阅读JSON的URL文件我的Android手机上返回黑屏 [英] reading json url file returns blank screen on my Android phone
问题描述
这是我的＃2的第一篇文章，我努力学习的Android。我需要从一个Android应用程序中读取一个JSON文件。
this is my first post on Stackoverflow and I am trying to learn Android. I need to read a json file from within an android application.
我跑我的手机上的以下code，它不会我的手机上显示什么，我只是得到一个空白屏幕。
I ran the following code on my phone and it doesn't display anything on my phone, I just get a blank screen.
我知道有很多方法可以使用Java库来解析JSON但是这不是我所期待的。我想完成阅读使用由Android提供的工具只是这个JSON。这里是我的JSON
I know there are ways to use Java libraries to parse json but that's is NOT what I am looking for. I would like to accomplish reading this json using ONLY tools provided by Android. Here's my json
我使用的是Android 4.0.3
这是我的JSON文件数据：
I am using Android 4.0.3 Here's my json file data:
{
"offers": [
{
"id": "1",
"type":"xyz",
"description":"blah blah",
"url":"http://www.example.com/"
},
{
"id": "1",
"type":"xyz",
"description":"some description",
"url":"http://www.example.com/"
},
{
"id": "1",
"type":"xyz",
"description":"some description",
"url":"http://www.example.com/"
}
]
}
下面是我的MainActivity.java
Here's my MainActivity.java
package com.pega.parsejson;
import java.io.IOException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
TextView jsonWrapper;
HttpClient httpClient;
JSONObject json;
final static String offersUrl="http://somewebsite.com/offers.json";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
jsonWrapper=(TextView) findViewById(R.id.jsonWrap);
httpClient=new DefaultHttpClient();
new Read().execute("description");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public JSONObject jsonOffers() throws ClientProtocolException, IOException, JSONException {
//StringBuilder url=new StringBuilder(offersUrl);
HttpGet get=new HttpGet(offersUrl);
HttpResponse res=httpClient.execute(get);
int status=res.getStatusLine().getStatusCode();
if(status==200){
HttpEntity e=res.getEntity();
String data=EntityUtils.toString(e);
JSONArray timeline=new JSONArray("offers");
JSONObject jsonOffer=timeline.getJSONObject(0); //returns most recent offer
return jsonOffer;
}else{
Toast.makeText(getApplicationContext(), "Error", Toast.LENGTH_SHORT).show();
return null;
}
}
public class Read extends AsyncTask<String, Integer, String>{
@Override
protected String doInBackground(String... params) {
try {
json=jsonOffers();
return (String) json.get("description"); //returns string w/ parameter passed in as "description"
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String result) {
jsonWrapper.setText(result);
}
}
}
我也使用互联网的权限：
I am also using the INTERNET PERMISSIONS:
下面是我的清单文件：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.pega.parsejson"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.INTERNET"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.pega.parsejson.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
和这里是我的TextView正确如下：
And here's my textview right below:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="@+id/jsonWrap"
android:layout_width="match_parent"
android:layout_height="400dp"
android:text="" />
</RelativeLayout>
这是我的logcat的：
And here's my logcat:
[2013-08-07 23:35:41 - parseJson] ------------------------------
[2013-08-07 23:35:41 - parseJson] Android Launch!
[2013-08-07 23:35:41 - parseJson] adb is running normally.
[2013-08-07 23:35:41 - parseJson] Performing com.pega.parsejson.MainActivity activity launch
[2013-08-07 23:35:42 - parseJson] Uploading parseJson.apk onto device 'HT25EHX00690'
[2013-08-07 23:35:42 - parseJson] Installing parseJson.apk...
[2013-08-07 23:35:45 - parseJson] Success!
[2013-08-07 23:35:45 - parseJson] Starting activity com.pega.parsejson.MainActivity on device HT25EHX00690
[2013-08-07 23:35:46 - parseJson] ActivityManager: Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.pega.parsejson/.MainActivity }
请注意我不希望使用任何JSON库解析的json，我严格想用仅适用于Android解析JSON。我只是不明白为什么我的mainActivity.java不显示在手机上任何东西。
Please note I do NOT want to use any json libraries to parse my json, I strictly would like to use ONLY android to parse the json. I just don't get why my mainActivity.java doesn't display anything on phone.
道歉帖子的长度，真的需要帮助的这一个时间敏感的项目，是的，我已经阅读并＃1让利类似的问题似乎回答这个问题。
Apologize for the length of my post, really need help on this for a time sensitive project and YES, I have already read other similar questions on Stackoverflow and none seem to answer this question.
有谁请帮助我在这？
感谢
推荐答案
我相信你的错误就在于code：
I believe your error lies in the code:
HttpEntity e=res.getEntity();
String data=EntityUtils.toString(e);
JSONArray timeline=new JSONArray("offers");
JSONObject jsonOffer=timeline.getJSONObject(0); //returns most recent offer
return jsonOffer;
原因是，你正在创建一个新的JSONArray，而不是使用来自您收到JSON阵列。
The reason is that you are creating a NEW JSONArray instead of using the array from the JSON you receive.
相反，你应该分析收到的JSON，使用内置的JSONObject，然后选择阵列。假设数据持有的JSON文本，你可以这样做：
Instead, you should parse the JSON you receive, using the built-in JSONObject and then select the array. Assuming data holds the JSON text, you could do something like:
JSONObject json = new JSONObject(data);
JSONArray timeline = json.getJSONArray("offers");
return timeline.getJSONObject(0); // return most recent offer
这篇关于阅读JSON的URL文件我的Android手机上返回黑屏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！
