Spring (iii) AOP oriented tangent programming

Original link: http://www.orlion.ga/205/

I. Introduction to AOP

1. AOP Concept

Reference article: HTTP://WWW.ORLION.ML/57

2, the generation of AOP

For the following methods:

public class Userdaoimpl implements userdao{public void Saveuser (user user) {dosaveuser (); }    }

In the Saveuser method, before and after the save user to record the current time in order to saveuser how much time spent, methods there are many ways, the most intuitive way to write in Dosaveuser () and before and after the code to take out the current time:

public class Userdaoimpl implements userdao{public void Saveuser (user user) {int beginTime = GetCurrentTime ();        Dosaveuser ();    int endTime = GetCurrentTime (); }    }

Another way is to rewrite a class that inherits from Userdaoimpl and then overrides the Saveuser method, as follows:

public class USERDAOIMPL2 extends userdaoimpl{@Overridepublic void saveuser (user user) {int beginTime = Getcurrentt    IME (); Super.saveuser (); int endTime = GetCurrentTime ();} }

This method of coupling is too strong, once the parent class changes the subclass will also change, with caution with inheritance

Another way is to add code when calling the Saveuser () method:

public class userservice{public void Saveuser (user user) {Userdaoimpl Userdao = new Userdaoimpl (); int begin    Time = GetCurrentTime (); Userdao.saveuser (); int endTime = GetCurrentTime ();} }

Now, if you let us put all of the database CRUD operations on the project together with the code to get time, obviously the workload is too large, this time with the dynamic Agent : (can refer to http://www.orlion.ml/207/)

Userdaoimpl.java

Package Ml.orlion.dao.impl;    Import Ml.orlion.dao.UserDAO;        Import Ml.orlion.model.User; public class Userdaoimpl implements userdao{public void Saveuser (user user) {System.out.println ("Save Usering")    ; }    }

    timeinterceptor.java

    package ml.orlion.aop;        import  java.lang.reflect.InvocationHandler;    import java.lang.reflect.Method;         public class TimeInterceptor implements  invocationhandler{        private object target;//  The object being proxied         public object gettarget ()  {     return target;    }    public void  Settarget (Object target)  {    this.target = target;     }    public void beforemethod (method m) {     System.out.println (M.getname ()  +  "Begin start");    }      @Override     PUBLIC&NBSp;object invoke (Object proxy, method m, object[] args)  throws  Throwable {        this.beforemethod (m);//  insertion method      m.invoke (Target, args);     return null;    }     }

Test

public static void Testproxy () {//first produces a proxied object Userdao Userdao = new Userdaoimpl ();// The next step is to hand over the proxy object to Invocationhandler, Timeinterceptortimeinterceptor ti = new Timeinterceptor ();//Set the proxy object Ti.settarget ( Userdao);//generates a proxy Userdao userproxy = (Userdao) proxy.newproxyinstance (UserDAO.class.getClassLoader () According to the proxy object, new    Class[]{userdao.class}, TI); Userproxy.saveuser (new User ()); }

Run can see the console print: Saveuserbegin start save usering

Ii. using Spring AOP

Userdao.java:

Package Ml.orlion.dao;import Ml.orlion.model.user;public interface Userdao {public void Saveuser (user user);

Userdaoimpl.java:

Package Ml.orlion.dao.impl;import Ml.orlion.dao.userdao;import Ml.orlion.model.user;public class UserDAOImpl Implements Userdao{public void Saveuser (user user) {System.out.println ("save Usering");}}

Userservice.java

Package Ml.orlion.service;import Ml.orlion.dao.userdao;import Ml.orlion.dao.impl.userdaoimpl;import Ml.orlion.model.user;public class UserService {private Userdao Userdao = new Userdaoimpl ();p ublic Userdao GetUserDao () {R Eturn Userdao;} public void Setuserdao (Userdao userdao) {This.userdao = Userdao;} public void Saveuser (user user) {this.userDAO.saveUser (user);}}

Loginterceptor.java

Package Ml.orlion.aop;public class Loginterceptor {public void before () {System.out.println ("before");}}

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.xsd           http:// www.springframework.org/schema/aop           http:// Www.springframework.org/schema/aop/spring-aop.xsd "><bean id=" Loginterceptor " class=" Ml.orlion.aop.LogInterceptor "></bean>  <bean id=" Userdao " class=" Ml.orlion.dao.impl.UserDAOImpl ">   </bean>  <Bean id= "UserService"  class= "Ml.orlion.service.UserService" >  <property name= " Userdao " ref=" Userdao "/&GT;&NBSP;&NBSP;&LT;/BEAN&GT;&NBSP;&NBSP;&LT;AOP:CONFIG&GT;&NBSP;&NBSP;&LT;AOP: pointcut expression= "Execution (Public * ml.orlion.service. *.add (..)) "   id= "Servicepointcut"  />  <aop:aspect id= "LogAspect"  ref= " Loginterceptor ">  <aop:before method=" before " pointcut-ref=" ServicePointcut "/>   </aop:aspect>  </aop:config></beans>

Test:

Beanfactory appContext = new Classpathxmlapplicationcontext ("Beans.xml"); UserService UserService = (userservice) appcontext.getbean ("UserService"); Userservice.saveuser (new User ());

Spring (iii) AOP oriented tangent programming