could not be resolved as a collection/array/map/enumeration/iterator type的异常处理

<s:select name="specialityid" listKey="specialityid"

listValue="specialityname" list="#request.specialityArray"

headerKey="0" headerValue="==请选择==">

出现错误：

org.apache.jasper.JasperException: tag 'select', field 'list', name 'specialityid': The requested list key '#request.specialityArray' could not be resolved as a collection/array/map/enumeration/iterator type. Example: people or people.{name} - [unknown location]
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:549) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:403) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:347)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:164) org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186)
com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:371) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:275) org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265) org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:252) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:161) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246) org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563) org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)

原因分析：

配置了验证框架或者在action中写了validate方法，校验没有通过，未走action，直接返回了input，又指定回了当前界面 ，此时specialityArray为空，导致错误。

struts.xml:

<action name="Matri" class="com.action.MatriAction">

<result>/basicdata/matri.jsp</result>

<result name="input">/basicdata/matri.jsp</result>

</action>

解决办法：

把初始化的工作放到prepare拦截器中，因为prepare是在validate拦截器之前执行，即实现prepareble接口：

public class MatriAction extends ActionSupport
implements Preparable{

private static final long serialVersionUID = 1L;

public String action;

public int specialityid;

public String matrino;

public String studentname;

public int currentpage=1;

public long studentid;

public String errormsg;

@Override

public void prepare() throws Exception {

// TODO Auto-generated method stub

Connection conn=DBConn.createDBConn();

String sql="select * from Speciality";

Statement state=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);

ResultSet rs=state.executeQuery(sql);

ArrayList<Speciality> specialityArray=new ArrayList<Speciality>();

while(rs.next()){

Speciality spec=new Speciality();

spec.setSpecialityid(rs.getInt("SpecialityId"));

spec.setSpecialityname(rs.getString("SpecialityName"));

specialityArray.add(spec);

}

Map request = (Map)ActionContext.getContext().get("request");

request.remove("specialityArray");

request.put("specialityArray", specialityArray);

}

@Override

public String execute() throws Exception {

if(studentname!=null&&studentname.length()!=0)

studentname=studentname.trim();

else{

errormsg="please input name";

return INPUT;

}

if(specialityid==0)

{

errormsg="please input sepciality";

return INPUT;

}

......

}
}