Java客户端/服务器不通过Socket/ServerSocket进行通信

Question

我有一个简单的socket/serversocket示例，我正在试图运行，但客户端和服务器在BufferedReader试图读取时挂起。下面是每个代码：

服务器

package picturePerfect; 
--imports-- 

public class PictureServer implements Runnable{ 
static ServerSocket serverSocket; 

public static void main(String[] args) throws IOException { 
    serverSocket = new ServerSocket(2342); 
    Thread firstSessionThread = new Thread(new PictureServer()); 
    firstSessionThread.start(); 
} 

@Override 
public void run() { 
    Socket socket = null; 
    try { 
     socket = serverSocket.accept(); 
     BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream())); 
     String clientRequest = bufferedReader.readLine(); 
     System.out.println(clientRequest); 
     PrintWriter printWriter = new PrintWriter(socket.getOutputStream(), true); 
     printWriter.println("Sent from server!"); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    }  
} 

}

CLIENT

package picturePerfect; 
--imports-- 

public class PictureClient { 
    public static void main(String[] args) throws UnknownHostException, IOException, InterruptedException { 
     Socket socket = new Socket("localhost", 2342); 
     PrintWriter printWriter = new PrintWriter(socket.getOutputStream(), true); 
     printWriter.write("Sent from client!"); 
     BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream())); 
     String response = bufferedReader.readLine(); 
     System.out.println(response); 
     socket.close(); 
    } 
} 

这是我能简化我的代码，以最起码的。我有一个示例程序，我一直遵循，这似乎几乎完全相同。这是样板服务器和客户端（即做工作）：

示例服务器

--imports-- 

public class Server implements Runnable{ 
    static ServerSocket ss; 

    public static void main(String[] args) throws IOException { 
     ss = new ServerSocket(3142); 
     Thread thread = new Thread(new Server()); 
     thread.start(); 
    } 

    @Override 
    public void run() { 
     while (true) { 
      Socket s = null; 

      try { 
       s = ss.accept(); 
       BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream())); 
       String operands = br.readLine(); 
       System.out.println(operands + " was received"); 
       PrintWriter pw = new PrintWriter(s.getOutputStream(), true); 
       pw.println(operands + " right back!"); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
     } 
    } 
} 

样本客户

--imports-- 

public class Server implements Runnable{ 
    static ServerSocket ss; 


    public static void main(String[] args) throws IOException { 
     ss = new ServerSocket(3142); 
     Thread thread = new Thread(new Server()); 
     thread.start(); 
    } 

    @Override 
    public void run() { 
     while (true) { 
      Socket s = null; 

      try { 
       s = ss.accept(); 
       BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream())); 
       String operands = br.readLine(); 
       System.out.println(operands + " was received"); 
       PrintWriter pw = new PrintWriter(s.getOutputStream(), true); 
       pw.println(operands + " right back!"); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
     } 
    } 
} 

我试图把while循环进入我的服务器和我的客户端和服务器移动到默认包，但都没有帮助。我也尝试使用read()而不是readLine()，并以\r\n结束printWriter的行，但在那里没有成功。

为什么我的代码挂在readLine()上，特别是当示例代码不是？

Answer 1

什么readline()所做的是等到它看到一个新的行字符，直到它返回，因此readLine（）。

在你的客户端，你不写一个新行。您可以使用：

printWriter.write("Sent from client!"); 

相反，写一个换行符到使用的println流，

printWriter.println("Sent from client!"); 

Answer 2

Server希望读取行，所以你需要你的按摩后添加行分隔符。要做到这一点，而不是

printWriter.write("Sent from client!"); 

在客户端使用

printWriter.println("Sent from client!"); 
//   ^^^^^^^ 

或

printWriter.write("Sent from client!"+System.lineSeparator()); 
printWriter.flush(); 

您将需要flush自己，因为自动冲洗中的PrintWriter仅适用于println，printf，或format，不适用于write方法