jdbc - 由于 : java. io.EOFException 导致通信链路失败

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]"
 />

数据库是MySql 5.0。一切正常，除了有时，在“未使用”几个小时后，第一次访问时我得到了这个异常:

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，它再次运行良好。任何想法？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。

您需要做的是配置一个 Tomcat 在重用池连接之前应该应用的检查。为此，请将 ?autoReconnect=true&useUnicode=true&characterEncoding=utf8 添加到 URL 的末尾，并将 validationQuery="Select 1" 添加到 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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