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。