广播接收器

发送和接收普通消息

 activity_main.mxl

<?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">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="请输入要发送的信息"
         />
    <EditText
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:singleLine="false"
    android:inputType="text"
    android:id="@+id/id_et"
    />
    <Button
        android:id="@+id/text_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="发送"
        />
</LinearLayout>

修改MainActivity.java 监听按键的点击事件 并在onClick（）方法中发送普通广播信息

package com.commerce.myapplication;

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 AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button =findViewById(R.id.btn);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent=new Intent(MainActivity.this,MainActivity2.class);
                startActivity(intent);
            }
        });
    }
}

MyReceiver.java

package com.commerce.myapplication;

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

public class MyReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
        // an Intent broadcast.
//        throw new UnsupportedOperationException("Not yet implemented");
        Log.d("text","textsdds");

        String msg =intent.getStringExtra("msg");
        Toast.makeText(context,msg, Toast.LENGTH_SHORT).show();
    }
}

最后一步需要在AndroidManifest.xml文件中注册该消息接收器

 <receiver
            android:name=".MyReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.hello" />
            </intent-filter>
        </receiver>