动态注册Receiver接收系统广播

需求描述

当ToggleButton的状态为不检测时，TextView显示Hello Broad字符串

当点击ToggleButton后，TextView显示当前电量信息(要求能够实时刷新)

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

    <ToggleButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tb_broad"
        android:paddingVertical="20dp"
        android:textSize="30sp"
        android:textOn="检测"
        android:textOff="不检测"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toTopOf="@id/tv_broad"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv_broad"
        android:text="HelloWorld!"
        android:textSize="30sp"/>

</LinearLayout>
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package com.example.broadcasttest;

import androidx.appcompat.app.AppCompatActivity;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.Bundle;
import android.util.Log;
import android.widget.CompoundButton;
import android.widget.TextView;
import android.widget.ToggleButton;

public class MainActivity extends AppCompatActivity {
    private final String TAG = MainActivity.class.getSimpleName();
    private ToggleButton mTbBroad;
    private TextView mTvBroad;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTbBroad = findViewById(R.id.tb_broad);
        mTvBroad = findViewById(R.id.tv_broad);
        MyReceiver myReceiver = new MyReceiver();
        mTbBroad.setOnCheckedChangeListener((CompoundButton cb, boolean b)->{
            Log.d(TAG, Boolean.valueOf(b).toString());
            if(b) {
                IntentFilter filter = new IntentFilter();
                filter.addAction(Intent.ACTION_BATTERY_CHANGED);
                registerReceiver(myReceiver, filter);
            }else{
                mTvBroad.setText("Hello Broad");
                unregisterReceiver(myReceiver);
            }
        });
    }

    public class MyReceiver extends BroadcastReceiver {
        private final String TAG = MyReceiver.class.getSimpleName();
        @Override
        public void onReceive(Context context, Intent intent) {
            Log.d(TAG, intent.getAction());
            if(intent.getAction().equals(Intent.ACTION_BATTERY_CHANGED)) {
                Bundle extras = intent.getExtras();
                // 当前电量水平
                int level = extras.getInt(BatteryManager.EXTRA_LEVEL);
                // 电量最大值
                int scale = extras.getInt(BatteryManager.EXTRA_SCALE);
                // 电量百分数
                int percent = (int)(((double)level/(double)scale)*100);
                mTvBroad.setText("电量为："+percent+"%");
            }
        }
    }
}

静态注册Receiver

创建了一个静态的StaticReceiver后，代码如下

使用ide的新建静态Receiver之后，AndroidManifest.xml中就会自动插入以下代码

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<receiver
    android:name=".StaticReceiver"
    android:enabled="true"
    android:exported="true"></receiver>
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package com.example.broadcasttest;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.widget.Toast;

public class StaticReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        Log.d("StaticReceiver", "onReceive");
        Toast.makeText(context, "From static receive", Toast.LENGTH_SHORT).show();
    }
}

MainActivity.java中加入以下声明周期定义，

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@Override
protected void onResume() {
    super.onResume();
    mBtnStatic.setOnClickListener((View view)->{
        Intent intent = new Intent();
        intent.setClass(this, StaticReceiver.class);
        sendBroadcast(intent);
    });
}

普通广播定义

当点击ToggleButton时，若状态为普通广播，则通过广播修改TextView为Normal Broad，否则改为默认的Hello Broad

onResume()生命周期中添加

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NormalReceiver normalReceiver = new NormalReceiver();
mTbNormal.setOnCheckedChangeListener((CompoundButton cb, boolean b)->{
    if(b) {
        IntentFilter filter = new IntentFilter();
        filter.addAction("intent.normal");
        registerReceiver(normalReceiver, filter);

        Intent intent = new Intent();
        intent.setAction("intent.normal");
        sendBroadcast(intent);
    }else{
        mTvBroad.setText("Hello Broad");
        unregisterReceiver(normalReceiver);
    }
});

定义NormalReceiver内部类

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public class NormalReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        if(intent.getAction().equals("intent.normal")) {
            mTvBroad.setText("Normal Broad");
        }
    }
}

本地广播

效果同普通广播，只不过写代码的方式不同，仅能实现应用程序自身通信

onResume()生命周期中添加

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LocalReceiver localReceiver = new LocalReceiver();
LocalBroadcastManager localBroadcastManager = LocalBroadcastManager.getInstance(this);
mTbLocal.setOnCheckedChangeListener((CompoundButton cb, boolean b)->{
    if(b) {
        IntentFilter filter = new IntentFilter("intent.local");
        localBroadcastManager.registerReceiver(localReceiver,filter);
        Intent intent = new Intent("intent.local");
        localBroadcastManager.sendBroadcast(intent);
    }else{
        mTvBroad.setText("Hello Broad");
        localBroadcastManager.unregisterReceiver(localReceiver);
    }
});

定义 LocalReceiver内部类

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public class LocalReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        if(intent.getAction().equals("intent.local")) {
            mTvBroad.setText("Local Broad");
        }
    }
}

有序广播

onResume添加

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Order1Receiver order1Receiver = new Order1Receiver();
Order2Receiver order2Receiver = new Order2Receiver();
mTbOrder.setOnCheckedChangeListener((CompoundButton cb, boolean b)->{
    if(b) {
        IntentFilter filter1 = new IntentFilter("intent.order");
        filter1.setPriority(99);
        registerReceiver(order1Receiver, filter1);

        IntentFilter filter2 = new IntentFilter("intent.order");
        filter2.setPriority(101);
        registerReceiver(order2Receiver, filter2);

        Intent intent = new Intent("intent.order");
        sendOrderedBroadcast(intent,null);
    }else{
        mTvBroad.setText("Hello Broad");
        unregisterReceiver(order1Receiver);
        unregisterReceiver(order2Receiver);
    }
});

定义Receiver内部类

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public class Order1Receiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        if(intent.getAction().equals("intent.order")) {
            mTvBroad.setText("Order1 Broad");
        }
    }
}
public class Order2Receiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        if(intent.getAction().equals("intent.order")) {
            mTvBroad.setText("Order2 Broad");
        }
    }
}

结果如下，

先执行优先级大的，所以先执行order2，最后执行order1

终止传播

修改Order2Receiver定义，加入终止传播的代码

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public class Order2Receiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        if(intent.getAction().equals("intent.order")) {
            mTvBroad.setText("Order2 Broad");
            setResultData("From Order2");
            // 终止传播
            abortBroadcast();
        }
    }
}

完整代码如下

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package com.example.broadcasttest;

import androidx.appcompat.app.AppCompatActivity;
import androidx.localbroadcastmanager.content.LocalBroadcastManager;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.CompoundButton;
import android.widget.TextView;
import android.widget.ToggleButton;

public class MainActivity extends AppCompatActivity {
    private final String TAG = MainActivity.class.getSimpleName();
    private ToggleButton mTbBroad, mTbNormal,mTbLocal, mTbOrder;
    private TextView mTvBroad;
    private Button mBtnStatic;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTbBroad = findViewById(R.id.tb_broad);
        mTvBroad = findViewById(R.id.tv_broad);
        mBtnStatic = findViewById(R.id.btn_static);
        mTbNormal = findViewById(R.id.tb_normal_broad);
        mTbLocal = findViewById(R.id.tb_local_broad);
        mTbOrder = findViewById(R.id.tb_order_broad);

        MyReceiver myReceiver = new MyReceiver();
        mTbBroad.setOnCheckedChangeListener((CompoundButton cb, boolean b)->{
            Log.d(TAG, Boolean.valueOf(b).toString());
            if(b) {
                IntentFilter filter = new IntentFilter();
                filter.addAction(Intent.ACTION_BATTERY_CHANGED);
                registerReceiver(myReceiver, filter);
            }else{
                mTvBroad.setText("Hello Broad");
                unregisterReceiver(myReceiver);
            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        mBtnStatic.setOnClickListener((View view)->{
            Intent intent = new Intent();
            intent.setClass(this, StaticReceiver.class);
            sendBroadcast(intent);
        });

        NormalReceiver normalReceiver = new NormalReceiver();
        mTbNormal.setOnCheckedChangeListener((CompoundButton cb, boolean b)->{
            if(b) {
                IntentFilter filter = new IntentFilter();
                filter.addAction("intent.normal");
                registerReceiver(normalReceiver, filter);

                Intent intent = new Intent();
                intent.setAction("intent.normal");
                sendBroadcast(intent);
            }else{
                mTvBroad.setText("Hello Broad");
                unregisterReceiver(normalReceiver);
            }
        });

        LocalReceiver localReceiver = new LocalReceiver();
        LocalBroadcastManager localBroadcastManager = LocalBroadcastManager.getInstance(this);
        mTbLocal.setOnCheckedChangeListener((CompoundButton cb, boolean b)->{
            if(b) {
                IntentFilter filter = new IntentFilter("intent.local");
                localBroadcastManager.registerReceiver(localReceiver,filter);
                Intent intent = new Intent("intent.local");
                localBroadcastManager.sendBroadcast(intent);
            }else{
                mTvBroad.setText("Hello Broad");
                localBroadcastManager.unregisterReceiver(localReceiver);
            }
        });

        Order1Receiver order1Receiver = new Order1Receiver();
        Order2Receiver order2Receiver = new Order2Receiver();
        mTbOrder.setOnCheckedChangeListener((CompoundButton cb, boolean b)->{
            if(b) {
                IntentFilter filter1 = new IntentFilter("intent.order");
                filter1.setPriority(99);
                registerReceiver(order1Receiver, filter1);

                IntentFilter filter2 = new IntentFilter("intent.order");
                filter2.setPriority(101);
                registerReceiver(order2Receiver, filter2);

                Intent intent = new Intent("intent.order");
                sendOrderedBroadcast(intent,null);
            }else{
                mTvBroad.setText("Hello Broad");
                unregisterReceiver(order1Receiver);
                unregisterReceiver(order2Receiver);
            }
        });
    }

    public class Order1Receiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            if(intent.getAction().equals("intent.order")) {
                mTvBroad.setText("Order1 Broad");
            }
        }
    }
    public class Order2Receiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            if(intent.getAction().equals("intent.order")) {
                mTvBroad.setText("Order2 Broad");
                setResultData("From Order2");
                // 终止传播
                abortBroadcast();
            }
        }
    }
    public class LocalReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            if(intent.getAction().equals("intent.local")) {
                mTvBroad.setText("Local Broad");
            }
        }
    }

    public class NormalReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            if(intent.getAction().equals("intent.normal")) {
                mTvBroad.setText("Normal Broad");
            }
        }
    }

    public class MyReceiver extends BroadcastReceiver {
        private final String TAG = MyReceiver.class.getSimpleName();
        @Override
        public void onReceive(Context context, Intent intent) {
            Log.d(TAG, intent.getAction());
            if(intent.getAction().equals(Intent.ACTION_BATTERY_CHANGED)) {
                Bundle extras = intent.getExtras();
                // 当前电量水平
                int level = extras.getInt(BatteryManager.EXTRA_LEVEL);
                // 电量最大值
                int scale = extras.getInt(BatteryManager.EXTRA_SCALE);
                // 电量百分数
                int percent = (int)(((double)level/(double)scale)*100);
                mTvBroad.setText("电量为："+percent+"%");
            }
        }
    }
}
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical"
    android:gravity="center_horizontal">

    <ToggleButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tb_broad"
        android:paddingVertical="20dp"
        android:textSize="30sp"
        android:textOn="检测"
        android:textOff="不检测"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv_broad"
        android:text="HelloWorld!"
        android:textSize="30sp"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btn_static"
        android:textSize="30sp"
        android:text="静态注册"/>
    <ToggleButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tb_normal_broad"
        android:paddingVertical="20dp"
        android:textSize="30sp"
        android:textOn="普通广播"
        android:textOff="不注册普通广播"/>
    <ToggleButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tb_local_broad"
        android:paddingVertical="20dp"
        android:textSize="30sp"
        android:textOn="本地广播"
        android:textOff="不注册本地广播"/>
    <ToggleButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tb_order_broad"
        android:paddingVertical="20dp"
        android:textSize="30sp"
        android:textOn="有序广播"
        android:textOff="不注册有序广播"/>

</LinearLayout>