Spring对JDBC的DAO支持

Spring提供JdbcDaoSupport来实现对JDBC的DAO支持。在JdbcDaoSupport类中提供了两个方法，分别是：

void setDataSource(DataSource dataSource) :采用setter依赖注入来设置数据源

getJdbcTemplate():获得JdbcTemplate来执行CRUD操作。

下面举例来详细说明：

假设有一个名为dao的数据库，数据库中有一个student表，表中的字段为id,name,sex

1、首先创建一个JavaBean来作为数据传输对象：

StudentBean.java

package bean;

public class StudentBean {

private int id;

private String name;

private String sex;

public StudentBean() {

}

public StudentBean(int id, String name, String sex) {

super();

this.id = id;

this.name = name;

this.sex = sex;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getSex() {

return sex;

}

public void setSex(String sex) {

this.sex = sex;

}

}

2、编写DAO接口
StudentDao.java

package dao;

import bean.StudentBean;

public interface StudentDao {

/**

* 根据传入的StudentBean实例插入记录

* @param s 需要保存的StudentBean实例

*/

void createStudent(StudentBean s) throws Exception;

/**

* 根据传入的id属性，查找匹配名字字符串的StudentBean实例

* @param id 需要查找StudentBean的id

* @return 匹配名字字符串的StudentBean实例

*/

StudentBean getStudent(int id) throws Exception;

/**

* 根据传入的name属性，删除记录

* @param name 需要删除的StudentBean的name

*/

void deleteStudent(String name) throws Exception;

/**

* 根据传入的StudentBean实例更新对应的记录

* @param s 需要更新的StudentBean实例

*/

void updateStudent(StudentBean s) throws Exception;

}

3、编写DAO接口的实现类，继承了JdbcDaoSupport
StudentDaoJdbc.java

package dao;

import java.sql.ResultSet;

import java.sql.SQLException;

import org.springframework.jdbc.core.RowMapper;

import org.springframework.jdbc.core.support.JdbcDaoSupport;

import bean.StudentBean;

public class StudentDaoJdbc extends JdbcDaoSupport implements StudentDao {

public void createStudent(StudentBean s) throws Exception {

Object[] args = {new Integer(s.getId()),s.getName(),s.getSex()};

String sql = "insert into student(id,name,sex) values(?,?,?)";

//获得JdbcTemplate对象，并调用update方法对数据库进行操作

this.getJdbcTemplate().update(sql,args);

}

public void deleteStudent(String name) throws Exception {

Object[] args = {name};

String sql = "delete from student where name = ?";

this.getJdbcTemplate().update(sql, args);

}

public StudentBean getStudent(int id) throws Exception {

Object[] args = {new Integer(id)};

String sql = "select id,name,sex from student where id = ?";

//将查询的ResultSet包装成对象后返回

return (StudentBean)getJdbcTemplate().queryForObject(sql,args,new StudentRowMapper());

}

public void updateStudent(StudentBean s) throws Exception {

Object[] args = {s.getName(),s.getSex(),new Integer(s.getId())};

String sql = "update student set name = ?,sex = ? where id = ?";

this.getJdbcTemplate().update(sql, args);

}

/**

* @author Administrator

* 私有内部类

* 继承了RowMapper接口

* 用于将ResultSet包装成相应的值对象后返回

*/

private class StudentRowMapper implements RowMapper {

public Object mapRow(ResultSet rs,int rowNumber) throws SQLException {

StudentBean sb = new StudentBean(rs.getInt("id"),rs.getString("name"),rs.getString("sex"));

return sb;

}

}

}

4、最后描述配置文件（包括对数据源的配置，并将数据源对象注入到StudentDaoJdbc实例中）

applicationContext.xml

<?xml version="1.0" encoding="GB2312"?>

<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"

xmlns:tx="http://www.springframework.org/schema/tx"

xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">

<!-- 配置dbcp数据源 -->

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

<property name="driverClassName">

<value>com.mysql.jdbc.Driver</value>

</property>

<property name="url">

<value>jdbc:mysql://localhost:3306/dao</value>

</property>

<property name="username">

<value>root</value>

</property>

<property name="password">

<value>4231992</value>

</property>

</bean>

<!-- 配置用户的DAO bean -->

<bean id="studentDao" class="dao.StudentDaoJdbc">

<!-- 为DAO实例注入所需的DataSource实例，采用setter注入，setter方法位于StudentDaoJdbc的父类JdbcDaoSupport中 -->

<property name="dataSource">

<ref local="dataSource"/>

</property>

</bean>

</beans>

通过测试，我们可以看到通过Spring实现的DAO，代码简洁，不需要频繁地进行数据库连接和捕获异常，也不需要创建DAO工厂，而是由Spring自动地管理DAO实例的创建。