Java Android 如何在异常中获取 HTTPUrlConnection (POST) 响应代码和消息？

Question

这是我的情况。我正在使用 POST 消息调用 Web 身份验证 API。成功后，它会返回一个令牌。否则，它返回指定原因的错误消息 (json)（例如："incorrect password", "account lock", etc），响应代码为400, etc。

从浏览器查看的示例错误：

所以，我设法调用、获取并返回成功消息，但在出现错误时却不行。这是伪代码（我省略了多余的部分。主要关注“catch”范围）：

    HttpURLConnection conn = null; //Must define outside as null?
    try {
        ...
        byte[] postDataBytes = ...

        URL url = new URL(urlLogin);
        conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod( "POST" );
        ...
        conn.getOutputStream().write(postDataBytes);

        Reader in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
        StringBuilder sb = new StringBuilder();
        for (int c; (c = in.read()) >= 0;)
            sb.append((char)c);
        String response = sb.toString(); // Yeah I got this
        return response;
    }
    catch(IOException ex){
        //the variable ex doesn't tell anything about the response code
        //neither the response message

        //so i access the conn to get
        //
        try {
            int responseCode = conn.getResponseCode();
            return "code: " + responseCode; //somehow this line just doesn't work!
        }
        catch (Exception ex2){
        }
    }

更详细地说，IOException 没有说明任何有关响应的信息。所以我访问了HttpURLConnection 变量。

conn.getResponseCode() does return 400,

conn.getResponseMessage() does return "Bad Request"，但不是来自服务器的错误 json 消息。

有什么想法吗？

编辑：

我只是想知道，在异常/错误期间获取响应代码/消息的正确方法是什么。

Answer 1

HttpUrlConnection 中的getErrorStream() 可能就是您要找的。​​p>

    Reader in = new BufferedReader(new InputStreamReader(conn.getErrorStream(), "UTF-8"));

    // Do you response parsing here.