广播的实现--实现强制下线功能

/**
* 作为所有活动的父类
*/
public class BaseActivity extends Activity{
@Override
protected void onCreate(Bundle saveInstanceState){
super.onCreate(saveInstanceState);
ActivityCollector.addActivity(this);
}
@Override
protected void onDestroy(){
super.onDestroy();
ActivityCollector.removeActivity(this);
}
}

/**
* 用于管理所有活动*/
public class ActivityCollector {
public static List<Activity> activities=new ArrayList<Activity>();
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 LoginActivity extends BaseActivity {
private EditText accountEdit;
private EditText passwordEdit;
private Button login;
private CheckBox rememberPass;
private SharedPreferences pref;
private SharedPreferences.Editor editor;//获取SharedPreferences.Editor对象
@Override
protected void onCreate(Bundle saveInstanceState){
super.onCreate(saveInstanceState);
setContentView(R.layout.login);
//获取SharedPreferences对象，接受一个context参数this
pref= PreferenceManager.getDefaultSharedPreferences(this);
//控件初始化
accountEdit= (EditText) findViewById(R.id.account);
passwordEdit= (EditText) findViewById(R.id.password);
login= (Button) findViewById(R.id.loginBtn);
rememberPass=(CheckBox)findViewById(R.id.remember_pass);
//用于判断复选框是否被勾选
boolean isRemember=pref.getBoolean("remember_password",false);
if(isRemember){
//将账号和密码都设置到文本框中
String account=pref.getString("account","");
String password=pref.getString("password","");
accountEdit.setText(account);
passwordEdit.setText(password);
rememberPass.setChecked(true);
}
login.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String account=accountEdit.getText().toString();//获取账号输入框内容
String password=passwordEdit.getText().toString();//获取密码框输入的内容

//如果账号是admin且密码是123456，就认为登录成功
if(account.equals("admin")&&password.equals("123456")){
editor=pref.edit();
//检查复选框是否被选中
if(rememberPass.isChecked()){
editor.putBoolean("remember_password",true);
editor.putString("account",account);
editor.putString("password",password);
}else{
editor.clear();
}
editor.commit();
Intent intent=new Intent(LoginActivity.this,MainActivity.class);
startActivity(intent);
finish();
}
else {
Toast.makeText(LoginActivity.this,"账号或密码输入错误！请重新输入",Toast.LENGTH_LONG).show();
}

}
});
}
}

public class BroadOfflineReceiver extends BroadcastReceiver {
@Override
public void onReceive(final Context context, Intent intent) {
AlertDialog.Builder dialogBuilder=new AlertDialog.Builder(context);
dialogBuilder.setTitle("注意");
dialogBuilder.setMessage("你被强制下线，请重新登录");
dialogBuilder.setCancelable(false);
dialogBuilder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
ActivityCollector.finishAll();//销毁所有活动
Intent intent = new Intent(context, LoginActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(intent);//重新启动LoginActivity
}
});
AlertDialog alertDialog=dialogBuilder.create();
//需要设置AlertDialog的类型，保证在广播接收器中可以正常弹出
alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
alertDialog.show();
}
}

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("demo4.broadcastlogin.FORCE_OFFLINE");
sendBroadcast(intent);
}
});
}
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="demo4.broadcastlogin" >
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".LoginActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".MainActivity">
</activity>

<receiver android:name=".BroadOfflineReceiver">
<intent-filter>
<action android:name="demo4.broadcastlogin.FORCE_OFFLINE"/>
</intent-filter>
</receiver>
</application>

</manifest>