之前是一种建议类型，它确保在方法执行之前运行建议.以下是before advice的语法.
<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 : PointCut的ID.
methodName : 在被调用函数之前调用的函数的方法名称.
为了理解上述与Before Advice相关的概念，让我们写一个例子，它将实现Before Advice.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.
| Step | 描述 |
|---|---|
| 1 | 更新项目学生已创建在章节 Spring AOP - 应用程序. |
| 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，它定义了在不同点调用的方法.
package com.it1352;
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.it1352;
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.it1352;
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 = "https://img01.yuandaxia.cn/Content/img/tutorials/springaop/" xmlns:xsi = "https://img01.yuandaxia.cn/Content/img/tutorials/springaop/XMLSchema-instance" xmlns:aop = "https://img01.yuandaxia.cn/Content/img/tutorials/springaop/" xsi:schemaLocation = "http://www.springframework.org/schema/beans https://img01.yuandaxia.cn/Content/img/tutorials/springaop/spring-beans-3.0.xsd http://www.springframework.org/schema/aop https://img01.yuandaxia.cn/Content/img/tutorials/springaop/spring-aop-3.0.xsd "> <aop:config> <aop:aspect id = "log" ref = "logging"> <aop:PointCut id = "selectAll" expression = "execution(* com.IT屋.Student.getName(..))"/> <aop:before PointCut-ref = "selectAll" method = "beforeAdvice"/> </aop:aspect> </aop:config> <!-- Definition for student bean --> <bean id = "student" class = "com.IT屋.Student"> <property name = "name" value = "Zara" /> <property name = "age" value = "11"/> </bean> <!-- Definition for logging aspect --> <bean id = "logging" class = "com.IT屋.Logging"/> </beans>
完成源文件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，然后使用 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.
Going to setup student profile. Name : Zara Age : 11
