HTTP删除请求正文问题 [英] HTTP Delete with Request Body issues

问题描述

任何人都可以解释以下内容：

Can anyone explain the following:

package com.foo.bar;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.ProtocolException;
import java.net.URL;
import org.springframework.util.FileCopyUtils;

public class ATest {

    public static void main(String[] args) throws Exception {
       try {
           final String payload = "{\"parentExecutor\":\"foo1233\"}";
           URL url = new URL("http://localhost/notes");
           final HttpURLConnection connection = (HttpURLConnection) url.openConnection();
           connection.setRequestMethod("DELETE");
           connection.setRequestProperty("Accept", "application/json");
           connection.setRequestProperty("Content-Type", "application/json");
           FileCopyUtils.copy(payload.getBytes(), connection.getOutputStream());
           connection.connect();
           final InputStream is = connection.getInputStream();
           int b = is.read();
           String result = "";
           while (b != -1) {
               result += (char) b;
               b = is.read();
           }
           System.out.println(connection.getResponseCode());
           System.out.println(result);
           is.close();
       }
       catch (final ProtocolException e) {
          e.printStackTrace();
       }
   }
}

以上示例引发以下示例异常：

The example above throws the following exception:

java.net.ProtocolException: cannot write to a URLConnection if doOutput=false - call setDoOutput(true)
    at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:995)
    at com.foo.bar.ATest.main(ATest.java:24)

但是，如果我添加对 setDoOutput（true）的调用，则会抛出以下异常：

However if I add a call to setDoOutput(true), the following exception is thrown:

java.net.ProtocolException: HTTP method DELETE doesn't support output
    at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1004)
    at com.foo.bar.ATest.main(ATest.java:25)

然后，如果我将协议从 http 更改为 https ，则不会抛出任何异常，我会从中获取预期的响应代码和内容服务器。我查看了源代码，可以跟踪调用并跟踪异常发生的位置，但为什么通过HTTPS而不是HTTP发出这样的请求呢？

Then, if I change the protocol from http to https no exception is thrown and I get back the expected response code and content from the server. I looked at the source code and can follow the calls and trace where the exceptions are happening, but why would it be OK to make such a request via HTTPS but not HTTP?

推荐答案

这是 HttpURLConnection 的限制（我认为它是一个错误或至少是一个愚蠢的功能）。您至少并不是唯一一个在使用 URLConnection 处理REST Web服务时遇到此问题的人。

This is a limitation (I'd consider it to be a bug or at least a stupid feature) of HttpURLConnection. You're at least not the only one who encounters this when dealing with REST webservices using URLConnection.

考虑使用<改为使用href =http://hc.apache.org/httpcomponents-client-ga/> Apache HttpComponents客户端。

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