Question

我正在尝试在我的Android应用中上传图片文件，但我收到的响应代码 400 和 responseMessage = null 。 API接受image file和另外一个额外字段作为POST消息。

以下是我的代码：

public String sendPostRequest(String requestURL,
                              HashMap<String, String> postDataParams) {

    URL url;

    StringBuilder sb = new StringBuilder();
    try {
        url = new URL(requestURL);

        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setReadTimeout(15000);
        conn.setConnectTimeout(15000);
        conn.setRequestMethod("POST");
        conn.setDoInput(true);
        conn.setDoOutput(true);


        OutputStream os = conn.getOutputStream();
        BufferedWriter writer = new BufferedWriter(
                new OutputStreamWriter(os, "UTF-8"));
        writer.write(getPostDataString(postDataParams));

        writer.flush();
        writer.close();
        os.close();
        int responseCode = conn.getResponseCode();

        if (responseCode == HttpsURLConnection.HTTP_OK) {
            BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            sb = new StringBuilder();
            String response;
            while ((response = br.readLine()) != null){
                sb.append(response);
            }
        }

    } catch (Exception e) {
        e.printStackTrace();
    }
    return sb.toString();
}

修改

我的上面的函数在文件RequestHandler中定义，它从Activity调用如下：

public void uploadImage(){

    final String text = editText.getText().toString().trim();
    final String image = getStringImage(bitmap);
    class UploadImage extends AsyncTask<Void,Void,String> {
        ProgressDialog loading;
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            loading = ProgressDialog.show(FileUploadActivity.this,"Please wait...","uploading",false,false);
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            loading.dismiss();
            Toast.makeText(FileUploadActivity.this,s,Toast.LENGTH_LONG).show();
        }

        @Override
        protected String doInBackground(Void... params) {
            RequestHandler rh = new RequestHandler();
            HashMap<String,String> param = new HashMap<String,String>();
            param.put(KEY_TEXT,text);
            param.put(KEY_IMAGE,image);
            String result = rh.sendPostRequest(UPLOAD_URL, param);
            return result;
        }
    }
    UploadImage u = new UploadImage();
    u.execute();
}

EDIT2： 以下函数也是RequestHandler

的一部分

private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
    StringBuilder result = new StringBuilder();
    boolean first = true;
    for (Map.Entry<String, String> entry : params.entrySet()) {
        if (first)
            first = false;
        else
            result.append("&");

        result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
        result.append("=");
        result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
    }

    return result.toString();
}

Answer 1

Http 400表示＆＃34;错误请求。服务器无法理解请求...＆＃34;首先，您应该首先展示如何在getPostDataString（）函数中撰写请求。

我打赌你没有使用多部分表单数据。见SO answer

Answer 2

我无法发表评论，所以我提供了答案。这是一个奇怪的API。你确定你理解正确吗？您使用POST方法，但不提供内容类型。这既不是JSON也不是XML。这是像URL请求那样的纯字符串格式。服务器返回400并不奇怪。检查API说明。

响应代码400，将图像上传到服务器

修改

2 个答案: