Java

Question

我正在打开一个 HttpURLConnection 并使用 POST 方法，我正在发送一个 JSON 我从另一个 class 构建的请求。 JSON 的结构正确，因为我已经在调试时对其进行了验证。尝试读取服务器给出的输出响应时抛出异常。这是给定的错误

java.io.IOException: Server returned HTTP response code: 400 for URL:

然而，当我手动尝试从具有 POST 方法 chrome 扩展名的 Web 浏览器输入 Url 时。我可以查看响应并且一切正常。所以我确定它与我建立连接的以下代码有关 read/write.

    URL obj = new URL(url);

    HttpURLConnection connection = (HttpURLConnection) obj.openConnection();
    //add request header
    connection.setRequestMethod("POST");
    connection.setRequestProperty("Content-Type", "application/json");
    //mapping objects to json
    BatchRequest requestParameters = new BatchRequest(o,d);

    ObjectMapper mapper = new ObjectMapper();

    String json = mapper.writeValueAsString(requestParameters);

    connection.setDoOutput(true);
    DataOutputStream os = new DataOutputStream(connection.getOutputStream());

    os.writeBytes(json);
    os.flush();
    os.close();
         // this is where the program throws the exception  
    BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));

    String inputLine;
    StringBuilder response = new StringBuilder();

    while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
    }
    in.close();

URL 和 JSON 请求都是正确的，因为它们在我尝试通过浏览器手动连接时有效。

Answer 1

不需要 DataOutputStream。只是：

OutputStream os = con.getOutputStream();

Java - 从 HttpURLConnection 读取 POST 抛出响应代码 400

Java - Reading POST from HttpURLConnection throwing response code 400

post

json

httpurlconnection