android - Android Back Stack 不会清除
问题描述
编辑：我想出了问题所在。我有 2 个意图（一个用于用户登录时，一个用于用户已经登录），我只更改了第一个从未实际运行的意图。我对此感到愚蠢，但我感谢每个试图提供帮助的人。
所以我有一个登录活动和一个主要活动，我希望从后台堆栈中删除登录活动，这样用户一旦登录就无法返回它。我知道这应该相当简单，我已经尝试了很多东西，但它仍然无法正常工作。我已经尝试过所有 3 个这样的“标志”：
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
并一次添加一个。我也尝试过放置线条finish()或finishAffinity()围绕意图线，但仍然没有运气。我究竟做错了什么？
这是与意图相关的代码：
Intent intent = new Intent(LoginActivity.this, MainActivity.class);
startActivity(intent);
编辑：请求的代码：
AndroidManifest.xml：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.music">
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:networkSecurityConfig="@xml/network_security_config"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme"
android:usesCleartextTraffic="true">
<activity
android:name=".MainActivity"
android:label="@string/title_activity_main"/>
<activity
android:name=".RegisterActivity"
android:label="" />
<activity
android:name=".LoginActivity"
android:label="">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
登录活动.java：
package com.example.music;
import androidx.annotation.StringRes;
import androidx.appcompat.app.AppCompatActivity;
import android.app.ActivityOptions;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.util.Pair;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import com.android.volley.RequestQueue;
import com.android.volley.RetryPolicy;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import com.example.music.ui.Token;
import com.google.gson.Gson;
import org.json.JSONException;
import org.json.JSONObject;
public class LoginActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
GlobalVariables globalVariables = new GlobalVariables();
final TextView title = findViewById(R.id.title);
final EditText email = findViewById(R.id.emailInput);
final EditText password = findViewById(R.id.passwordInput);
final Button signUp = findViewById(R.id.signUp);
Button signIn = findViewById(R.id.signIn);
//check if token exists
SharedPreferences sharedPreferences = getSharedPreferences("StoredValues", MODE_PRIVATE);
String token = sharedPreferences.getString("token", "null");
if(!token.equals("null")){
globalVariables.setToken(token);
Intent myIntent = new Intent(LoginActivity.this, MainActivity.class);
LoginActivity.this.startActivity(myIntent);
}
signUp.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent openRegisterActivity = new Intent(LoginActivity.this, RegisterActivity.class);
Pair[] pairs = new Pair[4];
pairs[0] = new Pair<View, String>(title, "titleTransition");
pairs[1] = new Pair<View, String>(email, "emailTransition");
pairs[2] = new Pair<View, String>(password, "passwordTransition");
pairs[3] = new Pair<View, String>(signUp, "signUpTransition");
ActivityOptions options = ActivityOptions.makeSceneTransitionAnimation(LoginActivity.this, pairs);
getWindow().setExitTransition(null);
startActivity(openRegisterActivity, options.toBundle());
}
});
signIn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(final View view) {
Utils utils = new Utils(getApplicationContext());
GlobalVariables globalVariables = new GlobalVariables();
if(email.getText().toString().equals("") || password.getText().toString().equals("")){
//at least one input is empty
utils.DisplayPopup(view, getResources().getString(R.string.empty_input_box));
}
else{
//everything is good to go
String url = globalVariables.getIPAddress() + "login/";
RequestQueue requestQueue = Volley.newRequestQueue(getApplicationContext());
try {
JSONObject jsonObject = new JSONObject();
jsonObject.put("username", email.getText().toString());
jsonObject.put("password", password.getText().toString());
JsonObjectRequest objectRequest = new JsonObjectRequest(
com.android.volley.Request.Method.POST,
url,
jsonObject,
new com.android.volley.Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
Gson gson = new Gson();
Token token = gson.fromJson(response.toString(), Token.class);
SharedPreferences sharedPreferences = getSharedPreferences("StoredValues", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("token", token.toString());
editor.apply();
Intent intent;
intent = MainActivity.getIntentWithNewTask(getApplicationContext());
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
LoginActivity.this.finish();
Log.e("REST Response", response.toString());
}
},
new com.android.volley.Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Utils utils = new Utils(getApplicationContext());
Log.e("REST Response", error.toString());
if(error.networkResponse.statusCode == 400){
utils.DisplayPopup(view, getResources().getString(R.string.invalid_credentials));
}
}
});
objectRequest.setRetryPolicy(new RetryPolicy() {
@Override
public int getCurrentTimeout() {
return 10000;
}
@Override
public int getCurrentRetryCount() {
return 10000;
}
@Override
public void retry(VolleyError error) throws VolleyError {
Log.e("Volley error", error.toString());
}
});
requestQueue.add(objectRequest);
} catch (JSONException e){
Log.e("JSON Response", e.toString());
}
}
}
});
}
}
MainActivity.java：
package com.example.music;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
import com.google.android.material.tabs.TabLayout;
import androidx.viewpager.widget.ViewPager;
import androidx.appcompat.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import com.example.music.ui.main.SectionsPagerAdapter;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
ViewPager viewPager = findViewById(R.id.view_pager);
viewPager.setAdapter(sectionsPagerAdapter);
TabLayout tabs = findViewById(R.id.tabs);
tabs.setupWithViewPager(viewPager);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.logOut:
SharedPreferences sharedPreferences = getSharedPreferences("StoredValues", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("token", "null");
editor.apply();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
public static Intent getIntent(Context context) {
return new Intent(context, MainActivity.class);
}
public static Intent getIntentWithNewTask(Context context) {
if(context!=null)
{
Intent intent = getIntent(context);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
return intent;
}
return null;
}
}
最小 SDK： 21 目标 SDK： 29
编辑2：
我现在通过覆盖onBackPressedMainActivity 中的方法以“回家”而不是“返回”来解决这个问题。如果有人有不同的建议，请告诉我。
解决方案
您的问题是您的活动没有在执行 UI 操作的主线程上开始。我添加了一个处理程序来执行此操作，下面是您更新的LoginActivity代码。
我创建了一个基本上Handler是在其中创建的（因为附加到创建它的线程）并且当您获得成功响应时，处理程序将收到通知并且我们将检查活动是否处于活动状态（以避免泄漏因为用户可以杀死该应用程序并且您的响应随后出现）。onCreateMain ThreadHandlerHandler
public class LoginActivity extends AppCompatActivity {
private Handler startMainActivityHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
GlobalVariables globalVariables = new GlobalVariables();
startMainActivityHandler = new StartActivityHandler(this);
final TextView title = findViewById(R.id.title);
final EditText email = findViewById(R.id.emailInput);
final EditText password = findViewById(R.id.passwordInput);
final Button signUp = findViewById(R.id.signUp);
Button signIn = findViewById(R.id.signIn);
//check if token exists
SharedPreferences sharedPreferences = getSharedPreferences("StoredValues", MODE_PRIVATE);
String token = sharedPreferences.getString("token", "null");
if(!token.equals("null")){
globalVariables.setToken(token);
Intent myIntent = new Intent(LoginActivity.this, MainActivity.class);
LoginActivity.this.startActivity(myIntent);
}
signUp.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent openRegisterActivity = new Intent(LoginActivity.this, RegisterActivity.class);
Pair[] pairs = new Pair[4];
pairs[0] = new Pair<View, String>(title, "titleTransition");
pairs[1] = new Pair<View, String>(email, "emailTransition");
pairs[2] = new Pair<View, String>(password, "passwordTransition");
pairs[3] = new Pair<View, String>(signUp, "signUpTransition");
ActivityOptions options = ActivityOptions.makeSceneTransitionAnimation(LoginActivity.this, pairs);
getWindow().setExitTransition(null);
startActivity(openRegisterActivity, options.toBundle());
}
});
signIn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(final View view) {
Utils utils = new Utils(getApplicationContext());
GlobalVariables globalVariables = new GlobalVariables();
if(email.getText().toString().equals("") || password.getText().toString().equals("")){
//at least one input is empty
utils.DisplayPopup(view, getResources().getString(R.string.empty_input_box));
}
else{
//everything is good to go
String url = globalVariables.getIPAddress() + "login/";
RequestQueue requestQueue = Volley.newRequestQueue(getApplicationContext());
try {
JSONObject jsonObject = new JSONObject();
jsonObject.put("username", email.getText().toString());
jsonObject.put("password", password.getText().toString());
JsonObjectRequest objectRequest = new JsonObjectRequest(
com.android.volley.Request.Method.POST,
url,
jsonObject,
new com.android.volley.Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
Gson gson = new Gson();
Token token = gson.fromJson(response.toString(), Token.class);
SharedPreferences sharedPreferences = getSharedPreferences("StoredValues", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("token", token.toString());
editor.apply();
Log.e("REST Response", response.toString());
startMainActivityHandler.sendEmptyMessage(1);
}
},
new com.android.volley.Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Utils utils = new Utils(getApplicationContext());
Log.e("REST Response", error.toString());
if(error.networkResponse.statusCode == 400){
utils.DisplayPopup(view, getResources().getString(R.string.invalid_credentials));
}
}
});
objectRequest.setRetryPolicy(new RetryPolicy() {
@Override
public int getCurrentTimeout() {
return 10000;
}
@Override
public int getCurrentRetryCount() {
return 10000;
}
@Override
public void retry(VolleyError error) throws VolleyError {
Log.e("Volley error", error.toString());
}
});
requestQueue.add(objectRequest);
} catch (JSONException e){
Log.e("JSON Response", e.toString());
}
}
}
});
}
private static class StartActivityHandler extends Handler {
private final WeakReference<Activity> weakReference;
StartActivityHandler(Activity activity) {
weakReference = new WeakReference<Activity>(activity);
}
@Override
public void handleMessage(@NonNull Message msg) {
if (msg.what == 1 && weakReference.get() != null && !weakReference.get().isDestroyed()) {
Intent intent;
intent = MainActivity.getIntentWithNewTask(getApplicationContext());
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
weakReference.get().startActivity(intent);
weakReference.get().finish();
}
}
}
}
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