數據庫連接超時

Question

我已經在Internet上閱讀了很多關於此問題的文章，但似乎沒有一個明確的解決方案。 請有人給我一個明確的答案，說明我為什么會出現數據庫超時。 該應用程序是一個托管在Tomcat 5.5服務器上的GWT應用程序。 我使用spring，並在applicationContext.xml中創建會話工廠，如下所示

<bean id="sessionFactory"
      class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">${connection.dialect}</prop>
            <prop key="hibernate.connection.username">${connection.username}</prop>
            <prop key="hibernate.connection.password">${connection.password}</prop>
            <prop key="hibernate.connection.url">${connection.url}</prop>
            <prop key="hibernate.connection.driver_class">${connection.driver.class}</prop>
            <prop key="hibernate.show_sql">${show.sql}</prop>
            <prop key="hibernate.hbm2ddl.auto">update</prop>
            <prop key="hibernate.c3p0.min_size">5</prop>
            <prop key="hibernate.c3p0.max_size">20</prop>
            <prop key="hibernate.c3p0.timeout">1800</prop>
            <prop key="hibernate.c3p0.max_statements">50</prop>
            <prop key="hibernate.c3p0.idle_test_period">300</prop>
        </props>
    </property>
    <property name="annotatedClasses">
        <list>
            <value>za.co.xxxx.traintrack.server.model.Answer</value>
            <value>za.co.xxxx.traintrack.server.model.Company</value>
            <value>za.co.xxxx.traintrack.server.model.CompanyRegion</value>
            <value>za.co.xxxx.traintrack.server.model.Merchant</value>
            <value>za.co.xxxx.traintrack.server.model.Module</value>
            <value>za.co.xxxx.traintrack.server.model.Question</value>
            <value>za.co.xxxx.traintrack.server.model.User</value>
            <value>za.co.xxxx.traintrack.server.model.CompletedModule</value>
        </list>
    </property>
</bean>

<bean id="dao" class="za.co.xxxx.traintrack.server.DAO">
    <property name="sessionFactory" ref="sessionFactory"/>
    <property name="adminUsername" value="${admin.user.name}"/>
    <property name="adminPassword" value="${admin.user.password}"/>
    <property name="godUsername" value="${god.user.name}"/>
    <property name="godPassword" value="${god.user.password}"/>
</bean>

直到第二天一切正常：

INFO   | jvm 1    | 2010/06/15 14:42:27 | 2010-06-15 18:42:27,804 WARN 
[JDBCExceptionReporter] : SQL Error: 0, SQLState: 08S01
INFO   | jvm 1    | 2010/06/15 14:42:27 | 2010-06-15 18:42:27,821 ERROR 
[JDBCExceptionReporter] : The last packet successfully received from the server 
was 38729 seconds ago.The last packet sent successfully to the server was 38729
seconds ago, which  is longer than the server configured value of 'wait_timeout'.
You should consider either expiring and/or testing connection validity before 
use in your application, increasing the server configured values for client
timeouts, or using the Connector/J connection property 'autoReconnect=true' to
avoid this problem.
INFO   | jvm 1    | 2010/06/15 14:42:27 | Jun 15, 2010 6:42:27 PM 
org.apache.catalina.core.ApplicationContext log
INFO   | jvm 1    | 2010/06/15 14:42:27 | SEVERE: Exception while dispatching
incoming RPC call

我讀了很多不同的東西（都沒用），請幫忙

Answer 1

查看此鏈接http://www.databasesandlife.com/automatic-reconnect-from-hibernate-to-mysql/

 In “hibernate.cfg.xml”:

<!-- hibernate.cfg.xml -->
<property name="c3p0.min_size">5</property>
<property name="c3p0.max_size">20</property>
<property name="c3p0.timeout">1800</property>
<property name="c3p0.max_statements">50</property>
<property name="connection.provider_class">
   org.hibernate.connection.C3P0ConnectionProvider</property>
<!-- no "connection.pool_size" entry! -->

然后創建一個文件“ c3p0.properties”，該文件必須位於類路徑的根目錄中（即無法對應用程序的特定部分覆蓋它）：

# c3p0.properties
c3p0.testConnectionOnCheckout=true

Answer 2

羅曼，我沒有hibernate.cfg.xml（全部在applicationContext.XML中完成）

c3p0.properties

c3p0.testConnectionOnCheckout=true

applicationContext.xml中

<?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"
       xsi:schemaLocation="
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd
           http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
           http://www.springframework.org/schema/tx
           http://www.springframework.org/schema/tx/spring-tx-2.0.xsd
           ">

    <context:annotation-config/>

    <context:component-scan base-package="za.co.cmsoftware.traintrack.server"/>

    <!-- Application properties -->
    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>file:${user.dir}/@propertiesFile@</value>
            </list>
        </property>
    </bean>

    <bean id="sessionFactory"
          class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">${connection.dialect}</prop>
                <prop key="hibernate.connection.username">${connection.username}</prop>
                <prop key="hibernate.connection.password">${connection.password}</prop>
                <prop key="hibernate.connection.url">${connection.url}</prop>
                <prop key="hibernate.connection.driver_class">${connection.driver.class}</prop>
                <prop key="hibernate.show_sql">${show.sql}</prop>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
                <prop key="hibernate.c3p0.min_size">5</prop>
                <prop key="hibernate.c3p0.max_size">20</prop>
                <prop key="hibernate.c3p0.timeout">1800</prop>
                <prop key="hibernate.c3p0.max_statements">50</prop>
                <prop key="hibernate.c3p0.idle_test_period">300</prop>
                <prop key="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</prop>
            </props>
        </property>
        <property name="annotatedClasses">
            <list>
                <value>za.co.xxxx.traintrack.server.model.Answer</value>
                <value>za.co.xxxx.traintrack.server.model.Company</value>
                <value>za.co.xxxx.traintrack.server.model.CompanyRegion</value>
                <value>za.co.xxxx.traintrack.server.model.Merchant</value>
                <value>za.co.xxxx.traintrack.server.model.Module</value>
                <value>za.co.xxxx.traintrack.server.model.Question</value>
                <value>za.co.xxxx.traintrack.server.model.User</value>
                <value>za.co.xxxx.traintrack.server.model.CompletedModule</value>
            </list>
        </property>
    </bean>

    <bean id="dao" class="za.co.xxxx.traintrack.server.DAO">
        <property name="sessionFactory" ref="sessionFactory"/>
        <property name="adminUsername" value="${admin.user.name}"/>
        <property name="adminPassword" value="${admin.user.password}"/>
        <property name="godUsername" value="${god.user.name}"/>
        <property name="godPassword" value="${god.user.password}"/>
    </bean>

    <bean id="transactionManager"
          class="org.springframework.orm.hibernate3.HibernateTransactionManager">
        <property name="sessionFactory">
            <ref local="sessionFactory"/>
        </property>
    </bean>

    <!-- enable the configuration of transactional behavior based on annotations -->
    <tx:annotation-driven transaction-manager="transactionManager"/>

</beans>