android - 为什么两个 Activity 之间没有收到广播？

Question

我不知道为什么我的接收器没有收到任何东西。 我想在两个 Activity 之间发送广播。 tv1 不显示“消息”。

这是代码

发送:

Intent intent = new Intent(action);     
intent.putExtra("msg", "a");        
sendBroadcast(intent);  
startActivity(new Intent(MainActivity.this,sec.class)); 

接收者:

IntentFilter intentFilter = new IntentFilter(MainActivity.action);

registerReceiver(receiver, intentFilter);

BroadcastReceiver receiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        tv1.setText(intent.getExtras().getString("msg"));  
    }
};

Answer 1

你可以这样实现:

 package com.example.broadcastrecieverdemo;

import android.os.Bundle;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends Activity {
    private InternalReciever internalReciever;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        internalReciever = new InternalReciever();
        IntentFilter filter = new IntentFilter("kishan");
        registerReceiver(internalReciever, filter);
        findViewById(R.id.btnSendBroadcast).setOnClickListener(
                new View.OnClickListener() {

                    @Override
                    public void onClick(View v) {
                        Intent intent = new Intent();
                        intent.setAction("com.example.broadcastrecieverdemo.CUSTOM_INTENT");
                        sendBroadcast(intent);
                    }
                });

        findViewById(R.id.btnInternalSendBroadcast).setOnClickListener(
                new View.OnClickListener() {

                    @Override
                    public void onClick(View v) {
                        Intent intent = new Intent();
                        intent.setAction("kishan");
                        sendBroadcast(intent);
                    }
                });
    }



    @Override
    protected void onDestroy() {
        unregisterReceiver(internalReciever);
        super.onDestroy();
    }

}

class InternalReciever extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context, "Inernal Broadcast recieved",
                Toast.LENGTH_SHORT).show();
    }

}

Reciever.java

    package com.example.broadcastrecieverdemo;

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

public class Reciever extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context, "Broadcast recieved", Toast.LENGTH_SHORT)
                .show();
    }
}

list

<?xml version="1.0" encoding="utf-8"?>

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="18" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.example.broadcastrecieverdemo.MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <receiver android:name=".Reciever" >
        <intent-filter>
            <action android:name="com.example.broadcastrecieverdemo.CUSTOM_INTENT" >
            </action>
        </intent-filter>
    </receiver>
</application>

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
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=".MainActivity" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:text="Broad cast receiver"
    android:textAppearance="?android:attr/textAppearanceLarge" />

<Button
    android:id="@+id/btnSendBroadcast"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textView1"
    android:layout_below="@+id/textView1"
    android:layout_marginTop="21dp"
    android:gravity="center"
    android:text="Send" />

<Button
    android:id="@+id/btnInternalSendBroadcast"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textView1"
    android:layout_below="@+id/btnSendBroadcast"
    android:layout_marginTop="21dp"
    android:gravity="center"
    android:text="Send Internal" />