Java TCP 网络编程示例

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分别创建两个文件，TCPServer.java 和 TCPClient.java，先运行 TCPServer，开始监听。再运行 TCPClient，在 TCPClient 中输入字符串，TCPServer 接收到后将它转换成大写，传回 TCPClient。如果 TCPClient 输入了 "quit"，则退出程序。而 TCPServer 继续监听。

TCPServer.java：

import java.io.*;
import java.net.*;
public class TCPServer {
public static void main(String argv[]) throws Exception
{
String sClientSentence;
String sCapitalizedSentence;
System.out.println("Server Started.");
ServerSocket oWelcomeSocket = new ServerSocket(6789);
System.out.println("Server started a welcome socket in port 6789.");
while (true) {
Socket oConnectionSocket = oWelcomeSocket.accept();
long i;
BufferedReader oInFromClient = new BufferedReader(new InputStreamReader(oConnectionSocket.getInputStream()));
DataOutputStream oOutToClient = new DataOutputStream(oConnectionSocket.getOutputStream());
System.out.println("A new client connected. ");
i = 0;
while (true) {
sCapitalizedSentence = "";
sClientSentence = "";
try {
System.out.println("Try Count: " + i++);
sClientSentence = oInFromClient.readLine();
sCapitalizedSentence = sClientSentence.toUpperCase() + '\n';
System.out.println("Client: " + sClientSentence);
if (sClientSentence.equals("quit")) {
System.out.println("Client want to leave.");
sCapitalizedSentence = "OK, I will let you go.\n";
}
oOutToClient.writeBytes(sCapitalizedSentence);
System.out.println("Me: " + sCapitalizedSentence);
if (sClientSentence.equals("quit")) {
break;
}
} catch (Exception oError) {
sCapitalizedSentence = "QUIT" + '\n';
System.out.println("Client closed the connection.");
break;
} finally {
}
}
System.out.println("Connection closed.\n");
}
}
}

TCPClient.java

import java.io.*;
import java.net.*;
public class TCPClient {
public static void main(String argv[]) throws Exception
{
String sSentence;
String sModifiedSentence;
BufferedReader oInFromUser = new BufferedReader(new InputStreamReader(System.in));
Socket oClientSocket = new Socket("192.168.1.20", 6789);
sModifiedSentence = "Initialize";
System.out.println("Connected.");
while (sModifiedSentence != "QUIT") {
DataOutputStream oOutToServer = new DataOutputStream(oClientSocket.getOutputStream());
BufferedReader oInFromServer = new BufferedReader(new InputStreamReader(oClientSocket.getInputStream()));
sSentence = oInFromUser.readLine();
oOutToServer.writeBytes(sSentence + '\n');
sModifiedSentence = oInFromServer.readLine();
System.out.println("FROM SERVER: " + sModifiedSentence);
if (sSentence.equals("quit")) {
System.out.println("OK, I quited.");
break;
}
}
oClientSocket.close();
System.out.println("Program terminated.");
}
}