我正在尝试为学校制作一个 android 应用程序。这是我首先要发生的事情，当用户登录时，用户名第二次保存在 sharedpreferences 中，使用 sharedpreference 我将在数据库中检索用户信息。第三，解析数据并在文本视图中显示信息。这是我的 php 文件
<?php
/*
Our "config.inc.php" file connects to database every time we include or require
it within a php script. Since we want this script to add a new user to our db,
we will be talking with our database, and therefore,
let's require the connection to happen:
*/
require("config.inc.php");
if (!empty($_POST)) {
//initial query
$query = "Select * FROM userinfo where username = :user";
$query_params = array(':user' = > $_POST['username']);
//execute query
try {
$stmt = $db - > prepare($query);
$result = $stmt - > execute($query_params);
} catch (PDOException $ex) {
$response["success"] = 0;
$response["message"] = "Database Error!";
die(json_encode($response));
}
// Finally, we can retrieve all of the found rows into an array using fetchAll
$rows = $stmt - > fetchAll();
if ($rows) {
$response["success"] = 1;
$response["message"] = "Post Available!";
$response["users"] = array();
foreach($rows as $row) {
$user = array();
$user["username"] = $row["username"];
$user["firstname"] = $row["firstname"];
$user["middlename"] = $row["middlename"];
$user["lastname"] = $row["lastname"];
$user["course"] = $row["course"];
//update our repsonse JSON data
array_push($response["users"], $user);
}
// echoing JSON response
echo json_encode($response);
} else {
$response["success"] = 0;
$response["message"] = "No user available!";
die(json_encode($response));
}
} else {}
?>
这是我的java代码
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.util.Log;
import android.widget.TextView;
public class ProfileActivity extends Activity {
// All xml labels
TextView txtFname;
TextView txtMname;
TextView txtLname;
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jsonParser = new JSONParser();
// Profile json object
JSONArray user;
JSONObject hay;
// Profile JSON url
private static final String PROFILE_URL = "http://10.0.2.2/webservice1/userprofile.php";
// ALL JSON node names
private static final String TAG_PROFILE = "user";
// private static final String TAG_ID = "id";
private static final String TAG_USERNAME = "username";
private static final String TAG_FIRSTNAME = "firstname";
private static final String TAG_MIDDLENAME = "middlename";
private static final String TAG_LASTNAME = "lastname";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_profile);
txtFname = (TextView) findViewById(R.id.fname);
txtMname = (TextView) findViewById(R.id.mname);
txtLname = (TextView) findViewById(R.id.lname);
// Loading Profile in Background Thread
new LoadProfile().execute();
}
/**
* Background Async Task to Load profile by making HTTP Request
* */
class LoadProfile extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
public void test(){
/**
* Updating parsed JSON data into ListView
* */
// Storing each json item in variable
try {
String firstname = hay.getString(TAG_FIRSTNAME);
String middlename = hay.getString(TAG_MIDDLENAME);
String lastname = hay.getString(TAG_LASTNAME);
// displaying all data in textview
txtEmail.setText("Email: " + firstname);
txtMobile.setText("Mobile: " + middlename);
txtAddress.setText("Add: " + lastname);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(ProfileActivity.this);
pDialog.setMessage("Loading profile ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting Profile JSON
* */
protected String doInBackground(String... args) {
// Building Parameters
SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(ProfileActivity.this);
String post_username = sp.getString("username", "anon");
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("username", post_username));
// getting JSON string from URL
JSONObject json = jsonParser.makeHttpRequest(PROFILE_URL, "POST",
params);
// Check your log cat for JSON reponse
Log.d("Profile JSON: ", json.toString());
try {
// profile json object
user = json.getJSONArray(TAG_PROFILE);
} 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
test();
}
}
}
我得到一个空指针异常 ProfileActivity$LoadProfile.test 请帮助我，我只是一个初学者