由于以下原因导致通信链接失败:java.io.EOFException

Question

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)
 com.mysql.jdbc.Connection.execSQL(Connection.java:3255)
 com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1293)
 com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1428)
 org.apache.tomcat.dbcp.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
 com.blasetti.ordiniweb.dao.OrdiniDAO.caricaOrdine(OrdiniDAO.java:263)
...

我需要刷新,它再次运作良好.任何的想法？谢谢.

Answer 1

MySQL会在一段时间后丢弃未使用的连接,因为它假定对方忘记关闭它.

您需要做的是配置Tomcat在重用池化连接之前应该应用的检查.为此,请添加?autoReconnect=true&useUnicode=true&characterEncoding=utf8到URL的末尾并添加validationQuery="Select 1"到Resource元素:

<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?autoReconnect=true&useUnicode=true&characterEncoding=utf8" 
  username="[myusername]"
  validationQuery="Select 1"
 />

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