javax.servlet.ServletException: bean [name] 在范围内未找到
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javax.servlet.ServletException: bean [name] not found within scope
提问by stu
I'm getting this error:
我收到此错误：
javax.servlet.ServletException: bean not found within scope
on a page with this at the top.
在顶部有这个的页面上。
<jsp:useBean id="bean" type="com.example.Bean" scope="request" />
The class exists in the classpath, it worked this morning, and I don't get what not found within scope means.
该类存在于类路径中，今天早上它起作用了，我不明白在范围内找不到什么意思。
How is this caused and how can I solve it?
这是怎么引起的，我该如何解决？
采纳答案by BalusC
You need the classattribute instead of the typeattribute.
您需要class属性而不是type属性。
The following:
下列：
<jsp:useBean id="bean" type="com.example.Bean" scope="request" />
does basicallythe following behind the scenes:
确实基本上幕后如下：
Bean bean = (Bean) pageContext.getAttribute("bean", PageContext.REQUEST_SCOPE);
if (bean == null) {
throw new ServletException("bean not found within scope");
}
// Use bean ...
While the following:
而以下：
<jsp:useBean id="bean" class="com.example.Bean" scope="request" />
does basically the following behind the scenes:
在幕后基本上做了以下工作：
Bean bean = (Bean) pageContext.getAttribute("bean", PageContext.REQUEST_SCOPE);
if (bean == null) {
bean = new Bean();
pageContext.setAttribute("bean", bean, PageContext.REQUEST_SCOPE);
}
// Use bean ...
If it has worked before and it didn't work "in a sudden", then it means that somethingwhich is responsible for putting the bean in the scope has stopped working. For example a servlet which does the following in the doGet():
如果以前的工作，并没有“在突然”的工作，那么就意味着事情是负责把豆的范围已停止工作。例如一个 servlet，它在以下内容中执行以下操作doGet()：
request.setAttribute("bean", new Bean());
request.getRequestDispatcher("page.jsp").forward(request, response);
Maybe you've invoked the JSP page directly by URL instead of invoking the Servlet by URL. If you'd like to disable direct access to JSP pages, then put them in /WEB-INFand forward to it instead.
也许你是直接通过 URL 调用 JSP 页面，而不是通过 URL 调用 Servlet。如果您想禁用对 JSP 页面的直接访问，请将它们放入/WEB-INF并转发给它。
回答by victor hugo
You must add
你必须添加
<jsp:useBean id="givingFormBean" type="some.packg.GivingForm" scope="request" />
Because by default the bean is looked on the pagescope
因为默认情况下，bean在页面范围内查看
