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使用Spring的jdbcTemplate进一步简化JDBC操作

2011-12-02 09:20 453 查看

先看applicationContext.xml配置文件：

Code
<?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

Code
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:

Code
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阅读更多

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