??xml version="1.0" encoding="utf-8" standalone="yes"?>成人精品国产,日韩欧美极品在线观看,欧美一区日韩一区http://www.aygfsteel.com/ashutc/category/42983.html有多面试题是ctrl+c然后ctrl+v的呢Q考那么难的题真的d起么Q?/description>zh-cnMon, 21 Mar 2011 22:06:00 GMTMon, 21 Mar 2011 22:06:00 GMT60c3p0详细配置http://www.aygfsteel.com/ashutc/archive/2011/03/16/346365.html西瓜西瓜Wed, 16 Mar 2011 02:31:00 GMThttp://www.aygfsteel.com/ashutc/archive/2011/03/16/346365.htmlhttp://www.aygfsteel.com/ashutc/comments/346365.htmlhttp://www.aygfsteel.com/ashutc/archive/2011/03/16/346365.html#Feedback0http://www.aygfsteel.com/ashutc/comments/commentRss/346365.htmlhttp://www.aygfsteel.com/ashutc/services/trackbacks/346365.html
官方文档 : http://www.mchange.com/projects/c3p0/index.html
<c3p0-config>
<default-config>
<!--当连接池中的q接耗尽的时候c3p0一ơ同时获取的q接数。Default: 3 -->
 <property name="acquireIncrement">3</property>

<!--定义在从数据库获取新q接p|后重复尝试的ơ数。Default: 30 -->
<property name="acquireRetryAttempts">30</property>

<!--两次q接中间隔时_(d)单位毫秒。Default: 1000 -->
<property name="acquireRetryDelay">1000</property>

<!--q接关闭旉认将所有未提交的操作回滚。Default: false -->
<property name="autoCommitOnClose">false</property>

<!--c3p0徏一张名为Test的空表，q用其自带的查询语句进行测试。如果定义了q个参数那么
属性preferredTestQuery被忽略。你不能在这张Test表上q行M操作Q它?yu)只供c3p0试
使用。Default: null-->
 <property name="automaticTestTable">Test</property>

<!--获取q接p|会(x)引v所有等待连接池来获取连接的U程抛出异常。但是数据源仍有?br /> 保留Qƈ在下ơ调用getConnection()的时候l尝试获取连接。如果设为trueQ那么在试
获取q接p|后该数据源将x已断开q永久关闭。Default: false-->
 <property name="breakAfterAcquireFailure">false</property>

<!--当连接池用完时客L(fng)调用getConnection()后等待获取新q接的时_(d)时后将抛出
SQLException,如设?则无限期{待。单位毫U。Default: 0 -->
 <property name="checkoutTimeout">100</property>

<!--通过实现ConnectionTester或QueryConnectionTester的类?/span> 试q接。类名需制定全\径?br /> Default: com.mchange.v2.c3p0.impl.DefaultConnectionTester-->
 <property name="connectionTesterClassName"></property>

<!--指定c3p0 libraries的\径，如果Q通常都是q样Q在本地卛_获得那么无需讄Q默认null卛_
Default: null-->
 <property name="factoryClassLocation">null</property>

<!--Strongly disrecommended. Setting this to true may lead to subtle and bizarre bugs.
Q文档原文）作者强烈徏议不使用的一个属?->
 <property name="forceIgnoreUnresolvedTransactions">false</property>

<!--?0U检查所有连接池中的I闲q接。Default: 0 -->
 <property name="idleConnectionTestPeriod">60</property>

<!--初始化时获取三个q接Q取值应在minPoolSize与maxPoolSize之间。Default: 3 -->
 <property name="initialPoolSize">3</property>

<!--最大空闲时?60U内未用则q接被丢弃。若?则永不丢弃。Default: 0 -->
 <property name="maxIdleTime">60</property>

<!--q接池中保留的最大连接数。Default: 15 -->
 <property name="maxPoolSize">15</property>

<!--JDBC的标准参敎ͼ用以控制数据源内加蝲的PreparedStatements数量。但׃预缓存的statements
属于单个connection而不是整个连接池。所以设|这个参数需要考虑到多斚w的因素?br /> 如果maxStatements与maxStatementsPerConnection均ؓ(f)0Q则~存被关闭。Default: 0-->
 <property name="maxStatements">100</property>

<!--maxStatementsPerConnection定义了连接池内单个连接所拥有的最大缓存statements数。Default: 0 -->
 <property name="maxStatementsPerConnection"></property>

<!--c3p0是异步操作的Q缓慢的JDBC操作通过帮助q程完成。扩展这些操作可以有效的提升性能
通过多线E实现多个操作同时被执行。Default: 3-->
<property name="numHelperThreads">3</property>

<!--当用戯用getConnection()时root用户成ؓ(f)去获取连接的用户。主要用于连接池q接非c3p0
的数据源时。Default: null-->
 <property name="overrideDefaultUser">root</property>

<!--与overrideDefaultUser参数对应使用的一个参数。Default: null-->
 <property name="overrideDefaultPassword">password</property>

<!--密码。Default: null-->
 <property name="password"></property>

<!--定义所有连接测试都执行的测试语句。在使用q接试的情况下q个一显著提高?gu)试速度。注意：(x)
试的表必须在初始数据源的时候就存在。Default: null-->
<property name="preferredTestQuery">select id from test where id=1</property>

<!--用户修改pȝ配置参数执行前最多等?00U。Default: 300 -->
 <property name="propertyCycle">300</property>

<!--因性能消耗大请只在需要的时候用它。如果设为true那么在每个connection提交?br /> 时候都校验其有效性。徏议用idleConnectionTestPeriod或automaticTestTable
{方法来提升q接试的性能。Default: false -->
 <property name="testConnectionOnCheckout">false</property>

<!--如果设ؓ(f)true那么在取得连接的同时校验连接的有效性。Default: false -->
 <property name="testConnectionOnCheckin">true</property>

<!--用户名。Default: null-->
 <property name="user">root</property>

<!--早期的c3p0版本对JDBC接口采用动态反代理。在早期版本用途广泛的情况下这个参?br /> 允许用户恢复到动态反代理以解决不稳定的故障。最新的非反代理更快ƈ且已l开?br /> q泛的被使用Q所以这个参数未必有用。现在原先的动态反与新的非反代理同时受?br /> 支持Q但今后可能的版本可能不支持动态反代理。Default: false-->
 <property name="usesTraditionalReflectiveProxies">false</property>

<property name="automaticTestTable">con_test</property>
<property name="checkoutTimeout">30000</property>
<property name="idleConnectionTestPeriod">30</property>
<property name="initialPoolSize">10</property>
<property name="maxIdleTime">30</property>
<property name="maxPoolSize">25</property>
<property name="minPoolSize">10</property>
<property name="maxStatements">0</property>
<user-overrides user="swaldman">
</user-overrides>
</default-config>
<named-config name="dumbTestConfig">
<property name="maxStatements">200</property>
<user-overrides user="poop">
<property name="maxStatements">300</property>
</user-overrides>
</named-config>
</c3p0-config>


转：(x)http://www.wujianrong.com/archives/2007/08/c3p0.html
解决MYSQL 8时问题

最q的一个项目在Hibernate使用C3P0的连接池Q数据库为Mysql。开发测试没有问题，在运行中每个一D长的空闲时间就出现异常:

java 代码
  1. org.hibernate.exception.JDBCConnectionException: could not execute query
  2. at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java: 74 )
  3. at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java: 43 )
  4. .......
  5. Caused by: com.mysql.jdbc.exceptions.MySQLNonTransientConnectionException: No operations allowed after connection closed.Connection was implicitly closed due to underlying exception/error:
  6. ** BEGIN NESTED EXCEPTION **
  7. com.mysql.jdbc.CommunicationsException
  8. MESSAGE: Communications link failure due to underlying exception:
  9. ** BEGIN NESTED EXCEPTION **
  10. java.net.SocketException
  11. MESSAGE: Broken pipe
  12. STACKTRACE:
  13. java.net.SocketException: Broken pipe
  14. at java.net.SocketOutputStream.socketWrite0(Native Method)
  15. ......
  16. ** END NESTED EXCEPTION **

查看了Mysql的文档，以及Connector/J的文档以及在U说明发玎ͼ出现q种异常的原因是Q?/p>

Mysql服务器默认的“wait_timeout”?时Q也是说一个connectionI闲过8个小ӞMysql自动断开? connection。这是问题的所在，在C3P0 pools中的connections如果I闲过8时QMysql其断开Q而C3P0q不知道该connection已经失效Q如果这时有 ClienthconnectionQC3P0该失效的Connection提供lClientQ将?x)造成上面的异常?/p>

解决的方法有3U：(x)

  1. 增加wait_timeout的时间?
  2. 减少Connection pools中connection的lifetime?
  3. 试Connection pools中connection的有效性?

当然最好的办法是同时综合用上q?U方法，下面DBCP和C3P0分别做一说明Q假设wait_timeout为默认的8时

DBCP增加以下配置信息:

  1. //set to 'SELECT 1'
  2. validationQuery = "SELECT 1"
  3. //set to 'true'
  4. testWhileIdle = "true"
  5. //some positive integer
  6. timeBetweenEvictionRunsMillis = 3600000
  7. //set to something smaller than 'wait_timeout'
  8. minEvictableIdleTimeMillis = 18000000
  9. //if you don't mind a hit for every getConnection(), set to "true"
  10. testOnBorrow = "true"

C3P0增加以下配置信息:

  1. //获取connnection时测试是否有?/span>
  2. testConnectionOnCheckin = true
  3. //自动试的table名称
  4. automaticTestTable=C3P0TestTable
  5. //set to something much less than wait_timeout, prevents connections from going stale
  6. idleConnectionTestPeriod = 18000
  7. //set to something slightly less than wait_timeout, preventing 'stale' connections from being handed out
  8. maxIdleTime = 25000
  9. //if you can take the performance 'hit', set to "true"
  10. testConnectionOnCheckout = true

更多的配|信息大家可以查看C3P0文档QConnector/J文档Q以及DBCP的文档?/p>

? http://www.javaeye.com/article/38506

我自q配置:

jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.jdbcUrl = jdbc:mysql://localhost:3306/test
jdbc.user = root
jdbc.password = 12345
jdbc.miniPoolSize = 1
jdbc.maxPoolSize = 20
jdbc.initialPoolSize = 1
jdbc.maxIdleTime = 25000
jdbc.acquireIncrement = 1

jdbc.acquireRetryAttempts = 30
jdbc.acquireRetryDelay = 1000
jdbc.testConnectionOnCheckin = true
jdbc.automaticTestTable = c3p0TestTable
jdbc.idleConnectionTestPeriod = 18000
jdbc.checkoutTimeout=3000

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
   <property name="driverClass" value="${jdbc.driverClass}" />
   <property name="jdbcUrl" value="${jdbc.jdbcUrl}" />
   <property name="user" value="${jdbc.user}" />
   <property name="password" value="${jdbc.password}" />
   <property name="minPoolSize" value="${jdbc.miniPoolSize}" />
   <property name="maxPoolSize" value="${jdbc.maxPoolSize}"/>  
   <property name="initialPoolSize" value="${jdbc.initialPoolSize}"/>
   <property name="maxIdleTime" value="${jdbc.maxIdleTime}"/>
   <property name="acquireIncrement" value="${jdbc.acquireIncrement}"/>
  
   <property name="acquireRetryAttempts" value="${jdbc.acquireRetryAttempts}"/>
   <property name="acquireRetryDelay" value="${jdbc.acquireRetryDelay}"/>
   <property name="testConnectionOnCheckin" value="${jdbc.testConnectionOnCheckin}"/>
   <property name="automaticTestTable" value="${jdbc.automaticTestTable}"/>
   <property name="idleConnectionTestPeriod" value="${jdbc.idleConnectionTestPeriod}"/>
   <property name="checkoutTimeout" value="${jdbc.checkoutTimeout}"/>

</bean>

+++++++++++

报错误：(x)
APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!

一般设|maxStatements=0解决该问?
但是Q?
把max_statements讄??
c3p0在同时关闭statement和connection的时候，或者关闭他们之间的旉很短的时候，有时候connectionq没有被关闭Q因为有些preparedstatementq在被cached住。这是c3p0的作者自p的?
http://forum.hibernate.org/viewtopic.php?t=947246&highlight=apparent+deadlock+c3p0

C3P0增加以下配置信息:


//set to 'SELECT 1'      
preferredTestQuery = 'SELECT 1'    
//set to something much less than wait_timeout, prevents connections from going stale   
idleConnectionTestPeriod = 18000     
//set to something slightly less than wait_timeout, preventing 'stale' connections from being handed out   
maxIdleTime = 25000    
//if you can take the performance 'hit', set to "true"   
testConnectionOnCheckout = true    



A c3p0 pool with the settings you have should recover from a database reset, but that doesn't mean you will never see an Exception. Stale Connections from the old database session will still be broken, and if those Connections have already been checked out, or if they are in the pool and not tested on checkout, the application will see the broken Connection, in the form of an Exception.

You can use c3p0 to minimize the likelihood that your application will see a stale Connection on database shutdown/restart. The most reliable means of preventing this is to set hibernate.c3p0.validate to true (in a hibernate application -- all other c3p0 apps should use the c3p0-native property c3p0.testConnectionOnCheckout). If you set this property to true, c3p0 will test Connections prior to checkout, and your app will never see a stale Connection on database restart unless the Connection had already been checked out when the database went down.

Another less reliable, but potentially less expensive, strategy is to set c3p0.testConnectionsOnCheckin and hibernate.c3p0.idle_test_period (c3p0-native c3p0.idleConnectionTestPeriod) to a low value, in which case all connection tests are asynchronous and you are guanteed that no Connection will be checked out that hasn't been tested in the last idle_test_period seconds. Thus, your app will only see broken Connections from the pool if Connections are checked out during a short window of time.

In either case, I recommend setting "c3p0.preferredTestQuery " or "c3p0.automaticTestTable" in your c3p0 properties file, as c3p0's default Connection test is often slow.

See "Configuring Connection Testing" in c3p0's docs for more information.



? 使用c3p0作ؓ(f)q接池时Q其中的一些配|参数需要修攏V主要是maxIdleTime和idleConnectionTestPeriod? MySQL默认?时Q?8800U）后自动关闭已打开的连接，所以c3p0要在8时内关闭不使用的连接，上面?参数要小?8800U。附上在 hibernate中配|c3p0的关键字?

c3p0-native property name hibernate configuration key
c3p0.acquireIncrement hibernate.c3p0.acquire_increment
c3p0.idleConnectionTestPeriod hibernate.c3p0.idle_test_period
c3p0.initialPoolSize not available -- uses minimum size
c3p0.maxIdleTime hibernate.c3p0.timeout
c3p0.maxPoolSize hibernate.c3p0.max_size
c3p0.maxStatements hibernate.c3p0.max_statements
c3p0.minPoolSize hibernate.c3p0.min_size

转蝲自：(x)http://handawei.javaeye.com/blog/651046





西瓜 2011-03-16 10:31 发表评论
]]>C3P0在spring中的配置http://www.aygfsteel.com/ashutc/archive/2010/08/09/328287.html西瓜西瓜Mon, 09 Aug 2010 02:30:00 GMThttp://www.aygfsteel.com/ashutc/archive/2010/08/09/328287.htmlhttp://www.aygfsteel.com/ashutc/comments/328287.htmlhttp://www.aygfsteel.com/ashutc/archive/2010/08/09/328287.html#Feedback0http://www.aygfsteel.com/ashutc/comments/commentRss/328287.htmlhttp://www.aygfsteel.com/ashutc/services/trackbacks/328287.html
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"    destroy-method="close">
          <property name="driverClass"><value>${jdbc.driverClassName}</value></property>
          <property name="jdbcUrl"><value>${jdbc.url}</value></property>               
          <property name="user"><value>${jdbc.username}</value></property>
          <property name="password"><value>${jdbc.password}</value></property>
          
          <property name="minPoolSize"><value>1</value></property>
          <property name="maxPoolSize"><value>20</value></property>
          <property name="maxIdleTime"><value>1800</value></property>
          <property name="acquireIncrement"><value>2</value></property>
          <property name="maxStatements"><value>0</value></property>
          <property name="initialPoolSize"><value>2</value></property>
          <property name="idleConnectionTestPeriod"><value>1800</value></property>
          <property name="acquireRetryAttempts"><value>30</value></property>
          <property name="breakAfterAcquireFailure"><value>true</value></property>
          <property name="testConnectionOnCheckout"><value>false</value></property>           
</bean>


<!-- Hibernate SessionFactory -->
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
   <property name="dataSource" ref="dataSource"/>
   <property name="mappingDirectoryLocations">
       <list>
    <value>classpath:/com/licaionline/domain/</value>
       </list>
   </property>
   <property name="hibernateProperties">
    <props>
     <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
      <prop key="hibernate.show_sql">true</prop>
     <prop key="hibernate.generate_statistics">true</prop>
                 <prop key="hibernate.connection.release_mode">auto</prop>                      
                 <prop key="hibernate.autoReconnect">true</prop>
                 <prop key="hibernate.cglib.use_reflection_optimizer">true</prop>
    </props>
   </property>
</bean>






西瓜 2010-08-09 10:30 发表评论
]]>JDBC的作用及重要接口http://www.aygfsteel.com/ashutc/archive/2009/10/13/298122.html西瓜西瓜Tue, 13 Oct 2009 14:38:00 GMThttp://www.aygfsteel.com/ashutc/archive/2009/10/13/298122.htmlhttp://www.aygfsteel.com/ashutc/comments/298122.htmlhttp://www.aygfsteel.com/ashutc/archive/2009/10/13/298122.html#Feedback0http://www.aygfsteel.com/ashutc/comments/commentRss/298122.htmlhttp://www.aygfsteel.com/ashutc/services/trackbacks/298122.html阅读全文

西瓜 2009-10-13 22:38 发表评论
]]>JAVA调用Oracle存储q程 http://www.aygfsteel.com/ashutc/archive/2009/05/22/277359.html西瓜西瓜Fri, 22 May 2009 08:19:00 GMThttp://www.aygfsteel.com/ashutc/archive/2009/05/22/277359.htmlhttp://www.aygfsteel.com/ashutc/comments/277359.htmlhttp://www.aygfsteel.com/ashutc/archive/2009/05/22/277359.html#Feedback0http://www.aygfsteel.com/ashutc/comments/commentRss/277359.htmlhttp://www.aygfsteel.com/ashutc/services/trackbacks/277359.html　　JAVA跟Oracle之间最常用的是JAVA调用Oracle的存储过E，以下要说明下JAVA如何对Oracle存储q程q行调用?/p>

　　Ⅰ、不带输出参数情?/p>

　　q程名称为pro1Q参C?个，数据cd为整形数?/p>

import　java.sql. * ;
public　 class　ProcedureNoArgs　
{
public　 static　 void　main(String args[])　throws　Exception
{
// 加蝲Oracle驱动　
DriverManager.registerDriver( new　oracle.jdbc.driver.OracleDriver());
// 获得Oracle数据库连接　
Connection conn = DriverManager.getConnection( " jdbc:oracle:thin:@MyDbComputerNameOrIP:1521:ORCL", sUsr, sPwd " );
// 创徏存储q程的对象　
CallableStatement c = conn.divpareCall( " {call pro1(?)} " );
// lOracle存储q程的参数设|?Q将W一个参数的D|成188　
c.setInt( 1 , 188 );
// 执行Oracle存储q程　
c.execute();
conn.close();
}　
}　

　　Ⅱ、带输出参数的情?/p>

　　q程名称为pro2Q参C?个，数据cd为整形数据，q回gؓ(f)整Şcd

import java.sql.*;
public class ProcedureWithArgs　
{
public static void main(String args[]) throws Exception
{
//加蝲Oracle驱动
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
//获得Oracle数据库连?br /> Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@MyDbComputerNameOrIP:1521:ORCL", sUsr, sPwd ");
//创徏Oracle存储q程的对象，调用存储q程
CallableStatement c=conn.divpareCall("{call pro2(?,?)}");
//lOracle存储q程的参数设|?Q将W一个参数的D|成188
c.setInt(1,188);
//注册存储q程的第二个参数　
c.registerOutParameter(2,java.sql.Types.INTEGER);
//执行Oracle存储q程
c.execute();
//得到存储q程的输出参数值ƈ打印出来
System.out.println (c.getInt(2));　
conn.close();
}
}




二，使用JAVA创徏Oracle存储q程

　　先看下如何用JAVA来编写Oracle存储q程Q我们在Oracle的sql plus中编写语句?/p>

　　Ⅰ、启动SQL PLUS

　　Ⅱ、编写JAVAc，定义JAVAcd名，本存储过Eؓ(f)单地输出传入参数的^方倹{?/p>

　create or replace and compile java source named　"PF"　as
/**
*通过JAVAcL 创徏Oracle存储q程
*
**/
package　org.oraclejava.pro;
public　 class　javaCreatePro
{
public　 static　 String　test( int num)
{
return　num+ "的^方ؓ(f)Q?" +num*num;
}
}

　　Ⅲ、将JAVAcM的方法test创徏Z个Oracle函数Ҏ(gu)

　　create or replace function PF_FUN(name integer) return varchar2 as language java name 'org.oraclejava.pro.javaCreatePro.test(java.lang.Integer) return java.lang.String';

　　Ⅳ、在控制台直接调用创建的Oracle函数

　　select PF_FUN(10) from dual;

　　Ⅴ、输出结?/p>

　　10的^方ؓ(f)Q?00

　　以上x在Oracle中的SQL PLUS中用JAVAE序来生Oracle存储q程的演CZ子，演示了其基本语法的实现跟单的功能实现Q可以看出在JAVA跟Oracle之间存在很多有趣的用法，因ؓ(f)oracle中有java虚拟机，使得Oracle变得更加有趣更加丰富多彩




西瓜 2009-05-22 16:19 发表评论
]]> վ֩ģ壺 ľ| | | | | ³| ¹| Ĭ| ɽ| | | ҵ| | | | ʡ| Դ| | ̩| | ǭ| | ˿| | 彧| ͨ| | Ϫ| ½| | | | ƽ| | º| ٲ| | | | ന| Ͱ|