Spring的jdbcTemplate

     Spring的jdbcTemplate的queryForXXX,update,delete等方法可以幫我們大大簡化JDBC操作，像資料庫連接配接的打開關閉都無需我們手動去做。

    一：添加jar包

  這個沒什麼說的，不過還是貼上吧

    二：web.xml

<!-- 配置Spring ioc容器 -->
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>classpath:applicationContext.xml</param-value>
	</context-param>
           

    三：applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:task="http://www.springframework.org/schema/task" xmlns:jdbc="http://www.springframework.org/schema/jdbc"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd
	http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd
	http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.1.xsd
	http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
	http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd">
	<context:component-scan base-package="com.windblow"></context:component-scan>

	<!-- 配置c3p0資料源 -->
	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
		<property name="user" value="root"></property>
		<property name="password" value="root1234"></property>
		<property name="driverClass" value="com.mysql.jdbc.Driver"></property>
		<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/yourdbname"></property>
	</bean>
	<bean class="org.springframework.jdbc.core.JdbcTemplate" id="jdbcTemplate">
		<property name="dataSource">
			<ref bean="dataSource"/>
		</property>
	</bean>
           

    四：SprintUtil

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringUtil {
	private static ApplicationContext ctx = new ClassPathXmlApplicationContext(
			"applicationContext.xml");

	public static Object getBean(String beanName) {
		return ctx.getBean(beanName);
	}
}
           

   五：Emp類和EmpDao類

public class Emp {
	private int id;
	private String name;
	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;
	}
	
}
           

EmpDao類

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.springframework.jdbc.core.JdbcTemplate;

import com.windblow.util.SpringUtil;

public class EmpDao {
	private JdbcTemplate jdbcTemplate=(JdbcTemplate) SpringUtil.getBean("applicationContext.xml");
	
	//插入
	public void insert(Emp emp){
	String sql="insert into emp(id,ename)  value(?,?)";	
	}
	
	//除sql語句不一樣，删除、更新很類似
	public void delete(int id){
		String sql="delete from emp where id=?";
		jdbcTemplate.update(sql, id);
		//也可jdbcTemplate.update(sql, new Object[]{id});
	}
	//查詢一個值
	protected <E> E getValue(String sql, Object... args) {
		//System.out.println(jdbcTemplate);
		E result = null;
		List list = jdbcTemplate.queryForList(sql, args);
		if (list != null && list.size() > 0) {
			Map map = (Map) list.get(0);
			result = (E) map.values().iterator().next();
		}
		return result;
	}
	public String getName(int id){
		String result="";
		String sql="select ename from emp where id=?";
		List list=jdbcTemplate.queryForList(sql, new Object[]{id});
		if(list!=null && list.size()>0){
			Map map=(Map) list.get(0);
			result=(String) map.values().iterator().next();
		}
		return result;
	}
	//全查，注意的是這裡需要轉一下，不能直接傳回queryForlist，否則會報異常org.springframework.jdbc.IncorrectResultSetColumnCountException:
	public List<Emp> findAll(){
		List<Emp> empList=new ArrayList<Emp>();
		String sql="select id,ename from emp";
		List list=jdbcTemplate.queryForList(sql);
		Iterator it=list.iterator();
		
		Emp emp=null;
		while(it.hasNext()){
			emp=new Emp();
			Map map=(Map) it.next();
			emp.setId((Integer) map.get("id"));
			emp.setName((String) map.get("ename"));
			empList.add(emp);
		}
		return empList;
	}
	
}
           

此外，還可通過依賴注入來降低類之間的耦合度，讓spring來維護類之間的關系

在aplicationContext.xml中添加一組:

<bean id="bookDao" class="com.test.dao.EmpDao">
       <property name="jdbcTemplate">
          <ref bean="jdbcTemplate" />
       </property>
</bean>
           

或者直接在類中通過注解的方式來改寫（待續）