模拟实现Autowired

模拟实现Autowired

package com;
​
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
​
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface AutoWired {
}

package com;
​
import com.controller.UserController;
import java.util.stream.Stream;
​
public class MyTest {
​
    public static void main(String[] args) throws Exception {
        Class<UserController> cls = UserController.class;
        UserController uc = cls.newInstance();
        Stream.of(cls.getDeclaredFields()).forEach(field -> {
            field.setAccessible(true);
            AutoWired annotation = field.getAnnotation(AutoWired.class);
            if (annotation != null){
                Class<?> type = field.getType();
                try {
                    Object o = type.newInstance();
                    field.set(uc,o);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
        System.out.println(uc.getService());
    }
}