用ajaxfileupload+struts2上传出现空指针异常！求助！！

Question

HTML相关代码：
<ul>
<span class="title">标题图：</span>
   <input type="file" name="file_topadv" id="file_topadv" style="width:350px;" value=""/>
   <button class="shangchuan" onclick="return topadvUpload(<%=shop.getId()%>)">上传</button><img src="../images/loding022.gif" id="topadv_loading" style="display: none;margin-left:10px;"/>
   <input type="hidden" name="topadv" id="topadv" value=""/>
 </ul>
 <ul>
    <span id="preview_topadv">
</ul>JS代码：
function topadvUpload(shopid){
imgloading();
if($('#file_topadv').attr("value")!="")){
$.ajaxFileUpload
(
     {
                url:'UploadShoptop.action',//用于文件上传的服务器端请求地址
                secureuri:false,//一般设置为false
                fileElementId:'file_topadv',//文件上传空间的id属性  <input type="file" id="file" name="file" />
                data:{id:shopid},
                dataType: 'json',//返回值类型 一般设置为json
                success: function (data, status)  //服务器成功响应处理函数
                {
//                    alert("data.message="+data.message);//从服务器返回的json中取出message中的数据,其中message为在struts2中action中定义的成员变量
//                    var str=JSON.stringify(data.message);
//                    alert("str"+str);
                    $("#topadv").val(data.message);
                    var pre="<img src=\"../"+data.message+"\" class=\"imgsk\"/>";
                    $("#preview_topadv").html(pre);
                    if(typeof(data.error) != 'undefined')
                    {
                        if(data.error != '')
                        {
                            alert(data.error);
                        }
                    }
                },
                error: function (data, status, e)//服务器响应失败处理函数
                {
                    alert(e);
                }
            } );
return false;
}else{
alert("没有选择文件！");
}
} // end of function ajaxFileUpload()JAVA代码：
public String execute() throws Exception {
String path =ServletActionContext.getServletContext().getRealPath("/upload/shoptopadv");
System.out.println(path);
 DateAndTime dt=new DateAndTime();
 String newfilename="";
//  newfilename=dt.curDateTimeAsFilename()+".jpg";
 newfilename=id+".jpg";
 
        try {
            File f = this.getUploadfiles();
      System.out.println(f.getAbsolutePath());
            if(this.getUploadfilesFileName().endsWith(".exe")){
                error="对不起,你上传的文件格式不允许!!!";
                return ERROR;
            }
            FileInputStream inputStream = new FileInputStream(f);
            @SuppressWarnings("resource")
FileOutputStream outputStream = new FileOutputStream(path + "\\"+ newfilename);
            byte[] buf = new byte[1024];
            int length = 0;
            while ((length = inputStream.read(buf)) != -1) {
                outputStream.write(buf, 0, length);
            }
            //message="<input type=\"hidden\" name=\"path\" value=\""+path + "/"+ this.getUploadfilesFileName()+"\"/>";
           message= "upload/shoptopadv/"+ newfilename;
            inputStream.close();
            outputStream.flush();
            error="";
        } catch (Exception e) {
            e.printStackTrace();
            error = "对不起,文件上传失败了!!!!";
        }
        return SUCCESS;
}异常：
java.lang.NullPointerException
at com.action.UploadShoptop.execute(UploadShoptop.java:32)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:450)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:289)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:252)
at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:239)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:325)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:161)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:246)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:563)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:176)
at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145)
at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:394)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.logging.log4j.core.web.Log4jServletFilter.doFilter(Log4jServletFilter.java:66)
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:472)
at org.apache.catalina.core.StandardHostValve.invokestruts2java

Answer 1

at com.action.UploadShoptop.execute(UploadShoptop.java:32)

Answer 2

我查了，是File f = this.getUploadfiles();返回的是null。好像是无法文件。

Answer 3

这个ajaxfileupload组件是自己生成一个具有multipart/form-data 属性的form的啊！

Answer 4

这个应该是  fileElementId:'uploadfiles',  

Answer 5

解决了！是<input type="file" name="file_topadv" id="file_topadv" style="width:350px;" value=""/>这里的问题，name的"file_topadv"与action里的uploadfiles属性名称没有对应忘了struts里要求名称对应的，呵呵

Answer 6

虽然是自己找到了问题，但还是要谢谢rui888 ！！