以下是我的代码：
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.AsyncTask;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;
import com.example.stecs.async.HttpRequest;
public class Login extends Activity implements OnClickListener {
CheckBox rememberMe;
Button login;
EditText email, password;
// Progress Dialog
private ProgressDialog pDialog;
// JSON parser class
HttpRequest jsonParser = new HttpRequest();
// php login script location:
private static final String LOGIN_URL = "http://www.example.com/portal/webservice/get_user_data.php";
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
// setup input fields
rememberMe = (CheckBox) findViewById(R.id.checkBox1);
login = (Button) findViewById(R.id.login);
email = (EditText) findViewById(R.id.email);
password = (EditText) findViewById(R.id.password);
login.setOnClickListener(this);
// load from SharedPreference
loadSavedPreference();
}
private void loadSavedPreference() {
SharedPreferences sharedPreference = PreferenceManager
.getDefaultSharedPreferences(this);
boolean checkBoxValue = sharedPreference.getBoolean("CheckBox_Value",
false);
String name = sharedPreference.getString("storedName", "");
String pass = sharedPreference.getString("storedPassword", "");
if (checkBoxValue) {
rememberMe.setChecked(true);
} else {
rememberMe.setChecked(false);
}
email.setText(name);
password.setText(pass);
}
private void savePreferences(String key, boolean value) {
SharedPreferences sharedPreferences = PreferenceManager
.getDefaultSharedPreferences(this);
Editor editor = sharedPreferences.edit();
editor.putBoolean(key, value);
editor.commit();
}
private void savePreferences(String key, String value) {
SharedPreferences sharedPreferences = PreferenceManager
.getDefaultSharedPreferences(this);
Editor editor = sharedPreferences.edit();
editor.putString(key, value);
editor.commit();
}
@Override
public void onClick(View v) {
savePreferences("CheckBox_Value", rememberMe.isChecked());
if (rememberMe.isChecked()) {
savePreferences("storedName", email.getText().toString());
savePreferences("storedPassword", password.getText().toString());
finish();
}
switch (v.getId()) {
case R.id.login:
new AttemptLogin().execute();
break;
// Intent in = new Intent(Login.this, IncidentsActivity.class);
// startActivity(in);
}
}
class AttemptLogin extends AsyncTask<String, String, String> {
boolean failure = false;
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(Login.this);
pDialog.setMessage("Attempting login..");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected String doInBackground(String... args) {
// Check for success tag
int success = 1;
String eMail = email.getText().toString();
String passWord = password.getText().toString();
try {
// Building Parameters
JSONObject jo = new JSONObject();
jo.put("email", eMail);
jo.put("password", passWord);
Log.d("request!", "starting");
// getting product details by making HTTP request
String json = jsonParser.postData(LOGIN_URL, jo);
// check your log for json response
Log.d("Login attempt", json.toString());
// json success tag
if(success == 1){
Log.d("Login Credentials - UserName!!!", eMail);
Log.d("Login Credentials - Password!!!", passWord);
Log.d("Login Successful!", json.toString());
Intent i = new Intent(Login.this, IncidentsActivity.class);
// finish();
startActivity(i);
return json;
}else {
Log.d("Login Falure!", json.toString());
return json;
}
// success = json.getInt(TAG_SUCCESS);
// if (success == 1) {
// Log.d("Login Successful!", json.toString());
// Intent i = new Intent(Login.this, IncidentsActivity.class);
// finish();
// startActivity(i);
// return json.getString(TAG_MESSAGE);
// } else {
// Log.d("Login Falure!", json.getString(TAG_MESSAGE));
// return json.getString(TAG_MESSAGE);
// }
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
// After completing background task Dismiss the progress dialog
protected void onPostExecute(String file_url) {
// dismiss the dialog once product deleted
// pDialog.dismiss();
if (file_url != null) {
Toast.makeText(Login.this, file_url, Toast.LENGTH_LONG).show();
}
}
}
}
当我登录应用程序时;它崩溃并给我以下给出的错误，该错误是从LOGCAT中提取的： -
03-23 14:14:31.625: E/AndroidRuntime(11543): FATAL EXCEPTION: AsyncTask #4
03-23 14:14:31.625: E/AndroidRuntime(11543): Process: com.karmick.stecs, PID: 11543
03-23 14:14:31.625: E/AndroidRuntime(11543): java.lang.RuntimeException: An error occured while executing doInBackground()
03-23 14:14:31.625: E/AndroidRuntime(11543): at android.os.AsyncTask$3.done(AsyncTask.java:300)
03-23 14:14:31.625: E/AndroidRuntime(11543): at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
03-23 14:14:31.625: E/AndroidRuntime(11543): at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
03-23 14:14:31.625: E/AndroidRuntime(11543): at java.util.concurrent.FutureTask.run(FutureTask.java:242)
03-23 14:14:31.625: E/AndroidRuntime(11543): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
03-23 14:14:31.625: E/AndroidRuntime(11543): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
03-23 14:14:31.625: E/AndroidRuntime(11543): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
03-23 14:14:31.625: E/AndroidRuntime(11543): at java.lang.Thread.run(Thread.java:841)
03-23 14:14:31.625: E/AndroidRuntime(11543): Caused by: java.lang.NullPointerException
03-23 14:14:31.625: E/AndroidRuntime(11543): at com.karmick.stecs.Login$AttemptLogin.doInBackground(Login.java:161)
03-23 14:14:31.625: E/AndroidRuntime(11543): at com.karmick.stecs.Login$AttemptLogin.doInBackground(Login.java:1)
03-23 14:14:31.625: E/AndroidRuntime(11543): at android.os.AsyncTask$2.call(AsyncTask.java:288)
03-23 14:14:31.625: E/AndroidRuntime(11543): at java.util.concurrent.FutureTask.run(FutureTask.java:237)
03-23 14:14:31.625: E/AndroidRuntime(11543): ... 4 more
03-23 14:14:35.185: I/Process(11543): Sending signal. PID: 11543 SIG: 9
请帮帮我。我是新手，非常需要帮助。
非常感谢。
答案 0 :(得分：0)
从doInBackground()
Intent i = new Intent(Login.this, IncidentsActivity.class);
startActivity(i);
将其添加到onPostExecute()这样的
protected void onPostExecute(String file_url) {
// dismiss the dialog once product deleted
//pDialog.dismiss();
if (file_url != null) {
Toast.makeText(Login.this, file_url, Toast.LENGTH_LONG).show();
}
Intent i = new Intent(Login.this, IncidentsActivity.class);
startActivity(i);
}
答案 1 :(得分：0)
如果只有AsyncTask使用
，那么首先要做的事情private ProgressDialog pDialog;
然后不要在AsyncTask之外定义它的不良做法。并从doInBackground中删除所有与UI相关的东西，只有UI线程有权修改视图。
您的开始活动代码应该是onPostExecute（）方法。
主要问题是ProgressDialog对象，这就是为什么窗口泄漏错误即将来临，因为你的doInBackground正在崩溃。