2022-11-30

package cn.itsource._05test;

import java.lang.reflect.Field;

//测试类：
//    关于注解与反射综合的示例
public class Test {

    public static void main(String[] args) throws NoSuchFieldException, SecurityException, InstantiationException, IllegalAccessException {
        Injection ij = new Injection();
        
        //执行了第三方程序，通过注解标记，决定是否注入对象
        
        threeCode(ij);
        ij.pson.println();//会报错，空指针异常，因为pson没有对象，null
        

    }

    public static void threeCode(Object obj) throws NoSuchFieldException, SecurityException, InstantiationException, IllegalAccessException{
        //拿到了Injection的字节码文件
        Class cla = obj.getClass();
        //通过Injection的字节码文件拿到里面的pson字段
        Field pson = cla.getField("pson");
        //拿到pson字段的类型，拿到字节码文件
        Class typeperson = pson.getType();
        //判断字段pson，是否有注解AutoWired
        AutoWired annotation = pson.getAnnotation(AutoWired.class);
        //拿到注解类型对象annotation，通过annotation获得注解的值
        System.out.println(annotation.value());//取注解的值
        if(annotation == null){
            return;
        }
        //根据typePerson，创建要给Person对象
        Object person = typeperson.newInstance();
        
        //把创建的Person对象，放入字段pson
        pson.set(obj, person);
    }
    

}