你这样写明白着是一个NullPointerException.
最起码要写成这样啊:
<%
String command=null;
try{
command=request.getParameter("command");
if("add".equals(command))
{ out.print("<br>");
out.print("helloWorld");
out.print("</br>");
}
}
catch(NullPointerException e){}
%>
最起码要写成这样啊:
<%
String command=null;
try{
command=request.getParameter("command");
if("add".equals(command))
{ out.print("<br>");
out.print("helloWorld");
out.print("</br>");
}
}
catch(NullPointerException e){}
%>
<%
String command=null;
try{
command=request.getParameter("command");
if(command.equals("add"))// 这个地方不一样
{ out.print("<br>");
out.print("helloWorld");
out.print("</br>");
}
}
catch(NullPointerException e){}
%>
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:519)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:274)
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:810)
root cause java.lang.ArrayIndexOutOfBoundsException: 582
org.apache.jasper.compiler.JspReader.peekChar(JspReader.java:156)
org.apache.jasper.compiler.JspReader.isSpace(JspReader.java:349)
org.apache.jasper.compiler.JspReader.isDelimiter(JspReader.java:432)
org.apache.jasper.compiler.JspReader.parseToken(JspReader.java:397)
org.apache.jasper.compiler.Parser.checkUnbalancedEndTag(Parser.java:1699)
org.apache.jasper.compiler.Parser.parseElements(Parser.java:1561)
org.apache.jasper.compiler.Parser.parse(Parser.java:126)
org.apache.jasper.compiler.ParserController.doParse(ParserController.java:220)
org.apache.jasper.compiler.ParserController.parse(ParserController.java:101)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:203)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:461)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:442)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:430)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:274)
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:810)
note The full stack trace of the root cause is available in the Apache Tomcat/5.0.25 logs.
--------------------------------------------------------------------------------Apache Tomcat/5.0.25
s.equals("");//当s=null的时候就会出错。
"sdfs".equal(null); //这样就没有问题。