EventBus主要用于各个组件之间的通信，EventBus作为事件总线方便项目解耦。EventBus整个框架采用订阅者模式来操作。

这里我用两个activity进行通信

这个是第一个activity

public class MainActivity extends AppCompatActivity {
    @BindView(R.id.tv_m)
    TextView title;
    @BindView(R.id.secondActivityBtn)
    Button button;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        EventBus.getDefault().register(this);
        ButterKnife.bind(this);


    }

    @OnClick(R.id.tv_m)
    public void sayHi(TextView v) {
        v.setText("ni hao !");
    }
    @OnClick(R.id.secondActivityBtn)
    public void onClick(View v) {
        Intent intent = new Intent(MainActivity.this, SecondActivity.class);
        startActivity(intent);
    }
    //订阅方法，当接收到事件的时候，会调用该方法
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onEvent(MessageEvent messageEvent){
        Log.d("cylog","receive it");
        title.setText(messageEvent.getMessage());
        Toast.makeText(MainActivity.this, messageEvent.getMessage(), Toast.LENGTH_SHORT).show();
    }

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

}

对应的xml布局

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.eventbustest.MainActivity">

    <TextView
        android:id="@+id/tv_m"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:layout_constraintTop_creator="1"
        tools:layout_constraintRight_creator="1"
        tools:layout_constraintBottom_creator="1"
        tools:layout_constraintLeft_creator="1" />


    <Button
        android:id="@+id/secondActivityBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="117dp"
        android:text="点击打开新的Activity"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />



</android.support.constraint.ConstraintLayout>

第二个activity

public class SecondActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        Button button = (Button) findViewById(R.id.sendMessageBtn);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                EventBus.getDefault().post(new MessageEvent("Hello !....."));
            }
        });
    }

}

对应xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center">

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

还有一个实体类

public class MessageEvent {
    private String message;

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

    public String getMessage(){
        return message;
    }
}

model里面的build.gradle里面设置dependencies依赖

compile 'org.greenrobot:eventbus:3.0.0'
compile 'com.jakewharton:butterknife:8.5.1'
annotationProcessor 'com.jakewharton:butterknife-compiler:8.5.1'

然后运行一下你就可以看到结果了！

官方文档链接：http://greenrobot.org/eventbus/documentation