSize=in.read(receiveBuf))!=-1){
                out.write(receiveBuf,0,recvMsgSize);
            }
            //close the socket. we are done with this client
            clntSock.close();
        }
        //not reached
    }
}

二、简单的TCP应用程序

连接本地服务器IP/端口，并发送简单字符串，接收服务器的回馈消息并显示

package main;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.SocketException;

/**
 * @ClassName TCPEchoClient
 * @Description TODO
 * @Author Cays
 * @Date 2019/3/15 10:08
 * @Version 1.0
 **/
public class TCPEchoClient {
    public static void main(String []args) throws IOException {
        //Server name or IP address
        String server="127.0.0.1";
        //Convert argument String to bytes using the default character encoding
        //转换回馈字符串
        byte []data="Hello World!".getBytes();
        //确定回馈服务器的端口号8888
        int servPort=8888;
        //Create socket that is connected to server on specified port
        //创建服务器套接字，连接到由名字/ip指定的服务器
        Socket socket=new Socket(server,servPort);
        System.out.println("Connected to server...encoding echo string");
        //获取网络套接字的输入/输出流，通过将字节写入套接字的OutputStream
        //发送数据，通过InputStream读取数据
        InputStream in=socket.getInputStream();
        OutputStream out=socket.getOutputStream();
        out.write(data);//send the encoding string to the server
        //receive the same string back from the server
        int totalBytesRcvd=0;//total bytes received so far
        int bytesRcvd;//bytes received in last read
        //接收服务器数据
        while (totalBytesRcvd<data.length){
            if ((bytesRcvd=in.read(data,totalBytesRcvd,data.length-totalBytesRcvd))==-1){
                throw new SocketException("Connection closed prematurely");
            }
            totalBytesRcvd+=bytesRcvd;
        }
        //data array is full
        //打印接收的字符串
        System.out.println("Received:"+(new String(data)));
        socket.close();
    }
}

三、运行结果