EventBus后台发送消息到前台

最新推荐文章于 2024-06-24 16:05:45 发布

xiaoke804376088

最新推荐文章于 2024-06-24 16:05:45 发布

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本文链接：https://blog.youkuaiyun.com/xiaoke804376088/article/details/49905573

本文介绍如何利用EventBus在后台向前台发送消息，确保消息传递的可靠性，即使在应用的不同组件间也能保持通信畅通。首先，需要集成EventBus库并将其设置为Library。然后，在后台服务中发布事件，而在前台接收并处理这些事件。

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EventBus只能单向传递，但是该传递不会丢失信息。

导入EventBus工程，将其创建成Library，如图：

前台代码

package com.pangbao.myeventbus;

import de.greenrobot.event.EventBus;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener {
	TextView tv = null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		tv = (TextView) findViewById(R.id.tv_id);

		Button btn = (Button) findViewById(R.id.button1);
		btn.setOnClickListener(this);

		EventBus.getDefault().register(this);
	}

	@Override
	public void onClick(View v) {
		// 点击启动后台服务
		Intent service = new Intent(this, PangService.class);
		startService(service);
	}

	// 这里，EventBus回调接受消息，然后更新Main UI的TextView
	public void onEventMainThread(Comment event) {
		Log.d(this.getClass().getName(),
				"onEventMainThread:" + event.toString());

		tv.setText(event.str);
	}

	// EventBus回调接受消息
	public void onEventBackgroundThread(Comment event) {
		Log.d(this.getClass().getName(),
				"onEventBackgroundThread:" + event.toString());
	}

	// EventBus回调接受消息
	public void onEventAsync(Comment event) {
		Log.d(this.getClass().getName(), "onEventAsync:" + event.toString());
	}

}

后台代码

package com.pangbao.myeventbus;

import de.greenrobot.event.EventBus;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

public class PangService extends Service {

	@Override
	public void onCreate() {
		// TODO Auto-generated method stub
		super.onCreate();
	}

	public void startEvent() {
		new Thread(new Runnable() {

			@Override
			public void run() {

				int id = 0;
				for (int i = 0; i < 100; i++) {
					Comment event = new Comment();
					event.str = "hollow," + id + "word";
					EventBus.getDefault().post(event);
					id++;
					try {
						Thread.sleep(2000);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
			}
		}).start();
	}

	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {
		// TODO Auto-generated method stub

		startEvent();

		return super.onStartCommand(intent, flags, startId);
	}

	@Override
	public IBinder onBind(Intent arg0) {
		// TODO Auto-generated method stub
		return null;
	}

}

接收数据类

package com.pangbao.myeventbus;

public class Comment {
	public int id;
	public String str;
	
	@Override
	public String toString() {
		return "Comment [str=" + str + "]";
	}
	
}

布局代码

<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="com.pangbao.myeventbus.MainActivity" >

    <TextView
        android:id="@+id/tv_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tv_id"
        android:layout_marginTop="114dp"
        android:layout_toRightOf="@+id/tv_id"
        android:text="接收" />

</RelativeLayout>

记得最后在AndroidManif.xml中注册

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.pangbao.myeventbus"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="21" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".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>
        <service android:name=".PangService"/>
    </application>

</manifest>