我编写了一个简单的 Java 调度程序，它带有一个守护线程来处理传入的流量，并使用另一个线程来发送命令。
当服务器接收到第一条消息时，问题就出现了，然后客户端/服务器系统卡在服务器试图向客户端发送响应的位置。当服务器发送数据时，两端的套接字只是简单地冻结。
我已将原始问题简化为回显服务器和客户端；我想我在代码上一定有一个非常愚蠢的错误。我机器上的代码和结果复制如下。谁能解释出了什么问题？
谢谢！
这是结果，我们可以看到服务器和客户端在收到第一条消息后就卡住了。
Echo Server listening port...
Echo Server: Waiting from client connection.
Connecting to the server.
Connected to the server.
Dispatcher send: 10
Dispatcher send: 11
Dispatcher send: 12
Dispatcher send: 13
Dispatcher read...
Dispatcher read...
Dispatcher readed 10
代码：
回声测试：
import java.io.*;
import java.net.*;
public class EchoTest {
public static void main(String[] args) {
EchoServer.listen();
EchoClient client = new EchoClient();
EchoServer server = EchoServer.accept();
}
}
客户端和服务器：
class EchoClient implements Runnable {
private static final int PORT = 13244;
Socket socket;
Disp disp;
Thread client;
public EchoClient() {
client = new Thread(this);
client.start();
}
public void run() {
try {
System.out.println("Connecting to the server.");
Socket socket = new Socket("localhost", PORT);
System.out.println("Connected to the server.");
disp = new Disp(socket);
disp.send(10);
disp.send(11);
disp.send(12);
disp.send(13);
} catch(IOException e) {
System.out.println("Would not connect to local host: " + PORT);
System.exit(-1);
}
}
public void send(int m) {
disp.send(m);
System.out.println("Sent message " + m);
int echo = disp.getMsg();
if(m == echo) {
System.out.println("Message " + m + "sent and received.");
} else {
System.out.println("Message " + m + "cannot be echoed correctly.");
}
}
}
class EchoServer implements Runnable{
private static final int PORT = 13244;
private static ServerSocket serverSocket;
Disp disp;
public EchoServer(Socket s) {
disp = new Disp(s);
}
public static void listen() {
System.out.println("Echo Server listening port...");
try {
serverSocket = new ServerSocket(PORT);
} catch (IOException e) {
System.out.println("Could not listen on port: " + PORT);
System.exit(-1);
}
}
public static EchoServer accept(){
try {
System.out.println("Echo Server: Waiting from client connection.");
return new EchoServer(serverSocket.accept());
} catch(IOException e) {
System.out.println("Couldn't accept connection from client.");
System.exit(-1);
}
return null;
}
public void run() {
while(true) {
int m = disp.getMsg();
disp.send(m);
}
}
}
显示：
class Disp implements Runnable{
int msg = -1;
Socket socket;
BufferedInputStream input;
DataInputStream dis;
BufferedOutputStream output;
DataOutputStream dos;
Thread daemon;
public Disp(Socket s) {
this.socket = s;
try{
input = new BufferedInputStream(socket.getInputStream());
dis = new DataInputStream(input);
output = new BufferedOutputStream(socket.getOutputStream());
dos = new DataOutputStream(output);
}catch(IOException e) {
}
daemon = new Thread(this);
daemon.start();
}
public void run() {
while(true) {
int m = get();
setMsg(m);
}
}
public void send(int m) {
synchronized(dos) {
try{
System.out.println("Dispatcher send: " + m);
dos.writeInt(m);
dos.flush();
} catch(IOException e) {
}
}
}
public int get() {
System.out.println("Dispatcher read...");
synchronized(dis) {
try{
int m = dis.readInt();
System.out.println("Dispatcher readed " + m);
return m;
} catch(IOException e) {
}
}
return -1;
}
synchronized public void setMsg(int m) {
while(true) {
if(msg == -1) {
try {
wait();
} catch(InterruptedException e) {
}
} else {
msg = m;
notifyAll();
}
}
}
synchronized public int getMsg() {
while(true) {
if(msg != -1) {
try {
wait();
} catch(InterruptedException e) {
}
} else {
notifyAll();
return msg;
}
}
}
}