Android8.0中将静态注册改为动态注册(自定义标准广播)
布局文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.lenovo.broadcasttest.MainActivity">
<Button
android:id="@+id/button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Send Broadcast"/>
</RelativeLayout>
一、静态注册(以下代码在安卓7.0及其以下能运行)
MainActivity.java
package com.example.lenovo.broadcasttest;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button=(Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
//监听有com.example.broadcasttest.MY_BROADCAST这条广播的接收器会收到消息
Intent intent=new Intent("com.example.broadcasttest.MY_BROADCAST");
sendBroadcast(intent);
}
});
}
}
MyBroadcastReceiver.java
package com.example.lenovo.broadcasttest;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
public class MyBroadcastReceiver extends BroadcastReceiver {
public MyBroadcastReceiver() {
}
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context,"我收到广播",Toast.LENGTH_SHORT).show();
}
}
AndroidManifest.xml(在这里面进行注册----所以叫做静态注册)
<receiver
android:name=".MyBroadcastReceiver"
android:enabled="true"
android:exported="true">
<intent-filter><action android:name="com.example.broadcasttest.MY_BROADCAST"/></intent-filter>
</receiver>
效果图:(点击没有任何反应)
原因:Android8.0在AndroidManifest.xml文件中静态注册广播接收失效是由于官方对耗电量的优化,避免APP滥用广播的一种处理方式。除了少部分的广播仍支持静态注册(如开机广播),其余的都会出现失效的情况。
二、解决方案:改成动态注册(在Android8.0以及以后,都建议采用这种注册方式)
MainActivity.java
package com.example.lenovo.broadcasttest;
import android.content.Intent;
import android.content.IntentFilter;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
private MyBroadcastReceiver myBroadcastReceiver;
private IntentFilter intentFilter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
intentFilter=new IntentFilter();
//这里定义接受器监听广播的类型,这里添加相应的广播
intentFilter.addAction("com.example.broadcasttest.MY_BROADCAST");
//实例化接收器
myBroadcastReceiver=new MyBroadcastReceiver();
//注册事件,将监听类型赋给对应的广播接收器----所以这叫动态注册
registerReceiver(myBroadcastReceiver,intentFilter);
Button button=(Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
//这是一条自定义标准广播-----所有监听com.example.broadcasttest.MY_BROADCAST这条广播的接收器都会收到消息
Intent intent=new Intent("com.example.broadcasttest.MY_BROADCAST");
sendBroadcast(intent);
}
});
}
@Override
protected void onDestroy(){
super.onDestroy();
//注销事件
unregisterReceiver(myBroadcastReceiver);
}
}
MyBroadcastReceiver.java(没变)
package com.example.lenovo.broadcasttest;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
public class MyBroadcastReceiver extends BroadcastReceiver {
public MyBroadcastReceiver() {
}
@Override
public void onReceive(Context context, Intent intent) {
//广播接收器仅仅定义了对监听到的广播的反应,没有定义监听的类型(在MainActivity.java中动态注册)
Toast.makeText(context,"我收到广播",Toast.LENGTH_SHORT).show();
}
}
效果图:
核心思想
- 将在AndroidManifest.xml中注册的部分移到MainActivity.java中进行注册(记得销毁注册)