Java套接字 – 自定义对象发送

我创建了工作套接字，当我尝试发送文本或数字时，它确定，但是当我尝试发送我的自定义类对象时，我得到了NullPointerException …这是一些代码：

public boolean SendLi(List list) { try { out.writeObject(list); } catch (IOException e) { e.printStackTrace(); System.err.println("Send: Error on OutputStream.write(byte[])"); } return true; } public List RecvLi() { List data; data = new ArrayList(); try{ data = (List) in.readObject(); } catch (IOException e) { System.err.println("Send: Error on OutputStream.read(byte[]) - IOException"); return null; } catch (ClassNotFoundException e) { System.err.println("Send: Error on OutputStream.read(byte[]) - ClassNotFound"); e.printStackTrace(); } return data; } 

实际上，我为Lists制作的代码，但我希望有一些simmilar函数来发送其他对象。 谢谢你的回复！

Answer 1

在通过套接字发送之前，需要序列化自定义类。您要发送的对象

 out.writeObject(list); 

应该序列化，你的类应该实现java.io.Serializable接口

Answer 2

下面的代码片段适用于所有类型的可序列化对象。 请检查。

* IRequest是发送对象。 * IResponse是获得的对象。

客户代码：

  Socket clientSocket = new Socket(hostName, portNo); clientSocket.setSoTimeout(connectionTimeout); try { OutputStream outputStream = clientSocket.getOutputStream(); InputStream inputStream = clientSocket.getInputStream(); ObjectOutputStream objOutputStream = new ObjectOutputStream(outputStream); ObjectInputStream objInputStream = null; try { objOutputStream.writeObject(request); objOutputStream.flush(); objInputStream = new ObjectInputStream(inputStream); res = (IResponse) objInputStream.readObject(); } finally { if (objOutputStream != null) { objOutputStream.close(); } if (outputStream != null) { outputStream.close(); } if (objInputStream != null) { objInputStream.close(); } if (inputStream != null) { inputStream.close(); } } } finally { clientSocket.close(); clientSocket = null; } 

服务器代码：

  private IMessageProcessor messageProcessor = null; private Socket clientSocket = null; private Logger logger = null; String clientIP = clientSocket.getInetAddress().getHostAddress(); int clientPortNr = clientSocket.getPort(); InputStream inputStream = clientSocket.getInputStream(); OutputStream outputStream = clientSocket.getOutputStream(); try { ObjectInputStream objInputStream = null; ObjectOutputStream objOutputStream = null; try { IRequest request = null; objInputStream = new ObjectInputStream(inputStream); objOutputStream = new ObjectOutputStream(outputStream); request = (IRequest) objInputStream.readObject(); IResponse response = null; try { response = messageProcessor.processMessage(clientIP, clientPortNr, request, logger); objOutputStream.writeObject(response); } catch (Exception ex) { objOutputStream.writeObject(ex); } objOutputStream.flush(); objOutputStream.reset(); } finally { if (objInputStream != null) objInputStream.close(); if (objOutputStream != null) objOutputStream.close(); } } finally { inputStream.close(); outputStream.close(); clientSocket.close(); } } catch (Exception ex) { logger.error(ex.getMessage()); }