Springaop 简明教程
Spring AOP - XML Based Before Advice
Before 是一种建议类型，它确保建议在方法执行之前运行。以下是 before 建议的语法。
Syntax
<aop:config>
<aop:aspect id = "log" ref = "logging">
<aop:pointcut id = "PointCut-id" expression = "execution( expression )"/>
<aop:before pointcut-ref = "PointCut-id" method = "methodName"/>
</aop:aspect>
</aop:config>其中，
-
PointCut-id - 切点的 ID
-
methodName - 在被调用的函数之前要被调用的函数的方法名
为了理解与 Before 建议相关的上述概念，让我们编写一个示例，它将实现 Before 建议。为了编写我们带有少许建议的示例，让我们使用现成的 Eclipse IDE，并使用以下步骤来创建 Spring 应用程序。
Step |
Description |
1 |
更新在章节 Spring AOP - Application 创建的学生项目。 |
2 |
更新 bean 配置并按如下说明运行应用程序。 |
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 com.tutorialspoint;
public class Logging {
/**
* This is the method which I would like to execute
* before a selected method execution.
*/
public void beforeAdvice(){
System.out.println("Going to setup student profile.");
}
}以下是 Student.java 文件的内容。
package com.tutorialspoint;
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 com.tutorialspoint;
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.getName();
student.getAge();
}
}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:config>
<aop:aspect id = "log" ref = "logging">
<aop:pointcut id = "selectAll"
expression = "execution(* com.tutorialspoint.Student.getName(..))"/>
<aop:before pointcut-ref = "selectAll" method = "beforeAdvice"/>
</aop:aspect>
</aop:config>
<!-- Definition for student bean -->
<bean id = "student" class = "com.tutorialspoint.Student">
<property name = "name" value = "Zara" />
<property name = "age" value = "11"/>
</bean>
<!-- Definition for logging aspect -->
<bean id = "logging" class = "com.tutorialspoint.Logging"/>
</beans>