Question

jsp500错误是怎么回事呢

HTTP Status 500 – Internal Server Error

Type Exception Report

Message An exception occurred processing [/rog.jsp] at line [42]

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception
org.apache.jasper.JasperException: An exception occurred processing [/rog.jsp] at line [42]

39: </table>
40: </form>
41: <%
42: cal.calculate();
43: out.println("杩愮畻缁撴灉锛�"+cal.getResult());
44: %>
45: </body>

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:607)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:496)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Root Cause
java.lang.NullPointerException
sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
sun.misc.FloatingDecimal.parseDouble(Unknown Source)
java.lang.Double.parseDouble(Unknown Source)
com.ch4.Calculator.calculate(Calculator.java:43)
org.apache.jsp.rog_jsp._jspService(rog_jsp.java:165)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:458)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

Note The full stack trace of the root cause is available in the server logs.

Apache Tomcat/9.0.11

Answer 1

空指针异常，
在你rog.jsp文件的[42]行，cal.calculate(); 这个地方抛出的空指针异常。

Answer 2

乱码问题 修改编码 即可解决

Answer 3

页面出问题，导致无法解析