public class ActivityConllector {
  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();
      }
    }
  }

public class BaseActivity extends AppCompatActivity{
  @Override
  protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ActivityConllector.addActivity(this);
  }

  @Override
  protected void onDestroy() {
    super.onDestroy();
    ActivityConllector.removeActivity(this);
  }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical">
  <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="60dp"
    android:orientation="horizontal">
    <TextView
      android:layout_width="90dp"
      android:layout_height="wrap_content"
      android:text="User Name"
      android:textSize="18sp"
      android:layout_gravity="center_vertical"/>
    <EditText
      android:id="@+id/account"
      android:layout_width="0dp"
      android:layout_height="wrap_content"
      android:layout_weight="1"
      android:layout_gravity="center_vertical"
      />
  </LinearLayout>
  <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="60dp"
    android:orientation="horizontal">
    <TextView
      android:layout_width="90dp"
      android:layout_height="wrap_content"
      android:text="Password"
      android:textSize="18sp"
      android:layout_gravity="center_vertical"/>
    <EditText
      android:id="@+id/password"
      android:layout_width="0dp"
      android:layout_height="wrap_content"
      android:layout_weight="1"
      android:layout_gravity="center_vertical"
      android:inputType="textPassword"/>
  </LinearLayout>
  <Button
    android:id="@+id/login"
    android:layout_width="match_parent"
    android:layout_height="60dp"
    android:text="Login"/>
</LinearLayout>

public class LoginActivity extends BaseActivity implements View.OnClickListener{
  private EditText userName;
  private EditText passWord;
  private Button login;

  @Override
  protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    userName = (EditText)findViewById(R.id.account);
    passWord = (EditText)findViewById(R.id.password);
    login = (Button) findViewById(R.id.login);
    login.setOnClickListener(this);

  }

  @Override
  public void onClick(View v) {
    switch (v.getId()){
      case R.id.login:
        String username = userName.getText().toString();
        String password = passWord.getText().toString();
        if(username.equals("admin") && password.equals("123")){
          Intent intent = new Intent(LoginActivity.this, MainActivity.class);
          startActivity(intent);
          finish();
        } else {
          Toast.makeText(this, "用户名或者密码错误!", Toast.LENGTH_SHORT).show();
        }

    }

  }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/activity_main"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical">

  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="这是主页面"
    android:layout_gravity="center_horizontal"/>

  <Button
    android:id="@+id/force_offline"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="强制下线"/>
</LinearLayout>

public class MainActivity extends BaseActivity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Button forceOffline = (Button) findViewById(R.id.force_offline);
    forceOffline.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        Intent intent = new Intent("com.junzaivip.broadcastbestpractice.FORCE_OFFLINE");
        sendBroadcast(intent);
      }
    });
  }
}

public class BaseActivity extends AppCompatActivity{
  @Override
  protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ActivityConllector.addActivity(this);
  }
  @Override
  protected void onDestroy() {
    super.onDestroy();
    ActivityConllector.removeActivity(this);
  }
  class ForceOffLineReceiver extends BroadcastReceiver{
    @Override
    public void onReceive(final Context context, final Intent intent) {
      AlertDialog.Builder builder = new AlertDialog.Builder(context);
      builder.setTitle("warning");
      builder.setMessage("您被强制下线, 请您重新登录!");
      builder.setCancelable(false); // 将对话框设置为不可取消
      // 给按钮添加注册监听
      builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
          // 点击按钮所调用的方法
          ActivityConllector.finishAll();//销毁所有的活动
          Intent intent1 = new Intent(context, LoginActivity.class);
          context.startActivity(intent);
        }
      });
      builder.show();
    }
  }

}

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
    </activity>
    <activity android:name=".LoginActivity">
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
  </application>