Java program to read objects from a .ser file located in a server

Question

My idea is that I want to read an object from a serialized file located in a server. How to do that?

I can only read .txt file using the following code :

   void getInfo() {
    try {
        URL url;
        URLConnection urlConn;
        DataInputStream dis;

        url = new URL("http://localhost/Test.txt");

        // Note:  a more portable URL: 
        //url = new URL(getCodeBase().toString() + "/ToDoList/ToDoList.txt");

        urlConn = url.openConnection();
        urlConn.setDoInput(true);
        urlConn.setUseCaches(false);

        dis = new DataInputStream(urlConn.getInputStream());

        String s;
        while ((s = dis.readLine()) != null) {
            System.out.println(s);
        }
        dis.close();
    } catch (MalformedURLException mue) {
        System.out.println("Error!!!");
    } catch (IOException ioe) {
        System.out.println("Error!!!");
    }
   }

Answer 1

You can do this with this method

  public Object deserialize(InputStream is) {
    ObjectInputStream in;
    Object obj;
    try {
      in = new ObjectInputStream(is);
      obj = in.readObject();
      in.close();
      return obj;
    }
    catch (IOException ex) {
      ex.printStackTrace();
      throw new RuntimeException(ex);
    }
    catch (ClassNotFoundException ex) {
      ex.printStackTrace();
      throw new RuntimeException(ex);
    }
  }

feed it with urlConn.getInputStream() and you'll get the Object . DataInputStream is not fit to read serialized objets that are done with ObjectOutputStream . Use ObjectInputStream respectively.

To write an object to the file there's another method

  public void serialize(Object obj, String fileName) {
    FileOutputStream fos;
    ObjectOutputStream out;
    try {
      fos = new FileOutputStream(fileName);
      out = new ObjectOutputStream(fos);
      out.writeObject(obj);
      out.close();
    }
    catch (IOException ex) {
      ex.printStackTrace();
      throw new RuntimeException(ex);
    }
  }