Broadcast的最佳实践 强制下线

最终的效果图：

强制下线功能的实现首先需要一个关闭所有活动的功能。

我们新建一个ActivityController.java:

public class ActivityCollector {    public static List<Activity> activities = new ArrayList<>();    public static void addActivity(Activity activity){        activities.add(activity);    }    public static void removeActivity(Activity activity){        activities.remove(activity);    }    public static void finishAll(){        for (Activity activity : activities) {            if (!activity.isFinishing()){                activity.finish();            }        }    }}

继续建立一个BaseActivity.java:

public class BaseActivity extends AppCompatActivity {    @Override    public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {        super.onCreate(savedInstanceState, persistentState);        ActivityCollector.addActivity(this);    }    @Override    protected void onDestroy() {        super.onDestroy();        ActivityCollector.removeActivity(this);    }

建立登陆界面和活动：

<?xml version="1.0" encoding="utf-8"?><LinearLayout    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent"    xmlns:android="http://schemas.android.com/apk/res/android">    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content">        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="账号："            android:textSize="30dp"/>        <EditText            android:id="@+id/user_name"            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"/>    </LinearLayout>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content">        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="密码："            android:textSize="30dp"/>        <EditText            android:inputType="textPassword"            android:id="@+id/user_password"            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"/>    </LinearLayout>    <Button        android:id="@+id/user_login"        android:text="Login"        android:layout_width="match_parent"        android:layout_height="wrap_content"/></LinearLayout>

LoginActivity.java:

public class LoginActivity extends BaseActivity {    private EditText username;    private EditText password;    private Button login;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_login);        username = (EditText)findViewById(R.id.user_name);        password = (EditText)findViewById(R.id.user_password);        login = (Button)findViewById(R.id.user_login);        login.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                if (username.getText().toString().equals("123")&&password.getText().toString().equals("123")){                    Intent intent = new Intent(LoginActivity.this,MainActivity.class);                    startActivity(intent);                }else {                    Toast.makeText(LoginActivity.this,"账号或密码错误",Toast.LENGTH_SHORT).show();                }            }        });    }}

跳转页面

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="com.example.eason.broadcastdown.MainActivity">    <Button        android:id="@+id/down_login"        android:layout_width="368dp"        android:layout_height="wrap_content"        tools:layout_editor_absoluteX="8dp"        android:text="downlogin"        app:layout_constraintBottom_toBottomOf="parent"        android:layout_marginBottom="8dp"        app:layout_constraintTop_toTopOf="parent"        android:layout_marginTop="8dp"/></android.support.constraint.ConstraintLayout>

这里加入了一个强制下线的按钮。

修改MainActivity.java:

public class MainActivity extends BaseActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button downlogin = (Button)findViewById(R.id.down_login);        downlogin.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                //发送广播                Intent intent = new Intent("com.example.eason.DOWN");                sendBroadcast(intent);            }        });    }}

修改BaseActivity.java:

public class BaseActivity extends AppCompatActivity {    private downLoginReceiver mDownLoginReceiver;    @Override    public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {        super.onCreate(savedInstanceState, persistentState);        ActivityCollector.addActivity(this);    }    @Override    protected void onResume() {        super.onResume();        //过滤，接受广播        IntentFilter intentFilter = new IntentFilter();        intentFilter.addAction("com.example.eason.DOWN");        mDownLoginReceiver = new downLoginReceiver();        registerReceiver(mDownLoginReceiver,intentFilter);    }    @Override    protected void onPause() {        super.onPause();        if (mDownLoginReceiver != null){            unregisterReceiver(mDownLoginReceiver);            mDownLoginReceiver = null;        }    }    @Override    protected void onDestroy() {        super.onDestroy();        ActivityCollector.removeActivity(this);    }    class downLoginReceiver extends BroadcastReceiver{        @Override        public void onReceive(final Context context, final Intent intent) {            AlertDialog.Builder builder = new AlertDialog.Builder(context);            builder.setTitle("警告：");            builder.setMessage("您的账号在另一台设备登陆,请重新登陆");            builder.setCancelable(false);            builder.setPositiveButton("好的", new DialogInterface.OnClickListener() {                @Override                public void onClick(DialogInterface dialog, int which) {                    ActivityCollector.finishAll();//销毁全部活动                    Intent intent1 = new Intent(context,LoginActivity.class);//跳转                    startActivity(intent1);                }            });            builder.show();        }    }}

说明：这里我们会好奇为什么是在onResume()，onPause()内注册广播,销毁广播，因为这个时候该活动处于栈顶，非栈顶的活动没必要也不应该接收到这条广播。

修改LoginActivity为主界面:

<activity android:name=".LoginActivity">            <intent-filter>                <action android:name="android.intent.action.MAIN"/>                <category android:name="android.intent.category.LAUNCHER"/>            </intent-filter></activity>

效果图：