[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.)