Spring框架是架构设计层面的事情,它的出现可以让项目模块之间实现很好的解耦合,便于团队合作、开发效率、后期维护,但是对于初学者来说,它不像Spring MVC和MyBatis的那样好理解,因为Spring MVC和MyBatis对标的是替换Servlet、JDBC,有很好的参照物对比,可以瞬间理解它们的用处。
而对Spring的理解恰恰需要有大量的项目编写经验。尤其是不使用Spring框架管理的项目随着代码量增加是一个什么样的情况,才能充分理解Spring框架的作用及好处。
但是现在的市场行情是几乎所有的Java项目都在使用Spring,于是对想入这一行的Java开发工程师便有要求掌握Spring的技能。而初学者又不可能拥有大量的项目开发经验,于是充分理解Spring就成了一个悖论。
明白以上情形,我们初学者当前要做的,只能是顺应市场需求,对我们自身而言,要掌握如何使用Spring,而Spring和好处、原理,我们可以后续再慢慢领悟。
所以本次Spring的学习,我们也一改之前的先学习框架本身,再项目实战,像Spring MVC、MyBatis那样。而是先实战,再去学习框架本身。
之所以这样做学习方案,也是为了让大家更好的上手学习Spring框架。
首先搭建SSM框架,主要是引入Spring。
web.xml中引入Spring的监听器:
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
db.properties:
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/school?characterEncoding=utf-8
jdbc.username=root
jdbc.password=123456
log4j.properties:
log4j.rootLogger=DEBUG, Console
#Console
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n
log4j.logger.org.springframework=WARN
log4j.logger.org.apache.mybatis=WARN
log4j.logger.org.mybatis.spring=WARN
log4j.logger.java.sql.ResultSet=DEBUG
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG
applicationContext.xml:
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.2.xsd ">
<!-- 加载db.properties文件中的内容,db.properties文件中key命名要有一定的规则 -->
<context:property-placeholder location="classpath:db.properties" />
<!-- 扫描包,将标注Spring注解的类自动转化对象,同时完成Bean的注入 -->
<context:component-scan base-package="service" />
<context:component-scan base-package="dao" />
<!-- 配置数据源 ,dbcp -->
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
destroy-method="close">
<property name="driverClassName" value="${jdbc.driver}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<property name="maxActive" value="30" />
<property name="maxIdle" value="20" />
</bean>
<!-- sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<!-- 数据库连接池 -->
<property name="dataSource" ref="dataSource" />
<property name="configLocation" value="classpath:mybatisConfig.xml" />
<property name="mapperLocations" value="classpath:mapper/*.xml"></property>
</bean>
<!-- mapper扫描器 -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<!-- 扫描包路径,如果需要扫描多个包,中间使用半角逗号隔开 -->
<property name="basePackage" value="dao"></property>
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
</bean>
<!-- 事务管理器 对mybatis操作数据库事务控制,spring使用jdbc的事务控制类 -->
<bean id="transactionManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource" />
</bean>
<!-- 通知 -->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<!-- 传播行为 -->
<tx:method name="save*" propagation="REQUIRED" />
<tx:method name="delete*" propagation="REQUIRED" />
<tx:method name="add*" propagation="REQUIRED" />
<tx:method name="modify*" propagation="REQUIRED" />
<tx:method name="update*" propagation="REQUIRED" />
<tx:method name="find*" propagation="SUPPORTS" read-only="true" />
<tx:method name="get*" propagation="SUPPORTS" read-only="true" />
<tx:method name="select*" propagation="SUPPORTS" read-only="true" />
<tx:method name="search*" propagation="SUPPORTS" read-only="true" />
</tx:attributes>
</tx:advice>
<!-- aop -->
<aop:config>
<aop:advisor advice-ref="txAdvice"
pointcut="execution(* service.impl.*.*(..))" />
</aop:config>
</beans>
代码部分,主要知识点有依赖注入、AOP事务管理、Spring对Dao层框架的管理和数据库连接池的管理。
StudentController.java:
package controller;
import dao.BanJiDao;
import dao.MybatisSqlSession;
import dao.StudentDao;
import entity.BanJi;
import entity.Student;
import org.apache.ibatis.session.SqlSession;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import service.BanJiService;
import service.StudentService;
import service.impl.BanJiServiceImpl;
import service.impl.StudentServiceImpl;
import java.util.List;
@Controller
public class StudentController {
@Autowired
StudentService stuService;
@Autowired
BanJiService bjService;
@RequestMapping("show")
public ModelAndView search() {
List<Student> list = stuService.searchAll();
ModelAndView mv = new ModelAndView("show");
mv.addObject("stus", list);
return mv;
}
@RequestMapping("showAdd")
public ModelAndView showAdd() {
List<BanJi> bjList=bjService.searchAll();
ModelAndView mv = new ModelAndView("showAdd");
mv.addObject("bjs",bjList);
return mv;
}
@RequestMapping("add")
public String add(Student stu) {
boolean flag = stuService.add(stu);
if (flag) {
return "redirect:show.do";
}
return null;
}
@RequestMapping("showUpdate")
public ModelAndView showUpdate(int id) {
Student stu = stuService.search(id);
ModelAndView mv = new ModelAndView("showUpdate");
mv.addObject("stu", stu);
return mv;
}
@RequestMapping("update")
public String update(Student stu) {
boolean flag = stuService.update(stu);
if (flag) {
return "redirect:show.do";
}
return null;
}
@RequestMapping("delete")
public String delete(int id) {
boolean flag = stuService.delete(id);
if (flag) {
return "redirect:show.do";
}
return null;
}
}
StudentServiceImpl.java,因为数据连接池的引入,省却了关闭连接。因为Spring托管MyBatis,并对Service进行了声明式事务的管理,所以也不需要在对处理进行提交。所以Service层代码有了很大的简化:
package service.impl;
import dao.MybatisSqlSession;
import dao.StudentDao;
import entity.Student;
import org.apache.ibatis.session.SqlSession;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import service.StudentService;
import java.util.List;
@Service
public class StudentServiceImpl implements StudentService {
@Autowired
StudentDao stuDao;
@Override
public List<Student> searchAll() {
List<Student> list = stuDao.searchAll();
return list;
}
@Override
public Student search(int id) {
Student stu = stuDao.search(id);
return stu;
}
@Override
public boolean add(Student stu) {
int rs = stuDao.add(stu);
return rs > 0;
}
@Override
public boolean update(Student stu) {
int rs = stuDao.update(stu);
return rs > 0;
}
@Override
public boolean delete(int id) {
int rs = stuDao.delete(id);
return rs > 0;
}
}