今天使用SringMVC + Mybatis + JSP 搭建一個小 demo 的時候，報瞭如下錯誤
報錯資訊如下

type Exception report

message An exception occurred processing JSP page /WEB-INF/views/user_list.jsp at line 28

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: An exception occurred processing JSP page /WEB-INF/views/user_list.jsp at line 28
 


25:         <th>鍒犻櫎</th>
26:     </tr>
27:     </thead>
28:     <c:forEach items="${user}" var="user">
29:         <tr>
30:             <th>${user.id}</th>
31:             <th>${user.name}</th>


Stacktrace:
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:574
 
)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:461)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52
 
)
    org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:170)
    org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:314)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:877)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause

javax.servlet.ServletException: javax.servlet.jsp.JspTagException: Don't know how to iterate over supplied "items" in &lt;forEach&gt;
    org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:909)
    org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:838)
    org.apache.jsp.WEB_002dINF.views.user_005flist_jsp._jspService(user_005flist_jsp.java:158)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:170)
    org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:314)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:877)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

這是因為我在 JSP 中使用了 forEach 遍歷 user ：

<c:forEach items="${user}" var="user">
        <tr>
            <th>${user.id}</th>
            <th>${user.name}</th>
            <th>${user.address}</th>
        </tr>
    </c:forEach>

但是我控制器返回的是單個物件，而針對單個物件無法使用 foreach 迭代，故報錯如上。
解決辦法是將應答的物件封裝到一個 list 中：List<User>，然後再返回給檢視進行渲染解析。