Simple use of eventbus

summary

EventBus It's a Android Event publishing / Subscription framework , Simplify... By decoupling publishers and subscribers Android events , The event here can be understood as a message . Event passing can be used both for Android Communication between the four components , It can also be used for communication between asynchronous threads and mainthreads .
Traditional event delivery methods include ：Handler、BroadcastReceiver、Interface Callback , by comparison EventBus The point of is that the code is concise , Easy to use , And publish the event and Subscriptions are fully decoupled

1. The first step is to add a class library ,
//eventbus Transmit information 
implementation 'org.greenrobot:eventbus:3.1.1'

2. Popular said

To build a A class （ Received ）,

onCreate Register inside 

EventBus.getDefault().register(this);

onDestroy Internal deregistration 

EventBus.getDefault().unregister(this);

Creating subscription methods , When an event is received , This method is called

    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onEvent(Event messageEvent) {
        Log.e("TAG", "------------>"+ messageEvent.getMessage());
        Toast.makeText(MainActivity.this, messageEvent.getMessage(), Toast.LENGTH_SHORT).show();
    }

Create an entity class

public class Event {
    private String message;

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

    public String getMessage() {
        return message;
    }
}

stay B Class ,A Class onEvent Method

B Class to send message events

// Send events 
EventBus.getDefault().post(new Event("Just do it"));

build.gradle Add //eventbus Transmit information 
implementation 'org.greenrobot:eventbus:3.1.1'

Complete code

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    public Button button;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = findViewById(R.id.button);
        button.setOnClickListener(this);
        // Registration events 
        EventBus.getDefault().register(this);
    }


    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.button:// Click into another class , Send a message event in another class 
                Intent intent = new Intent(this, LoginActivity.class);
                startActivity(intent);
                break;
        }
    }

    // Subscription method , When an event is received , This method is called 
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onEvent(Event messageEvent) {
        Log.e("TAG", "------------>"+ messageEvent.getMessage());
        Toast.makeText(MainActivity.this, messageEvent.getMessage(), Toast.LENGTH_SHORT).show();
    }
// Unregister 
    @Override
    public void onDestroy() {
        super.onDestroy();
        EventBus.getDefault().unregister(this);
    }
}

Another class

public class LoginActivity extends AppCompatActivity  implements View.OnClickListener {
    Button login_image_QQlogin;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        login_image_QQlogin = findViewById(R.id.login_image_QQlogin);

        login_image_QQlogin.setOnClickListener(this);
    }


    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.login_image_QQlogin :
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        // Send events 
                        EventBus.getDefault().post(new Event("Just do it"));
                    }
                }).start();
                break;
        }
    }
}

Entity class

public class Event {
    private String message;

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

    public String getMessage() {
        return message;
    }
}

Register and unregister in which class you receive events , Rewrite the receiving method , Deepen understanding EventBus It is suggested to go to the official website to see the source code