Broadcast实现强制下线功能

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徐的张 2022-11-11 14:10:21 博主文章分类：Android ©著作权

文章标签 broadcastreceiver 强制下线 Android android xml 文章分类 代码人生

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实现强制下线功能的思路就是弹出一个对话框，让用户无法进行任何操作，必须选择对话框中的确定按钮，然后Intent跳转到Login页面即可。现在存在这样一个问题，我们被通知强制下线的时候可能处于任何一个页面，难道我们需要在每个界面上都编写一个弹出对话框的逻辑？我们可以借助广播，来轻松实现这一功能。

首先我们考虑强制下线功能需要先关闭掉所有的活动，然后回到登录界面，怎么实现关闭所有活动的功能呢？我们可以先创建一个ActivityCollector类用于管理所有的活动：

<pre class="java" name="code">package com.example.forceoffline;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;

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();
   }
  }
 }

然后创建BaseActivity类作为所有活动的父类。

package com.example.forceoffline;

import android.app.Activity;
import android.os.Bundle;

public class BaseActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    ActivityCollector.addActivity(this);
  }

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

}

登录login.xml代码如下：

<TableLayout 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.forceoffline.LoginActivity"
    tools:ignore="MergeRootFrame" >

    <TableRow>

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

        <EditText
            android:id="@+id/account"
            android:layout_height="wrap_content"
            android:minWidth="50dp" />
    </TableRow>

    <TableRow>

        <TextView
            android:layout_height="wrap_content"
            android:text="Password:" />

        <EditText
            android:id="@+id/password"
            android:layout_height="wrap_content"
            android:inputType="textPassword"
            android:minWidth="50dp" />
    </TableRow>

    <TableRow>

        <Button
            android:id="@+id/login"
            android:layout_height="wrap_content"
            android:layout_span="2"
            android:text="Login" />
    </TableRow>

</TableLayout>

新建LoginActivity继承BaseActivity:

package com.example.forceoffline;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class LoginActivity extends BaseActivity {
  private EditText accEditText = null;
  private EditText passEditText = null;
  private Button loginButton = null;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);
    this.accEditText = (EditText) super.findViewById(R.id.account);
    this.passEditText = (EditText) super.findViewById(R.id.password);
    this.loginButton = (Button) super.findViewById(R.id.login);
    this.loginButton.setOnClickListener(new OnClickListener() {

      public void onClick(View v) {
        String account = accEditText.getText().toString();
        String passwordString = passEditText.getText().toString();
        if (account.equals("admin") && passwordString.equals("admin")) {
          Intent intent = new Intent(LoginActivity.this,
              MainActivity.class);
          startActivity(intent);
          finish();
        } else {
          Toast.makeText(LoginActivity.this,
              "account or password is invalid!",
              Toast.LENGTH_SHORT).show();
        }
      }
    });

  }

}

main.xml代码如下：

<TableLayout 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.forceoffline.LoginActivity"
    tools:ignore="MergeRootFrame" >

    <Button
        android:id="@+id/offline"
        android:layout_height="wrap_content"
        android:layout_span="2"
        android:text="Offline" />

</TableLayout>

MainActivity.java如下：

package com.example.forceoffline;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends BaseActivity {
  private Button offlineButton;

  @Override
  protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    this.offlineButton = (Button) super.findViewById(R.id.offline);
    offlineButton.setOnClickListener(new OnClickListener() {

      @Override
      public void onClick(View arg0) {
        Intent intent = new Intent("com.example.offline.FORCE_OFFLINE");
        sendBroadcast(intent);

      }
    });
  }

}

接下来我们要创建一个广播接收器了：

package com.example.forceoffline;

import android.app.AlertDialog;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.view.WindowManager;

public class ForceOfflineReceiver extends BroadcastReceiver {

  @Override
  public void onReceive(final Context context, Intent intent) {
    AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(context);
    dialogBuilder.setTitle("Warning");
    dialogBuilder
        .setMessage("You are forced to be offline.Please try to login again!");
    dialogBuilder.setCancelable(false);
    dialogBuilder.setPositiveButton("OK",
        new DialogInterface.OnClickListener() {

          @Override
          public void onClick(DialogInterface arg0, int which) {
            ActivityCollector.finishAll();
            Intent intent = new Intent(context, LoginActivity.class);
            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            context.startActivity(intent);

          }
        });
    AlertDialog alertDialog = dialogBuilder.create();
    alertDialog.getWindow().setType(
        WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
    alertDialog.show();

  }

}

最后不要忘了配置manifest：

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

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />

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

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.forceoffline.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="com.example.forceoffline.ForceOfflineReceiver" >
            <intent-filter>
                <action android:name="com.example.offline.FORCE_OFFLINE" />
            </intent-filter>
        </receiver>
    </application>

</manifest>