spring 使用c3po連接池
1 數據源:能夠簡單理解為數據的來源。
2 連接池:是緩存一定數量的數據庫連接,當程序須要數據庫連接的時候,直接在連接池中獲取空暇的連接,使用完再放回連接池中,此連接又變成空暇狀態,等待下一次連接。
有於開啟連接和關閉連接比較耗費系統資源,有類連接池的管理能夠降低這方面的開支。
3 常見連接池:c3p0,dbcp,proxool是常見開源的三種連接池。
Spring提供的DriverManagerDataSource總是新建一個連接,根本沒有起到連接池的作用。
4 連接池獲取連接的方法: Connection conn=dataSource.getConnection();
5 例如以下是數據源的使用:
c3p0:
UserDao:
package com.dao; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.SQLException; import javax.sql.DataSource; public class UserDao { private DataSource dataSource; public DataSource getDataSource() { return dataSource; } public void setDataSource(DataSource dataSource) { this.dataSource = dataSource; } public void save(){ try { Connection conn=dataSource.getConnection(); String sql="insert into t_student values(?,?)"; PreparedStatement ps=conn.prepareStatement(sql); ps.setInt(1, 1); ps.setString(2, "zhang"); ps.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
UserService:
package com.service; import com.dao.UserDao; public class UserService { private UserDao userDao; public UserDao getUserDao() { return userDao; } public void setUserDao(UserDao userDao) { this.userDao = userDao; } public void save(){ userDao.save(); } }
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:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd"> <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="driverClass" value="oracle.jdbc.driver.OracleDriver"></property> <property name="jdbcUrl" value="jdbc:oracle:thin:@localhost:1521:XE"></property> <property name="user" value="orcl"></property> <property name="password" value="newsnews"></property> </bean> <bean id="userDao" class="com.dao.UserDao"> <property name="dataSource" ref="dataSource"></property> </bean> <bean id="userService" class="com.service.UserService"> <property name="userDao" ref="userDao"></property> </bean> </beans>
測試類:
package com.aop; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.service.UserService; public class Test { public static void main(String[] args) { ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml"); UserService uc=(UserService) ac.getBean("userService"); uc.save(); } }
6 為了方便維護,改動數據源,能夠把數據源的值寫在配置中,這樣的方式是通過設置站位符實現的。使用Spring的 PropertyPlaceholderConfigurer。
須要在spring配置中添加一個管理配置的bean,用來管理數據源取值的配置。
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <value>classpath:c3p0.properties</value> </property> </bean>
classpath:配置的路徑。從src文件夾開始。
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:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:component-scan base-package="com.*" /> <context:annotation-config /> <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <value>classpath:c3p0.properties</value> </property> </bean> <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="driverClass" value="${driverClass}"></property> <property name="jdbcUrl" value="${jdbcUrl}"></property> <property name="user" value="${user}"></property> <property name="password" value="${password}"></property> </bean> </beans>
c3p0.properties
driverClass=oracle.jdbc.driver.OracleDriver jdbcUrl=jdbc:oracle:thin:@localhost:1521:XE user=orcl password=newsnews
=前面的值要和${}裏面的值相應。
spring 使用c3po連接池