如何用Java注解和反射实现依赖注入

@Retention(RetentionPolicy.RUNTIME)
public @interface Autowired {

}

public class Demo {
    private String str;

    @Autowired
    public void setStr (String str) {
       this.str = str;
    }

    public String getStr () {
        return str;
    }
}

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Test {
    
    public static Object injectStrToInstance (String ClassName,String str) throws ClassNotFoundException {
        // 获取Demo的Class对象
        Class demoClass = Class.forName(ClassName);
        // 从Class对象中获取Demo中声明方法对应的Method对象
        Method [] methods = demoClass.getDeclaredMethods();
        for (Method method : methods) {
            // 判断方法是否被加上了@Autowired这个注解
            if(method.isAnnotationPresent(Autowired.class)) {
                // 将方法设置为可调用的
                method.setAccessible(true);
                try {
                    Object object = demoClass.newInstance();
                    // 调用method方法，向其中注入str字符串
                    method.invoke(object,str);
                    return object;
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                } catch (InvocationTargetException e) {
                    e.printStackTrace();
                } catch (InstantiationException e) {
                    e.printStackTrace();
                }
            }
        }
        return null;
    }

    public static void main (String args []) throws ClassNotFoundException {
        // 进行依赖注入，并取得注入后的Demo的对象实例
       Demo demo1 = (Demo)injectStrToInstance("Demo", "我是被注入的文本");
       // 输出一下看看我们的文本是不是被成功注入进去了
       System.out.println(demo1.getStr());
    }
}