Android的广播机制基础1---动态注册监听的使用，以获得电池的使用状态为例

悠悠 2022-05-23 09:20 214阅读 0赞

以一个显示手机电量和电池状态的Demo为例。  
1.要获得电池的使用状态，需在AndroidManifest.xml中添加使用权限：

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

2.广播有发送方和接收方，接收方为BroadCastReceiver的实例或其子类  
3.首先我们写出activity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">
    //电池电量
        <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/current" android:textSize="30sp"/>
    
        <ProgressBar android:layout_width="match_parent" android:layout_height="20dp" style="@style/Base.Widget.AppCompat.ProgressBar.Horizontal" android:id="@+id/progressbar"/>
    //电池充电状态
        <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:textSize="30sp" android:id="@+id/battryeStatus"/>
    //电池健康状态
        <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/batteryHealth" android:textSize="30sp"/>
    
    </LinearLayout>

4.activity实现部分

package com.example.apple.broadcast.BatteryMonitor;
    
    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.support.annotation.Nullable;
    import android.support.v7.app.AppCompatActivity;
    import android.widget.ProgressBar;
    import android.widget.TextView;
    
    import com.example.apple.broadcast.R;
    
    /** * Created by apple on 2018/6/6. */
    
    public class BatteryMonitorActivity extends AppCompatActivity { 
    
        private TextView tv_level,tv_status,tv_health;
        private ProgressBar progressbar;
    
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.battry_layout);
    //初始化控件
            tv_level=(TextView)findViewById(R.id.current);
            tv_health=(TextView)findViewById(R.id.batteryHealth);
            tv_status=(TextView)findViewById(R.id.battryeStatus);
            progressbar=(ProgressBar)findViewById(R.id.progressbar);
            progressbar.setMax(100);
        }
    //注册广播
        @Override
        protected void onResume() {
            super.onResume();
            //IntentFilter传递相应的action
            IntentFilter intentFilter=new IntentFilter();
            intentFilter.addAction(Intent.ACTION_BATTERY_CHANGED);
            //注册传入参数为BroadcastReceiver和Intentfilter的实例
            registerReceiver(mBroadcastReceiver,intentFilter);
    
        }
    //取消广播
        @Override
        protected void onDestroy() {
            super.onDestroy();
            unregisterReceiver(mBroadcastReceiver);
        }
    
    //BroadcastReceiver的实例，也可以用BroadcastReceiver的子类实现，书写一个内部类，要重写父类的onReceive方法
        private BroadcastReceiver mBroadcastReceiver=new BroadcastReceiver() {
        //Int 类型值用来判断电池的状态
            int health,level,status;
            @Override
            public void onReceive(Context context, Intent intent) {
            //获取广播的action
                String action=intent.getAction();
                //如果电池电量改变
                if(action==Intent.ACTION_BATTERY_CHANGED){
              level=intent.getIntExtra(BatteryManager.EXTRA_LEVEL,0);
    
    //电池的充电状态，默认为未充电 
                status=intent.getIntExtra(BatteryManager.EXTRA_STATUS,BatteryManager.BATTERY_STATUS_DISCHARGING);
    
     //获取电池的健康状态
                    health=intent.getIntExtra(BatteryManager.EXTRA_HEALTH,BatteryManager.BATTERY_HEALTH_GOOD);
                }
    
                changeBattry(health,level,status);
            }
        };
    //改变布局，将状态变化显示在布局文件中
        private void changeBattry(int health, int level, int status) {
            tv_level.setText("当前电量为："+level+"%");
            progressbar.setProgress(level);
            if(status==BatteryManager.BATTERY_STATUS_CHARGING){
                tv_status.setText("充电状况：正在充电");
            }else if(status==BatteryManager.BATTERY_STATUS_DISCHARGING){
                tv_status.setText("充电状况：未充电");
            }
    
            if(health==BatteryManager.BATTERY_HEALTH_GOOD){
                tv_health.setText("电池状况：Good");
            }else if(health==BatteryManager.BATTERY_HEALTH_UNKNOWN){
                tv_health.setText("电池状况：unkown");
            }else if(health==BatteryManager.BATTERY_HEALTH_DEAD){
                tv_health.setText("电池状况：Dead");
            }
        }
    }

![这里写图片描述][70]

[70]: /images/20220523/0eaff212ef1f4af1874f1e5619e1fa20.png