Android 中 LocalBroadcastManager 的基本使用

BroadActivity2 发广播, BroadActivity 接受.

BroadActivity 文件

package com.example.hello.broadcast;

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.Bundle;
import android.widget.Button;
import android.widget.TextView;

import com.example.hello.R;

public class BroadActivity extends AppCompatActivity {
     

    private Button btnClick;
    private TextView tvTest;
    private MyBroadcast myBroadcast;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
     
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_broad);
        btnClick = findViewById(R.id.btn_click);
        tvTest = findViewById(R.id.tv_test);
        btnClick.setOnClickListener(v -> {
     
            Intent intent = new Intent(BroadActivity.this, BroadActivity2.class);
            startActivity(intent);
        });
        myBroadcast = new MyBroadcast();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("com.example.hello.broadcast.BroadActivity2");
        LocalBroadcastManager.getInstance(this).registerReceiver(myBroadcast, intentFilter);
    }

    private class MyBroadcast extends BroadcastReceiver {
     
        @Override
        public void onReceive(Context context, Intent intent) {
     
            switch (intent.getAction()) {
     
                case "com.example.hello.broadcast.BroadActivity2":
                    CharSequence newText = "123";
                    tvTest.setText(newText);
                    break;
                default:
                    throw new IllegalStateException("Unexpected value: " + intent.getAction());
            }
        }
    }

    @Override
    protected void onDestroy() {
     
        super.onDestroy();
        LocalBroadcastManager.getInstance(this).unregisterReceiver(myBroadcast);
    }
}

<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"
    android:padding="15dp"
    tools:context=".broadcast.BroadActivity">

    <Button
        android:id="@+id/btn_click"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/click" />

    <TextView
        android:id="@+id/tv_test"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15dp"
        android:gravity="center"
        android:text="@string/app_name"
        android:textColor="@color/black"
        android:textSize="25sp" />

LinearLayout>

BroadActivity2 文件

package com.example.hello.broadcast;

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

import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;

import com.example.hello.R;

public class BroadActivity2 extends AppCompatActivity {
     

    private Button btnClick;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
     
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_broad2);
        btnClick = findViewById(R.id.btn_click);
        btnClick.setOnClickListener(v -> {
     
            LocalBroadcastManager.getInstance(BroadActivity2.this).sendBroadcast(new Intent("com.example.hello.broadcast.BroadActivity2"));
        });
    }

}

<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"
    android:padding="15dp"
    tools:context=".broadcast.BroadActivity2">

    <Button
        android:id="@+id/btn_click"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/click" />

LinearLayout>