相关疑难解决方法(0)

问候,目前正在开发小型Web服务应用程序,其中Web服务(使用CXF + Spring)的响应处理并保存到数据库.使用数据库我正在使用Hibernate(3.5).在Web上浏览一些Hibernate + Spring示例,我经常可以看到HibernateTemplate的用法,所以我对这一刻感到有点困惑,并想问:

你在Hibernate3应用程序中使用HibernateTemplate吗？什么时候HibernateTemplate可以让您的开发生活更美好,并且根据我可以决定的点,我是否需要使用它？

谢谢.

我的应用程序(Spring 4 MVC/Hibernate 4/MySQL/Maven)使用基于注释的配置将Spring与Hibernate集成在一起.几个小时后它没有使用数据库我总是看到这个错误:

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 84,510,841 milliseconds ago.  The last packet sent successfully to the server was 84,510,841 milliseconds ago. 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.
    sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    java.lang.reflect.Constructor.newInstance(Constructor.java:526)
    com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121)
    com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3938)
    com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2551) …

我正在使用MYSQL 5.0和Tomcat 5.5.8小时后,MYSQL默认关闭所有空闲连接,所以我得到一个SQL异常.这个问题的任何解决方案

我的webapp在Tomcat 5.5上运行,我在web.xml中声明了数据源:

<resource-ref>
    <res-ref-name>jdbc/OrdiniWebDS</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
    <res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>

在context.xml(tomcat conf)中:

<Resource 
  auth="Container" 
  driverClassName="com.mysql.jdbc.Driver" 
  maxActive="100" 
  maxIdle="30" 
  maxWait="10000" 
  name="jdbc/OrdiniWebDS" 
  password="[mypassword]" 
  type="javax.sql.DataSource" 
  url="jdbc:mysql://[myHost:port]/ordiniweb" 
  username="[myusername]"
 />

该数据库是MySql 5.0.一切都运作良好,除了有时,经过几个小时的"不使用",在第一次访问时,我得到了这个例外:

com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception: 

** BEGIN NESTED EXCEPTION ** 

java.io.EOFException

STACKTRACE:

java.io.EOFException
 at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1956)
 at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2368)
 at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2867)
 at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1616)
 at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1708)
 at com.mysql.jdbc.Connection.execSQL(Connection.java:3255)
 at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1293)
 at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1428)
 at org.apache.tomcat.dbcp.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
 at com.blasetti.ordiniweb.dao.OrdiniDAO.caricaOrdine(OrdiniDAO.java:263)
...
** END NESTED EXCEPTION **



Last packet sent to the server was 0 ms ago.
 com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2579)
 com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2867)
 com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1616)
 com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1708) …