tomcat的服务器过十几个小时就连不到数据库，重启一下tomcat就好了，每次都要重启tomcat，是哪出问题？？

打开页面提示以下错误，注意：重启一下tomcat就又好了，每次都是这样，是哪里出问题呢？据说是连接池出问题……但实在找不出哪有问题，重启过后又正常了……typeExcep... 打开页面提示以下错误，注意：重启一下tomcat就又好了，每次都是这样，是哪里出问题呢？据说是连接池出问题……但实在找不出哪有问题，重启过后又正常了……

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

java.lang.NullPointerException
com.product.dao.DB.query(DB.java:52)
com.product.action.DoProduct.getMqeProduct(DoProduct.java:260)
com.product.servlet.Marquee.doPost(Marquee.java:45)
com.product.servlet.Marquee.doGet(Marquee.java:28)
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
sun.reflect.GeneratedMethodAccessor20.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:244)
java.security.AccessController.doPrivileged(Native Method)
javax.security.auth.Subject.doAsPrivileged(Subject.java:517)
org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:276)
org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:162)
java.security.AccessController.doPrivileged(Native Method)
com.product.util.filter.CharsetEncodingFilter.doFilter(CharsetEncodingFilter.java:32)
sun.reflect.GeneratedMethodAccessor40.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:244)
java.security.AccessController.doPrivileged(Native Method)
javax.security.auth.Subject.doAsPrivileged(Subject.java:517)
org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:276)
org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:218)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.18 logs. 展开

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