如何使用 HttpURLConnection 将序列化对象从 Java 类发送到 Servlet？

How to use HttpURLConnection to send serialized object to a Servlet from Java class?

提问by Rajath

I want to send a serialized object from a Java class to a servlet where the servlet should retrieve and save the object as a file. I'm aware that I have to use HttpURLConnection to make a POST request to a servlet, but I don't know whether the below code is correct.

我想将序列化对象从 Java 类发送到 servlet，servlet 应在其中检索对象并将其保存为文件。我知道我必须使用 HttpURLConnection 向 servlet 发出 POST 请求，但我不知道下面的代码是否正确。

private static HttpURLConnection urlCon;
private static ObjectOutputStream out;

public static void main(String[] args) {

    Names names = new Names();
    names.setName("ABC");
    names.setPlace("Bangalore");
    URL url;
    try {
        url = new URL("http://localhost:6080/HttpClientSerializable/HttpPostServlet");
    try {
        out = (ObjectOutputStream) urlCon.getOutputStream();
        out.writeObject(names);
        urlCon = (HttpURLConnection) url.openConnection();
        urlCon.setRequestMethod("POST");
        urlCon.setDoOutput(true);
        out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

        } catch (MalformedURLException e1) {
            e1.printStackTrace();
        }
}

And in the servlet, I have the following code:

在 servlet 中，我有以下代码：

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ObjectInputStream in = new ObjectInputStream(request.getInputStream());
        try {
            names = (Names) in.readObject();

        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        in.close();
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("C:/Documents and Settings/RAGASTH/Desktop/Names"));
        out.writeObject(names);
        out.close();

    }

What should I do to make it work? Also, I want the servlet to send back the object it receives as response.

我该怎么做才能让它发挥作用？此外，我希望 servlet 将它接收到的对象作为响应发回。

Any help would be appreciated. Thanks!

任何帮助，将不胜感激。谢谢！

采纳答案by Vikdor

You would need to

你需要

• Make sure the Namesclass implements java.io.Serializablemarker interface.

• Create an ObjectOutputStream from the servlet's outputstream as follows:

  out = new ObjectOutputStream(urlCon.getOutputStream());
  

• On the receiver side, once you read the object from the servlet's inputstream and persist in the file, write it back to the response's output stream as follows:

  out = new ObjectOutputStream(response.getOutputStream());
  out.writeObject(names);
  out.close();
  

• 确保Names该类实现了java.io.Serializable标记接口。

• 从 servlet 的输出流创建一个 ObjectOutputStream，如下所示：

  out = new ObjectOutputStream(urlCon.getOutputStream());
  

• 在接收方，一旦您从 servlet 的输入流中读取对象并将其保存在文件中，就将其写回响应的输出流，如下所示：

  out = new ObjectOutputStream(response.getOutputStream());
  out.writeObject(names);
  out.close();
  

On the sender's side:

在发送方：

Names names = new Names();
names.setName("ABC");
names.setPlace("Bangalore");
URL url;
try {
    url = new URL("http://localhost:6080/HttpClientSerializable/HttpPostServlet");
    urlCon = (HttpURLConnection) url.openConnection();

    urlCon.setDoOutput(true); // to be able to write.
    urlCon.setDoInput(true); // to be able to read.

    out = new ObjectOutputStream(urlCon.getOutputStream());
    out.writeObject(names);
    out.close();

    ObjectInputStream ois = new ObjectInputStream(urlCon.getInputStream());
    names = (Names) ois.readObject();
    ois.close();
} catch (IOException e) {
    e.printStackTrace();
}
catch (MalformedURLException e1) {
    e1.printStackTrace();
}

On the receiver's side:

在接收方：

ObjectInputStream in = new ObjectInputStream(request.getInputStream());
try {
    names = (Names) in.readObject();
} catch (ClassNotFoundException e) {
    e.printStackTrace();
}
in.close();
ObjectOutputStream out = new ObjectOutputStream(
    new FileOutputStream("C:/Documents and Settings/RAGASTH/Desktop/Names"));
out.writeObject(names);
out.close();

ObjectOutputStream oos = new ObjectOutputStream(response.getOutputStream());
oos.writeObject(names);
oos.close();