Android学习之EventBus基础篇

一、概述

EventBus是一款针对Android优化的发布/订阅事件总线。主要功能是替代Intent,Handler,BroadCast在Fragment，Activity，Service，线程之间传递消息.优点是开销小，代码更优雅。以及将发送者和接收者解耦。
Github地址：https://github.com/greenrobot/EventBus

二、实例演示

点击MainActivity页面里的跳转按钮进入SecondActivity页面，点击发送EventBus事件按钮，进行事件消息发送操作，我们在返回到MainActivity页面发现，我们成功的接收到SecondActivity页面发送过来的消息。

1.添加依赖：

compile 'org.greenrobot:eventbus:3.0.0'

2.MainActivity.java

package com.czhappy.eventbusdemo.activity;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.text.TextUtils;import android.util.Log;import android.view.View;import android.widget.TextView;import com.czhappy.eventbusdemo.R;import com.czhappy.eventbusdemo.model.MessageEvent;import org.greenrobot.eventbus.EventBus;import org.greenrobot.eventbus.Subscribe;import org.greenrobot.eventbus.ThreadMode;public class MainActivity extends AppCompatActivity {    private TextView receive_tv;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //注册eventBus        EventBus.getDefault().register(this);        receive_tv = (TextView) this.findViewById(R.id.receive_tv);    }    public void goSecondBtn(View view){        SecondActivity.startActivity(this);    }    @Override    protected void onDestroy() {        super.onDestroy();        //取消注册        EventBus.getDefault().unregister(this);    }    @Subscribe(threadMode = ThreadMode.MAIN)    public void onEventMainThread(MessageEvent event) {        if (!TextUtils.isEmpty(event.getMsg())) {            receive_tv.setText("接收到消息：" + event.getMsg());        }    }}

3.activity_main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    android:padding="10dp">    <Button        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:padding="10dp"        android:text="跳转"        android:onClick="goSecondBtn"/>    <TextView        android:id="@+id/receive_tv"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:padding="10dp"        android:textColor="#333333"        android:textSize="16sp"/></LinearLayout>

4.SecondActivity.java

package com.czhappy.eventbusdemo.activity;import android.content.Context;import android.content.Intent;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import com.czhappy.eventbusdemo.R;import com.czhappy.eventbusdemo.model.MessageEvent;import org.greenrobot.eventbus.EventBus;/** * author: chenzheng * created on: 2017/8/2 8:08 * description: */public class SecondActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_second);    }    public void sendEventBtn(View view){        EventBus.getDefault().post(new MessageEvent("大家好，我是小明！"));    }    public static void startActivity(Context context){        Intent intent = new Intent(context, SecondActivity.class);        context.startActivity(intent);    }}

5.activity_second.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:padding="10dp"    android:orientation="vertical">    <Button        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:padding="10dp"        android:text="发送EventBus事件"        android:onClick="sendEventBtn"/></LinearLayout>