Android-简单IOC框架

ContentView注解

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME) //一直保留到加载虚拟机中
//@Retention(RetentionPolicy.CLASS) //编译到字节码中，当虚拟机加载这个字节码时，注解信息会被清除
//@Retention(RetentionPolicy.SOURCE) //只会在源码出现，当源码编译成字节码时，注解信息会被清除
public @interface ContentView {
    int value();
}

ViewInject注解

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface ViewInject {
    int value();
}

OnClick注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface OnClick {
    int[] value();
}

绑定

public class ViewInjector {

    public static void bind(Activity activity) {
        injectLayout(activity);
        injectView(activity);
        injectEvents(activity);
    }

    /*绑定ContentView*/
    private static void injectLayout(Activity activity) {
        Class<?> clazz = activity.getClass();
        ContentView inject = clazz.getAnnotation(ContentView.class);
        if (inject != null) {
            int id = inject.value();
            try {
                Method setContentView = clazz.getMethod("setContentView", int.class);
                setContentView.invoke(activity, id);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /*绑定ViewInject*/
    private static void injectView(Activity activity) {
        Class<?> clazz = activity.getClass();
        Field[] declaredFields = clazz.getDeclaredFields();
        for (int i = 0; i < declaredFields.length; i++) {
            Field field = declaredFields[i];
            ViewInject inject = field.getAnnotation(ViewInject.class);
            if (inject != null) {
                int id = inject.value();
                try {
                    Method findViewById = clazz.getMethod("findViewById", int.class);
                    View view = (View) findViewById.invoke(activity, id);
                    field.setAccessible(true);
                    field.set(activity, view);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /*绑定OnClick*/
    private static void injectEvents(final Activity activity) {
        Class<?> clazz = activity.getClass();
        Method[] methods = clazz.getDeclaredMethods();
        for (final Method method : methods) {
            OnClick onClick = method.getAnnotation(OnClick.class);
            if (onClick != null) {
                int[] ids = onClick.value();
                for (int id : ids) {
                    final View view = activity.findViewById(id);
                    if(view != null){
                        view.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View v) {
                                method.setAccessible(true);
                                try {
                                    method.invoke(activity, view);
                                } catch (Exception e) {
                                    e.printStackTrace();
                                }
                            }
                        }); 
                    }
                }
            }
        }
    }
}

测试

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

    @ViewInject(R.id.btn_test1)
    Button btn1;

    @ViewInject(R.id.btn_test2)
    Button btn2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ViewInjector.bind(this);
    }

    @OnClick({R.id.btn_test1, R.id.btn_test2})
    public void onClick(View view) {
       System.out.println(this);
        if (view == btn1) {
            Toast.makeText(MainActivity.this, "点击了btn1", Toast.LENGTH_SHORT).show();
        }
        if (view == btn2) {
            Toast.makeText(MainActivity.this, "点击了btn2", Toast.LENGTH_SHORT).show();
        }
    }
}