广播的最佳实践-实现强制下线功能-Android第一行代码第5章节

MTier
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创建 ActivityCollector 管理所有Activity

package com.example.broadcastbestpractice;

import android.app.Activity;

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

public class ActivityCollector {
    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();
            }
        }
    }

}

BaseActivity为所有活动的父类

package com.example.broadcastbestpractice;


import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;


import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

public class BaseActivity extends AppCompatActivity {

      @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
    }

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

LoginActivity的布局文件：

<?xml version="1.0" encoding="utf-8"?>
<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:orientation="horizontal"
       android:layout_width="match_parent"
       android:layout_height="60dp">

       <TextView
           android:layout_width="90dp"
           android:layout_height="wrap_content"
           android:layout_gravity="center_vertical"
           android:textSize="18sp"
           android:text="Account:"/>

       <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:orientation="horizontal"
       android:layout_width="match_parent"
       android:layout_height="60dp">

       <TextView
           android:layout_width="90dp"
           android:layout_height="wrap_content"
           android:layout_gravity="center_vertical"
           android:textSize="18sp"
           android:text="Password:"/>

       <EditText
           android:id="@+id/password"
           android:layout_width="0dp"
           android:layout_height="wrap_content"
           android:layout_weight="1"
           android:layout_gravity="center_vertical"/>

   </LinearLayout>

   <Button
       android:id="@+id/login"
       android:layout_width="match_parent"
       android:layout_height="60dp"
       android:text="Login"/>

</LinearLayout>

LoginActivity：

package com.example.broadcastbestpractice;

import androidx.appcompat.app.AppCompatActivity;

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

public class LoginActivity extends BaseActivity {


    private EditText accountEdit;
    private EditText passwordEdit;
    private Button login;

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

        accountEdit = (EditText) findViewById(R.id.account);
        passwordEdit = (EditText) findViewById(R.id.password);
        login = (Button) findViewById(R.id.login);

        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String account = accountEdit.getText().toString();
                String password = passwordEdit.getText().toString();
                if(account.equals("admin") && password.equals("123456")){
                    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();
                }
            }
        });

    }
}

MainActivity布局:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

    <Button
        android:id="@+id/force_offline"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="send force offline broadcast"/>

</LinearLayout>

MainActivity:

package com.example.broadcastbestpractice;

import androidx.appcompat.app.AppCompatActivity;

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

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("package com.example.broadcastbestpractice.FORCE_OFFLINE");
                sendBroadcast(intent);//发送广播
            }
        });
    }
}

将广播接收者定义成BaseActivity的一个内部类， 因为每个活动都会继承BaseActivity 因此每次执行onResume()都会注册 每次执行onPause()都会取消注册

package com.example.broadcastbestpractice;


import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;


import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

public class BaseActivity extends AppCompatActivity {

    private ForceOfflineReceiver receiver;



    class ForceOfflineReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            AlertDialog.Builder builder = new AlertDialog.Builder(context);
            builder.setTitle("Warning");
            builder.setMessage("you are forced to be offline. Please try to login again.");
            builder.setCancelable(false);
            builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    ActivityCollector.finishAll();
                    Intent intent = new Intent(context, LoginActivity.class);
                    context.startActivity(intent);
                }
            });
            builder.show();
        }
    }


    @Override
    protected void onResume() {
        super.onResume();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("package com.example.broadcastbestpractice.FORCE_OFFLINE");
        receiver = new ForceOfflineReceiver();
        registerReceiver(receiver,intentFilter);
    }


    @Override
    protected void onPause() {
        super.onPause();
        if(receiver != null){
            unregisterReceiver(receiver);
            receiver = null;
        }
    }

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
    }

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

}

AndroidManifest.xml：

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.BroadcastBestPractice">
        <activity
            android:name=".MainActivity"
            android:exported="true" />
        <activity
            android:name=".LoginActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

演示：

输入默认账号和密码，点击登录按钮 image.png

点击发送广播按钮 image.png

点击ok，会毁掉所有Activity，并且返回loginActivity页面。 image.png

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