我是android开发的初学者。我上传了文件，并从服务器获取响应。但是，响应包含我不想要的值。服务器响应为：值{“time_used”：53840，“result_idcard”：{“index1”：0，“index2”：0，“置信度”：87.42464，“}}。
我只想要置信水平。我怎么能提取出来的？当我运行下面的代码时，logcat显示：
错误：org.json.JSONObject类型的org.json.JSONException无法转换为JSONArray。
请帮我..
/ ** *将文件上传到服务器* /
private class UploadFileToServer extends AsyncTask<Void, Integer, String> {
String docPath= null;
String facePath=null;
public UploadFileToServer(String docPath, String facePath) throws JSONException {
this.docPath = docPath;
this.facePath = facePath;
}
@Override
protected void onPreExecute() {
// setting progress bar to zero
progressBar.setProgress(0);
super.onPreExecute();
}
@Override
protected void onProgressUpdate(Integer... progress) {
// Making progress bar visible
progressBar.setVisibility(View.VISIBLE);
// updating progress bar value
progressBar.setProgress(progress[0]);
// updating percentage value
txtPercentage.setText(String.valueOf(progress[0]) + "%");
//code to show progress in notification bar
FileUploadNotification fileUploadNotification = new FileUploadNotification(UploadActivity.this);
fileUploadNotification.updateNotification(String.valueOf(progress[0]), "Image 123.jpg", "Camera Upload");
}
@Override
protected String doInBackground(Void... params) {
return uploadFile();
}
@SuppressWarnings("deprecation")
public String uploadFile() {
String responseString = null;
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(Config.FILE_UPLOAD_URL);
try {
AndroidMultiPartEntity entity = new AndroidMultiPartEntity(
new ProgressListener() {
@Override
public void transferred(long num) {
publishProgress((int) ((num / (float) totalSize) * 100));
}
});
entity.addPart("imageIdCard", new FileBody(new File(docPath)));
entity.addPart("imageBest", new FileBody(new File(facePath)));
totalSize = entity.getContentLength();
httppost.setEntity(entity);
// Making server call
HttpResponse response = httpclient.execute(httppost);
HttpEntity r_entity = response.getEntity();
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == 200) {
// Server response
responseString = EntityUtils.toString(r_entity);
} else {
responseString = "Error occurred! Http Status Code: "
+ statusCode;
}
} catch (ClientProtocolException e) {
responseString = e.toString();
} catch (IOException e) {
responseString = e.toString();
}
return responseString;
}
@Override
protected void onPostExecute(String result) {
//super.onPostExecute(result);
//if (result != null)
try
{
//Convert response string to Json Array
JSONArray ja = new JSONArray(result);
//Iterate through and retrieve club fields
int n = ja.length();
for (int i = 0; i < n; i++) {
//Get individual Json object from Json Array
JSONObject jo = ja.getJSONObject(i);
//Retrieve each Json object's fields
String request_id = jo.getString("request_id");
Double confidence = jo.getDouble("confidence");
//float confidence= BigDecimal.valueOf(jo.getDouble("result_idcard/confidence")).floatValue();
}
} catch (JSONException e) {
Log.e("JSONException", "Error: " + e.toString());
}
//Log.e(TAG, "Response from server: " + result);
// showing the server response in an alert dialog
showAlert(result);
}
}
您将JSON结果转换为JSONArray，但结果只是一个对象。因此，直接将其解析为对象并获取所需的节点。而且，result_idcard是对象，你还需要将其转换为JSONObject然后获得confidence节点。
试试这个：
@Override
protected void onPostExecute(String result) {
try {
JSONObject jsonObject = new JSONObject(result);
//Retrieve each Json object's fields
JSONObject request_id = jsonObject.getJSONObject("result_idcard");
Double confidence = request_id.getDouble("confidence");
showAlert(confidence);
} catch (JSONException e) {
e.printStackTrace();
}
}
基于OP的问题（到目前为止）和（无效的）JSON示例，OP提供了我已经破解了一些测试，让他们尝试。也许OP会了解这是如何工作的。
只需将此代码放在您的活动中并调用startJsonTest();即可。您将在logcat中看到响应。
private void startJsonTest(){
// The JSON the OP provide in their question!
String json = "{'time_use':53840,'result_idcard':{'index1':0,'index2':0,'confidence':87.42464}}";
testYourJson(json);
}
private void testYourJson(String result) {
try {
if(result == null || result.isEmpty()){
Log.e("testYourJson", "Something went wrong!");
return;
}
Log.e("testYourJson", result);
JSONObject jsonObject = new JSONObject(result);
//Retrieve each Json object's fields
int time = jsonObject.optInt("time_use", -1);
Log.e("testYourJson", "time = " + time);
JSONObject request_id = jsonObject.getJSONObject("result_idcard");
Double confidence = request_id.optDouble("confidence", -222.0f);
int index1 = request_id.optInt("index1", -1);
int index2 = request_id.optInt("index2", -1);
// Show a little confidence ;-)
Log.e("testYourJson", "confidence = " + confidence);
Log.e("testYourJson", "index1 = " + index1);
Log.e("testYourJson", "index2 = " + index2);
} catch (JSONException e) {
Log.e("testYourJson", e.getMessage());
}
}
与Tenten的解决方案（这是正确的）的唯一区别是我使用了optInt和optDouble，因为你可以替换可选值。
这有效！我测试了它。但我怀疑你拥有的JSON与你提供的不同。祝好运！
编辑经过长时间的硬看看屏幕截图，OP已经链接到他的问题，看起来好像index1和index2实际上是Double值！所以实际工作代码需要补偿！