代码如下:<%@ page contentType="text/html; charset=gb2312"%>
<% String sage=request.getParameter("age");
String sname=request.getParameter("username");
if(sname==null)
{out.print("请输入用户名!!");
%>
<br><form action="a.jsp" method="post">
<p>你的姓名:<input type="text' name="username'size="20"><br></p>
<p>你的年龄:<br>
<input type="radio" name="age" value="小于20岁" checked><20<br>
<input type="radio" name="age" value="小于30岁" ><30<br>
<input type="radio" name="age" value="小于40岁" ><40<br>
<input type="radio" name="age" value="超过40岁" >others<br>
<input type="submit" value="确定">
/form>
<%}
else
{byte b1[]=sname.getBytes("ISO-8859-1");
sname=new String(b1);
byte b2[]=sage.getBytes("ISO-8859-1");
sage=new String(b2);
out.println("hello");
out.println(sname);
out.println(",您");
out.println(sage); }
%>错误效果:HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: java.lang.ClassNotFoundException: org.apache.jsp.index_jsp
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:178)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
root cause java.lang.ClassNotFoundException: org.apache.jsp.index_jsp
java.net.URLClassLoader$1.run(Unknown Source)
java.security.AccessController.doPrivileged(Native Method)
java.net.URLClassLoader.findClass(Unknown Source)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:132)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:63)
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:172)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
note The full stack trace of the root cause is available in the Apache Tomcat/7.
<% String sage=request.getParameter("age");
String sname=request.getParameter("username");
if(sname==null)
{out.print("请输入用户名!!");
%>
<br><form action="a.jsp" method="post">
<p>你的姓名:<input type="text' name="username'size="20"><br></p>
<p>你的年龄:<br>
<input type="radio" name="age" value="小于20岁" checked><20<br>
<input type="radio" name="age" value="小于30岁" ><30<br>
<input type="radio" name="age" value="小于40岁" ><40<br>
<input type="radio" name="age" value="超过40岁" >others<br>
<input type="submit" value="确定">
/form>
<%}
else
{byte b1[]=sname.getBytes("ISO-8859-1");
sname=new String(b1);
byte b2[]=sage.getBytes("ISO-8859-1");
sage=new String(b2);
out.println("hello");
out.println(sname);
out.println(",您");
out.println(sage); }
%>错误效果:HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: java.lang.ClassNotFoundException: org.apache.jsp.index_jsp
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:178)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
root cause java.lang.ClassNotFoundException: org.apache.jsp.index_jsp
java.net.URLClassLoader$1.run(Unknown Source)
java.security.AccessController.doPrivileged(Native Method)
java.net.URLClassLoader.findClass(Unknown Source)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:132)
org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:63)
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:172)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
note The full stack trace of the root cause is available in the Apache Tomcat/7.
2./form>应为</form>修改后的JSP:<%@ page contentType="text/html; charset=gb2312"%>
<%
String sage = request.getParameter("age");
String sname = request.getParameter("username");
if (sname == null) {
out.print("请输入用户名!!");
%>
<br>
<form action="a.jsp" method="post">
<p>你的姓名:<input type="text' name=" username'size="20"><br>
</p>
<p>你的年龄:<br>
<input type="radio" name="age" value="小于20岁" checked><20<br>
<input type="radio" name="age" value="小于30岁"><30<br>
<input type="radio" name="age" value="小于40岁"><40<br>
<input type="radio" name="age" value="超过40岁">others<br>
<input type="submit" value="确定">
</form>
<%
} else {
byte b1[] = sname.getBytes("ISO-8859-1");
sname = new String(b1);
byte b2[] = sage.getBytes("ISO-8859-1");
sage = new String(b2);
out.println("hello");
out.println(sname);
out.println(",您");
out.println(sage);
}
%>
<input type="text' name=" username'size="20">应该为<input type="text" name="username" size="20">