Question

Spring文档指出：

CGLIB代理仅拦截公共方法调用！不要打电话这种代理上的非公开方法。他们没有被委派给实际作用域目标对象。

https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#beans-factory-scopes-other

但是经过观察，我认为我的实验（下面的代码）不好，或者这种行为随着时间而改变了。

我观察到只有最终方法或私有方法被绕过了。

这里是实验：（春季版：5.1.3）

@SpringBootApplication
public class DemoApplication implements CommandLineRunner {

@Autowired
private StudentService studentService;

public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
}

@Bean
StudentService studentService() {
    ProxyFactory proxyFactory = new ProxyFactory(new StudentService());
    proxyFactory.setProxyTargetClass(true);
    proxyFactory.addAdvice(new MethodInterceptor() {
        @Override
        public Object invoke(MethodInvocation invocation) throws Throwable {
            System.out.println("method " + invocation.getMethod() + " is called on " +
                    invocation.getThis() + " with args " + invocation.getArguments());
            Object ret = invocation.proceed();
            System.out.println("method " + invocation.getMethod() + " returns " + ret);
            return ret;
        }
    });
    return (StudentService) proxyFactory.getProxy();
}

@Override
public void run(String... args) throws Exception {
    studentService.doIt();
}

class StudentService {

    void doIt() {
        System.out.println("doIt");
    }
}

输出：

method void com.example.demo.DemoApplication$StudentService.doIt() is called on com.example.demo.DemoApplication$StudentService@127a7a2e with args [Ljava.lang.Object;@14008db3
doIt
method void com.example.demo.DemoApplication$StudentService.doIt() returns null

-通过实验-CGLIB库（不使用spring，使用Enhancer类）也允许代理包级方法。

更新

我有另一个观察结果（与上面相反）。在典型的jdbc应用程序中：

@SpringBootApplication
public class DemoApplication implements CommandLineRunner {

    @Autowired
    private ExampleService exampleService;
    @Autowired
    private XExampleService xExampleService;
    @Autowired
    private XXExampleService xxExampleService;

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

    @Override
    public void run(String... args) throws Exception {
        System.out.println(exampleService.getClass());
        System.out.println(xExampleService.getClass());
        System.out.println(xxExampleService.getClass());
    }


    @Service
    class ExampleService {

        void tranx() {

        }
    }

    @Service
    class XExampleService {

        @org.springframework.transaction.annotation.Transactional
        void tranx() {

        }
    }

    @Service
    class XXExampleService {

        @Transactional
        public void tranx() {

        }
    }
}

输出：

class com.example.demo.DemoApplication$ExampleService
class com.example.demo.DemoApplication$XExampleService
class com.example.demo.DemoApplication$XXExampleService$$EnhancerBySpringCGLIB$$2b1603e8

这意味着，如果在春季以我的行为创建代理-就像TransactionInterceptor中一样-CGLIB代理仅针对公共方法创建。

UPDATE2

我认为我发现这种接受公共方法的行为仅在哪里发生。它发生在PointCut（AnnotationTransactionAttributeSource）使用的TransactionAttributeSourcePointcut上。

来自代码：

/**
 * Create a custom AnnotationTransactionAttributeSource, supporting
 * public methods that carry the {@code Transactional} annotation
 * or the EJB3 {@link javax.ejb.TransactionAttribute} annotation.
 * @param publicMethodsOnly whether to support public methods that carry
 * the {@code Transactional} annotation only (typically for use
 * with proxy-based AOP), or protected/private methods as well
 * (typically used with AspectJ class weaving)
 */
public AnnotationTransactionAttributeSource(boolean publicMethodsOnly) {

Answer 1

可能的答案是，由于基于Java的代理不能与package-private方法一起使用（因为Java实现类不能为接口实现的方法分配较弱的访问特权）。

因此，即使CGLib可以代理它们，这也可能阻止spring团队使用程序包私有方法。

Spring CGLIB代理仅拦截公共方法调用

1 个答案: