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使用反射和动静代理实现一个View注解绑定库

反对的功能
@ContentView 绑定layout 代替setContentView()
@BindView 绑定View 代替findViewById()
@OnClick 绑定点击事件 代替setOnClickListener()
@OnLongClick 绑定长按事件 代替setOnLongClickListener()

代码
注解类
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface ContentView {

int value();

}
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@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface BindView {

int value();

}
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@Target(ElementType.ANNOTATION_TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface OnEvent {

//订阅形式String setCommonListener();//事件源对象Class<?> commonListener();

}
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@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@OnEvent(setCommonListener = "setOnClickListener",

    commonListener = View.OnClickListener.class)

public @interface OnClick {

int value();

}
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@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@OnEvent(setCommonListener = "setOnLongClickListener",

    commonListener = View.OnLongClickListener.class)

public @interface OnLongClick {

int value();

}
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实现类
public class MsInjector {

public static void inject(Object object) {    injectContentView(object);    injectView(object);    injectEvent(object);}private static void injectContentView(Object object) {    Class<?> clazz = object.getClass();    //获取到ContentView注解    ContentView contentView = clazz.getAnnotation(ContentView.class);    if (contentView == null) {        return;    }    //获取到注解的值，也就是layoutResID    int layoutResID = contentView.value();    try {        //反射出setContentView方法并调用        Method method = clazz.getMethod("setContentView", int.class);        method.invoke(object, layoutResID);    } catch (Exception e) {        e.printStackTrace();    }}private static void injectView(Object object) {    Class<?> clazz = object.getClass();    //获取到所有字段并遍历    Field[] fields = clazz.getDeclaredFields();    for (Field field : fields) {        field.setAccessible(true);        //获取字段上的BindView注解        BindView bindView = field.getAnnotation(BindView.class);        if (bindView == null) {            continue;        }        //获取到viewId        int viewId = bindView.value();        try {            //通过反射调用findViewById失去view实例对象            Method method = clazz.getMethod("findViewById", int.class);            Object view = method.invoke(object, viewId);            //赋值给注解标注的对应字段            field.set(object, view);        } catch (Exception e) {            e.printStackTrace();        }    }}private static void injectEvent(Object object) {    Class<?> clazz = object.getClass();    //获取到当前页年一切办法并遍历    Method[] declaredMethods = clazz.getDeclaredMethods();    for (Method declaredMethod : declaredMethods) {        declaredMethod.setAccessible(true);        //获取方法上的所有注解并遍历        Annotation[] annotations = declaredMethod.getDeclaredAnnotations();        for (Annotation annotation : annotations) {            //获取注解本身            Class<? extends Annotation> annotationType = annotation.annotationType();            //获取注解上的OnEvent注解            OnEvent onEvent = annotationType.getAnnotation(OnEvent.class);            if (onEvent == null) {                continue;            }            //拿到注解中的元素            String setCommonListener = onEvent.setCommonListener();            Class<?> commonListener = onEvent.commonListener();            try {                //因为上边没有明确获取是哪个注解，所以这里需要使用反射获取viewId                Method valueMethod = annotationType.getDeclaredMethod("value");                valueMethod.setAccessible(true);                int viewId = (int) valueMethod.invoke(annotation);                //通过反射findViewById获取到对应的view                Method findViewByIdMethod = clazz.getMethod("findViewById", int.class);                Object view = findViewByIdMethod.invoke(object, viewId);                //通过反射获取到view中对应的setCommonListener方法                Method viewMethod = view.getClass().getMethod(setCommonListener, commonListener);                //使用动静代理监听回调                Object proxy = Proxy.newProxyInstance(                        clazz.getClassLoader(),                        new Class[]{commonListener},                        new InvocationHandler() {                            @Override                            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {                                //最终执行被标注的方法                                return declaredMethod.invoke(object, null);                            }                        }                );                //调用view的setCommonListener方法                viewMethod.invoke(view, proxy);            } catch (Exception e) {                e.printStackTrace();            }        }    }}

}
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使用
@ContentView(R.layout.activity_main)
public class MainActivity extends AppCompatActivity {

@BindView(R.id.button1)private Button button1;@BindView(R.id.button2)Button button2;@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    MsInjector.inject(this);}@OnClick(R.id.button1)public void clickButton1() {    Toast.makeText(this, "click button1", Toast.LENGTH_SHORT).show();}@OnClick(R.id.button2)public void clickButton2() {    Toast.makeText(this, "click button2", Toast.LENGTH_SHORT).show();}@OnLongClick(R.id.button1)public boolean longClickButton1() {    Toast.makeText(this, "long click button1", Toast.LENGTH_SHORT).show();    return false;}@OnLongClick(R.id.button2)public boolean longClickButton2() {    Toast.makeText(this, "long click button2", Toast.LENGTH_SHORT).show();    return false;}

}