Question

jsp出现500错误

11: <%
12: request.setCharacterEncoding("GBK");
13: String titleName = request.getParameter("secondTitleName");
14: String i=(request.getParameter("selectFirstTitleName")).toString();
15: int parentTitleId = Integer.parseInt(i);
16: String filePath = request.getParameter("secondFilePath");

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:524)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:435)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
java.lang.NullPointerException
org.apache.jsp.Back.doAddSecondLevelTitle_jsp._jspService(doAddSecondLevelTitle_jsp.java:67)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

Answer 1

javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
java.lang.NullPointerException
空指针问题，

String i=(request.getParameter("selectFirstTitleName")).toString();
int parentTitleId = Integer.parseInt(i);
这两句有问题，看看参数selectFirstTitleName，前台传进来名字是否一样，大小写一致，是否传值了，是否是整数格式，按照报错信息应该是没有取到值，所以Integer.parseInt(i)报错

Answer 2

java.lang.NullPointerException
org.apache.jsp.Back.doAddSecondLevelTitle_jsp._jspService(doAddSecondLevelTitle_jsp.java:67)
空指针错误！去看看doAddSecondLevleTitle.jsp里哪里可能没有拿到值吧。

Answer 3

String titleName = request.getParameter("secondTitleName");
在java里面应该是
String titleName = request.getAttribute("secondTitleName");
在Action里面采用Parameter接参数。

Answer 4

可能问题：
14: String i=(request.getParameter("selectFirstTitleName")).toString();
//中的request.getParameter("selectFirstTitleName"))没取到值
15: int parentTitleId = Integer.parseInt(i);
//i既然没值，就会出现解析不了，就会报500错误