Spring framework study Note 5: SpringAOP example, springspringaop

Spring framework study Note 5: SpringAOP example, springspringaop

1. Import package:

Import the two packages in spring

 

Import other packages (download them online ):

 

2. Prepare the target object:

Package service; public class UserServiceImpl implements UserService {@ Override public void save () {System. out. println ("save User! ") ;}@ Override public void delete () {System. out. println (" delete a user! ") ;}@ Override public void update () {System. out. println (" update user! ") ;}@ Override public void find () {System. out. println (" find a user! ");}}

View Code

 

3. Preparation notice:

Package springaop; import org. aspectj. lang. proceedingJoinPoint; // notification class public class MyAdvice {// pre-notification // |-call the method before running // post-notification (if an exception occurs, it will not be called) // |-called after the target method is run // surround notification // |-called before and after the target method // exception interception notification // |-if an exception occurs, the post-notification will be called. // The post-notification will be called no matter whether an exception occurs or not. // |-call the post-notification after the target method is run. // the pre-notification public void before () {System. out. println ("this is a pre-notification !! ");} // Post notification public void afterReturning () {System. out. println (" this is post notification (if an exception occurs, it will not be called )!! ");} // The surround notification public Object around (ProceedingJoinPoint pjp) throws Throwable {System. out. println (" This is part before the surround notification !! "); Object proceed = pjp. proceed (); // call the target method System. out. println (" This is part after the notification !! "); Return proceed;} // public void afterException () {System. out. println (" an exception occurred! ");} // Post-Notification public void after () {System. out. println (" this is post-notification (it will be called if an exception occurs )! ");}}

 

 

4. Configure to weave notifications into the target object

(Import aop constraints)

 

User object of the bean package:

Package bean; import javax. annotation. postConstruct; import javax. annotation. preDestroy; import javax. annotation. resource; import org. junit. validator. publicClassValidator; import org. springframework. beans. factory. annotation. autowired; import org. springframework. beans. factory. annotation. qualifier; import org. springframework. beans. factory. annotation. value; import org. springframework. context. annotation. scope; import org. springframework. stereotype. component; import org. springframework. stereotype. controller; import org. springframework. stereotype. repository; import org. springframework. stereotype. service; // the content of the configuration file <bean name = "user" class = "bean. user "/> // @ Component (" user ") // The four types are essentially the same. To facilitate understanding, we recommend that you use the following three types of // @ Service (" user ") // use the service layer // @ Controller ("user") // use the web layer @ Repository ("user ") // use the dao layer // specify the Scope of action of the object @ Scope (scopeName = "singleton") public class User {@ Value ("Tom") // assign a Value to private String name; private Integer age; // @ Autowired // object assignment, automatic assembly // problem: if multiple objects of the same type are involved, @ Resource (name = "car") cannot be distinguished ") // this method can explicitly specify (recommended) private Car; public car getCar () {return Car;} public void setCar (car Car) {this. car = car;} public String getName () {return name;} public void setName (String name) {this. name = name;} public Integer getAge () {return age;} @ Value ("20") // you can assign a Value in the set method. The effect is the same, but does not destroy encapsulation public void setAge (Integer age) {this. age = age ;}@ Override public String toString () {return "User [name =" + name + ", age =" + age + ", car = "+ car +"] ";}@ PostConstruct // initialization method when the init-mothod public void init () {System. out. println ("initialization") ;}@ PreDestroy // destroy method public void destory () {System. out. println ("Destroy ");}}

 

 

 

Xml configuration file:

<? Xml version = "1.0" encoding = "UTF-8"?> <Beans xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance" xmlns = "http://www.springframework.org/schema/beans" xmlns: context = "http://www.springframework.org/schema/context" xmlns: aop = "http://www.springframework.org/schema/aop" xsi: schemaLocation = "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/conte Xt http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd "> <! -- Preparations: import the aop (constraint) namespace --> <! -- 1. Configure the target object --> <bean name = "userService" class = "service. UserServiceImpl"> </bean> <! -- 2. Configure the notification object --> <bean name = "myAdvice" class = "springaop. MyAdvice"> </bean> <! -- 3. Configure to route notifications to the target object --> <aop: config> <! -- Configure the entry point public void service. userServiceImpl. the cut point of save () is the void service of the save () method. userServiceImpl. save () public can omit * service. userServiceImpl. the save () return value is not required. You can * replace * service. userServiceImpl. * () indicates all null parameters of a certain type. * service. * ServiceImpl. *(..) final form: Find all the methods of the class ending with serviceimpl from a package * service .. * ServiceImpl. *(..) --> <aop: pointcut expression = "execution (* service. * ServiceImpl. *(..)) "id =" pc "/> <aop: aspect ref =" myAdvice "> <! -- Specify the before method as the pre-notification --> <aop: before method = "before" pointcut-ref = "pc"/> <! -- Post --> <aop: after-returning method = "afterReturning" pointcut-ref = "pc"/> <! -- Surround notification --> <aop: around method = "around" pointcut-ref = "pc"/> <! -- Exception interception notification --> <aop: after-throwing method = "afterException" pointcut-ref = "pc"/> <! -- Post --> <aop: after method = "after" pointcut-ref = "pc"/> </aop: aspect> </aop: config> </beans>

 

 

Test class:

package springaop;import javax.annotation.Resource;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import bean.User;import service.UserService;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration("classpath:springaop/applicationContext.xml")public class Demo {    @Resource(name="userService")    private UserService us;        @Test    public void fun1(){        us.save();    }    }

 

 

Call the sava method: the console prints the following

 

 

 

 

Supplement ):

You do not need to use the xml configuration file.

Package annotationaop; import org. aspectj. lang. proceedingJoinPoint; import org. aspectj. lang. annotation. after; import org. aspectj. lang. annotation. afterReturning; import org. aspectj. lang. annotation. afterThrowing; import org. aspectj. lang. annotation. around; import org. aspectj. lang. annotation. aspect; import org. aspectj. lang. annotation. before; import org. aspectj. lang. annotation. pointcut; // notification class @ Aspect // indicates that this class is a notification class p Ublic class MyAdvice {@ Pointcut ("execution (* service. * ServiceImpl. *(..)) ") public void pc () {}// pre-notification // specifies that this method is a pre-notification and specifies the entry point @ Before (" MyAdvice. pc () ") public void before () {System. out. println ("this is a pre-notification !! ");} // Post notification @ AfterReturning (" MyAdvice. pc () ") public void afterReturning () {System. out. println ("this is a post-notification (it will not be called if an exception occurs )!! ");} // Surround notification @ Around (" MyAdvice. pc () ") public Object around und (ProceedingJoinPoint pjp) throws Throwable {System. out. println ("This is part before the notification !! "); Object proceed = pjp. proceed (); // call the target method System. out. println (" This is part after the notification !! "); Return proceed;} // exception notification @ AfterThrowing (" MyAdvice. pc () ") public void afterException () {System. out. println (" exception occurred! ");} // Post notification @ After (" MyAdvice. pc () ") public void after () {System. out. println ("this is a post-notification (it will also be called if an exception occurs )!! ");}}

 

Modify the configuration file:

<? Xml version = "1.0" encoding = "UTF-8"?> <Beans xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance" xmlns = "http://www.springframework.org/schema/beans" xmlns: context = "http://www.springframework.org/schema/context" xmlns: aop = "http://www.springframework.org/schema/aop" xsi: schemaLocation = "http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/conte Xt http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd "> <! -- Preparations: import the aop (constraint) namespace --> <! -- 1. Configure the target object --> <bean name = "userService" class = "service. UserServiceImpl"> </bean> <! -- 2. Configure the notification object --> <bean name = "myAdvice" class = "annotationaop. MyAdvice"> </bean> <! -- 3. Enable annotation-based weaving --> <aop: aspectj-autoproxy> </beans>