JSP编译出错，请大家帮帮忙，本人是菜鸟
HTTP Status 500 -

--------------------------------------------

type Exception report

message

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
soccertable.BlobBean.readBlob(BlobBean.java:155)
org.apache.jsp.categoryshow_jsp._jspService(categoryshow_jsp.java:107)
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)


note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.


--------------------------------------------

Apache Tomcat/5.0.28

[解决办法]
从内置对象request中获得变量值为空，但是在后面代码中有通过此变量获得此变量的属性。如果变量为空，当获得空值的属性就会报空指针异常。
如：String aaa=request.getParameter( "*** ");
String类型的aaa获得后是空值
如果后面代码想从aaa执行一些操作时就会报错（如：aaa.split( "- ");)
因为是空值，空值没有任何属性。
这样报错异常为空指针异常。

大多空指针异常也是由于这样的失误造成，解决办法：判断是否为空然后进行操作。

我的异常网推荐解决方案：The server encountered an internal error () that prevented it from fulfilling this request.,http://www.myexception.cn/java-web/317.html