Go语言视频零基础入门到精通

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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。