JavaSpring缓存会破坏反射吗？

我最近正在使用spring引导和集成缓存。在我的测试中，我使用了一些反射

这里有一个例子：

@Service
public class MyService {

    private boolean fieldOfMyService = false;

    public void printFieldOfMyService() {
        System.out.println("fieldOfMyService:" + fieldOfMyService);
    }

    @Cacheable("noOpMethod")
    public void noOpMethod() {
    }

}

@RunWith(SpringRunner.class)
@SpringBootTest(classes = { MyApplication.class })
public class MyServiceTest {

    @Autowired
    private MyService myService;

    @Test
    public void test() throws Exception {

        myService.printFieldOfMyService();

        boolean fieldOfMyService = (boolean) FieldUtils.readField(myService, "fieldOfMyService", true);

        System.out.println("fieldOfMyService via reflection before change:" + fieldOfMyService);

        FieldUtils.writeField(myService, "fieldOfMyService", true, true);

        boolean fieldOfMyServiceAfter = (boolean) FieldUtils.readField(myService, "fieldOfMyService", true);

        System.out.println("fieldOfMyService via reflection after change:" + fieldOfMyServiceAfter);

        myService.printFieldOfMyService();

    }

}

这就是测试：

@Service
public class MyService {

    private boolean fieldOfMyService = false;

    public void printFieldOfMyService() {
        System.out.println("fieldOfMyService:" + fieldOfMyService);
    }

    @Cacheable("noOpMethod")
    public void noOpMethod() {
    }

}

@RunWith(SpringRunner.class)
@SpringBootTest(classes = { MyApplication.class })
public class MyServiceTest {

    @Autowired
    private MyService myService;

    @Test
    public void test() throws Exception {

        myService.printFieldOfMyService();

        boolean fieldOfMyService = (boolean) FieldUtils.readField(myService, "fieldOfMyService", true);

        System.out.println("fieldOfMyService via reflection before change:" + fieldOfMyService);

        FieldUtils.writeField(myService, "fieldOfMyService", true, true);

        boolean fieldOfMyServiceAfter = (boolean) FieldUtils.readField(myService, "fieldOfMyService", true);

        System.out.println("fieldOfMyService via reflection after change:" + fieldOfMyServiceAfter);

        myService.printFieldOfMyService();

    }

}

正如您所看到的，它非常简单：

• MyService

  有一个私有字段

  fieldOfMyService

• 测试通过反射将其从

  false

  更改为

  true

问题

• 没有缓存，一切都正常。。这是输出：

现在，我通过以下方式激活缓存：

• @EnableCaching

  春季
• 然后你会发现：

。。然后它仍然有效

我想这与缓存激活时添加的层有关。但是为什么？有解决办法吗

---

提前感谢您的帮助：-）

行为上的差异是由于Spring框架所做的代理。当bean需要任何特殊处理时（在本例中为缓存），将在运行时为bean创建一个代理。Spring中有两种代理技术-。有关更多详细信息，请阅读共享的文档链接

在示例代码共享中，CGLIB代理发挥了作用（提示：

MyService

没有实现接口）。由CGLIB创建的运行时子类将具有原始类的所有字段，但根据数据类型（此处

false

）将保持null/default。此外，对代理的方法调用被委托给原始实例方法

下面对代码进行的更改将提供有关其工作原理的更多详细信息

更改1：同时打印

对象.getClass（）

@Service
public class MyService {

    private Boolean fieldOfMyService = false;

    public void printFieldOfMyService() {
        System.out.println("fieldOfMyService:" + this.getClass()+" : "+fieldOfMyService);
    }

    @Cacheable("noOpMethod")
    public void noOpMethod() {
    }

}

测试班

@SpringBootTest(classes = { MyApplication.class })
public class MyServiceTest {

    @Autowired
    private MyService myService;

    @Test
    public void test() throws Exception {

        myService.printFieldOfMyService();

        boolean fieldOfMyService = (boolean) FieldUtils.readField(myService, "fieldOfMyService", true);

        System.out.println(
                "fieldOfMyService via reflection before change:" + myService.getClass() + " " + fieldOfMyService);

        FieldUtils.writeField(myService, "fieldOfMyService", true, true);

        boolean fieldOfMyServiceAfter = (boolean) FieldUtils.readField(myService, "fieldOfMyService", true);

        System.out.println(
                "fieldOfMyService via reflection after change:" + myService.getClass() + " " + fieldOfMyServiceAfter);

        myService.printFieldOfMyService();

    }

}

使用

@EnableCaching

可打印此代码

fieldOfMyService:class rg.so.qn.MyService : false
fieldOfMyService via reflection before change:class rg.so.qn.MyService$$EnhancerBySpringCGLIB$$dfa75fca false
fieldOfMyService via reflection after change:class rg.so.qn.MyService$$EnhancerBySpringCGLIB$$dfa75fca true
fieldOfMyService:class rg.so.qn.MyService : false

fieldOfMyService:class rg.so.qn.MyService : false
fieldOfMyService via reflection before change:class rg.so.qn.MyService false
fieldOfMyService via reflection after change:class rg.so.qn.MyService true
fieldOfMyService:class rg.so.qn.MyService : true

这里，通过反射更新的值是针对运行时子类实例的

如果没有

@EnableCaching

，此代码将打印出来

fieldOfMyService:class rg.so.qn.MyService : false
fieldOfMyService via reflection before change:class rg.so.qn.MyService$$EnhancerBySpringCGLIB$$dfa75fca false
fieldOfMyService via reflection after change:class rg.so.qn.MyService$$EnhancerBySpringCGLIB$$dfa75fca true
fieldOfMyService:class rg.so.qn.MyService : false

fieldOfMyService:class rg.so.qn.MyService : false
fieldOfMyService via reflection before change:class rg.so.qn.MyService false
fieldOfMyService via reflection after change:class rg.so.qn.MyService true
fieldOfMyService:class rg.so.qn.MyService : true

这里，通过反射更新的值是针对实际实例的

更改2：将

MyService.fieldOfMyService的数据类型修改为
Boolean

@Service
public class MyService {

    private Boolean fieldOfMyService = false;

    public void printFieldOfMyService() {
        System.out.println("fieldOfMyService:" + this.getClass()+" : "+fieldOfMyService);
    }

    @Cacheable("noOpMethod")
    public void noOpMethod() {
    }

}

使用
@EnableCaching
此代码将在
myservicest.test（）
，
boolean fieldOfMyService=（boolean）FieldUtils.readField（myService，“fieldOfMyService”，true）产生NPE因为运行时代理将字段初始化为null

如果没有
@EnableCaching
，此代码将按预期运行

希望这有帮助

注意：可以避免使用
@ExtendWith
和
@RunWith
进行元注释

-------------------------------更新---------------------------------------

也想过分享这个问题的答案“有解决方案吗？”

或者使用setter方法更新字段的状态

或

如果反射是唯一选项，则获取实际实例并使用反射更新字段

下面的代码假设缓存是通过
@EnableCaching
启用的，并且强制转换可以在不进行任何检查的情况下工作。请做必要的修改，使它万无一失

@Test
public void test() throws Exception {

    myService.printFieldOfMyService();

    MyService actualInstance = (MyService)((Advised) myService).getTargetSource().getTarget();

    boolean fieldOfMyService = (boolean) FieldUtils.readField(actualInstance, "fieldOfMyService", true);

    System.out.println(
            "fieldOfMyService via reflection before change:" + myService.getClass() + " " + fieldOfMyService);

    FieldUtils.writeField(actualInstance, "fieldOfMyService", true, true);

    boolean fieldOfMyServiceAfter = (boolean) FieldUtils.readField(actualInstance, "fieldOfMyService", true);

    System.out.println(
            "fieldOfMyService via reflection after change:" + myService.getClass() + " " + fieldOfMyServiceAfter);

    myService.printFieldOfMyService();

}

您还需要进一步澄清吗？是的@R.G非常感谢-这澄清了我的怀疑，通过您的更新，我甚至可以在测试中激活缓存。再次感谢-谢谢。