java - HttpUrlConnection "PUT"请求还发送 "GET"请求

Question

我的问题是，当我使用 HttpURLConnection 时发送 PUT请求我的REST API ，它发送 GET先请求，然后 PUT要求。我想知道我的代码是否必须发送 PUT请求导致它还发送 GET请求。

我知道这个问题出现在我的 Android 中代码，因为我也使用 Postman发送PUT请求，我从来没有遇到过问题。

下面是我用来发送 HttpUrlConnection 的函数的副本要求。

public String HTTPConnection(String requestType, String url, String input, Context context, Activity activity){
        HttpURLConnection connection = null;
        try {
            URL OBJ = new URL(url);
            connection = (HttpURLConnection) OBJ.openConnection();
            connection.setRequestMethod(requestType);
            switch (requestType.toLowerCase()) {
                case "get":
                    BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                    String inputLine;
                    StringBuilder response = new StringBuilder();
                    int i = 1;
                    while ((inputLine = in.readLine()) != null) {
                        response.append(inputLine);
                        i++;
                    }
                    in.close();
                    return response.toString();
                case "put":
                    if (!input.equals("")){
                        OBJ.openStream();
                        connection.setRequestProperty("Content-type", "application/json");
                        connection.setRequestProperty("Accept", "application/json");
                        connection.setDoOutput(true);
                    }
                    Writer writer = new BufferedWriter(new OutputStreamWriter(connection.getOutputStream(), "UTF-8"));
                    writer.write(input);
                    writer.flush();
                    writer.close();
                    connection.getInputStream();
                    return "";
                default:
                    return "";
            }
        } catch (IOException e){
            e.printStackTrace();
            return null;
        }
    }

Answer 1

OBJ.openStream(); 发送 GET 请求(请参阅 java.net.URL.openStream )，因为它打开一个输入流来读取该 URL 的内容。