大虾们帮帮忙啊，这种问题怎么解决。

Question

我用ajax判断登陆账号是否正确，判断无误，但后台报错：
严重: Servlet.service() for servlet default threw exception
java.lang.IllegalStateException
at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:407)
at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:839)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:533)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsExecuteFilter.doFilter(StrutsExecuteFilter.java:88)
at com.go.tsc.filter.BaseExecuteFilter.doFilter(BaseExecuteFilter.java:28)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareFilter.doFilter(StrutsPrepareFilter.java:82)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.go.tsc.filter.BaseFilter.doFilter(BaseFilter.java:38)
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)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)
at java.lang.Thread.run(Thread.java:619)
这个要怎么解决啊，我网上查了说是action改return为null  我改了  还是没有用，求解啊！ajaxactionexception

Answer 1

$.ajax( {
url : "login_getValidateCode.action",
type : "post",
dateType : "text",
async : false,
success : function(text) {
retCode = text;
if ($.trim(code.toLowerCase()) != $.trim(retCode.toLowerCase())) {
$("#errorMessage").html("验证码输入错误，请重新输入！");
reloadImage();
flag = false;
} else {
flag = true;
}
}
});public void getValidateCode() throws Exception {
String tmpCode = (String) getSession().get("randomString");
ResponseUtil.writeToPage(getResponse(), tmpCode);
}