Android EventBus 如何使用

1.添加依赖

implementation 'org.greenrobot:eventbus:3.0.0'

2.新建一个发送消息的实体类MessageEvent

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;
    }
}

3.接收消息的活动

import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
 
import org.greenrobot.eventbus.EventBus;
import org.greenrobot.eventbus.Subscribe;
import org.greenrobot.eventbus.ThreadMode;
 
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
 
public class MainActivity extends AppCompatActivity {
    
    
 
    private Button button;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = findViewById(R.id.textview);
        button = findViewById(R.id.button);
        textView.setText("你好");
        //这行代码是注册EventBus
        EventBus.getDefault().register(this);
        Log.d("TAG", "onCreate: ===========注册");
        button.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View view) {
    
    
                Intent intent = new Intent(MainActivity.this, MainActivity2.class);
                startActivity(intent);
            }
        });
    }
 
    //三个参数1.线程选择，2.是否是粘性事件，3.优先级
     //在这里写接收通知的逻辑操作。setEvent方法名可以随便取
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void setEvent(MessageEvent messageEvent) {
    
    
        Log.d("TAG", "onCreate: ===========执行");
        textView.setText(messageEvent.getMessage());
    }
 
    @Override
    protected void onDestroy() {
    
    
        if (EventBus.getDefault().isRegistered(this)) {
    
    
        //这行代码是取消注册
            EventBus.getDefault().unregister(this);
        }
        super.onDestroy();
    }
}

4.发起消息的活动

import androidx.appcompat.app.AppCompatActivity;
 
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
 
import org.greenrobot.eventbus.EventBus;
import org.greenrobot.eventbus.Subscribe;
import org.greenrobot.eventbus.ThreadMode;
 
public class MainActivity2 extends AppCompatActivity {
    
    
 
    private Button button;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        button = findViewById(R.id.button1);
 
        button.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View view) {
    
    
                //发送通知消息
                EventBus.getDefault().post(new MessageEvent("大家好"));
                Log.d("TAG", "onCreate: ===========发送");
                finish();
            }
        });
    }
}

5.两个活动的布局文件就不展示出来了，比较简单。