Android 广播接收和信息的传递

    实现内容为点击按钮打印接收到的广播内容

1.静态注册

静态注册需要在Manifest.xml去配置：

		<receiver android:name=".MyBroadcastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="myBroadCast"/>
            </intent-filter>
        </receiver>

2.动态注册接收广播消息

动态注册是在类里面去注册：

MainActivity.java:

//实现MyBroadcastReceiver的接口
public class MainActivity extends AppCompatActivity implements MyBroadcastReceiver.MyReceiver {
    private TextView mTv_fruit;
    IntentFilter filter;
    MyBroadcastReceiver myReceiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTv_fruit = findViewById(R.id.tv_fruit);
        //动态注册广播
        myReceiver = new MyBroadcastReceiver();
        filter = new IntentFilter("myBroadCast");
        registerReceiver(myReceiver, filter);
        //调用MyBroadcastReceiver类里面的MyThis方法传入MainActivity对象；
        myReceiver.MyThis(this);

    }

	//布局里面的点击事件
    public void getReceiver(View view) {
        Intent intent = new Intent("myBroadCast");
        //android版本为8以上的，静态声明广播注册需要设置包名
        intent.setPackage("com.example.broadcat2");
        intent.putExtra("fruit", "bana");
        sendBroadcast(intent);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        //页面被销毁了，如finish时，注销广播
        //注意如果这个Activity被销毁时，没被注销会报一个异常
        unregisterReceiver(myReceiver);
    }
    //从MyBroadcastReceiver类获取广播接收到的消息内容，并设置给TextView
    @Override
    public void interFruit(String fruit) {
        mTv_fruit.setText(fruit);
    }
}

MyBroadcastReceiver.java

package com.example.broadcat2;
public class MyBroadcastReceiver extends BroadcastReceiver {
    private MyReceiver mReceiver;
    private String fruit;
    @Override
    public void onReceive(Context context, Intent intent) {
    	//接收广播消息
        fruit = intent.getStringExtra("fruit");
        //调用接口MyReceiver里面的interFruit方法传入接收的内容
        mReceiver.interFruit(fruit);
        //使用Toast显示广播消息
      Toast.makeText(context,fruit,Toast.LENGTH_SHORT).show();
    }
	//创建一个接口把接收到的广播内容传递回MainActivity
    interface MyReceiver{
       void interFruit(String fruit);
    }
    public void MyThis(MyReceiver mr){
        mReceiver = mr;
    }
}

activity_main.xml:

<?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"
    android:orientation="vertical"
    tools:context=".MainActivity">
   <TextView
       android:id="@+id/tv_fruit"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:textSize="20sp"
       android:layout_gravity="center"/>
   <Button
       android:id="@+id/Btn_receiver"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:onClick="getReceiver"
       android:text="发送广播"
       android:textAllCaps="false"
       />
</LinearLayout>

实现图：
点击按钮发送广播，然后使用Toast显示发出的信息并赋值给TextView控件