EventBus3.0使用

最新推荐文章于 2022-11-12 16:30:42 发布

VipPeterGee

最新推荐文章于 2022-11-12 16:30:42 发布

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分类专栏： android开发文章标签： android

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本文介绍如何使用EventBus实现Android应用内组件间的解耦通信。包括添加依赖、创建消息实体类、发送与接收消息等步骤，并展示了不同线程模式下消息接收的顺序。

使用EventBus降低耦合性

1、添加依赖

 compile 'org.greenrobot:eventbus:3.0.0'

2、在MainActivity中发送消息，我是在onStop()方法中发送的消息，这个可以根据自己的需要灵活使用

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.btn_send_message).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(MainActivity.this,SecondActivity.class));

            }
        });
    }

    @Override
    protected void onStop() {
        super.onStop();
        MessageBean bean=new MessageBean();
        bean.setMessage("你好");
        EventBus.getDefault().post(bean);
    }
}

layout xml文件

<?xml version="1.0" encoding="utf-8"?>
<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"
    tools:context="net.edaibu.eventbusdemo.MainActivity">

    <Button
        android:id="@+id/btn_send_message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="发消息"/>

</RelativeLayout>

3、消息实体类

public class MessageBean {


    private String mMessage;
    private String message;

    public MessageBean(){}

    public MessageBean(String message){
        this.mMessage=message;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

4、接收消息的Activity 在onCreate()中注册EventBus，在onDestory()中取消注册

public class SecondActivity extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //注册EventBus
        EventBus.getDefault().register(this);
    }

    //在ui线程执行
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void receiveMainMessage(MessageBean event) {
        Log.e("tag", "event---->" +event+"_____mainMessage="+ event.getMessage());
        Toast.makeText(this,event.getMessage(),Toast.LENGTH_SHORT).show();
    }

    //在background线程执行
    @Subscribe(threadMode = ThreadMode.BACKGROUND)
    public void receiveMessageBackground(MessageBean event) {
        Log.e("tag", "event---->" +event+"_____backgroundMessage="+ event.getMessage());

    }
    //在async线程执行
    @Subscribe(threadMode = ThreadMode.ASYNC)
    public void receiveMessageAsync(MessageBean event) {
        Log.e("tag", "event---->" +event+"_____asyncMessage="+ event.getMessage());

    }
    //在posting线程执行
    @Subscribe(threadMode = ThreadMode.POSTING)
    public void receiveMessagePosting(MessageBean event) {
        Log.e("tag", "event---->" +event+"_____postingMessage="+ event.getMessage());

    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        //取消注册EventBus
        EventBus.getDefault().unregister(this);
    }
}

5、Demo中分别在EventBus的四个接收方法中打印了log，依次执行的顺序如下

ThreadMode.MAIN-->ThreadMode.POSTING-->ThreadMode.ASYNC->ThreadMode.BACKGROUND

’

6、当然也可以通过设置优先级来改变接收顺序，如下对ThreadMode.POSTING设置priority=100，优先级最高，则ThreadMode.POSTING先接收到数据

//在posting线程执行
    @Subscribe(threadMode = ThreadMode.POSTING,priority = 100)
    public void receiveMessagePosting(MessageBean event) {
        Log.e("tag", "event---->" +event+"_____postingMessage="+ event.getMessage());

    }