使用Spring的jdbcTemplate进一步简化JDBC操作

先看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"

xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
<bean id="springDSN"

class="org.springframework.jdbc.datasource.DriverManagerDataSource">

<property name="driverClassName"

value="com.microsoft.jdbc.sqlserver.SQLServerDriver">

</property>

<property name="url"

value="jdbc:microsoft:sqlserver://localhost:1433;databasename=bbs">

</property>

<property name="username" value="sa"></property>

<property name="password" value="sa"></property>

</bean>

<bean id="jdbcTemplate"

class="org.springframework.jdbc.core.JdbcTemplate" abstract="false"

lazy-init="false" autowire="default" dependency-check="default">

<property name="dataSource">

<ref bean="springDSN" />

</property>

</bean>

</beans>
在看SpringUtil类



package com.r.dao;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public final class SpringUtil {

private static ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");

public static Object getBean(String beanName){

return ctx.getBean(beanName);

}

}

最后看DAO:



import java.math.BigDecimal;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import org.springframework.jdbc.core.JdbcTemplate;

import com.r.vo.Book;

public class BookDao {

private JdbcTemplate jdbcT = (JdbcTemplate) SpringUtil

.getBean("jdbcTemplate");

public List findALL() {

String sql = "select * from BookInfo";

return jdbcT.queryForList(sql);

}

public List<Book> findALLBooks() {

List<Book> books = new ArrayList<Book>();;

String sql = "select * from BookInfo";

List list = jdbcT.queryForList(sql);

Iterator iterator = list.iterator();

Book book = null;

while (iterator.hasNext()) {

Map map4book = (Map) iterator.next();

book = new Book();

book.setBid((Integer) map4book.get("bid"));

book.setBookName((String)map4book.get("bookName"));

book.setBookType((String)map4book.get("bookType"));

book.setBookPic(((BigDecimal)map4book.get("bookPic")).doubleValue() );

book.setCount((Integer) map4book.get("count"));

books.add(book);

}

return books;

}

public int delete(int bid){

String sql = "delete from BookInfo where bid =?";

return jdbcT.update(sql, new Object[]{bid});

}

public static void main(String[] args) {

List<Book> books = new BookDao().findALLBooks();;

for(Book book:books){

System.out.println(book.getBid()+","+book.getBookName()+","+book.getBookType());

}

}

}

细心你，会发现JdbcTemplate的实例中有一系列的方法如：queryForXXX,update,delete大大简化了JDBC操作。

当然,还可以再进一步的优化一下,就是通过依赖注入，直接把jdbcTemplate注入到dao类的jdbcT字段。

先看新的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"

xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
<bean id="springDSN"

class="org.springframework.jdbc.datasource.DriverManagerDataSource">

<property name="driverClassName"

value="com.microsoft.jdbc.sqlserver.SQLServerDriver">

</property>

<property name="url"

value="jdbc:microsoft:sqlserver://localhost:1433;databasename=bbs">

</property>

<property name="username" value="sa"></property>

<property name="password" value="sa"></property>

</bean>

<bean id="jdbcTemplate"

class="org.springframework.jdbc.core.JdbcTemplate" abstract="false"

lazy-init="false" autowire="default" dependency-check="default">

<property name="dataSource">

<ref bean="springDSN" />

</property>

</bean>

<bean id="bookDao" class="com.yy.struts.dao.BookDao">

<property name="jdbcT">

<ref bean="jdbcTemplate" />

</property>

</bean>

</beans>

那么新的DAO类：

import java.math.BigDecimal;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import org.springframework.jdbc.core.JdbcTemplate;

import com.r.vo.Book;

public class BookDao {

private JdbcTemplate jdbcT;

public List findALL() {

String sql = "select * from BookInfo";

return jdbcT.queryForList(sql);

}

public List<Book> findALLBooks() {

List<Book> books = new ArrayList<Book>();;

String sql = "select * from BookInfo";

List list = jdbcT.queryForList(sql);

Iterator iterator = list.iterator();

Book book = null;

while (iterator.hasNext()) {

Map map4book = (Map) iterator.next();

book = new Book();

book.setBid((Integer) map4book.get("bid"));

book.setBookName((String)map4book.get("bookName"));

book.setBookType((String)map4book.get("bookType"));

book.setBookPic(((BigDecimal)map4book.get("bookPic")).doubleValue() );

book.setCount((Integer) map4book.get("count"));

books.add(book);

}

return books;

}

public int delete(int bid){

String sql = "delete from BookInfo where bid =?";

return jdbcT.update(sql, new Object[]{bid});

}

public static void main(String[] args) {

List<Book> books = new BookDao().findALLBooks();;

for(Book book:books){

System.out.println(book.getBid()+","+book.getBookName()+","+book.getBookType());

}

}

}

通过依赖注入，对象之间的关系由SPRING来维护，这样能降低类与类的耦合度。