如何打开和关闭数据库连接?显示打开和关闭数据库连接有什么好处？

打开就是调用open方法，关闭就是调用close方法，例如

首先建立连接

sqlconnection conn =new sqlconnection（）；

然后打开连接

conn.open()

中间就是你处理的事情的代码，处理完后看

最后就是关闭连接

conn.close()

至于好处就是：

因为如果你没关闭的话，可能打开的多了，数据库连接就满了或者打开的多了速度变慢 。

关键你给的分太少！如下是上线达1年，稳定运行的配置。

---------------------------------------------------------、

属性文件

c3p0.driverClass=com.mysql.jdbc.Driver

c3p0.user=root

c3p0.password=edwin

c3p0.jdbcUrl=jdbc\:mysql\://192.168.1.123\:3306/edwin?useUnicode\=true&characterEncoding\=utf-8

c3p0.minPoolSize = 1

c3p0.maxPoolSize = 50

c3p0.initialPoolSize = 1

c3p0.maxIdleTime = 25000

c3p0.acquireIncrement = 1

c3p0.acquireRetryAttempts = 30

c3p0.acquireRetryDelay = 1000

c3p0.testConnectionOnCheckin = true

c3p0.automaticTestTable = t_c3p0

c3p0.idleConnectionTestPeriod = 18000

c3p0.checkoutTimeout=5000

---------------------------------------------------------

spring配置

<?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:aop="http://www.springframework.org/schema/aop"

xmlns:tx="http://www.springframework.org/schema/tx"

xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd

http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd

http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd" default-autowire="byName" default-lazy-init="false">

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

<property name="location">

<value>classpath:com/edwin/db/config/c3p0.properties</value>

</property>

</bean>

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">

<property name="driverClass">

<value>${c3p0.driverClass}</value>

</property>

<property name="jdbcUrl">

<value>${c3p0.jdbcUrl}</value>

</property>

<property name="user">

<value>${c3p0.user}</value>

</property>

<property name="password">

<value>${c3p0.password}</value>

</property>

<property name="minPoolSize">

<value>${c3p0.minPoolSize}</value>

</property>

<property name="maxPoolSize">

<value>${c3p0.maxPoolSize}</value>

</property>

<property name="initialPoolSize">

<value>${c3p0.initialPoolSize}</value>

</property>

<property name="maxIdleTime">

<value>${c3p0.maxIdleTime}</value>

</property>

<property name="acquireIncrement">

<value>${c3p0.acquireIncrement}</value>

</property>

<property name="acquireRetryAttempts">

<value>${c3p0.acquireRetryAttempts}</value>

</property>

<property name="acquireRetryDelay">

<value>${c3p0.acquireRetryDelay}</value>

</property>

<property name="testConnectionOnCheckin">

<value>${c3p0.testConnectionOnCheckin}</value>

</property>

<property name="automaticTestTable">

<value>${c3p0.automaticTestTable}</value>

</property>

<property name="idleConnectionTestPeriod">

<value>${c3p0.idleConnectionTestPeriod}</value>

</property>

<property name="checkoutTimeout">

<value>${c3p0.checkoutTimeout}</value>

</property>

</bean>

</beans>

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t_c3p0 就是一个测试表！

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