EventBus广播

第一步:添加依赖

 compile 'org.greenrobot:eventbus:3.0.0'

第二步:定义消息事件类

public class MessageEvent{
    private String message; public MessageEvent(String message){ this.message=message; } public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } } 

第三步:注册和解除注册

分别在FirstActivity的onCreate()方法和onDestory()方法里，进行注册EventBus和解除注册。

package com.example.lenovo.testapp.ui;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.Button; import android.widget.TextView; import com.example.lenovo.testapp.R; import com.example.lenovo.testapp.event.MessageEvent; import org.greenrobot.eventbus.EventBus; import org.greenrobot.eventbus.Subscribe; import org.greenrobot.eventbus.ThreadMode; /** * Created by ZZG on 2018/1/10. */ public class FirstActivity extends AppCompatActivity { private Button mButton; private TextView mText; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.first_activity); mButton = (Button) findViewById(R.id.btn1); mText = (TextView) findViewById(R.id.tv1); mText.setText("今天是星期三"); EventBus.getDefault().register(this); jumpActivity(); } private void jumpActivity() { mButton.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent intent=new Intent(FirstActivity.this,SecondActivity.class); startActivity(intent); } }); } @Subscribe(threadMode = ThreadMode.MAIN) public void Event(MessageEvent messageEvent) { mText.setText(messageEvent.getMessage()); } @Override protected void onDestroy() { super.onDestroy(); if(EventBus.getDefault().isRegistered(this)) { EventBus.getDefault().unregister(this); } } } 

事件处理

在这里，事件的处理线程在主线程，是因为，我要让TextView去显示值。
在 SecondActivity里去进行事件的发送。

package com.example.lenovo.tezs;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.view.View; import android.widget.Button; import org.greenrobot.eventbus.EventBus; /** * Created by ZZG on 2018/1/10. */ public class SecondActivity extends AppCompatActivity { private Button mButton2; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.second_activity); mButton2=(Button) findViewById(R.id.btn2); jumpActivity(); } private void jumpActivity() { mButton2.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { EventBus.getDefault().post(new MessageEvent("欢迎大家浏览我写的博客")); finish(); } }); } } 

很简单，当点击按钮的时候，发送了一个事件。