用于我的登录android的异步任务

在我将登录代码实现到异步任务doInBackground方法中之后，我的应用程序崩溃了。我需要这个帮助，因为如果我不为登录实现异步任务，我在实际设备中的应用程序将由于策略问题而崩溃。我能知道我的错误在哪里吗

以下是我的背景任务：

// Checking login in background
    protected String doInBackground(String... params) {
        String email = inputEmail.getText().toString();
        String password = inputPassword.getText().toString();
        UserFunctions userFunction = new UserFunctions();
        JSONObject json = userFunction.loginUser(email, password);

        // check for login response
        try {
            if (json.getString(KEY_SUCCESS) != null) {
                loginErrorMsg.setText("");
                String res = json.getString(KEY_SUCCESS);
                if (Integer.parseInt(res) == 1) {
                    // user successfully logged in
                    // Store user details in SQLite Database
                    DatabaseHandler db = new DatabaseHandler(getApplicationContext());
                    JSONObject json_user = json.getJSONObject("user");

                    // Clear all previous data in database
                    userFunction.logoutUser(getApplicationContext());
                    db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));

                    // Launch HomePage Screen
                    Intent homepage = new Intent(getApplicationContext(), HomepageActivity.class);

                    // Close all views before launching HomePage
                    homepage.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(homepage);

                    // Close Login Screen
                    finish();
                } else {
                    // Error in login
                    loginErrorMsg.setText("Incorrect username/password");
                }
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return null;
    }

这是我的日志：

08-18 22:34:59.088: E/JSON(382): {"tag":"login","success":1,"error":0,"uid":"502cfeb2e60004.54904838","user":{"name":"user1","email":"user1@gmail.com","created_at":"2012-08-16 22:07:46","updated_at":null}}
08-18 22:34:59.137: E/AndroidRuntime(382): FATAL EXCEPTION: AsyncTask #1
08-18 22:34:59.137: E/AndroidRuntime(382): java.lang.RuntimeException: An error occured while executing doInBackground()
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.os.AsyncTask$3.done(AsyncTask.java:200)
08-18 22:34:59.137: E/AndroidRuntime(382):  at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
08-18 22:34:59.137: E/AndroidRuntime(382):  at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
08-18 22:34:59.137: E/AndroidRuntime(382):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
08-18 22:34:59.137: E/AndroidRuntime(382):  at java.util.concurrent.FutureTask.run(FutureTask.java:137)
08-18 22:34:59.137: E/AndroidRuntime(382):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
08-18 22:34:59.137: E/AndroidRuntime(382):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
08-18 22:34:59.137: E/AndroidRuntime(382):  at java.lang.Thread.run(Thread.java:1096)
08-18 22:34:59.137: E/AndroidRuntime(382): Caused by: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.view.ViewRoot.checkThread(ViewRoot.java:2802)
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.view.ViewRoot.invalidateChild(ViewRoot.java:607)
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.view.ViewRoot.invalidateChildInParent(ViewRoot.java:633)
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.view.ViewGroup.invalidateChild(ViewGroup.java:2505)
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.view.View.invalidate(View.java:5139)
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.widget.TextView.checkForRelayout(TextView.java:5364)
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.widget.TextView.setText(TextView.java:2688)
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.widget.TextView.setText(TextView.java:2556)
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.widget.TextView.setText(TextView.java:2531)
08-18 22:34:59.137: E/AndroidRuntime(382):  at com.stts.sparetimetradingsystem.LoginActivity$Login.doInBackground(LoginActivity.java:119)
08-18 22:34:59.137: E/AndroidRuntime(382):  at com.stts.sparetimetradingsystem.LoginActivity$Login.doInBackground(LoginActivity.java:1)
08-18 22:34:59.137: E/AndroidRuntime(382):  at android.os.AsyncTask$2.call(AsyncTask.java:185)
08-18 22:34:59.137: E/AndroidRuntime(382):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
08-18 22:34:59.137: E/AndroidRuntime(382):  ... 4 more
08-18 22:35:01.867: E/WindowManager(382): Activity com.stts.sparetimetradingsystem.LoginActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@44f0a510 that was originally added here
08-18 22:35:01.867: E/WindowManager(382): android.view.WindowLeaked: Activity com.stts.sparetimetradingsystem.LoginActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@44f0a510 that was originally added here
08-18 22:35:01.867: E/WindowManager(382):   at android.view.ViewRoot.<init>(ViewRoot.java:247)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.Window$LocalWindowManager.addView(Window.java:424)
08-18 22:35:01.867: E/WindowManager(382):   at android.app.Dialog.show(Dialog.java:241)
08-18 22:35:01.867: E/WindowManager(382):   at com.stts.sparetimetradingsystem.LoginActivity$Login.onPreExecute(LoginActivity.java:106)
08-18 22:35:01.867: E/WindowManager(382):   at android.os.AsyncTask.execute(AsyncTask.java:391)
08-18 22:35:01.867: E/WindowManager(382):   at com.stts.sparetimetradingsystem.LoginActivity$1.onClick(LoginActivity.java:60)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.View.performClick(View.java:2408)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.View.onKeyUp(View.java:4121)
08-18 22:35:01.867: E/WindowManager(382):   at android.widget.TextView.onKeyUp(TextView.java:4431)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.KeyEvent.dispatch(KeyEvent.java:1061)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.View.dispatchKeyEvent(View.java:3740)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
08-18 22:35:01.867: E/WindowManager(382):   at android.widget.ScrollView.dispatchKeyEvent(ScrollView.java:318)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:788)
08-18 22:35:01.867: E/WindowManager(382):   at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent(PhoneWindow.java:1667)
08-18 22:35:01.867: E/WindowManager(382):   at com.android.internal.policy.impl.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1102)
08-18 22:35:01.867: E/WindowManager(382):   at android.app.Activity.dispatchKeyEvent(Activity.java:2063)
08-18 22:35:01.867: E/WindowManager(382):   at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1643)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2471)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2441)
08-18 22:35:01.867: E/WindowManager(382):   at android.view.ViewRoot.handleMessage(ViewRoot.java:1735)
08-18 22:35:01.867: E/WindowManager(382):   at android.os.Handler.dispatchMessage(Handler.java:99)
08-18 22:35:01.867: E/WindowManager(382):   at android.os.Looper.loop(Looper.java:123)
08-18 22:35:01.867: E/WindowManager(382):   at android.app.ActivityThread.main(ActivityThread.java:4627)
08-18 22:35:01.867: E/WindowManager(382):   at java.lang.reflect.Method.invokeNative(Native Method)
08-18 22:35:01.867: E/WindowManager(382):   at java.lang.reflect.Method.invoke(Method.java:521)
08-18 22:35:01.867: E/WindowManager(382):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
08-18 22:35:01.867: E/WindowManager(382):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
08-18 22:35:01.867: E/WindowManager(382):   at dalvik.system.NativeStart.main(Native Method)

08-18 22:34:59.088:E/JSON（382）：{“标记”：“登录”，“成功”：1，“错误”：0，“uid”：“502cfeb2e60004.54904838”，“用户”：{“名称”：“用户1”，“电子邮件”：”user1@gmail.com，“创建时间”：“2012-08-16 22:07:46”，“更新时间”：null}
08-18 22:34:59.137:E/AndroidRuntime（382）：致命异常：AsyncTask#1
08-18 22:34:59.137:E/AndroidRuntime（382）：java.lang.RuntimeException:执行doInBackground（）时出错
08-18 22:34:59.137:E/AndroidRuntime（382）：在android.os.AsyncTask$3.done（AsyncTask.java:200）
08-18 22:34:59.137:E/AndroidRuntime（382）：位于java.util.concurrent.FutureTask$Sync.innerSetException（FutureTask.java:273）
08-18 22:34:59.137:E/AndroidRuntime（382）：在java.util.concurrent.FutureTask.setException（FutureTask.java:124）
08-18 22:34:59.137:E/AndroidRuntime（382）：在java.util.concurrent.FutureTask$Sync.innerRun（FutureTask.java:307）
08-18 22:34:59.137:E/AndroidRuntime（382）：在java.util.concurrent.FutureTask.run（FutureTask.java:137）
08-18 22:34:59.137:E/AndroidRuntime（382）：位于java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1068）
08-18 22:34:59.137:E/AndroidRuntime（382）：位于java.util.concurrent.ThreadPoolExecutor$Worker.run（ThreadPoolExecutor.java:561）
08-18 22:34:59.137:E/AndroidRuntime（382）：在java.lang.Thread.run（Thread.java:1096）
08-18 22:34:59.137:E/AndroidRuntime（382）：原因：android.view.ViewRoot$CalledFromErrorThreadException:只有创建视图层次结构的原始线程才能接触其视图。
08-18 22:34:59.137:E/AndroidRuntime（382）：在android.view.ViewRoot.checkThread（ViewRoot.java:2802）
08-18 22:34:59.137:E/AndroidRuntime（382）：在android.view.ViewRoot.invalidateChild（ViewRoot.java:607）
08-18 22:34:59.137:E/AndroidRuntime（382）：在android.view.ViewRoot.invalidateChildInParent（ViewRoot.java:633）
08-18 22:34:59.137:E/AndroidRuntime（382）：在android.view.ViewGroup.invalidateChild（ViewGroup.java:2505）上
08-18 22:34:59.137:E/AndroidRuntime（382）：在android.view.view.invalidate（view.java:5139）
08-18 22:34:59.137:E/AndroidRuntime（382）：在android.widget.TextView.checkForRelayout（TextView.java:5364）
08-18 22:34:59.137:E/AndroidRuntime（382）：位于android.widget.TextView.setText（TextView.java:2688）
08-18 22:34:59.137:E/AndroidRuntime（382）：在android.widget.TextView.setText（TextView.java:2556）
08-18 22:34:59.137:E/AndroidRuntime（382）：位于android.widget.TextView.setText（TextView.java:2531）
08-18 22:34:59.137:E/AndroidRuntime（382）：在com.stts.sparetimetradingsystem.LoginActivity$Login.doInBackground（LoginActivity.java:119）
08-18 22:34:59.137:E/AndroidRuntime（382）：在com.stts.sparetimetradingsystem.LoginActivity$Login.doInBackground（LoginActivity.java:1）
08-18 22:34:59.137:E/AndroidRuntime（382）：在android.os.AsyncTask$2.call（AsyncTask.java:185）
08-18 22:34:59.137:E/AndroidRuntime（382）：在java.util.concurrent.FutureTask$Sync.innerRun（FutureTask.java:305）
2008-18 22:34:59.137:E/AndroidRuntime（382）：。。。4更多
08-18 22:35:01.867:E/WindowManager（382）：活动com.stts.sparetimetradingsystem.LoginActivity已泄漏window com.android.internal.policy.impl.PhoneWindow$DecorView@44f0a510原来是加在这里的
08-18 22:35:01.867:E/WindowManager（382）：android.view.WindowLeaked:Activity com.stts.sparetimetradingsystem.LoginActivity已泄漏window com.android.internal.policy.impl.PhoneWindow$DecorView@44f0a510原来是加在这里的
08-18 22:35:01.867:E/WindowManager（382）：在android.view.ViewRoot上（ViewRoot.java:247）
08-18 22:35:01.867:E/WindowManager（382）：在android.view.WindowManagerImpl.addView（WindowManagerImpl.java:148）
08-18 22:35:01.867:E/WindowManager（382）：在android.view.WindowManagerImpl.addView（WindowManagerImpl.java:91）
08-18 22:35:01.867:E/WindowManager（382）：在android.view.Window$LocalWindowManager.addView（Window.java:424）
08-18 22:35:01.867:E/WindowManager（382）：在android.app.Dialog.show（Dialog.java:241）
08-18 22:35:01.867:E/WindowManager（382）：位于com.stts.sparetimetradingsystem.LoginActivity$Login.onPreExecute（LoginActivity.java:106）
08-18 22:35:01.867:E/WindowManager（382）：在android.os.AsyncTask.execute（AsyncTask.java:391）
08-18 22:35:01.867:E/WindowManager（382）：位于com.stts.sparetimetradingsystem.LoginActivity$1.onClick（LoginActivity.java:60）
08-18 22:35:01.867:E/WindowManager（382）：在android.view.view.performClick（view.java:2408）上
08-18 22:35:01.867:E/WindowManager（382）：在android.view.view.onKeyUp（view.java:4121）
08-18 22:35:01.867:E/WindowManager（382）：在android.widget.TextView.onKeyUp（TextView.java:4431）
08-18 22:35:01.867:E/WindowManager（382）：在android.view.KeyEvent.dispatch（KeyEvent.java:1061）
08-18 22:35:01.867:E/WindowManager（382）：在android.view.view.dispatchKeyEvent（view.java:3740）上
08-18 22:35:01.867:E/WindowManager（382）：在android.view.ViewGroup.dispatchKeyEvent（ViewGroup.java:788）上
08-18 22:35:01.867:E/WindowManager（382）：在android.view.ViewGroup.dispatchKeyEvent（ViewGroup.java:788）上
08-18 22:35:01.867:E/WindowManager（382）：在android.widget.ScrollView.dispatchKeyEvent（ScrollView.java:318）
08-18 22:35:01.867:E/WindowManager（382）：在android.view.ViewGroup.dispatchKeyEvent（ViewGroup.java:788）上
08-18 22:35:01.867:E/WindowManager（382）：在android.view.ViewGroup.dispatchKeyEvent（ViewGroup.java:788）上
08-18 22:35:01.867:E/WindowManager（382）：在android.view.ViewGroup.dispatchKeyEvent（ViewGroup.java:788）上
08-18 22:35:01.867:E/WindowManager（382）：位于com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent（PhoneWindow.java:1667）
08-18 22:35:01.867:E/WindowManager（382）：位于com.android.internal.policy.impl.PhoneWindow.sup
protected String doInBackground(String... params) {
    String email = inputEmail.getText().toString();
    String password = inputPassword.getText().toString();
    UserFunctions userFunction = new UserFunctions();
    JSONObject json = userFunction.loginUser(email, password);

    return json;
}

protected void onPostExecute(JSONObject json) {

    // check for login response
    try {
        if (json.getString(KEY_SUCCESS) != null) {
            loginErrorMsg.setText("");
            String res = json.getString(KEY_SUCCESS);
            if (Integer.parseInt(res) == 1) {
                // user successfully logged in
                // Store user details in SQLite Database
                DatabaseHandler db = new DatabaseHandler(getApplicationContext());
                JSONObject json_user = json.getJSONObject("user");

                // Clear all previous data in database
                userFunction.logoutUser(getApplicationContext());
                db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));

                // Launch HomePage Screen
                Intent homepage = new Intent(getApplicationContext(), HomepageActivity.class);

                // Close all views before launching HomePage
                homepage.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(homepage);

                // Close Login Screen
                finish();
            } else {
                // Error in login
                loginErrorMsg.setText("Incorrect username/password");
            }
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }
}

loginErrorMsg.post(new Runnable() {
        public void run() {
            loginErrorMsg.setText("");
        }
    });