android广播的实践----实现强制下线

参考：《第一行代码》
效果

创建ActivityController类用于管理所有的活动

public class ActivityController {
    public static ArrayList<Activity> activityList=new ArrayList<Activity>();

    public static void add(Activity activity)
    {
        activityList.add(activity);
    }
    public static void remove(Activity activity)
    {
        activityList.remove(activity);
    }
    public static void finishAll()
    {
        for(Activity a:activityList)
        {
            if(!a.isFinishing())
            {
                a.finish();
            }
        }
    }
}

创建BaseActivity类作为所有活动的父类

public class BaseActivity extends Activity{
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        ActivityController.add(this);
    }

    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        ActivityController.remove(this);
    }
}

登录布局

<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:stretchColumns="1" >

    <TableRow>
        <TextView
            android:layout_height="wrap_content"
            android:text="Account" />

        <EditText
            android:id="@+id/account"
            android:layout_height="wrap_content"
            android:hint="Input your account" />
    </TableRow>
    <TableRow>
        <TextView
            android:layout_height="wrap_content"
            android:text="Password" />
        <EditText
            android:id="@+id/password"
            android:layout_height="wrap_content"
            android:hint="Input your password" />
    </TableRow>   
    <TableRow >
        <Button
            android:layout_span="2"
            android:id="@+id/login"
            android:layout_height="wrap_content"
            android:text="Login"/>
        </TableRow>
</TableLayout>

创建登录LoginActivity类，继承BaseActivity类

public class LoginActivity extends BaseActivity{

    private EditText accountEdit;

    private EditText passwordEdit;

    private Button login;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);
        init();
        myListener();
    }
    public void init()
    {
        accountEdit=(EditText) findViewById(R.id.account);
        passwordEdit=(EditText) findViewById(R.id.password);
        login=(Button) findViewById(R.id.login);
    }
    private void myListener() {
        login.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String account=accountEdit.getText().toString();
                String password=passwordEdit.getText().toString();
                if(account.equals("csdn")&&password.equals("123"))
                {
                    Intent intent=new Intent(LoginActivity.this,MainActivity.class);
                    startActivity(intent);
                    //关掉当前活动
                    finish();
                }else{
                    Toast.makeText(LoginActivity.this, 
                            "账号或者密码输入不正确，请再次输入！", Toast.LENGTH_SHORT).show();
                }
            }
        });

    }

}

主页面布局

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.Controller.MainActivity"
    tools:ignore="MergeRootFrame">
    <Button
        android:id="@+id/force_offline"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="send force offline broadcast"
        ></Button>   
</FrameLayout>

MainActivity 类

点击按钮后会发个广播

public class MainActivity extends BaseActivity {

    Button forceOffline;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        forceOffline=(Button) findViewById(R.id.force_offline);
        myListener();

    }
    private void myListener() {
        forceOffline.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Intent intent=new Intent("com.example.Controller.FORCE_OFFLINE");
                sendBroadcast(intent);
            }
        });
    }

}

广播接收者

接收到MainActivity 发来的广播后，创建对话框，实现强制下线功能

public class ForOfflineReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(final Context context, Intent intent) {
        // 创建一个对话框，用于提醒用户强制下线，然后确定退出到登录界面
        /*
         * 不能直接通过AlertDialog的构造函数来生产一个AlertDialog。
         * 研究AlertDialog的源码发现AlertDialog所有的构造方法都是写保护的
         */
        AlertDialog.Builder alertDialogBuilder=new AlertDialog.Builder(context);

        alertDialogBuilder.setTitle("Warning");
        alertDialogBuilder.setMessage("You are forced to offline");
        alertDialogBuilder.setCancelable(false);//设置不能返回

        alertDialogBuilder.setPositiveButton("OK", new OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                //销毁所有活动
                ActivityController.finishAll();
                Intent intent=new Intent(context,LoginActivity.class);
                //根据配置的Affinity决定创建的活动在哪个栈
                intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                //因为本身不是Activity，使用上下文来启动另一个活动
                context.startActivity(intent);
            }
        });

        AlertDialog alertDialog=alertDialogBuilder.create();
        //需要设置AlertDialog的类型，保护在广播接收器中可以正常弹出, 系统提示。它总是出现在应用程序窗口之上
        alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
        alertDialog.show();

    }

}

配置

加上

  <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

否则对话框无法在广播接收器弹出
还有广播接收器是静态注册，所以不需程序启动即可接收，完整配置

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.Controller"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="14" />

    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
     <!-- allowBackup="true"表示允许备份的意思,涉及设置存在敏感信息泄露 -->
    <application 
        android:allowBackup="true"
        android:icon="@drawable/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" />

        <receiver android:name=".ForOfflineReceiver" >
            <intent-filter>
                <action android:name="com.example.Controller.FORCE_OFFLINE" />
            </intent-filter>
        </receiver>
    </application>

</manifest>