有时候出这种错误!
type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause java.lang.NullPointerException
note The full stack trace of the root cause is available in the Apache Tomcat/5.0.27 logs.
type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause java.lang.NullPointerException
note The full stack trace of the root cause is available in the Apache Tomcat/5.0.27 logs.
解决方案 »
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select * from exam
看看输出结果是否正确,是否把所有记录都输出了
请问如果数据库出问题,是什么导致的呢?(排除外界攻击因素)NullPointerException,这种问题一般都什么情况下出现?谢谢!
大多数的情况下都是对一些空的对象进行一些方法操作造成的。如定义了一个 List ll = getXXList(),如果ll得到的null,这是作ll.size()操作就会有java.lang.NullPointerException。这种情况最多见。
至于上面的那一段:
java.lang.NullPointerException
org.apache.jsp.ivsoclubset.adminbbslist_jsp._jspService(adminbbslist_jsp.java:228)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
你可以看看jsp被tomcat编译出来的adminbbslist_jsp.java文件的第228行有什么错误。
就是if(!RS.next()) break;我觉得这个用法不太好吧??
小弟初学jsp,还望各位达人指教!谢谢!:)
------------------------------------------------------------------------------------------<jsp:useBean id="MyDBconn" scope="page" class="database.DBconn"/>
<%
int intPageSize;
int intRowCount;
int intPageCount;
int intPage;
String strPage;
String sql;
int i;
intPageSize=30;
strPage=request.getParameter("page");
if(strPage==null){
intPage=1;
}
else{
intPage=java.lang.Integer.parseInt(strPage);
if(intPage<1)intPage=1;
}
sql="select * from bbslist where RootID=0 order by JoinTime desc limit 200";
ResultSet RS = MyDBconn.executeQuery(sql);
RS.last();
intRowCount=RS.getRow();
intPageCount=(intRowCount+intPageSize-1)/intPageSize;
if(intPage>intPageCount) intPage=intPageCount;
if(intPageCount>0){
RS.absolute((intPage-1)*intPageSize+1);
for(i=0;i<intPageSize;i++){
out.print(RS.getString("Subject"));//显示标题
if(!RS.next()) break;
}
}
if(intPage != 1)
{
out.print("["+"<a href=adminbbslist.jsp?page="+ (intPage-1) +"><font color='#000000'>上一页</font></a>]");
}
if(intPage!=intPageCount)
{
out.print("["+"<a href=adminbbslist.jsp?page="+ (intPage+1) +"><font color='#000000'>下一页</font></a>]");
}
aq.executeQuery:Server configuration denies access to data source
我没写出来表访问的是bbslist