廣播的實現--實現強制下線功能

1、登錄部分內容（直接上代碼咯）
BaseActivity

/**
 * 作爲所有活動的父類
 */
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);
    }
}

ActivityCollector

/**
 * 用於管理所有活動*/
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();
            }
        }
    }
}

LoginActivity

public class LoginActivity extends BaseActivity {
    private EditText accountEdit;
    private EditText passwordEdit;
    private Button login;
    private CheckBox rememberPass;
    private SharedPreferences pref;
    private SharedPreferences.Editor editor;//獲取SharedPreferences.Editor對象
    @Override
    protected void onCreate(Bundle saveInstanceState){
        super.onCreate(saveInstanceState);
        setContentView(R.layout.login);
        //獲取SharedPreferences對象，接受一個context參數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);
        //用於判斷複選框是否被勾選
        boolean isRemember=pref.getBoolean("remember_password",false);
        if(isRemember){
            //將賬號和密碼都設置到文本框中
            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();//獲取賬號輸入框內容
                String password=passwordEdit.getText().toString();//獲取密碼框輸入的內容

                //如果賬號是admin且密碼是123456，就認爲登錄成功
                if(account.equals("admin")&&password.equals("123456")){
                    editor=pref.edit();
                    //檢查複選框是否被選中
                    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,"賬號或密碼輸入錯誤！請重新輸入",Toast.LENGTH_LONG).show();
                }

            }
        });
    }
}

BroadOfflineReceiver

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("你被強制下線，請重新登錄");
        dialogBuilder.setCancelable(false);
        dialogBuilder.setPositiveButton("確定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                ActivityCollector.finishAll();//銷燬所有活動
                Intent intent = new Intent(context, LoginActivity.class);
                intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                context.startActivity(intent);//重新啓動LoginActivity
            }
        });
        AlertDialog alertDialog=dialogBuilder.create();
        //需要設置AlertDialog的類型，保證在廣播接收器中可以正常彈出
        alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
        alertDialog.show();
    }
}

MainActivity

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);
            }
        });
    }
}

配置文件

<?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>