文章目录
1. 什么是AOP
AOP(Aspect Oriented Programming)意为:面向切面编程,通过预编译方式和运行期动态代理实现程序功能的统一维护的一种技术。AOP是OOP的延续,是软件开发中的一个热点,也是Spring框架中的一个重要内容,是函数式编程的一种衍生范型。利用AOP可以对业务逻辑的各个部分进行隔离,从而使得业务逻辑各部分之间的耦合度降低,提高程序的可重用性,同时提高了开发的效率。
不影响原来的业务情况下,动态新增功能。
2. 使用Spring实现AOP
2.1 使用Spring的API 接口实现
主要SpringAPI接口实现
(1)创建一个新maven项目,导入pom依赖
pom.xml文件:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.zz</groupId>
<artifactId>spring03</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.1.9.RELEASE</version>
</dependency>
<!-- AOP的织入包 -->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.9.4</version>
</dependency>
</dependencies>
</project>
(2)创建一个接口,创建一个接口的实现类
UserService接口:
package com.zz.service;
//用户业务层
public interface UserService {
public void add();
public void delete();
public void update();
public void search();
}
UserServiceImpl 接口实现类:
package com.zz.service.impl;
import com.zz.service.UserService;
public class UserServiceImpl implements UserService {
public void add() {
System.out.println("增加用户");
}
public void delete() {
System.out.println("删除用户");
}
public void update() {
System.out.println("更新用户");
}
public void search() {
System.out.println("查询用户");
}
}
(3)创建两个增加类(前置,后置)
Log 日志增强类(前置):
package com.zz.config;
//日志增强类 前置
import org.springframework.aop.MethodBeforeAdvice;
import java.lang.reflect.Method;
public class Log implements MethodBeforeAdvice {
public void before(Method method, Object[] args, Object target) throws Throwable {
System.out.println(target.getClass().getName()+"的"+method.getName()+"方法被执行了");
}
}
LogAfter日志增强类(后置):
package com.zz.config;
//日志增强类 后置
import org.springframework.aop.AfterReturningAdvice;
import java.lang.reflect.Method;
public class LogAfter implements AfterReturningAdvice {
public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
System.out.println(target.getClass().getName()+"的"+method.getName()+"方法返回了"+returnValue);
}
}
(4)在applicationContext.xml文件中配置增强类实现增强:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
https://www.springframework.org/schema/aop/spring-aop.xsd">
<!--注册bean-->
<bean id="userService" class="com.zz.service.impl.UserServiceImpl"/>
<bean id="log" class="com.zz.config.Log"/>
<bean id="afterlog" class="com.zz.config.LogAfter"/>
<!--aop的配置方式一:配置增强类-->
<aop:config>
<!--切入点,哪些方法需要增强
expression 表达式是类名的全称,确定到实现类中的方法
-->
<aop:pointcut id="pc-userservice" expression="execution(* com.zz.service.impl.UserServiceImpl.*(..))"/>
<!--环绕 即将UserServiceImpl中的所有方法做前置和后置增强-->
<aop:advisor advice-ref="log" pointcut-ref="pc-userservice"/>
<aop:advisor advice-ref="afterlog" pointcut-ref="pc-userservice"/>
</aop:config>
</beans>
(5)Test 测试类:
import com.zz.service.UserService;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
//客户端
public class MyTest {
@Test
public void test1(){
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
UserService userService = (UserService) context.getBean("userService");
userService.add();
}
}
测试结果:
2.2 自定义实现
主要是切面定义,切面就是一个类
(1)创建一个自定义类 DiyPointCut:
package com.zz.config;
//自定义类 /增强类/切面
public class DiyPointCut {
public void before(){
System.out.println("=====方法执行前=====");
}
public void after(){
System.out.println("=====方法执行后=====");
}
}
(2)在applicationContext.xml文件中配置:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
https://www.springframework.org/schema/aop/spring-aop.xsd">
<!--注册bean-->
<bean id="diy" class="com.zz.config.DiyPointCut"/>
<!--aop的配置方式二:配置增切面-->
<aop:config>
<aop:aspect ref="diy">
<aop:pointcut id="pc-userservice" expression="execution(* com.zz.service.impl.UserServiceImpl.*(..))"/>
<aop:before method="before" pointcut-ref="pc-userservice"/>
<aop:after method="after" pointcut-ref="pc-userservice"/>
</aop:aspect>
</aop:config>
</beans>
(3)Test 测试类:
代码与上面相同
测试结果:
2.3 使用注解实现
(1)创建一个类 AnnotationPointCut
package com.zz.config;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
//注解实现增强,切面原理
@Aspect
public class AnnotationPointCut {
@Before("execution(* com.zz.service.impl.UserServiceImpl.*(..))")
public void before(){
System.out.println("=====方法执行前=====");
}
@After("execution(* com.zz.service.impl.UserServiceImpl.*(..))")
public void after(){
System.out.println("=====方法执行后=====");
}
}
(2)在applicationContext.xml文件中配置:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
https://www.springframework.org/schema/aop/spring-aop.xsd">
<!--注册bean-->
<bean id="annotationPointCut" class="com.zz.config.AnnotationPointCut"/>
<!--aop的配置方式三:使用注解实现增强类-->
<!--让spring识别注解,一定要添加-->
<aop:aspectj-autoproxy/>
</beans>
(3)Test 测试类:
代码与上面相同
测试结果:
3. 整合MyBatis
参考学习网站:http://mybatis.org/spring/zh/index.html
3.1 MyBatis-Spring简述
MyBatis-Spring 会帮助你将 MyBatis 代码无缝地整合到 Spring 中。它将允许 MyBatis 参与到 Spring 的事务管理之中,创建映射器 mapper 和 SqlSession 并注入到 bean 中,以及将 Mybatis 的异常转换为 Spring 的 DataAccessException。最终,可以做到应用代码不依赖于 MyBatis,Spring 或 MyBatis-Spring。
3.2 知识基础
在开始使用 MyBatis-Spring 之前,你需要先熟悉 Spring 和 MyBatis 这两个框架和有关它们的术语。这很重要——因为本手册中不会提供二者的基本内容,安装和配置教程。
MyBatis-Spring 需要以下版本:配套
3.3 整合mybatis的测试
目录:
(1)在pom.xml文件中导入所有依赖
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.zz</groupId>
<artifactId>spring04</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.12</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.2</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<!-- spring-webmvc -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.1.10.RELEASE</version>
</dependency>
<!--Spring jdbc(new)-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.1.10.RELEASE</version>
</dependency>
<!--aop aspectjweaver-->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.9.4</version>
</dependency>
<!--mybatis-spring-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>2.0.2</version>
</dependency>
</dependencies>
<!-- 如果xml在java文件下,就要设置资源过滤-->
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
</resources>
</build>
</project>
(2)实体类User:
对应MySQL数据库里的user表
package com.zz.pojo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
private int id;
private String name;
private String pwd;
}
(3)UserMapper接口:
package com.zz.mapper;
import com.zz.pojo.User;
import java.util.List;
public interface UserMapper {
public List<User> getUserList();
}
(4)接口的实现类UserMapperImpl:
package com.zz.mapper.impl;
import com.zz.mapper.UserMapper;
import com.zz.pojo.User;
import org.mybatis.spring.SqlSessionTemplate;
import java.util.List;
public class UserMapperImpl implements UserMapper {
//注入sqlSession
private SqlSessionTemplate sqlSession ;
public void setSqlSession(SqlSessionTemplate sqlSession) {
this.sqlSession=sqlSession;
}
public List<User> getUserList(){
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
return mapper.getUserList();
}
}
(5)接口的配置文件UserMapper.xml:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.zz.mapper.UserMapper">
<select id="getUserList" resultType="User">
select * from user
</select>
</mapper>
(6)配置文件applicationContext.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"
xsi:schemaLocation="http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd">
<!--1.数据源整合-->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis? useUnicode=true&characterEncoding=utf8&useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</bean>
<!--2. 注入sqlSessionFactory-->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!--扫描包-->
<property name="typeAliasesPackage" value="com.zz.pojo"/>
<property name="mapperLocations" value="classpath:com/zz/mapper/xml/*.xml"/>
</bean>
<!--3.创建sqlSession-->
<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
<constructor-arg index="0" ref="sqlSessionFactory"/>
</bean>
<!--4. 将sqlSession放入Bean中-->
<bean id="userMapperImpl" class="com.zz.mapper.impl.UserMapperImpl">
<property name="sqlSession" ref="sqlSession"/>
</bean>
</beans>
(7)测试类MyTest:
import com.zz.mapper.UserMapper;
import com.zz.pojo.User;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MyTest {
@Test
public void test1(){
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
UserMapper userMapperImpl = (UserMapper) context.getBean("userMapperImpl");
for (User user : userMapperImpl.getUserList()) {
System.out.println(user);
}
}
}
测试结果:
4. 事务
4.1 回顾事务
- 把一组业务当成一个业务来做;要么都成功,要么都失败!
- 事务在项目开发中,十分的重要,涉及到数据的一致性问题,不能马虎!
- 确保完整性和一致性
事务ACID原则:
- 原子性
- 一致性
- 隔离性
- 多个业务可能操作同一个资源,防止数据损坏
- 持久性
- 事务一旦提交,无论系统发生什么问题,结果都不会再被影响,被持久化的写到存储器中!
4.2 spring中的事务管理
- 声明式事务 : AOP
- 编程式事务: 需要再代码中,进行事务的管理
思考:
为什么需要事务?
- 如果不配置事务,可能存在数据提交不一致的情况下;
- 如果我们不在SPRING中去配置声明式事务,我们就需要在代码中手动配置事务!
- 事务在项目的开发中十分重要,设计到数据的一致性和完整性问题,不容马虎!
4.3 事务的测试
(1)在UserMapper接口中加入两个方法
//添加事务
int addUser(User user);
//删除用户
int deleteUser(int id);
(2)在接口的配置文件UserMapper.xml中编写对应的sql语句
注意:故意将删除语句写错,写为deletes
<insert id="addUser" parameterType="User">
insert into user (id,name,pwd) values (#{id},#{name},#{pwd});
</insert>
<delete id="deleteUser" parameterType="int">
deletes from user where id=#{id}
</delete>
(3)在接口的实现类UserMapperImpl中重写方法
package com.zz.mapper.impl;
import com.zz.mapper.UserMapper;
import com.zz.pojo.User;
import org.mybatis.spring.SqlSessionTemplate;
import java.util.List;
public class UserMapperImpl implements UserMapper {
//注入sqlSession
private SqlSessionTemplate sqlSession ;
public void setSqlSession(SqlSessionTemplate sqlSession) {
this.sqlSession=sqlSession;
}
public List<User> getUserList(){
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
//错误操作
User user = new User(4,"小丽","123456");
mapper.addUser(user);
mapper.deleteUser(3); //sql存在错误
return mapper.getUserList();
}
public int addUser(User user) {
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
return mapper.addUser(user);
}
public int deleteUser(int id) {
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
return mapper.deleteUser(id);
}
}
(4)其他代码与上面均不变,进行测试,并分析测试结果
发现控制台结果确实报错,但是点开MySQL,刷新user表,发现添加4号用户成功,删除3号用户失败。
这在实际的应用中,显然是不满足要求的,我们必须加入事务,使它符合事务的原则,让一组操作保证同时成功或同时失败!
(5)在applicationContext.xml中添加事务配置
导入事务tx和aop的命名空间:
还添加如下配置:
<!--整合事务-->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<constructor-arg ref="dataSource" />
</bean>
<!-- 事务配置增强(一个连接 aop,一个练连接transactionManager ) -->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<!--propagation事务的传播特性-->
<tx:method name="*" propagation="REQUIRED"/>
</tx:attributes>
</tx:advice>
<!-- AOP配置 -->
<aop:config>
<aop:pointcut id="txPointCut" expression="execution(* com.zz.mapper.*.*(..))"/>
<aop:advisor advice-ref="txAdvice" pointcut-ref="txPointCut"/>
</aop:config>
(6)再次测试(此时还未改正sql语句)
发现控制台结果报错,再点开MySQL,刷新user表,发现添加用户和删除用户均失败。
(7)最后将删除用户的sql语句改正正确,再次测试
发现添加用户和删除用户均正确,控制台和数据库user列表显示完全一致!