本文主要介绍apache-dbcp基本参数配置和应用示例,dbcp目前最新版是1.4需要在jdk1.6的环境下运行,如果要在jdk1.4、1.5环境下运行,需要下载前一版本1.3,具体详细可以查看它的官网。
本文结构目录分两大部分:
- 一、基础参数说明
- 二、dbcp在spring、hibernate等应用中的配置示例
以后会陆续给出有关c3p0、proxool等相关参数介绍和应用配置实例。
c3p0的配置介绍已经发表参见:http://www.micmiu.com/j2ee/jdbc-tech/c3p0-simple
proxool的配置介绍已经发表参见:http://www.micmiu.com/j2ee/jdbc-tech/proxool-simple
[ 一 ]、参数介绍
[ 1 ]、基础参数说明
- defaultAutoCommit: 对于事务是否 autoCommit, 默认值为 true
- defaultReadOnly:对于数据库是否只能读取, 默认值为 false
- initialSize:连接池启动时创建的初始化连接数量(默认值为0)
- driverClassName:连接数据库所用的 JDBC Driver Class,
- url: 连接数据库的 URL
- username:登陆数据库所用的帐号
- password: 登陆数据库所用的密码
- maxActive: 连接池中可同时连接的最大的连接数,为0则表示没有限制,默认为8
- maxIdle: 连接池中最大的空闲的连接数(默认为8,设 0 为没有限制),超过的空闲连接将被释放,如果设置为负数表示不限制(maxIdle不能设置太小,因为假如在高负载的情况下,连接的打开时间比关闭的时间快,会引起连接池中idle的个数 上升超过maxIdle,而造成频繁的连接销毁和创建)
- minIdle:连接池中最小的空闲的连接数(默认为0,一般可调整5),低于这个数量会被创建新的连接(该参数越接近maxIdle,性能越好,因为连接的创建和销毁,都是需要消耗资源的;但是不能太大,因为在机器很空闲的时候,也会创建低于minidle个数的连接)
- maxWait: 超过时间会丟出错误信息 最大等待时间(单位为 ms),当没有可用连接时,连接池等待连接释放的最大时间,超过该时间限制会抛出异常,如果设置-1表示无限等待(默认为-1,一般可调整为60000ms,避免因线程池不够用,而导致请求被无限制挂起)
- validationQuery: 验证连接是否成功, SQL SELECT 指令至少要返回一行
- removeAbandoned:超过removeAbandonedTimeout时间后,是否进行没用连接的回收(默认为false)
- removeAbandonedTimeout: 超过时间限制,回收五用的连接(默认为 300秒),removeAbandoned 必须为 true
- logAbandoned: 是否记录中断事件, 默认为 false
一般优化的配置示例:
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<bean id="dbcpDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName" value="${jdbc.driverClassName}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> <property name="maxActive" value="20" /> <property name="initialSize" value="1" /> <property name="maxWait" value="60000" /> <property name="maxIdle" value="15" /> <property name="minIdle" value="5" /> <property name="removeAbandoned" value="true" /> <property name="removeAbandonedTimeout" value="180" /> <property name="connectionProperties"> <value>clientEncoding=utf-8</value> </property> </bean> |
[ 2 ]、validate配置参数说明
- minEvictableIdleTimeMillis:大于0 ,进行连接空闲时间判断,或为0,对空闲的连接不进行验证;默认30分钟
- timeBetweenEvictionRunsMillis:失效检查线程运行时间间隔,如果小于等于0,不会启动检查线程,默认-1
- testOnBorrow:在进行borrowObject进行处理时,对拿到的connection进行validateObject校验,默认为false
- testOnReturn:就是在进行returnObject对返回的connection进行validateObject校验,默认为false
- testWhileIdle:GenericObjectPool中针对pool管理,起了一个Evict的TimerTask定时线程进行控制(可通过设置参数timeBetweenEvictionRunsMillis>0),定时对线程池中的链接进行validateObject校验,对无效的链接进行关闭后,会调用ensureMinIdle,适当建立链接保证最小的minIdle连接数,默认为false
- numTestsPerEvictionRun:每次检查链接的数量,建议设置和maxActive一样大,这样每次可以有效检查所有的链接.
- validateQuery:验证检查执行的sql
- validateQueryTimeout:在执行检查时超时设置,通过statement 设置,statement.setQueryTimeout(validationQueryTimeout)
配置示例:
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<property name="testWhileIdle" value="true" /> <property name="testOnBorrow" value="false" /> <property name="testOnReturn" value="false" /> <property name="validationQuery"> <value>select sysdate from dual</value> </property> <property name="validationQueryTimeout" value="1" /> <property name="timeBetweenEvictionRunsMillis" value="30000" /> <property name="numTestsPerEvictionRun" value="20" /> |
[ 二 ]、dbcp在spring、hibernate等应用中的配置示例
dbcp.jdbc.properties
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jdbc.driverClassName=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost/iecms jdbc.username=root jdbc.password= |
[ 1 ]、最基本的应用
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package michael.jdbc.dbcp; import javax.sql.DataSource; import java.sql.Connection; import java.sql.Statement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Properties; import org.apache.commons.dbcp.BasicDataSource; /** * @see http://www.micmiu.com * @author michael sjsky007@gmail.com */ public class DbcpDataSourceExample { /** * @param args */ public static void main(String[] args) { String testSql = "select * from TB_MYTEST"; String cfgFileName = "dbcp.jdbc.properties"; System.out.println("Setting up data source."); DataSource dataSource = setupDataSource(cfgFileName); System.out.println("dataSource Done."); printDataSourceStats(dataSource); Connection conn = null; Statement stmt = null; ResultSet rset = null; try { System.out.println("Creating connection start."); conn = dataSource.getConnection(); System.out.println("Creating statement start."); stmt = conn.createStatement(); System.out.println("Executing statement start."); rset = stmt.executeQuery(testSql); System.out.println("executeQuery Results:"); int numcols = rset.getMetaData().getColumnCount(); while (rset.next()) { for (int i = 1; i <= numcols; i++) { System.out.print("\t" + rset.getString(i)); } System.out.println(""); } System.out.println("Results display done."); } catch (SQLException e) { e.printStackTrace(); } finally { try { if (rset != null) rset.close(); } catch (Exception e) { } try { if (stmt != null) stmt.close(); } catch (Exception e) { } try { if (conn != null) conn.close(); shutdownDataSource(dataSource); } catch (Exception e) { } } } /** * @param cfgFileName * @return DataSource */ public static DataSource setupDataSource(String cfgFileName) { BasicDataSource ds = new BasicDataSource(); try { Properties cfgpp = new Properties(); cfgpp.load(DbcpDataSourceExample.class .getResourceAsStream(cfgFileName)); ds.setDriverClassName(cfgpp.getProperty("jdbc.driverClassName")); ds.setUrl(cfgpp.getProperty("jdbc.url")); ds.setUsername(cfgpp.getProperty("jdbc.username")); ds.setPassword(cfgpp.getProperty("jdbc.password")); } catch (Exception e) { e.printStackTrace(); return null; } return ds; } /** * @param ds */ public static void printDataSourceStats(DataSource ds) { BasicDataSource bds = (BasicDataSource) ds; System.out.println("NumActive: " + bds.getNumActive()); System.out.println("NumIdle: " + bds.getNumIdle()); } /** * @param ds * @throws SQLException */ public static void shutdownDataSource(DataSource ds) throws SQLException { BasicDataSource bds = (BasicDataSource) ds; bds.close(); } } |
运行结果:
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Setting up data source. dataSource Done. NumActive: 0 NumIdle: 0 Creating connection start. Creating statement start. Executing statement start. executeQuery Results: 1 batch add 0 2011-06-16 14:29:08.0 2 batch add 1 2011-06-16 14:29:08.0 3 batch add 2 2011-06-16 14:29:08.0 4 batch add 3 2011-06-16 14:29:08.0 5 batch add 4 2011-06-16 14:29:08.0 Results display done. |
[ 2 ]、结合spring的应用测试
michael/jdbc/dbcp/dbcp.ds.spring.xml
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<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd"> <beans> <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <list> <value> classpath:michael/jdbc/dbcp/dbcp.jdbc.properties </value> </list> </property> </bean> <bean id="dbcpDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName" value="${jdbc.driverClassName}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> <property name="maxActive" value="20" /> <property name="initialSize" value="1" /> <property name="maxWait" value="60000" /> <property name="maxIdle" value="15" /> <property name="minIdle" value="5" /> <property name="removeAbandoned" value="true" /> <property name="removeAbandonedTimeout" value="180" /> <property name="connectionProperties"> <value>clientEncoding=utf-8</value> </property> </bean> </beans> |
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package michael.jdbc.dbcp; import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import javax.sql.DataSource; import org.apache.commons.dbcp.BasicDataSource; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; /** * @see http://www.micmiu.com * @author michael sjsky007@gmail.com */ public class DbcpSpringExample { /** * @param args */ public static void main(String[] args) { System.out.println("spring xml init start "); ApplicationContext appCt = new ClassPathXmlApplicationContext( "michael/jdbc/dbcp/dbcp.ds.spring.xml"); System.out.println("spring bean create DataSource"); DataSource dataSource = (BasicDataSource) appCt .getBean("dbcpDataSource"); String testSql = "select * from TB_MYTEST"; Connection conn = null; Statement stmt = null; ResultSet rset = null; try { System.out.println("Creating connection start."); conn = dataSource.getConnection(); System.out.println("Creating statement start."); stmt = conn.createStatement(); System.out.println("Executing statement start."); rset = stmt.executeQuery(testSql); System.out.println("executeQuery Results:"); int numcols = rset.getMetaData().getColumnCount(); while (rset.next()) { for (int i = 1; i <= numcols; i++) { System.out.print("\t" + rset.getString(i)); } System.out.println(""); } System.out.println("Results display done."); } catch (SQLException e) { e.printStackTrace(); } finally { try { if (rset != null) rset.close(); } catch (Exception e) { } try { if (stmt != null) stmt.close(); } catch (Exception e) { } try { if (conn != null) conn.close(); } catch (Exception e) { } } } } |
运行结果:
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spring xml init start spring bean create DataSource Creating connection start. Creating statement start. Executing statement start. executeQuery Results: 1 batch add 0 2011-06-16 14:29:08.0 2 batch add 1 2011-06-16 14:29:08.0 3 batch add 2 2011-06-16 14:29:08.0 4 batch add 3 2011-06-16 14:29:08.0 5 batch add 4 2011-06-16 14:29:08.0 Results display done. |
[ 3 ]、结合hibernate的应用测试
DBCP在Hibernate2中受支持,目前在hibernate3.0,已经不再支持dbcp了,hibernate的作者在hibernate.org中,明确指出在实践中发现dbcp有 BUG,在某些种情会产生很多空连接不能释放,所以推荐使用c3p0连接,本文重点只是描述其基本使用配置,不是比较两者的优劣,故不过多展开描述。
michael/jdbc/dbcp/hibernate.cfg.xml
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<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!--database connection settings --> <property name="connection.driver_class"> com.mysql.jdbc.Driver </property> <property name="connection.url"> jdbc:mysql://localhost/iecms </property> <property name="connection.username">root</property> <property name="connection.password"></property> <!-- dbcp --> <!-- 连接池的最大活动个数 --> <property name="dbcp.maxActive">100</property> <!-- 当连接池中的连接已经被耗尽的时候,DBCP将怎样处理( 0 = 失败, 1 = 等待, 2= 增长) --> <property name="dbcp.whenExhaustedAction">1</property> <!-- 最大等待时间(ms) --> <property name="dbcp.maxWait">60000</property> <!-- 最大闲置的连接个数 --> <property name="dbcp.maxIdle">10</property> <!-- 下面是对 prepared statement --> <property name="dbcp.ps.maxActive">100</property> <property name="dbcp.ps.whenExhaustedAction">1</property> <property name="dbcp.ps.maxWait">60000</property> <property name="dbcp.ps.maxIdle">10</property> <property name="current_session_context_class">thread</property> <property name="show_sql">false</property> <property name="dialect"> org.hibernate.dialect.MySQL5Dialect </property> <property name="hbm2ddl.auto">update</property> </session-factory> </hibernate-configuration> |
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package michael.jdbc.dbcp; import java.util.List; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.AnnotationConfiguration; import org.hibernate.cfg.Configuration; /** * @see http://www.micmiu.com * @author michael sjsky007@gmail.com */ public class DbcpHibernateExample { /** * @param args */ public static void main(String[] args) { SessionFactory sessionFactory = null; try { System.out.println(" hibernate config start"); Configuration config = new AnnotationConfiguration() .configure("michael/jdbc/dbcp/hibernate.cfg.xml"); System.out.println(" create sessionFactory "); sessionFactory = config.buildSessionFactory(); System.out.println(" create session "); Session session = sessionFactory.getCurrentSession(); String testSql = "select * from TB_MYTEST"; System.out.println(" beginTransaction "); Transaction ta = session.beginTransaction(); org.hibernate.Query query = session.createSQLQuery(testSql); List<Object[]> list = query.list(); System.out.println(" createSQLQuery list: "); for (Object[] objArr : list) { for (Object obj : objArr) { System.out.print("\t" + obj); } System.out.println(""); } System.out.println(" beginTransaction commit "); ta.commit(); } catch (Exception e) { e.printStackTrace(); } finally { if (null != sessionFactory) { sessionFactory.close(); } } } } |
运行结果:
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hibernate config start create sessionFactory create session beginTransaction createSQLQuery list: 1 batch add 0 2011-06-16 14:29:08.0 2 batch add 1 2011-06-16 14:29:08.0 3 batch add 2 2011-06-16 14:29:08.0 4 batch add 3 2011-06-16 14:29:08.0 5 batch add 4 2011-06-16 14:29:08.0 beginTransaction commit |
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