DirectFieldAccessor的使用场景（好多图）

1、背景：

在项目中遇到某实例中的某个属性被声明为private ,而且实体类中，不提供该属性的get方法，导致无法通过get获取该属性值。这个时候，我们可以利用DirectFieldAccessor这个类进行获取我们想要的属性值。

2、作用

它的功能是直接操作Bean的属性值，代替使用get/set方法去操作Bean。

3、使用案例

class User {

    private int id ;

    private Ving ving = new Ving();

    public User(int id) {
        this.id = id;
    }
}

class Ving{
    public int activeCount = 6;
}

public class TestDirectClass {

    @Test
    public void testDirectFieldAccessor() {
        User user = new User(111);

        DirectFieldAccessor accessor = new DirectFieldAccessor(user);
        TypeDescriptor id = accessor.getPropertyTypeDescriptor("id");
        System.out.println(id.getName());
        Object idValue = accessor.getPropertyValue("id");
        System.out.println("idValue:" +idValue);

        Ving ving = (Ving)accessor.getPropertyValue("ving");
        System.out.println(ving.activeCount);

    }

    @Test
    public void testPropertyAccessorFactory() {
        User user = new User(111);

        ConfigurablePropertyAccessor configurablePropertyAccessor = PropertyAccessorFactory.forDirectFieldAccess(user);

        TypeDescriptor id = configurablePropertyAccessor.getPropertyTypeDescriptor("id");

        System.out.println(id.getName());

        Object idValue = configurablePropertyAccessor.getPropertyValue("id");
        System.out.println("idValue:" +idValue);

        Ving ving = (Ving)configurablePropertyAccessor.getPropertyValue("ving");
        System.out.println(ving.activeCount);


    }
}