3

我已经在我的 Web 应用程序的服务层中实现了 JSR303 JavaBean 验证（根据这篇文章）。现在我想将所有验证异常（例如 javax.validation.ConstraintViolationException）转换为我的自定义异常。

我创建了一个切面，只要在服务层中抛出异常就会调用它：

@Aspect
public class ExceptionConversionAspect {

    @AfterThrowing(pointcut="execution(* com.myexample.service.*.*(..))", throwing="e")
    public void convertServiceException(Exception e) {

        if (e instanceof ConstraintViolationException) {
             // this is my custom exception
            throw new InvalidServiceInputException("The service inputs failed validation", e);
        }
    }
}

但是当我的服务使用 ConstraintViolationException 验证失败时，不会触发我的异常转换方面。我怀疑这是因为验证异常本身是由 Aspect 触发的：

@Aspect
public class ValidateAspect {

    @Autowired
    private Validator validator;

    // Match any public methods in a class annotated with @AutoValidating
    @Around("execution(public * *(..)) && @within(com.myexample.validator.annotation.Validate)")
    public Object validateMethodInvocation(ProceedingJoinPoint pjp) throws Throwable {

    // some code here
    ....
}

如何以正确的顺序链接我的方面？先ValidateAspect，然后是ExceptionConversionAspect？

4

2 回答 2

1

Raul Bertone 几乎是对的，但并不完全正确。逻辑必须颠倒，并且ExceptionConversionAspect必须是优先的。

Java SE 的完整工作示例（我只是模拟 Java EE 异常）：

助手类： 

package javax.validation;

public class ConstraintViolationException extends RuntimeException {
    private static final long serialVersionUID = -8041265519275356912L;

    public ConstraintViolationException(String arg0) {
        super(arg0);
    }
}

package com.myexample.validator.annotation;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

@Retention(RetentionPolicy.RUNTIME)
public @interface Validate {}

package com.myexample.service;

public class InvalidServiceInputException extends RuntimeException {
    public InvalidServiceInputException(String arg0, Throwable arg1) {
        super(arg0, arg1);
    }
}

示例驱动程序应用程序：

驱动程序应用程序由服务注释@Validate并模拟服务 - 请参阅包名称。它循环执行 10 个方法调用，捕获异常并将它们打印到标准输出，以表明它们确实按照需要进行了转换。

package com.myexample.service;

import com.myexample.validator.annotation.Validate;

@Validate
public class Application {
    public void doSomething(int i) {
        System.out.printf("Doing something #%d%n", i);
    }

    public static void main(String[] args) {
        Application application = new Application();
        for (int i = 0; i < 10; i++) {
            try {
                application.doSomething(i + 1);
            }
            catch (Exception e) {
                System.out.println(e);
                System.out.println("  cause: " + e.getCause());
            }
        }
    }
}

方面：

验证方面随机抛出一个ConstraintViolationException用于演示目的。

package com.myexample.aspect;

import java.util.Random;
import javax.validation.ConstraintViolationException;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;

@Aspect
public class ValidateAspect {
    private static final Random RANDOM = new Random();

    @Around("execution(public !static * *(..)) && @within(com.myexample.validator.annotation.Validate)")
    public Object validateMethodInvocation(ProceedingJoinPoint thisJoinPoint) throws Throwable {
        Object result = thisJoinPoint.proceed();
        if (RANDOM.nextBoolean())
            throw new ConstraintViolationException("uh-oh");
        return result;
    }
}

异常转换方面现在有一个额外的@DeclarePrecedence注释。

package com.myexample.aspect;

import javax.validation.ConstraintViolationException;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.DeclarePrecedence;
import com.myexample.service.InvalidServiceInputException;

@Aspect
@DeclarePrecedence("ExceptionConversionAspect, *")
public class ExceptionConversionAspect {
    @AfterThrowing(pointcut = "execution(* com.myexample.service..*(..))", throwing = "e")
    public void convertServiceException(Exception e) {
        if (e instanceof ConstraintViolationException) {
            throw new InvalidServiceInputException("The service inputs failed validation", e);
        }
    }
}

控制台输出：

Doing something #1
Doing something #2
com.myexample.service.InvalidServiceInputException: The service inputs failed validation
  cause: javax.validation.ConstraintViolationException: uh-oh
Doing something #3
com.myexample.service.InvalidServiceInputException: The service inputs failed validation
  cause: javax.validation.ConstraintViolationException: uh-oh
Doing something #4
Doing something #5
Doing something #6
com.myexample.service.InvalidServiceInputException: The service inputs failed validation
  cause: javax.validation.ConstraintViolationException: uh-oh
Doing something #7
Doing something #8
Doing something #9
Doing something #10
于 2014-10-30T12:15:47.663 回答
0

当多个方面共享一个共同的连接点时，您可以使用 @DeclarePrecedence 语句手动设置执行顺序。在您的情况下，您可以创建一个新方面：

@Aspect
@DeclarePrecedence("ValidateAspect, ExceptionConversionAspect")
    public class SystemArchitecture {
        // ...
    }

如果未指定优先级，则执行顺序默认为此处定义的规则

于 2014-10-29T20:19:38.667 回答