建立简单的服务器端程序

参考自core java

package com.lujinhong.corejava;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class EchoServer {

public static void main(String[] args) {

try {
ServerSocket serverSocket = new ServerSocket(8019);
Socket socket = serverSocket.accept();

InputStream is = socket.getInputStream();
OutputStream os = socket.getOutputStream();

PrintWriter pw = new PrintWriter(os);
Scanner sc = new Scanner(is);

Boolean flag = false;
String line = null;
String exitString = "bye";

while(!flag && sc.hasNextLine()){
pw.println("Hello, type " + exitString + " to exit!");
line = sc.nextLine();
if(line.trim().equals(exitString)){
flag = true;
}else{
pw.println("Hello, "+line);
}
}
pw.close();
sc.close();
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

使用线程实现多个客户端同时访问：

package com.lujinhong.corejava;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

public class MultiEchoServer {

public static void main(String[] args) {
try {
ServerSocket serverSocket = new ServerSocket(8189);
while (true) {
Socket socket = serverSocket.accept();

Runnable r = new ThreadedEchoHandler(socket);
Thread thread = new Thread(r);
thread.start();
}

} catch (IOException e) {
e.printStackTrace();
}

}

}

class ThreadedEchoHandler implements Runnable {

private Socket s = null;

public ThreadedEchoHandler(Socket socket) {
s = socket;
}

@Override
public void run() {
try {
InputStream is = s.getInputStream();
OutputStream os = s.getOutputStream();

PrintWriter pw = new PrintWriter(os);
Scanner sc = new Scanner(is);

Boolean flag = false;
String line = null;
String exitString = "bye";

while (!flag && sc.hasNextLine()) {
pw.println("Hello, type " + exitString + " to exit!");
line = sc.nextLine();
if (line.trim().equals(exitString)) {
flag = true;
} else {
pw.println("Hello, " + line);
}
}
sc.close();
pw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

In this program, we spawn a separate thread for each connection. This approach is not satisfactory for highperformance servers. You can achieve greater server throughput by using features of the java.nio package. See www.ibm.com/developerworks/java/library/j-javaio
for more information.