经过一会儿（几个小时）后，我们从DBCP获得了CommunicationsException。错误消息（位于“异常”中）在此问题的末尾-
但我看不到任何配置文件中定义的wait_timeout。（我们应该看哪里？在tomcat / conf目录之外的某个地方？）。

其次，如异常所建议，将“ Connector / J连接属性’autoReconnect = true’”放在哪里？这是在Tomcat中设置的conf /
context.xml文件中的资源定义：

<Resource name="jdbc/TomcatResourceName" auth="Container" type="javax.sql.DataSource"
           maxActive="100" maxIdle="30" maxWait="10000"
           removeAbandoned="true" removeAbandonedTimeout="60" logAbandoned="true"
           username="xxxx" password="yyyy"
           driverClassName="com.mysql.jdbc.Driver"
           url="jdbc:mysql://127.0.0.1:3306/dbname?autoReconnect=true"/>

第三，为什么JVM等待直到对executeQuery（）的调用引发异常？如果连接超时，则getConnection方法应该抛出Exception，不是吗？这是我正在谈论的源代码部分：

        try {
                conn = getConnection (true);
                stmt = conn.createStatement (ResultSet.TYPE_SCROLL_INSENSITIVE,
                                                ResultSet.CONCUR_READ_ONLY);
                rset = stmt.executeQuery (bQuery);
                while (rset.next()) {
                     ....

最后，这是堆栈跟踪的第一行…

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 84,160,724 milliseconds ago.  The last packet sent successfully to the server was 84,160,848 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.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3291)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1938)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2107)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2642)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2571)
at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1451)
at org.apache.tomcat.dbcp.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:208)

这就是我们中的一些人认为“忘记dbcp的原因，它可能过于依赖IDE配置和高级功能，以至于DriverManager.getConnection（…）可能更可靠”。对此有何评论？谢谢您的见解-
MS