我正在尝试学习AOP spring。所以我已经安装了AspectJ插件,并在Luna eclipse中创建了AspectJ项目,这里是项目探索的快照:
[Project Explore][1] [1]: https://i.stack.imgur.com/el0TZ.jpg
,这是我的代码:
AopMain.java
package org.koushik.javabrains;
import org.koushik.javabrains.service.ShapeService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class AopMain {
public static void main(String[] args) {
ApplicationContext ctx = new
ClassPathXmlApplicationContext("spring.xml");
ShapeService shapeService = ctx.getBean("shapeService",ShapeService.class);
System.out.println(shapeService.getCircle().getCircleName());
}
}
LoggingAspect.java
package org.koushik.javabrains.aspect;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
@Aspect
public class LoggingAspect {
@Before( "allCircleMethod()")
public void loggingAdvice(JoinPoint joinPoint){
System.out.println(joinPoint.toString());
}
//@Before("args(name)")
//public void stringArgumentMethods(String name){
// System.out.println("name: "+name);
//}
@Pointcut("execution(* get*())")
public void allGetters(){}
@Pointcut("within(org.koushik.javabrains.model.Circle)")
public void allCircleMethod(){}
}
Circle.java
package org.koushik.javabrains.model;
public class Circle {
private String circleName;
public String getCircleName() {
return circleName;
}
public void setCircleName(String circleName) {
this.circleName = circleName;
}
}
Triangle.java
package org.koushik.javabrains.model;
public class Triangle {
private String triangleName;
public String getTriangleName() {
return triangleName;
}
public void setTriangleName(String triangleName) {
this.triangleName = triangleName;
}
}
ShapeServices.java
package org.koushik.javabrains.service;
import org.koushik.javabrains.model.Circle;
import org.koushik.javabrains.model.Triangle;
public class ShapeService {
private Circle circle;
private Triangle triangle;
public Circle getCircle() {
return circle;
}
public void setCircle(Circle circle) {
this.circle = circle;
}
public Triangle getTriangle() {
return triangle;
}
public void setTriangle(Triangle triangle) {
this.triangle = triangle;
}
}
为了<?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"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-2.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-2.5.xsd">
<aop:aspectj-autoproxy></aop:aspectj-autoproxy>
<bean name="triangle" class="org.koushik.javabrains.model.Triangle">
<property name="name" value ="Triangle name"></property>
</bean>
<bean name="circle" class="org.koushik.javabrains.model.Circle">
<property name="name" value ="Circle Name"></property>
</bean>
<bean name="shapeService" class="org.koushik.javabrains.service.ShapeService" autowire="byName"/>
<bean name ="loggingAspect" class ="org.koushik.javabrains.aspect.LoggingAspect"/>
</beans>
不使用LoggingAspect.java:
代码也可以正常工作@Before("args(name)")
public void stringArgumentMethods(String name){
System.out.println("name: "+name);
}
但是当我添加它时,我会得到java.lang.stackOverflowError:
Exception in thread "main" java.lang.StackOverflowError
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
at org.koushik.javabrains.aspect.LoggingAspect.stringArgumentMethods(LoggingAspect.java)
谁能告诉我为什么会这样?怎么解决呢? From java docs,
StackOverFlowError - What:
当应用程序递归导致堆栈溢出时抛出太深。
这意味着内存(堆栈)是满的,没有空间可以进一步存储
原因:
在大多数情况下,这种情况是由递归/深度调用方法造成的。
在你的情况下, @Before("args(name)")
-这一行试图找到所有方法与参数"name", 它发现自己导致递归调用和stackoverflow错误。因为stringArgumentMethods(String name)
也有参数name
public void stringArgumentMethods(String name){
System.out.println("name: "+name);
}
如何解决:
重写你的AspectJ表达式 - @Before("args(name)")
或
将参数重命名为stringArgumentMethods(String name123)