[Spring框架]Spring JDBCTmplate基础入门总结.

前言:
前面有讲过 Spring IOC以及AOP的基本使用方法, 这里就再来讲下Spring JDBCTemplate的使用方法.

一, 概述
这里先说一下Spring 整合的一些模板:

从上图中可以看出 Spring为各种支持的持久化技术，都提供了简单操作的模板和回调.

二, 使用JdbcTemplate

2.1 Spring JDBC是Spring提供的持久层技术
简化JDBC API开发，使用上和Apache公司的DBUtils框架非常类似

具体开发使用的jar包结构如图:
    |

2.2, Spring配置连接池
　　1, 配置Spring的内置的连接池 

 <!-- 配置Spring的内置的连接池 -->
 <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
     <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
     <property name="url" value="jdbc:mysql:///spring_day02"/>
     <property name="username" value="root"/>
     <property name="password" value="123"/>
 </bean>

　　2, 配置DBCP连接池

 <!-- 配置DBCP连接池 -->
 <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
     <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
     <property name="url" value="jdbc:mysql:///spring_day02"/>
     <property name="username" value="root"/>
     <property name="password" value="123"/>
 </bean>

注: 这里如果使用DBCP连接池的话还需要导入Spring 整合DBCP的两个jar包.

　　3. C3P0连接池

 <!-- 配置C3P0连接池 -->
 <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
     <property name="driverClass" value="com.mysql.jdbc.Driver"/>
     <property name="jdbcUrl" value="jdbc:mysql:///spring_day02"/>
     <property name="user" value="root"/>
     <property name="password" value="123"/>
 </bean>

　　4,引入属性文件: 写jdbc.properties 文件, 然后直接将配置文件注入到Spring中
      jdbc.properties 配置文件:

jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql:///spring_day02
jdbc.user=root
jdbc.password=123

　　在Spring的核心配置中引入属性文件: 两种 方式

 <!-- 引入方式一:引入属性文件 -->
 <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
     <property name="location" value="classpath:jdbc.properties"/>
 </bean>
 <!--引入方式二:引入context的约束-->
 <context:property-placeholder location="classpath:jdbc.properties"/>

三, 开发案例, 使用Spring JDBCTemplate 进行CRUD操作.

Customer.java:

 public class Customer {
     private Integer cid;
     private String cname;
     private Integer age;
     public Integer getCid() {
         return cid;
     }
     public void setCid(Integer cid) {
         this.cid = cid;
     }
     public String getCname() {
         return cname;
     }
     public void setCname(String cname) {
         this.cname = cname;
     }
     public Integer getAge() {
         return age;
     }
     public void setAge(Integer age) {
         this.age = age;
     }
     @Override
     public String toString() {
         return "Customer [cid=" + cid + ", cname=" + cname + ", age=" + age
                 + "]";
     }

 }

CustomerDao.java:

 /**
  * 完成对Customer的CRUD的操作
  *
  */
 public class CustomerDao extends JdbcDaoSupport {

     public void save(Customer customer) {
         this.getJdbcTemplate().update("insert into customer values (null,?,?)",
                 customer.getCname(), customer.getAge());
     }

     public void update(Customer customer) {
         this.getJdbcTemplate().update(
                 "update customer set cname = ?,age = ? where cid = ?",
                 customer.getCname(), customer.getAge(), customer.getCid());
     }

     public void delete(Integer cid) {
         this.getJdbcTemplate()
                 .update("delete from customer where cid = ?", cid);
     }

     public Integer findCount() {
         int count = this.getJdbcTemplate().queryForInt(
                 "select count(*) from customer");
         return count;
     }

     public String findNameById(Integer cid) {
         String cname = this.getJdbcTemplate().queryForObject(
                 "select cname from customer where cid = ?", String.class, cid);
         return cname;
     }

     public Customer findById(Integer cid) {
         Customer customer = this.getJdbcTemplate().queryForObject(
                 "select * from customer where cid = ?",
                 new BeanPropertyRowMapper<Customer>(Customer.class), cid);
         return customer;
     }

     public List<Customer> findAll() {
         List<Customer> list = this.getJdbcTemplate().query("select * from customer",
                 new BeanPropertyRowMapper<Customer>(Customer.class));
         return list;
     }
 }

SpringDemo2.java 测试类:

 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration("classpath:applicationContext2.xml")
 public class SpringDemo2 {

     @Resource(name="customerDao")
     private CustomerDao customerDao;

     @Test
     public void demo1(){

         Customer customer = new Customer();
         customer.setCname("马大帅");
         customer.setAge(48);

         customerDao.save(customer);
     }

     @Test
     public void demo2(){

         Customer customer = new Customer();
         customer.setCid(8);
         customer.setCname("马小帅");
         customer.setAge(38);

         customerDao.update(customer);
     }

     @Test
     public void demo3(){
         customerDao.delete(7);
     }

     @Test
     public void demo4(){
         int count = customerDao.findCount();
         System.out.println(count);
     }

     @Test
     public void demo5(){
         String cname = customerDao.findNameById(8);
         System.out.println(cname);
     }

     @Test
     public void demo6(){
         Customer customer = customerDao.findById(8);
         System.out.println(customer);
     }

     @Test
     public void demo7(){
         List<Customer> customers = customerDao.findAll();
         for (Customer customer : customers) {
             System.out.println(customer);
         }
     }
 }

applicationContext.xml 配置文件:

 <?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:context="http://www.springframework.org/schema/context"
        xsi:schemaLocation="
 http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

     <context:property-placeholder location="classpath:jdbc.properties"/>

     <!-- 配置C3P0连接池 -->
     <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
         <property name="driverClass" value="${jdbc.driverClass}"/>
         <property name="jdbcUrl" value="${jdbc.url}"/>
         <property name="user" value="${jdbc.user}"/>
         <property name="password" value="${jdbc.password}"/>
     </bean>

     <!-- 配置DAO -->
     <bean id="customerDao" class="cn.itcast.jdbc.demo2.CustomerDao">
         <property name="dataSource" ref="dataSource"/>
     </bean>
 </beans>

好了, 一个基本的CRUD操作就完成了, 在这里我们可以发现配置文件特别的简洁, 我们只是给customerDao注入了一个dataSource , 然后在CustomerDao.java中就可以用this.getJdbcTemplate()获取到JDBCTemplate的实例了, 这个原理是因为我们的CustomerDao继承了 JdbcDaoSupport , 这里我们就来看下它的源码:

首先我们使用this.getJdbcTemplate而获取到一个jdbcTemplate实例:

 /**
  * Return the JdbcTemplate for this DAO,
  * pre-initialized with the DataSource or set explicitly.
  */
 public final JdbcTemplate getJdbcTemplate() {
   return this.jdbcTemplate;
 }

那么又返回的这个this.jdbcTemplate是否是有值得呢?  再看源代码原来是在我们setDataSource的时候生成了jdbcTemplate实例.

 /**
  * Set the JDBC DataSource to be used by this DAO.
  */
 public final void setDataSource(DataSource dataSource) {
     if (this.jdbcTemplate == null || dataSource != this.jdbcTemplate.getDataSource()) {
         this.jdbcTemplate = createJdbcTemplate(dataSource);
         initTemplateConfig();
     }
 }

好了, 到了这里就没有了, 关于JDBCTemplate的总结就这么多了. (该睡觉了.)