通过JSON解析器将数据接收到android上的ListView时出错
尝试通过JSON请求从数据库获取数据时出错。我使用的是arrayList哈希映射。我收到一个JSON错误。 这是我的日志。请帮忙通过JSON解析器将数据接收到android上的ListView时出错,android,mysql,json,android-asynctask,android-json,Android,Mysql,Json,Android Asynctask,Android Json,尝试通过JSON请求从数据库获取数据时出错。我使用的是arrayList哈希映射。我收到一个JSON错误。 这是我的日志。请帮忙 03-20 04:59:18.245:E/JSON解析器（2438）：解析数据org.JSON.JSONException:Value时出错http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd 无法将java.lang.String类型的转换为JSONObject 03-20 04:59:20.716:E/AndroidR
03-20 04:59:18.245:E/JSON解析器（2438）：解析数据org.JSON.JSONException:Value时出错http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd 无法将java.lang.String类型的转换为JSONObject
03-20 04:59:20.716:E/AndroidRuntime（2438）：致命异常：AsyncTask#1
03-20 04:59:20.716:E/AndroidRuntime（2438）：进程：com.example.shariety，PID:2438
03-20 04:59:20.716:E/AndroidRuntime（2438）：java.lang.RuntimeException:执行doInBackground（）时出错
03-20 04:59:20.716:E/AndroidRuntime（2438）：在android.os.AsyncTask$3.done（AsyncTask.java:300）
03-20 04:59:20.716:E/AndroidRuntime（2438）：在java.util.concurrent.FutureTask.finishCompletion（FutureTask.java:355）
03-20 04:59:20.716:E/AndroidRuntime（2438）：位于java.util.concurrent.FutureTask.setException（FutureTask.java:222）
03-20 04:59:20.716:E/AndroidRuntime（2438）：在java.util.concurrent.FutureTask.run（FutureTask.java:242）处
03-20 04:59:20.716:E/AndroidRuntime（2438）：在android.os.AsyncTask$SerialExecutor$1.run（AsyncTask.java:231）
03-20 04:59:20.716:E/AndroidRuntime（2438）：位于java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1112）
03-20 04:59:20.716:E/AndroidRuntime（2438）：位于java.util.concurrent.ThreadPoolExecutor$Worker.run（ThreadPoolExecutor.java:587）
03-20 04:59:20.716:E/AndroidRuntime（2438）：在java.lang.Thread.run（Thread.java:818）处
03-20 04:59:20.716:E/AndroidRuntime（2438）：原因：java.lang.NullPointerException:尝试对空对象引用调用虚拟方法“java.lang.String org.json.JSONObject.toString（）”
03-20 04:59:20.716:E/AndroidRuntime（2438）：在com.example.shaerity.ListTest$LoadAllProducts.doInBackground（ListTest.java:134）
03-20 04:59:20.716:E/AndroidRuntime（2438）：在com.example.shaerity.ListTest$LoadAllProducts.doInBackground（ListTest.java:1）
03-20 04:59:20.716:E/AndroidRuntime（2438）：在android.os.AsyncTask$2.call（AsyncTask.java:288）
03-20 04:59:20.716:E/AndroidRuntime（2438）：在java.util.concurrent.FutureTask.run（FutureTask.java:237）
03-20 04:59:20.716:E/AndroidRuntime（2438）：。。。4更多
03-20 04:59:29.035:E/WindowManager（2438）：android.view.WindowLeaked:Activity com.example.shareity.ListTest泄漏了最初添加到此处的window com.android.internal.policy.impl.PhoneWindow$DecorView{32244a1 V.E…..R……d0,0-480174}
03-20 04:59:29.035:E/WindowManager（2438）：在android.view.ViewRootImpl。（ViewRootImpl.java:363）
03-20 04:59:29.035:E/WindowManager（2438）：在android.view.WindowManagerGlobal.addView（WindowManagerGlobal.java:261）
03-20 04:59:29.035:E/WindowManager（2438）：在android.view.WindowManagerImpl.addView（WindowManagerImpl.java:69）
03-20 04:59:29.035:E/WindowManager（2438）：在android.app.Dialog.show（Dialog.java:298）
03-20 04:59:29.035:E/WindowManager（2438）：在com.example.shareity.ListTest$LoadAllProducts.onPreExecute（ListTest.java:121）
03-20 04:59:29.035:E/WindowManager（2438）：位于android.os.AsyncTask.executeOnExecutor（AsyncTask.java:587）
03-20 04:59:29.035:E/WindowManager（2438）：在android.os.AsyncTask.execute（AsyncTask.java:535）
03-20 04:59:29.035:E/WindowManager（2438）：在com.example.shareity.ListTest.onCreate（ListTest.java:61）上
03-20 04:59:29.035:E/WindowManager（2438）：位于android.app.Activity.performCreate（Activity.java:5933）
03-20 04:59:29.035:E/WindowManager（2438）：位于android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1105）
03-20 04:59:29.035:E/WindowManager（2438）：在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2251）
03-20 04:59:29.035:E/WindowManager（2438）：在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2360）
03-20 04:59:29.035:E/WindowManager（2438）：在android.app.ActivityThread.access$800（ActivityThread.java:144）
03-20 04:59:29.035:E/WindowManager（2438）：在android.app.ActivityThread$H.handleMessage（ActivityThread.java:1278）
03-20 04:59:29.035:E/WindowManager（2438）：位于android.os.Handler.dispatchMessage（Handler.java:102）
03-20 04:59:29.035:E/WindowManager（2438）：位于android.os.Looper.loop（Looper.java:135）
03-20 04:59:29.035:E/WindowManager（2438）：位于android.app.ActivityThread.main（ActivityThread.java:5221）
03-20 04:59:29.035:E/WindowManager（2438）：位于java.lang.reflect.Method.invoke（本机方法）
03-20 04:59:29.035:E/WindowManager（2438）：位于java.lang.reflect.Method.invoke（Method.java:372）
03-20 04:59:29.035:E/WindowManager（2438）：位于com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run（ZygoteInit.java:899）
03-20 04:59:29.035:E/WindowManager（2438）：位于com.android.internal.os.ZygoteInit.main（ZygoteInit.java:694）
`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));
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"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
//from here
while ((line = reader.readLine()) != null) {
if(!line.startsWith("<", 0)){
if(!line.startsWith("(", 0)){
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;
}`
package com.example.shareity;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import com.example.shareity.library.JSONParser;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class ListTest extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> productsList;
// url to get all products list
private static String url_all_products = "http://10.0.2.2/shareity/get_all.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "products";
private static final String TAG_PID = "eid";
private static final String TAG_NAME = "ename";
// products JSONArray
JSONArray products = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_events);
// Hashmap for ListView
productsList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProducts().execute();
// Get listview
ListView lv = getListView();
// on seleting single product
// launching Edit Product Screen
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String pid = ((TextView) view.findViewById(R.id.pid)).getText()
.toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(),
ListTest.class);
// sending pid to next activity
in.putExtra(TAG_PID, pid);
// starting new activity and expecting some response back
startActivityForResult(in, 100);
}
});
}
// Response from Edit Product Activity
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// if result code 100
if (resultCode == 100) {
// if result code 100 is received
// means user edited/deleted product
// reload this screen again
Intent intent = getIntent();
finish();
startActivity(intent);
}
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllProducts extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(ListTest.this);
pDialog.setMessage("Loading products. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All products from url
* */
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_PID);
String name = c.getString(TAG_NAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, id);
map.put(TAG_NAME, name);
// adding HashList to ArrayList
productsList.add(map);
}
} else {
// no products found
// Launch Add New product Activity
Intent i = new Intent(getApplicationContext(),
ListTest.class);
// Closing all previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
ListTest.this, productsList,
R.layout.list_item, new String[] { TAG_PID,
TAG_NAME},
new int[] { R.id.pid, R.id.name });
// updating listview
setListAdapter(adapter);
}
});
}
}