我是Java EE的新手,我知道类似以下三行
<%= x+1 %>
<%= request.getParameter("name") %>
<%! counter++; %>
是一种旧式的编码方式,在JSP版本2中,存在一种避免JSP文件中的Java代码的方法.有人可以告诉我替代的JSP 2行,以及这种技术的名称是什么？
我收到错误:"只能导入一个类型.XYZ会解析为一个包."
有人在这里解释了原因,但我不确定我应该做些什么来解决这个问题.仅供参考:我正在使用Eclipse.我添加了下面导入的代码.java.util.*import工作正常.
<%@ page import="java.util.*"%>
<%@ page import="org.eresearch.knowledgeportal.model.Category"%>
<%@ page import="org.eresearch.knowledgeportal.dao.CategoryDao"%>
<%
CategoryDao catDao = new CategoryDao();
ArrayList<Category> catList = catDao.selectCategory();
//
%>
编辑:实际错误如下:
org.apache.jasper.JasperException: Unable to compile class for JSP:
An error occurred at line: 7 in the generated java file
Only a type can be imported. org.eresearch.knowledgeportal.model.Category resolves to a package
我在JSP文件中编写了以下代码:
<c:catch var="e">
<%
int accountNumber = Integer.parseInt(request.getParameter("accountNumber"));
int depositAmount = Integer.parseInt(request.getParameter("depositAmount"));
%>
<sql:query var='account' dataSource="jdbc/bank">
select * from account where AccountNumber=<%= accountNumber %>
</sql:query>
<c:choose>
<c:when test="${account.first() == false}">
<p>Account not found</p>
</c:when>
<c:otherwise>
<h3>Deposit Made</h3>
<p>Account number: <%= accountNumber %></p>
<p>Deposit amount: <%= depositAmount %></p>
<p>New balance: </p>
</c:otherwise>
</c:choose>
</c:catch>
<c:if test="${e != null}">
error
</c:if>
我遇到的问题是以下代码抛出一个javax.el.MethodNotFoundException:无法找到[0]参数异常的方法[first]:
<c:when test="${account.first() == false}">
<p>Account not found</p>
</c:when>
我需要访问sql:query中的帐户变量,以便检查第一行是否存在.
当我在JSP中使用<%@ include%>指令时,有没有办法让Eclipse语法检查我的包含文件(或者最佳实践是什么).我的意思是,如果我包含在父项中声明变量的文件,我会得到一堆关于未声明变量的错误(有意义).
那么人们如何解决这个问题呢？
我在jsp中得到一个空指针异常,我想找出哪个行有null变量,所以我可以修复它.有没有简单的方法来做到这一点？printStackTrace似乎没有给我任何相关信息.
堆栈跟踪:
java.lang.NullPointerException
at org.apache.jsp.data.index2_jsp._jspService(index2_jsp.java:176)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at sun.reflect.GeneratedMethodAccessor103.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:244)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAsPrivileged(Subject.java:537)
at org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:276)
at org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:162)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:262)
at org.apache.catalina.core.ApplicationFilterChain.access$0(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain$1.run(ApplicationFilterChain.java:171)
at java.security.AccessController.doPrivileged(Native Method)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:167)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.co
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:525)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.authenticator.SingleSignOn.invoke(SingleSignOn.java:420)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Thread.java:636)
我有一个我正在处理的JSP页面,我对一些格式化/编码感到困惑.
有些部分很明显发生了什么:
<%
if (.....)
{
%>
<input type=hidden name="blahblah" value="moreblah">
<%
}
%>
但现在我看到的部分我不知道它是如何工作/编译的:
<%
{
// do stuff here
String sClass = "blahblah"
if ( sClass.equals("") )
{
sClass = "blah";
}
}
%>
在那些花括号的开头没有if或while或for或者任何东西.为什么要编译并生成一个好的jsp页面？
Apache在尝试上传文件时返回此错误(我只保留了堆栈跟踪的第一行和根本原因):
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: Exception in JSP: /upload.jsp:40
37:
38: try {
39:
40: items = upload.parseRequest(request);
41: } catch (FileUploadException e) {
42: out.println(e);
43: }
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:451)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
root cause
javax.servlet.ServletException: org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(Lorg/apache/commons/fileupload/RequestContext;)Ljava/util/List;
root cause
java.lang.NoSuchMethodError: org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(Lorg/apache/commons/fileupload/RequestContext;)Ljava/util/List;
org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:126)
这是我的代码:
if(ServletFileUpload.isMultipartContent(request)){
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
List items = null;
try {
items …针对home.jsp
<jsp:useBean id="username" class="java.lang.String" scope="application"/>
<%
username="Jitendra";
%>
<jsp:include page="include.jsp"/>
include.jsp
<%=username%>
这给出了一个错误,即在include.jsp中未定义"username",即使Bean的范围是应用程序...