关于struts2的checkboxlist、select等标签发生could not be resolved as a collection/array/ma

 在项目中Struts2.0页面中采用枚举常量的使用：

<s:select id="payType2" list="@com.unutrip.commonbiz.enums.OrderPaymentType@values()" listKey="code" listValue="description"></s:select>

OrderPaymentType一个枚举对象：

 

由于多个地方应用时：

public enum OrderPaymentType {

 CREDITCARD(0, "信用卡"), ONLINE(1, "网上支付"), // ->网银支付给环游
 UNSCARD(2, "商联卡POS"), // ->包含在环游商联卡里面
 CASH(3, "现金"), CHECK(4, "支票"), BANKPOS(5, "银行卡POS"), TRANSLATE(6, "银行转帐"), VOICE(7, "商联卡语音");

 private int code;
 private String description;

 public static final List<OrderPaymentType> FRONT_VALUE = Arrays.asList(OrderPaymentType.values()).subList(0, 4);

 public static final List<OrderPaymentType> SETTLE_VALUE = Arrays.asList(CREDITCARD, ONLINE);
 public static final List<OrderPaymentType> BACK_VALUE = Arrays.asList(CASH, CHECK, CREDITCARD, VOICE, ONLINE);

 private OrderPaymentType(int code, String description) {
  this.code = code;
  this.description = description;
 }

 public int getCode() {
  return code;
 }

 public void setCode(int code) {
  this.code = code;
 }

 public String getDescription() {
  return description;
 }

 public void setDescription(String description) {
  this.description = description;
 }

 public static OrderPaymentType fromCode(int code) {
  return EnumUtils.fromEnumProperty(OrderPaymentType.class, "code", code);
 }
}

      

 

 

今天研究struts2的标签功能，在用select的时候，
代码如采用部分是：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> <s:select id="payType2" list="@com.unutrip.commonbiz.enums.OrderPaymentType@SETTLE_VALUES" listKey="code" listValue="description"></s:select>

出现了如下异常：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> org.apache.jasper.JasperException: tag  ' checkboxlist ' , field  ' list ' , name  ' selectRoleId ' : The requested list key  ' roles '  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: 541 )
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java: 435 )
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java: 320 )
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java: 266 )
    javax.servlet.http.HttpServlet.service(HttpServlet.java: 803 )
    org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java: 154 )
    org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java: 186 )
    com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java: 361 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 265 )
    com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java: 249 )
    org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java: 68 )
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java: 87 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java: 122 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java: 195 )
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java: 87 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java: 195 )
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java: 87 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java: 148 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java: 93 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java: 235 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java: 89 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java: 128 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    org.apache.struts2.interceptor.ProfilingActivationInterceptor.intercept(ProfilingActivationInterceptor.java: 104 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java: 267 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java: 126 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java: 138 )
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java: 87 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java: 148 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java: 164 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java: 128 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java: 176 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    org.apache.struts2.interceptor.TokenInterceptor.handleValidToken(TokenInterceptor.java: 178 )
    org.apache.struts2.interceptor.TokenInterceptor.doIntercept(TokenInterceptor.java: 144 )
    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java: 87 )
    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java: 236 )
    org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java: 52 )
    org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java: 468 )
    org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java: 77 )
    org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java: 76 )

 

在网上Google一把网上说：

 

出现这个错误的原因可能如下：

1 刚进入该界面的时候发生错误，原因是 list="roles"中的这个集合是空的，导致错误

解决办法很简单，不能让list为空

2 刚进入该界面的时候list是有数据的，当点击提交等按钮的时候，数据被提交到后台,如果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。
此时的checkboxlist中的list丢失了，导致了如上错误（这个错误提示的不太友好，让人认为是类转换错误）

解决办法是把初始化list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：

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> --> public   class  RoleAction  extends  ActionSupport  implements  Preparable{
    @Override
     public   void  prepare()  throws  Exception {
         // 初始化list
    }
}

 

本人代碼不可能出现这样的错误,我很郁闷，继续探索中....

希望有人知道的告诉一下，谢谢！！

 

 

终于发现在struts2.16之前，struts2.0支持OGNL直接访问静态常量，之后不再支持OGNL直接访问静态常量，仅仅支持访问静态方法。问题终于解决。