从键盘接受，客户端发送，服务器接收，添加处理后再传回。
简单例子：
可能遇到问题：
readline阻塞， 解决办法：PrintWriter.println（） ，该方法同write，print相同，只是会添加换行，使readline不阻塞。
readline在文件和socket操作时区别：文件结束返回-1；而socket则阻塞。
PrintWriter.flush();
serverSocket.accept() 阻塞；
客户端核心代码：
package com.io;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
public class Client {
public Client() {
// TODO Auto-generated constructor stub
init();
}
public void init() {
try {
Socket socket = new Socket("127.0.0.1", 5241);
BufferedReader text = new BufferedReader(new InputStreamReader(
System.in));// keyboard input
PrintWriter sout = new PrintWriter(socket.getOutputStream());
String send = text.readLine();// 只能来一次
System.out.println("text : " + send);
System.out.println("client send : " + send);
sout.println(send);// 区别print println(readline非阻塞)
sout.flush();
BufferedReader sin = new BufferedReader(new InputStreamReader(
socket.getInputStream()));// io input
System.out.println("client get :" + sin.readLine());
// while ((readline = in.readLine()) != null) {
// sout.write(readline);
// sout.flush();// server mashangjieshoudao
// System.out.println("c-client input is " + readline);
// // System.out.println("c-Server output is :" + sin.readLine());
// }
sin.close();
sout.close();
// sin.close();
socket.close();
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
System.out.println("host");
} catch (IOException e) {
// TODO Auto-generated catch block
System.out.println("client io");
}
}
public static void main(String[] args) {
new Client();
}
}
服务器端核心代码：
package com.io;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class Server {
public Server() {
// TODO Auto-generated constructor stub
init();
}
public void init() {
ServerSocket serverSocket = null;
try {
serverSocket = new ServerSocket(5241);
while (true) {
Socket socket = serverSocket.accept();
System.out.println("accept");
PrintWriter sout = new PrintWriter(socket.getOutputStream());
BufferedReader sin = new BufferedReader(new InputStreamReader(
socket.getInputStream()));
String text = sin.readLine();
System.out.println(" server get: " + text);
sout.println(text + "-----");
System.out.println(" server send: " + text + "-----");
sout.flush();
sout.close();
sin.close();
socket.close();
}
} catch (IOException e) {
System.out.println("server init error");
}
try {
serverSocket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
System.out.println("server close error");
}
}
public static void main(String[] args) {
new Server();
}
}