我正在尝试创建一个登录页面。单击按钮，我正在调用一种方法来验证登录凭据（如果已存在于后端django服务器中）。我可以获取用户名和密码的值。我目前面临的问题是，如果我提供后端服务器中已存在的登录凭据，则应用程序正常工作。但是，如果我提供不在后端数据库中的登录凭据，则应用程序崩溃。请帮助
Login.xml代码
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/login_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:background="@drawable/login_background"
android:focusable="true"
android:focusableInTouchMode="true"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin" >
<TextView
android:id="@+id/appName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="50dp"
android:text="Teacher Diary"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="@color/white" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="By"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="@color/white" />
<ImageView
android:id="@+id/logo"
android:layout_width="100sp"
android:layout_height="100sp"
android:layout_gravity="center"
android:contentDescription="@string/home_screen_description"
android:src="@drawable/lo_logo" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:text="@string/app_name"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="@color/white" />
<EditText
android:id="@+id/etUserName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:layout_marginRight="5dp"
android:layout_marginTop="25dp"
android:background="@drawable/apptheme_edit_text_holo_light"
android:ems="10"
android:hint="@string/edit_text_username"
android:singleLine="true"
android:textColor="@color/blue" />
<EditText
android:id="@+id/etPassword"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:layout_marginRight="5dp"
android:background="@drawable/apptheme_edit_text_holo_light"
android:ems="10"
android:hint="@string/edit_text_password"
android:imeOptions="actionGo"
android:inputType="textPassword"
android:textColor="@color/blue" />
<Button
android:id="@+id/btLogin"
android:layout_width="match_parent"
android:layout_height="45dp"
android:layout_marginLeft="5dp"
android:layout_marginRight="5dp"
android:layout_marginTop="20dp"
android:background="@drawable/button_background"
android:text="@string/login"
android:textColor="@color/white"
android:textSize="20dp" />
<TextView
android:id="@+id/tvDisplayMessage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="5dp"
android:text=""
android:textAppearance="?android:attr/textAppearanceMedium"
android:textColor="@color/white" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="150dp"
android:text="The easiest way to conduct assessments!"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="@color/white" />
</LinearLayout>
login.java代码
public class Login extends Activity implements View.OnClickListener {
private SQLiteDatabase m_database;
private LODatabaseHelper m_databaseHelper;
private Button m_btLogin;
private Animation m_anim;
private EditText m_etUsername, m_etPassword;
private String m_username, m_password, m_role, m_schoolId;
private TextView m_displayMessage;
private String ACCESS_TOKEN = "f59Gh28E6@2h13Y";
private static RequestToServiceCallback mGetRequestToServiceCallback;
public static void setCallback(RequestToServiceCallback callback) {
mGetRequestToServiceCallback = callback;
}
public interface RequestToServiceCallback {
void statusReporting(int id);
void stopService();
}
boolean login = true;
ProgressDialog pDialog;
//List of type books this list will store type Book which is our data model
private static List<LoginModel> logindata;
/**
* ATTENTION: This was auto-generated to implement the App Indexing API.
* See https://g.co/AppIndexing/AndroidStudio for more information.
*/
private GoogleApiClient client;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// getActionBar().hide();
ActionBar bar = getActionBar();
bar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#CC25AAE2")));
int titleId = getResources().getIdentifier("action_bar_title", "id",
"android");
TextView abTitle = (TextView) findViewById(titleId);
abTitle.setTextSize(15.5f);
abTitle.setTextColor(Color.WHITE);
SharedPreferences prefs = this.getSharedPreferences("global_settings",
Context.MODE_PRIVATE);
m_username = prefs.getString("username", "");
m_role = prefs.getString("role", "");
if (m_username.contentEquals("")) {
// do Nothing and continue further the user hasn't logged in yet.
// mSync.adminSync("2");
} else {
Intent intent;
if (m_role.contentEquals("admin"))
intent = new Intent(getApplicationContext(), AdminSync.class);
else
intent = new Intent(getApplicationContext(), Home.class);
finish();
startActivity(intent);
}
setContentView(R.layout.login);
/** Initialise m_database variables */
m_databaseHelper = LODatabaseHelper.getHelper(getApplicationContext());
m_database = m_databaseHelper.getWritableDatabase();
LODatabaseUtility.getInstance().setDatabase(m_database);
m_btLogin = (Button) findViewById(R.id.btLogin);
m_btLogin.setOnClickListener(this);
m_displayMessage = (TextView) findViewById(R.id.tvDisplayMessage);
m_etUsername = (EditText) findViewById(R.id.etUserName);
m_etPassword = (EditText) findViewById(R.id.etPassword);
/* Put the last login credentials into the edit texts */
String lastUsername = prefs.getString("username_last", "");
String lastPassword = prefs.getString("password_last", "");
if (lastUsername.contentEquals("")) {
/* Do Nothing */
} else {
m_etUsername.setText(lastUsername);
m_etPassword.setText(lastPassword);
}
setAnimationValue();
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}
private void setAnimationValue() {
m_anim = new AlphaAnimation(0.0f, 1.0f);
m_anim.setDuration(100); // You can manage the time of the blink with
// this parameter
m_anim.setStartOffset(20);
m_anim.setRepeatMode(Animation.REVERSE);
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.btLogin:
/* check the username and password */
if (m_etUsername.getText().length() == 0) {
m_displayMessage.setText("Enter User Name");
if (m_etPassword.getText().length() == 0) {
m_displayMessage.setText("Enter User Name and Password");
}
return;
}
if (m_etPassword.getText().length() == 0) {
m_displayMessage.setText("Enter User Password");
return;
}
m_username = m_etUsername.getText().toString();
m_password = m_etPassword.getText().toString();
//Calling the method that will fetch data
getLoginDetails(m_username, m_password, ACCESS_TOKEN);
break;
}
}
private void getLoginDetails(final String m_username, final String m_password, final String ACCESS_TOKEN) {
//While the app fetched data we are displaying a progress dialog
final ProgressDialog loading = ProgressDialog.show(Login.this, "Please wait... ", "Login in progress", false, false);
Log.e("m_username:", m_username);
Log.e("m_password:", m_password);
App.getRestClient()
.getLoginService()
.getLoginData(m_username, m_password, ACCESS_TOKEN,
new Callback<List<LoginAPIModel>>() {
@Override
public void failure(RetrofitError arg0) {
if(arg0.getKind() == RetrofitError.Kind.CONVERSION || arg0.getKind() == RetrofitError.Kind.NETWORK){
Log.e("Exception","");
}
/*Log.e( "TAG" + "ERROR", "Logindetails table: start = "
+ "" + retrofitError.getMessage());
if (retrofitError.getKind() == RetrofitError.Kind.CONVERSION
|| retrofitError.getKind() == RetrofitError.Kind.NETWORK) {
getLoginDetails(m_username, m_password, ACCESS_TOKEN);
} else {
mGetRequestToServiceCallback.stopService();
}*/
}
@Override
public void success(List<LoginAPIModel> arg0,
Response response) {
//Dismissing the loading progressbar
loading.dismiss();
Log.e("schoolid", arg0.get(0).getSchoolId());
Log.e("username:", arg0.get(0).getUsername());
Log.e("role:", arg0.get(0).getRole());
SharedPreferences prefs = getSharedPreferences(
"global_settings",
Context.MODE_PRIVATE);
Editor editor = prefs.edit();
editor.putString("school_id",
arg0.get(0).getSchoolId());
editor.putString("username",
arg0.get(0).getUsername());
editor.putString("password",
arg0.get(0).getPassword());
editor.putString("role",
arg0.get(0).getRole());
editor.putString("email",
arg0.get(0).getEmail());
editor.putString("user",
arg0.get(0).getUser());
editor.putString("otp",
arg0.get(0).getOtp());
editor.putString("telephone_no",
arg0.get(0).getTelephoneNo());
editor.commit();
String temp1 = arg0.get(0).getRole();
Log.e("Temp1 values:", temp1);
String tempUsername=arg0.get(0).getUsername();
Log.e("username values:", tempUsername);
String tempPassword=arg0.get(0).getPassword();
Log.e("password values:", tempPassword);
Intent intent = null;
if (temp1.contentEquals("admin")) {
intent = new Intent(Login.this, AdminSync.class);
intent.putExtra("mSchoolId", m_schoolId);
finish();
startActivity(intent);
new loginUser().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
}else if (temp1.contentEquals("teacher")) {
loading.dismiss();
m_displayMessage.setText("Invalid username password !");
} else {
//intent = new Intent(Login.this, Home.class);
}
//
}
});
}
我的Logcat：
05-03 13:02:17.156 13719-13719/? E/m_username:: GChjvbj
05-03 13:02:17.156 13719-13719/? E/m_password:: chknmnvv
05-03 13:02:17.293 7409-7419/? E/Parcel: Reading a NULL string not supported here.
05-03 13:02:17.555 13719-13719/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.learningoutcomes, PID: 13719
java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
at java.util.ArrayList.get(ArrayList.java:308)
at com.learningoutcomes.Login$1.success(Login.java:206)
at com.learningoutcomes.Login$1.success(Login.java:184)
at retrofit.CallbackRunnable$1.run(CallbackRunnable.java:45)
at android.os.Handler.handleCallback(Handler.java:808)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5341)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:825)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641)
at dalvik.system.NativeStart.main(Native Method)