java_advanced_review(3)补充：利用网络套接字实现类似qq 的控制台通讯

【0】README
1）本文旨在实现 利用网络套接字实现类似qq 的控制台通讯， client 采用telnet and java app， server采用 java app；
2）also， you can check out the source code from https://github.com/pacosonTang/core-java-volume/tree/master/coreJavaAdvanced/chapter3/qq_resembled
3）本代码的问题不足在于 没有实现 server 发送到 多个 client 的 socket 连接，即，server 发送的消息属于群发，而不是 peer to peer  的 发送，如果需要完成这个工作的话，需要 socket 连接池，对于每个 client 都建立相应的 socket，即建立相应的
OutputStream and InputStream；
4）编译本代码，可能会报错（错误：找不到符号），解决方法参见：　http://blog.csdn.net/pacosonswjtu/article/details/51804636

【1】server by java app

public class ServerPlainTest {
public static void main(String[] args) {
try {
ServerSocket ss = new ServerSocket(8189);
System.out.println("the server has startuped, waiting for connections.");
while (true) { // accept multiple clients connection request.
Socket s = ss.accept();
System.out.println("a client has connected successfully.");
new Thread(new ReceiveHandler(s, Role.SERVER)).start();
new Thread(new SendHandler(s, Role.SERVER)).start();
}
} catch (Exception e) {
System.out.println(e);
}
}
}

public class MessageHandler {
}

// receive msg.
class ReceiveHandler implements Runnable {
private Socket socket;
private Role role;

public ReceiveHandler(Socket socket, Role role) {
this.socket = socket;
this.role = role;
}

public void run() {
try {
System.out.println(role + " executes ReceiveHandler.run method.");
InputStream is = socket.getInputStream();
Scanner in = new Scanner(is);

// echo client input
boolean done = false;
while (!done && in.hasNextLine()) {
String line = in.nextLine();
System.out.println(line);

if (line.trim().equalsIgnoreCase("bye")) {
done = true;
}
}
// close relative instance.
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

// send msg.
class SendHandler implements Runnable {
private Socket socket;
private Role role;

public SendHandler(Socket socket, Role role) {
this.socket = socket;
this.role = role;
}

public void run() {
PrintWriter pw = null;
try {
System.out.println(role + " executes SendHandler.run method.");
Scanner s = new Scanner(System.in);
OutputStream os = socket.getOutputStream();
pw = new PrintWriter(os, true); // autoFlush=true.

if (role.equals(Role.SERVER)) {
pw.println("from server: you've connected with the server.");
}

while (s.hasNext()) {
String line = s.nextLine();
pw.println("from " + role + ": " + line);
}
pw.println("connection closed successfully. bye!");
} catch (Exception e) {
e.printStackTrace();
}
}
}

【2】client by java app
1）source code is as following

public class ClientPlainTest {
public static void main(String[] args) {
Socket s = null;
try {
s = new Socket("localhost", 8189);
System.out.println("connection with the server successfully.");
new Thread(new ReceiveHandler(s, Role.CLIENT)).start();
new Thread(new SendHandler(s, Role.CLIENT)).start();
} catch (Exception e) {
System.out.println(e);
}
}
}

2）console info：



【3】client by telnet (connect with server by telnet localhost 8189)