Android 点击事件注解

 1、定义事件类型注解

@Target(ElementType.ANNOTATION_TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface EventType {
    Class listenerType();

    String listenerSetter();

}

2、点击注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@EventType(listenerType = View.OnClickListener.class, listenerSetter = "setOnClickListener")
public @interface OnClick {
    int[] value();
}

3、长按注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@EventType(listenerType = View.OnLongClickListener.class, listenerSetter = "setOnLongClickListener")
public @interface OnLongClick {
    int[] value();
}

4、工具类

package com.enjoy.reflect;

import android.app.Activity;
import android.view.View;

import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class InjectUtils {


    public static void injectEvent(Activity activity) {
        Class<? extends Activity> activityClass = activity.getClass();
        Method[] declaredMethods = activityClass.getDeclaredMethods();


        for (Method method : declaredMethods) {
            //获得方法上所有注解
            Annotation[] annotations = method.getAnnotations();

            for (Annotation annotation : annotations) {
                //注解类型
                Class<? extends Annotation> annotationType = annotation.annotationType();
                if (annotationType.isAnnotationPresent(EventType.class)) {
                    EventType eventType = annotationType.getAnnotation(EventType.class);
                    // OnClickListener.class
                    Class listenerType = eventType.listenerType();
                    //setOnClickListener
                    String listenerSetter = eventType.listenerSetter();

                    try {
                        // 不需要关心到底是OnClick 还是 OnLongClick
                        Method valueMethod = annotationType.getDeclaredMethod("value");
                        int[] viewIds = (int[]) valueMethod.invoke(annotation);

                        method.setAccessible(true);
                        ListenerInvocationHandler<Activity> handler = new ListenerInvocationHandler(activity, method);
                        Object listenerProxy = Proxy.newProxyInstance(listenerType.getClassLoader(),
                                new Class[]{listenerType}, handler);
                        // 遍历注解的值
                        for (int viewId : viewIds) {
                            // 获得当前activity的view（赋值）
                            View view = activity.findViewById(viewId);
                            // 获取指定的方法(不需要判断是Click还是LongClick)
                            // 如获得：setOnClickLisnter方法，参数为OnClickListener
                            // 获得 setOnLongClickLisnter，则参数为OnLongClickLisnter
                            Method setter = view.getClass().getMethod(listenerSetter, listenerType);
                            // 执行方法
                            setter.invoke(view, listenerProxy); //执行setOnclickListener里面的回调 onclick方法
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }

        }
    }

    /**
     * 还可能在自定义view注入，所以是泛型： T = Activity/View
     *
     * @param <T>
     */
    static class ListenerInvocationHandler<T> implements InvocationHandler {

        private Method method;
        private T target;

        public ListenerInvocationHandler(T target, Method method) {
            this.target = target;
            this.method = method;
        }

        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            return this.method.invoke(target, args);
        }
    }
}

5、使用

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        InjectUtils.injectEvent(this);
    }

    @OnClick({R.id.btn1, R.id.btn2})
    public void click(View view) {
        switch (view.getId()) {
            case R.id.btn1:
                Log.i(TAG, "click: 按钮1");
                break;
            case R.id.btn2:
                Log.i(TAG, "click: 按钮2");
                break;
        }
    }


    @OnLongClick({R.id.btn1, R.id.btn2})
    public boolean longClick(View view) {
        switch (view.getId()) {
            case R.id.btn1:
                Log.i(TAG, "longClick: 按钮1");
                break;
            case R.id.btn2:
                Log.i(TAG, "longClick: 按钮2");
                break;
        }
        return false;
    }
}