有人可以帮帮我吗？我正在使用 JQuery $.getJSON() 根据选定的下拉列表（类别）加载一个下拉列表（子类别）的内容。
由于某种原因，我收到了 IllegalStateException。提前谢谢你。
<script>
$(document)
.ready(
function() {
// reload subcategories when changing category
$('#categories').change(loadSubcategories);
});
// load the subcategories based on selected category
function loadSubcategories() {
$.getJSON('findSubcategoriesForCategory.html', {
categoryId : $('#categories').val(),
ajax : 'true'
}, function(data) {
var html = '<option value="">Select Subcategory</option>';
var len = data.length;
for ( var i = 0; i < len; i++) {
html += '<option value="' + data[i].id + '">' + data[i].name
+ '</option>';
}
html += '</option>';
$('#subcategories').html(html);
});
}
</script>
这是控制器方法的代码：
@RequestMapping(value = "findSubcategoriesForCategory", method = RequestMethod.GET)
public @ResponseBody
List<Subcategory> findSubcategoriesForCategory(
@RequestParam(value = "categoryId", required = true) String categoryId) {
List<Subcategory> returnList = new ArrayList<Subcategory>();
try {
returnList = categoryService
.findSubcategoriesForCategory(categoryId);
} catch (Exception e) {
LOGGER.error("An Error occured when Finding sub-categories for category id: " + categoryId);
}
return returnList;
}
java.lang.IllegalStateException: getOutputStream() 已经在 org.apache.catalina.connector.Response.getWriter(Response.java:611) at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade. java:198) 在 javax.servlet.ServletResponseWrapper.getWriter(ServletResponseWrapper.java:112) 在 org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125) 在 org.apache.jasper.runtime.JspWriterImpl.flushBuffer (JspWriterImpl.java:118) at org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:273) at java.io.PrintWriter.write(Unknown Source) at org.apache.jasper.runtime.JspWriterImpl.flushBuffer (JspWriterImpl.java:119) 在 org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:326) 在 org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:342) 在 org.apache.jsp.WEB_002dINF.jsp.include.header_jsp._jspx_meth_c_005fforEach_005f1(header_jsp.java:341) 在 org.apache.jsp.WEB_002dINF.jsp.include.header_jsp._jspx_meth_c_005fforEach_005f0(header_jsp.java)在 org.apache.jsp.WEB_002dINF.jsp.include.header_jsp._jspService(header_jsp.java:133) 在 org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 在 javax.servlet.http.HttpServlet .service(HttpServlet.java:717) 在 org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388) 在 org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313) 在 org. org.apache.catalina.core.ApplicationFilterChain 上的 javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 上的 apache.jasper.servlet.JspServlet.service(JspServlet.java:260)。internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646) at org.apache .catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551) 在 org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488) 在 org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java :968) 在 org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) 在 javax.servlet.http 的 org.apache.jsp.WEB_002dINF.jsp.errorMsg_jsp._jspService(errorMsg_jsp.java:69)。 org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388) 中的 org.apache.jasper 中的 HttpServlet.service(HttpServlet.java:717)。servlet.JspServlet.serviceJspFile(JspServlet.java:313) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org .apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) 在 org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 在 org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher .java:646）在 org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551) 在 org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488) 在 org.springframework.web。 org.springframework.web.servlet.view.AbstractView 上的 servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:229)。在 org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817) 在 org.springframework.render(DispatcherServlet.java:1047) 在 org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047) 渲染(AbstractView.java:250) .web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719) 在 org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669) 在 org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java :574) 在 javax.servlet.http.HttpServlet.service(HttpServlet.java:617) 在 javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 在 org.apache.catalina.core.ApplicationFilterChain.internalDoFilter( ApplicationFilterChain.java:290) 在 org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 在 org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain. java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core .StandardContextValve.invoke(StandardContextValve.java:191) 在 org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) 在 org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) 在org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) 在 org.apache。catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:291) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol. java:602) 在 org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) 在 java.lang.Thread.run(Unknown Source)