Android中的eventBus传值

第一步：在build.gradle中添加依赖
dependencies {
    
    compile 'org.greenrobot:eventbus:3.0.0'
}

第二步：创建一个 Event类： 注意：enum 不是class

public enum  Event {
    //消息名，可以根据这个名字判断是哪个消息
    IMAGE_LOADER_SUCCESS;
}

//------------主布局文件------------------------

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/tv_text" />
<Button
    android:layout_width="match_parent"
    android:layout_height="40dp"
    android:text="点击跳转到TwoActivity"
    android:id="@+id/bt_button"/>

//-----------TwoActivity布局-----------------------

<Button
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/bt_button2"
    android:text="发送消息"/>

//---------创建一个消息了---MessageEvent ------------------------

public class MessageEvent {
    private String message;

    public String getMessage() {
        return message;
    }

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

    public MessageEvent(String message) {
        this.message = message;
    }

    public MessageEvent() {
    }
}

//--------------MainActivity -中我们注册事件，用于接收消息，退出时需要注销-----------------

package eventbusdemo.wode.com.eventbusdemo;

import android.content.Intent;
import android.support.v7.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 MainActivity extends AppCompatActivity implements View.OnClickListener{

    private Button bt_button;
    private TextView tv_text;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //找到控件
        bt_button = (Button) findViewById(R.id.bt_button);
        tv_text = (TextView) findViewById(R.id.tv_text);
        //在需要订阅事件的地方注册事件
        EventBus.getDefault().register(this);
        //设置监听
        bt_button.setOnClickListener(this);

    }
    //用于接收传MessageEvent这个类的消息
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onShowMessageEvent(MessageEvent messageEvent) {
        tv_text.setText("MainActivity:" + messageEvent.getMessage());
    }

    //用于接收没有传值的消息
  /* @Subscribe
    public void onEventMainThread(Event event){
        switch (event){
            case IMAGE_LOADER_SUCCESS:
                Log.i("MainActivity--","IMAGE_LOADER_SUCCESS");
                tv_text.setText("IMAGE_LOADER_SUCCESS");
                break;
        }
    }*/

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.bt_button:
                Intent intent=new Intent(MainActivity.this,TwoActivity.class);
                startActivity(intent);
                break;
        }
    }

    //(5)取消消息订阅
    @Override
    protected void onDestroy() {
        super.onDestroy();
        EventBus.getDefault().unregister(this);
    }
}

//--------------TwoActivity 中，用于发送消息------------------------

package eventbusdemo.wode.com.eventbusdemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import org.greenrobot.eventbus.EventBus;

public class TwoActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_two);
        Button bt_button2= (Button) findViewById(R.id.bt_button2);
        bt_button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //(3)产生事件，即发送消息
               // EventBus.getDefault().post(Event.IMAGE_LOADER_SUCCESS);
            //传值
                EventBus.getDefault().post(new MessageEvent("哈哈哈哈哈"));
            }
        });

    }
}