Android应用程序中jsonObject的空值 [英] Null value for jsonObject in android app
本文介绍了Android应用程序中jsonObject的空值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我昨晚发布了此问题，但无法解决我的问题.所以我再次发表这篇文章，希望大家可以帮助我.谢谢 ！ 我有从json对象获取值的问题.json_encode将空字符串返回给android.
I posted this problem last night but I can't solve my problem . so I post this again hope members can help me . Thanks ! I have problem with getting value from json object .json_encode return null string to android.
Logcat:
05-01 22:36:21.653: D/Create Response(801): {}
05-01 22:36:21.653: W/System.err(801): org.json.JSONException: No value
for success
05-01 22:36:21.663: W/System.err(801): at
org.json.JSONObject.get(JSONObject.java:354)
05-01 22:36:21.663: W/System.err(801): at
org.json.JSONObject.getInt(JSONObject.java:443)
MyPhp.php
MyPhp.php
<?php
header('Content-type=application/json; charset=utf-8');
$response = array();
// check for required fields
if (isset($_POST['B_Name']) && isset($_POST['Au_Name']) &&
isset($_POST['Pub']) && isset($_POST['Pr']) &&
isset($_POST['B_Genre'])) {
$B_Name = $_POST['B_Name'];
$Au_Name = $_POST['Au_Name'];
$Pub = $_POST['Pub'];
$Pr = $_POST['Pr'];
$B_Genre = $_POST['B_Genre'];
// include db connect class
require_once( __DIR__ . '/android/db_connect.php');
// connecting to db
$db = new DB_CONNECT();
// mysql inserting a new row
$result = mysql_query("INSERT INTO products(Book_Name, Author_Name, Book_Genre, Price, Publication) VALUES('$B_Name', '$Au_Name', '$B_Genre', '$Pr', '$Pub')");
// check if row inserted or not
if ($result) {
// successfully inserted into database
$response["success"] = 1;
$response["message"] = "Product successfully created.";
$encoded_rows = array_map('utf8_encode', $response);
echo json_encode($encoded_rows);
} else {
// failed to insert row
$response["success"] = 0;
$response["message"] = "Oops! An error occurred.";
$encoded_rows = array_map('utf8_encode', $response);
echo json_encode($encoded_rows);
}
} else {
$response["success"] = 0;
$response["message"] = "Required field(s) is missing";
$encoded_rows = array_map('utf8_encode', $response);
echo json_encode($encoded_rows);
}
这是我的doInBackground:
And here is my piece of doInBackground :
String B_Name = BookName.getText().toString();
String Au_Name = AuthorName.getText().toString();
String Pub = Publication.getText().toString();
String Pr = Price.getText().toString();
String B_Genre = BookGenre.getText().toString();
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("B_Name", B_Name));
params.add(new BasicNameValuePair("Au_Name", Au_Name));
params.add(new BasicNameValuePair("Pub", Pub));
params.add(new BasicNameValuePair("Pr", Pr));
params.add(new BasicNameValuePair("B_Genre", B_Genre));
// getting JSON Object
// Note that create product url accepts POST method
JSONObject json = jsonParser.makeHttpRequest(url_create_product,
"POST", params);
// check log cat fro response
Log.d("Create Response", json.toString());
// check for success tag
try {
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
Intent i = new Intent(getApplicationContext(),
MainActivity.class);
startActivity(i);
finish();
}
} catch (JSONException e) {
e.printStackTrace();
}
Jsonparser:
Jsonparser :
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
// function get json from url
// by making HTTP POST or GET mehtod
public JSONObject makeHttpRequest(String url, String method,
List<NameValuePair> params) {
// Making HTTP request
try {
// check for request method
if(method.equals("POST")){
HttpClient httpclient = getNewHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setHeader("Content-type", "application/json");
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse httpResponse = httpclient.execute(httpPost);
if(httpResponse != null){
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}
}else if(method.equals("GET")){
// request method is GET
HttpClient httpclient = getNewHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpclient.execute(httpGet);
if(httpResponse != null){
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
sb.append("{");
sb.append(StringUtils.substringBeforeLast(StringUtils.substringAfter(json, "{"), "}"));
sb.append("}");
String line = null;
if(reader != null){
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
public HttpClient getNewHttpClient() {
try {
KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType());
trustStore.load(null, null);
SSLSocketFactory sf = new MySSLSocketFactory(trustStore);
sf.setHostnameVerifier(SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
HttpParams params = new BasicHttpParams();
HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
HttpProtocolParams.setContentCharset(params, HTTP.UTF_8);
SchemeRegistry registry = new SchemeRegistry();
registry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
registry.register(new Scheme("https", sf, 443));
ClientConnectionManager ccm = new ThreadSafeClientConnManager(params, registry);
return new DefaultHttpClient(ccm, params);
} catch (Exception e) {
return new DefaultHttpClient();
}
}
}
Sale.java
Sale.java
public class Sale extends Activity {
// Progress Dialog
private ProgressDialog pDialog;
JSONParser jsonParser = new JSONParser();
EditText BookName;
EditText AuthorName;
EditText Publication;
EditText Price;
EditText BookGenre;
// url to create new product
private static String url_create_product = "https://5.144.130.36:2083/android/create_product.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
setContentView(R.layout.sale);
BookName = (EditText) findViewById(R.id.BookName);
AuthorName = (EditText) findViewById(R.id.AuthorName);
Publication = (EditText) findViewById(R.id.Publication);
Price = (EditText) findViewById(R.id.Price);
BookGenre = (EditText) findViewById(R.id.BookGenre);
Button confirm = (Button) findViewById(R.id.Confirm);
confirm.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
new CreateNewBook().execute();
}
});
}
CreateNewBook类扩展了AsyncTask {
class CreateNewBook extends AsyncTask {
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(Sale.this);
pDialog.setMessage("?? ??? ??? ???? ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
protected String doInBackground(String... args) {
Sale.this.runOnUiThread(new Runnable() {
public void run() {
String B_Name = BookName.getText().toString();
String Au_Name = AuthorName.getText().toString();
String Pub = Publication.getText().toString();
String Pr = Price.getText().toString();
String B_Genre = BookGenre.getText().toString();
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("B_Name", B_Name));
params.add(new BasicNameValuePair("Au_Name", Au_Name));
params.add(new BasicNameValuePair("Pub", Pub));
params.add(new BasicNameValuePair("Pr", Pr));
params.add(new BasicNameValuePair("B_Genre", B_Genre));
// getting JSON Object
// Note that create product url accepts POST method
JSONObject json = jsonParser.makeHttpRequest(url_create_product,
"POST", params);
// check log cat fro response
Log.d("Create Response", json.toString());
// check for success tag
try {
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
Intent i = new Intent(getApplicationContext(), MainActivity.class);
startActivity(i);
finish();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String result) {
// dismiss the dialog once done
pDialog.cancel();
/*
if (result !=null && result.equals("1"))
Toast.makeText(getApplicationContext(), "submit ", Toast.LENGTH_LONG).show();
*/
}
}
}
推荐答案
尝试使用此解析器:
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
// function get json from url
// by making HTTP POST or GET mehtod
public JSONObject makeHttpRequest(String url, String method,
List<NameValuePair> params) {
// Making HTTP request
try {
// check for request method
if (method == "POST") {
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} else if (method == "GET") {
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpGet);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 10000);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
如果您使用的是$encoded_rows = array_map('utf8_encode', $response);
successs的变量类型从INTEGER更改为STRING.
If you are using $encoded_rows = array_map('utf8_encode', $response);
the variable type of successs is changed from INTEGER to STRING.
例如，带有$encoded_rows = array_map('utf8_encode', $response);的响应将如下所示:
for example, the response with $encoded_rows = array_map('utf8_encode', $response); will look like this:
{"success":"0"}
，并且只有echo json_encode($response);:
{"success":0}
所以，我认为，这:int success = json.getInt(TAG_SUCCESS);不起作用.
So, I think, this: int success = json.getInt(TAG_SUCCESS); won't work.
请勿使用array_map('utf8_encode', $response);或在Java中使用此行:
Don't use array_map('utf8_encode', $response); or use this line in Java:
String success = json.getString(TAG_SUCCESS);
这篇关于Android应用程序中jsonObject的空值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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