Question

我想使用TCP从我的手机向我的计算机发送消息。我的电脑是服务器而我的手机是客户端。我可以从手机发送消息到我的电脑，但在输出中，我得到空字符..

我在下方粘贴代码;;

客户端::

public void startApp（）{ 尝试{ //与远程服务器建立套接字连接 streamConnection = （StreamConnection）Connector.open（connectString）;

  // create DataOuputStream on top of the socket connection
  outputStream = streamConnection.openOutputStream();
  dataOutputStream = new DataOutputStream(outputStream);

  // send the HTTP request
  dataOutputStream.writeChars("Hello");
  dataOutputStream.flush();

  // create DataInputStream on top of the socket connection
  inputStream = streamConnection.openInputStream();
  dataInputStream = new DataInputStream(inputStream);

  // retrieve the contents of the requested page from Web server
  String test="";
  int inputChar;
  System.out.println("Entering read...........");
  while ( (inputChar = dataInputStream.read()) != -1) {
     // test=test+((char)inputShar);
    results.append((char) inputChar);
  }
  System.out.println("Leaving read...........");
  // display the page contents on the phone screen
  //System.out.println(" Result are "+results.toString());
  System.out.println("   ");
  resultField = new StringItem(null, results.toString());
  System.out.println("Client says "+resultField);
  resultScreen.append(resultField);
  myDisplay.setCurrent(resultScreen);

} catch (IOException e) {
  System.err.println("Exception caught:" + e);
} finally {
  // free up I/O streams and close the socket connection
  try {
    if (dataInputStream != null)
      dataInputStream.close();
  } catch (Exception ignored) {}
  try {
    if (dataOutputStream != null)
      dataOutputStream.close();
  } catch (Exception ignored) {}
  try {
    if (outputStream != null)
      outputStream.close();
  } catch (Exception ignored) {}
  try {
    if (inputStream != null)
      inputStream.close();
  } catch (Exception ignored) {}
  try {
    if (streamConnection != null)
      streamConnection.close();
  } catch (Exception ignored) {}
}

}

我的服务器：

public class Main {

/**
 * @param args the command line arguments
 */
public static void main(String[] args)  {
    // TODO code application logic here
  try{
      ServerSocket sck=new ServerSocket(880);
      Socket client=sck.accept();
      InputStream inp= client.getInputStream();
      int  i;
      OutputStream out=client.getOutputStream();
      out.write("Testing ".getBytes());
      System.out.println("Server has responded          ");
      String str="";
      while((i=inp.read())!=-1){

          str=str+((char) i);
           System.out.println("USer says "+ str);
      }

  }
  catch(Exception e){
      System.out.println("Error "+e);
  }

}

}

我的服务器输出;;

服务器已响应
USer说null H 用户说null H null 用户说null H null e 等等

我不应该得到这个空字符，为什么我得到它？另一件事，我的服务器正在写入流但客户端无法接收，为什么呢？我需要使用单独的线程吗？

先谢谢

Answer 1

我猜这不是你真正的代码，你的真实代码将str初始化为null。

为什么我在输出中收到null？

1 个答案: