没有收到回应通过TCP/IP使用Java发送XML

Question

我是Java的新手（基本上不得不为此项目动态学习它），但我试图发送一个XML命令到服务器（一个传感器在我的实验室）从它获得一些数据。为此，我编写了一个Java程序，并从命令行运行它。连接建立成功，并且（我认为）该消息正在成功发送 - 但它正陷入“等待响应”。

这里是我的Java代码以供参考。我从客户端/服务器TCP教程中获得了大部分内容，并相应地调整了IP，端口和外发消息。再次，我对此很陌生，所以任何帮助表示赞赏。

// 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 } 
 
}

这是极有可能的东西与传感器多 - 但我想它不会伤害到对码的第二双眼睛。

Answer 1

传感器预计由二进制5字节的报头前面的XML，但是要发送的报头作为8个字符的十六进制编码的串代替。

此外，您正在使用ObjectOutputStream和ObjectInputStream，这是为了序列化Java对象，但您不发送/读取Java对象。所以这些是完全错误的流类使用。

因此，您的代码没有发送传感器期望的内容，所以它不会正确接收您的请求，更不用说发送您可以接收的响应。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); 
    } 
}