沒有收到迴應通過TCP/IP使用Java發送XML

Question

我是Java的新手（基本上不得不爲此項目動態學習它），但我試圖發送一個XML命令到服務器（一個傳感器在我的實驗室）從它獲得一些數據。爲此，我編寫了一個Java程序，並從命令行運行它。連接建立成功，並且（我認爲）該消息正在成功發送 - 但它正陷入「等待響應」。

這裏是我的Java代碼以供參考。我從客戶端/服務器TCP教程中獲得了大部分內容，並相應地調整了IP，端口和外發消息。再次，我對此很陌生，所以任何幫助表示讚賞。

// Java Socket Example - Client 
 

 
import java.io.IOException; // Throws exception if there is an issue with input or output 
 
import java.io.ObjectInputStream; 
 
import java.io.ObjectOutputStream; 
 
import java.net.InetAddress; // This class represents an Internet Protocol address 
 
import java.net.Socket; 
 
import java.net.UnknownHostException; 
 

 
/** 
 
* This class implements java socket Client 
 
*/ 
 

 
public class SocketClientExample { 
 
\t public static void main(String[] args) throws UnknownHostException, IOException, ClassNotFoundException, InterruptedException { 
 
\t \t // get the localhostIP address, if server is running on some other IP, use that 
 
\t \t System.out.println("Attempting connection to GE Reuter Stokes"); 
 
\t \t InetAddress host = InetAddress.getByName("10.212.160.4"); // IP GOES HERE 
 
\t \t Socket socket = null; // start out as null, protocal 
 
\t \t ObjectOutputStream oos = null; // This will change, just setting default 
 
\t \t ObjectInputStream ois = null; 
 
\t \t // establish the socket connection to the server 
 
\t \t socket = new Socket("10.212.160.4", 3010); // 9876 is just the port number 
 
\t \t System.out.println("Made it past Socket Initialization"); 
 
\t \t // write to socket using ObjectOutputStream 
 
\t \t oos = new ObjectOutputStream(socket.getOutputStream()); // new instance of OOS that will write to the socket 
 
\t \t System.out.println("Sending request to Socket Server"); 
 
\t \t // Initializing request string 
 
\t \t String request = new String("0xF00041 " + "<Discovery><CommChannelName>Unknown</CommChannelName></Discovery>"); 
 
\t \t // In our version, this is where the XML script would go 
 
\t \t oos.writeObject(request); 
 
\t \t System.out.println("Request was sent. Awaiting response."); 
 
\t \t // read the server response message 
 
\t \t ois = new ObjectInputStream(socket.getInputStream()); 
 
\t \t // convert the response into a string 
 
\t \t String message = (String) ois.readObject(); 
 
\t \t System.out.println("Message: " + message); 
 
\t \t // close your resources 
 
\t \t ois.close(); 
 
\t \t oos.close(); 
 
\t \t Thread.sleep(100); 
 
\t } 
 
}

這是極有可能的東西與傳感器多 - 但我想它不會傷害到對碼的第二雙眼睛。

Answer 1

傳感器預計由二進制5字節的報頭前面的XML，但是要發送的報頭作爲8個字符的十六進制編碼的串代替。

此外，您正在使用ObjectOutputStream和ObjectInputStream，這是爲了序列化Java對象，但您不發送/讀取Java對象。所以這些是完全錯誤的流類使用。

因此，您的代碼沒有發送傳感器期望的內容，所以它不會正確接收您的請求，更不用說發送您可以接收的響應。第一

import java.io.IOException; 
import java.io.DataOutputStream; 
import java.io.DataInputStream; 
import jva.io.BufferedInputStream; 
import java.net.Socket; 
import java.net.UnknownHostException; 
import java.nio.charset.StandardCharsets; 
import java.nio.ByteBuffer; 

public class SocketClientExample { 
    public static void main(String[] args) throws UnknownHostException, IOException, ClassNotFoundException, InterruptedException { 
     System.out.println("Attempting connection to GE Reuter Stokes"); 

     // establish the socket connection to the server 
     // using the local IP address, if server is running on some other IP, use that 
     Socket socket = new Socket("10.212.160.4", 3010); 
     System.out.println("Socket Connected"); 

     // write to socket using OutputStream 
     DataOutputStream dos = new DataOutputStream(socket.getOutputStream()); 

     // Initializing request content 
     byte[] request = "<Discovery><CommChannelName>Unknown</CommChannelName></Discovery>".getBytes(StandardCharsets.UTF_8); 

     // DataOutputStream.writeInt() writes in big endian and 
     // DataInputStream.readInt() reads in big endian. 
     // using a ByteBuffer to handle little endian instead. 

     byte[] header = new byte[5]; 
     ByteBuffer buf = ByteBuffer.wrap(header, 1, 4); 
     buf.order(ByteOrder.LITTLE_ENDIAN); 

     // Initializing request header 
     header[0] = (byte) 0xF0; 
     buf.putInt(request.length); 

     System.out.println("Sending request to Socket Server"); 

     // Sending request 
     dos.write(header); 
     dos.write(request); 
     dos.flush(); 

     System.out.println("Request was sent. Awaiting response."); 

     // read from socket using InputStream 
     DataInputStream dis = new DataInputStream(new BufferedInputStream(socket.getInputStream())); 

     // Read response header 
     dis.readFully(header); 
     buf.flip(); 

     // Read response content 
     byte[] response = new byte[buf.getInt()]; 
     dis.readFully(response); 

     // convert the content into a string 
     String message = new String(response, StandardCharsets.UTF_8); 
     System.out.println("Message: " + message); 

     // close your resources 
     dis.close(); 
     dos.close(); 
     socket.close(); 

     Thread.sleep(100); 
    } 
}