java使用spring表达式语言计算二维数组中的单元格
在SpringMVC应用程序中，我有一个jsp，它需要遍历两个共享相同索引的集合i。blocks列表包含时间值。filledblocks数组是一个2d数组，其每行中的第一个元素是块索引i。对于i的每个值，jsp需要检查行中第二个元素的值，并根据第二个元素的值是否为0来确定要发送给用户的输出
以下是触发错误的代码行：
<spring:eval expression="filledblocks[i][1]!=0" var="appointment" />
下面是引发的异常：
org.springframework.core.convert.ConverterNotFoundException:
No converter found capable of converting from type
javax.servlet.jsp.jstl.core.LoopTagSupport$1Status
to type java.lang.Integer
下面是上面一行所在的jsp代码：
<table>
<thead>
<tr>
<th>Time Slots</th>
<th>Appointments</th>
</tr>
</thead>
<c:forEach var="block" items="${calendar.blocks}" varStatus="i">
<spring:eval expression="calendar.getBlockMillis(block)" var="dateTime"/>
<tr class="${i.index % 2 == 0 ? 'even' : ''}">
<td width="100px" class="block">
<joda:format value="${block}" style="-S" />
</td>
<spring:eval expression="filledblocks[i][1]!=0" var="appointment" />
<c:choose>
<c:when test="${appointment == true}">
<td class="filled" data-dateTime="<c:out value="${dateTime}" />" >
<a href="${testLink}" style="display:block;"> There is an appointment.</a>
<c:url var="testLink" value="/">
<c:param name="somevarname" value="test" />
</c:url>
</td>
</c:when>
<c:otherwise>
<c:url var="testLink" value="/">
<c:param name="somevarname" value="test" />
</c:url>
<td class="open" data-dateTime="<c:out value="${dateTime}" />" >
<a href="${testLink}" style="display:block;">No Appointment</a>
</td>
</c:otherwise>
</c:choose>
</tr>
</c:forEach>
</table>
以下是完整的堆栈跟踪：
Feb 14, 2014 10:49:50 AM org.apache.catalina.core.ApplicationDispatcher invoke
SEVERE: Servlet.service() for servlet jsp threw exception
org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type javax.servlet.jsp.jstl.core.LoopTagSupport$1Status to type java.lang.Integer
at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:276)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:172)
at org.springframework.expression.spel.support.StandardTypeConverter.convertValue(StandardTypeConverter.java:66)
at org.springframework.expression.spel.ExpressionState.convertValue(ExpressionState.java:142)
at org.springframework.expression.spel.ast.Indexer.getValueRef(Indexer.java:418)
at org.springframework.expression.spel.ast.Indexer.getValueInternal(Indexer.java:78)
at org.springframework.expression.spel.ast.CompoundExpression.getValueRef(CompoundExpression.java:55)
at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:82)
at org.springframework.expression.spel.ast.OpNE.getValueInternal(OpNE.java:37)
at org.springframework.expression.spel.ast.OpNE.getValueInternal(OpNE.java:29)
at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:93)
at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:89)
at org.springframework.web.servlet.tags.EvalTag.doEndTag(EvalTag.java:121)
at org.apache.jsp.WEB_002dINF.jsp.appointments.calendar_jsp._jspx_meth_spring_005feval_005f2(calendar_jsp.java:652)
at org.apache.jsp.WEB_002dINF.jsp.appointments.calendar_jsp._jspx_meth_c_005fforEach_005f0(calendar_jsp.java:557)
at org.apache.jsp.WEB_002dINF.jsp.appointments.calendar_jsp._jspService(calendar_jsp.java:176)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:487)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:263)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1208)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:992)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:939)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.github.dandelion.datatables.core.web.filter.DatatablesFilter.doFilter(DatatablesFilter.java:73)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.github.dandelion.datatables.extras.servlet2.filter.DatatablesFilter.doFilter(DatatablesFilter.java:71)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Feb 14, 2014 10:49:50 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [KnowledgeManager] in context with path [/KnowledgeManager] threw exception [org.springframework.expression.spel.SpelEvaluationException: EL1001E:(pos 12): Type conversion problem, cannot convert from javax.servlet.jsp.jstl.core.LoopTagSupport$1Status to java.lang.Integer] with root cause
org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type javax.servlet.jsp.jstl.core.LoopTagSupport$1Status to type java.lang.Integer
at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:276)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:172)
at org.springframework.expression.spel.support.StandardTypeConverter.convertValue(StandardTypeConverter.java:66)
at org.springframework.expression.spel.ExpressionState.convertValue(ExpressionState.java:142)
at org.springframework.expression.spel.ast.Indexer.getValueRef(Indexer.java:418)
at org.springframework.expression.spel.ast.Indexer.getValueInternal(Indexer.java:78)
at org.springframework.expression.spel.ast.CompoundExpression.getValueRef(CompoundExpression.java:55)
at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:82)
at org.springframework.expression.spel.ast.OpNE.getValueInternal(OpNE.java:37)
at org.springframework.expression.spel.ast.OpNE.getValueInternal(OpNE.java:29)
at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:93)
at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:89)
at org.springframework.web.servlet.tags.EvalTag.doEndTag(EvalTag.java:121)
at org.apache.jsp.WEB_002dINF.jsp.appointments.calendar_jsp._jspx_meth_spring_005feval_005f2(calendar_jsp.java:652)
at org.apache.jsp.WEB_002dINF.jsp.appointments.calendar_jsp._jspx_meth_c_005fforEach_005f0(calendar_jsp.java:557)
at org.apache.jsp.WEB_002dINF.jsp.appointments.calendar_jsp._jspService(calendar_jsp.java:176)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:487)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238)
at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:263)
at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1208)
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:992)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:939)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.github.dandelion.datatables.core.web.filter.DatatablesFilter.doFilter(DatatablesFilter.java:73)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.github.dandelion.datatables.extras.servlet2.filter.DatatablesFilter.doFilter(DatatablesFilter.java:71)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
# 1 楼答案
正如错误所说，您正在尝试一个时髦的类演员，这是行不通的。改用这个：