我知道这里也存在同样的问题，但我相信我的情况不同，我觉得很困惑。当我的JSON链接是private static String url = "http://10.0.2.2/shareity/test.php/";时，我会得到这个错误。但是，当我在文本文件private static String url = "http://10.0.2.2/shareity/json.txt";中有完全相同的JSON数据时，它可以完美地工作。我的问题是，当我只从PHP文件本身获取JSON时，为什么会发生这种情况？
我的日志：
03-30 09:31:01.250: E/JSON Parser(3129): Error parsing data org.json.JSONException: Value [{"eid":"1","ename":"First","edesc":"Chirath"}, {"eid":"2","ename":"New one","edesc":"Checking if tiisssf"}, {"eid":"3","ename":"Blood Donation","edesc":"Giv the blud"}, {"eid":"4","ename":"Clean","edesc":"cleant eh thin g"}] of type org.json.JSONArray cannot be converted to JSONObject
03-30 09:31:01.260: W/EGL_emulation(3129): eglSurfaceAttrib not implemented
03-30 09:31:01.260: W/OpenGLRenderer(3129): Failed to set EGL_SWAP_BEHAVIOR on surface 0x7ff0079d5140, error=EGL_SUCCESS
03-30 09:31:01.310: D/AndroidRuntime(3129): Shutting down VM
03-30 09:31:01.310: E/AndroidRuntime(3129): FATAL EXCEPTION: main
03-30 09:31:01.310: E/AndroidRuntime(3129): Process: learn2crack.listview, PID: 3129
03-30 09:31:01.310: E/AndroidRuntime(3129): java.lang.NullPointerException: Attempt to invoke virtual method 'org.json.JSONArray org.json.JSONObject.getJSONArray(java.lang.String)' on a null object reference
03-30 09:31:01.310: E/AndroidRuntime(3129): at learn2crack.listview.MainActivity$JSONParse.onPostExecute(MainActivity.java:108)
03-30 09:31:01.310: E/AndroidRuntime(3129): at learn2crack.listview.MainActivity$JSONParse.onPostExecute(MainActivity.java:1)
03-30 09:31:01.310: E/AndroidRuntime(3129): at android.os.AsyncTask.finish(AsyncTask.java:632)
03-30 09:31:01.310: E/AndroidRuntime(3129): at android.os.AsyncTask.access$600(AsyncTask.java:177)
03-30 09:31:01.310: E/AndroidRuntime(3129): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
03-30 09:31:01.310: E/AndroidRuntime(3129): at android.os.Handler.dispatchMessage(Handler.java:102)
03-30 09:31:01.310: E/AndroidRuntime(3129): at android.os.Looper.loop(Looper.java:135)
03-30 09:31:01.310: E/AndroidRuntime(3129): at android.app.ActivityThread.main(ActivityThread.java:5221)
03-30 09:31:01.310: E/AndroidRuntime(3129): at java.lang.reflect.Method.invoke(Native Method)
03-30 09:31:01.310: E/AndroidRuntime(3129): at java.lang.reflect.Method.invoke(Method.java:372)
03-30 09:31:01.310: E/AndroidRuntime(3129): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
03-30 09:31:01.310: E/AndroidRuntime(3129): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
这是我的主要活动
public class MainActivity extends Activity {
ListView list;
TextView eid;
TextView ename;
TextView edesc;
Button Btngetdata;
ArrayList<HashMap<String, String>> oslist = new ArrayList<HashMap<String, String>>();
//URL to get JSON Array
private static String url = "http://10.0.2.2/shareity/test.php/";
//JSON Node Names
private static final String TAG_OS = "events";
private static final String TAG_EID = "eid";
private static final String TAG_ENAME = "ename";
private static final String TAG_EDESC = "edesc";
JSONArray events = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
oslist = new ArrayList<HashMap<String, String>>();
Btngetdata = (Button)findViewById(R.id.getdata);
Btngetdata.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
new JSONParse().execute();
}
});
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
@Override
protected void onPreExecute() {
super.onPreExecute();
eid = (TextView)findViewById(R.id.vers);
ename = (TextView)findViewById(R.id.name);
edesc = (TextView)findViewById(R.id.api);
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected JSONObject doInBackground(String... args) {
JSONParser jParser = new JSONParser();
// Getting JSON from URL
JSONObject json = jParser.getJSONFromUrl(url);
return json;
}
@Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
try {
// Getting JSON Array from URL
events = json.getJSONArray(TAG_OS);
for(int i = 0; i < events.length(); i++){
JSONObject c = events.getJSONObject(i);
// Storing JSON item in a Variable
String eid = c.getString(TAG_EID);
String ename = c.getString(TAG_ENAME);
String edesc = c.getString(TAG_EDESC);
// Adding value HashMap key => value
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_EID, eid);
map.put(TAG_ENAME, ename);
map.put(TAG_EDESC, edesc);
oslist.add(map);
list=(ListView)findViewById(R.id.list);
ListAdapter adapter = new SimpleAdapter(MainActivity.this, oslist,
R.layout.list_v,
new String[] { TAG_EID,TAG_ENAME, TAG_EDESC }, new int[] {
R.id.vers,R.id.name, R.id.api});
list.setAdapter(adapter);
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(MainActivity.this, "You Clicked at "+oslist.get(+position).get("name"), Toast.LENGTH_SHORT).show();
}
});
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
这是我的php API：
<?php
//Create Database connection
$db = mysql_connect("localhost","root","");
if (!$db) {
die('Could not connect to db: ' . mysql_error());
}
//Select the Database
mysql_select_db("shareity",$db);
//Replace * in the query with the column names.
$result = mysql_query("select * from event2", $db);
//Create an array
$json_response = array();
while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
$row_array['eid'] = $row['eid'];
$row_array['ename'] = $row['ename'];
$row_array['edesc'] = $row['edesc'];
//$row_array['esdate'] = $row['esdate'];
//$row_array['eedate'] = $row['eedate'];
//$row_array['estime'] = $row['estime'];
//$row_array['eetime'] = $row['eetime'];
//$row_array['egoal'] = $row['egoal'];
//$row_array['createdby'] = $row['createdby'];
//push the values in the array
array_push($json_response,$row_array);
}
echo json_encode($json_response);
//Close the database connection
fclose($db);
?>
这是我的JSONParser类：
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
//BufferedReader reader = new BufferedReader(new InputStreamReader(
//is, "iso-8859-1"), 8);
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"UTF-8"));
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "'n");
}
is.close();
Log.d("JSON before to string: ", "> " + json);
json = sb.toString();
Log.d("JSON after to string: ", "> " + json);
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
Log.d("JSONObject: ", "> " + jObj);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
试试这个，它会起作用的将以下内容放在您的php代码的顶部
header('Content-Type: application/json');
并且首先关闭mysql连接而不是fclose（我不确定）
mysql_close();
echo json_encode(array('events'=>$json_response));
您从字符串创建jsonObject，但是这个字符串jsonaray
JSONArray jsonArray = new JSONArray(yourJSONString);
for(int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObj = jsonArray.getJSONObject(i);
}