After Throwing Advice
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2023-12-01
@AfterThrowing是一种通知类型,可确保在方法抛出异常时运行通知。 以下是@AfterThrowing建议的语法。
语法 (Syntax)
@AfterThrowing(PointCut = "execution(* cn.xnip.Student.*(..))",
throwing = "error")
public void afterThrowingAdvice(JoinPoint jp, Throwable error){
System.out.println("Method Signature: " + jp.getSignature());
System.out.println("Exception: "+error);
}
Where,
@AfterThrowing - 如果方法抛出异常,则将函数标记为在PointCut覆盖的方法之前执行的建议。
PointCut - 提供用于选择函数的表达式。
execution( expression ) - 覆盖要应用建议的方法的表达式。
throwing - 要返回的异常的名称。
为了理解上述与@AfterThrowing建议相关的概念,让我们编写一个实现@AfterThrowing建议的例子。 要编写我们的示例并提供一些建议,让我们使用一个可用的Eclipse IDE,并使用以下步骤创建一个Spring应用程序。
步 | 描述 |
---|---|
1 | 更新项目Student根据Spring AOP - Application章节创建。 |
2 | 更新bean配置并运行应用程序,如下所述。 |
以下是Logging.java文件的内容。 这实际上是方面模块的一个示例,它定义了在各个点调用的方法。
package cn.xnip;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.AfterThrowing;
@Aspect
public class Logging {
/**
* This is the method which I would like to execute
* after a selected method execution throws exception.
*/
@AfterThrowing(PointCut = "execution(* cn.xnip.Student.*(..))",
throwing = "error")
public void afterThrowingAdvice(JoinPoint jp, Throwable error){
System.out.println("Method Signature: " + jp.getSignature());
System.out.println("Exception: "+error);
}
}
以下是Student.java文件的内容。
package cn.xnip;
public class Student {
private Integer age;
private String name;
public void setAge(Integer age) {
this.age = age;
}
public Integer getAge() {
System.out.println("Age : " + age );
return age;
}
public void setName(String name) {
this.name = name;
}
public String getName() {
System.out.println("Name : " + name );
return name;
}
public void printThrowException(){
System.out.println("Exception raised");
throw new IllegalArgumentException();
}
}
以下是MainApp.java文件的内容。
package cn.xnip;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainApp {
public static void main(String[] args) {
ApplicationContext context =
new ClassPathXmlApplicationContext("Beans.xml");
Student student = (Student) context.getBean("student");
student.printThrowException();
}
}
以下是配置文件Beans.xml 。
<?xml version = "1.0" encoding = "UTF-8"?>
<beans xmlns = "http://www.springframework.org/schema/beans"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop = "http://www.springframework.org/schema/aop"
xsi:schemaLocation = "http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd ">
<aop:aspectj-autoproxy/>
<!-- Definition for student bean -->
<bean id = "student" class = "cn.xnip.Student">
<property name = "name" value = "Zara" />
<property name = "age" value = "11"/>
</bean>
<!-- Definition for logging aspect -->
<bean id = "logging" class = "cn.xnip.Logging"/>
</beans>
运行项目 (Run Project)
完成源和配置文件的创建后,运行您的应用程序。 右键单击应用程序中的MainApp.java,并使用run as Java Application命令。 如果您的应用程序一切正常,它将打印以下消息。
Exception raised
Method Signature: void cn.xnip.Student.printThrowException()
Exception: java.lang.IllegalArgumentException
Exception in thread "main" java.lang.IllegalArgumentException
at cn.xnip.Student.printThrowException(Student.java:25)
at cn.xnip.Student$$FastClassBySpringCGLIB$$7dc55815.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:58)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
at cn.xnip.Student$$EnhancerBySpringCGLIB$$99b0a988.printThrowException(<generated>)
at cn.xnip.MainApp.main(MainApp.java:13)