Struts上传文件request为空系列问题

问题一：upload.parseRequest(request)得到的items为空

    private HttpServletRequest request;    FileItemFactory factory = new DiskFileItemFactory();    ServletFileUpload upload = new ServletFileUpload(factory);    List items = upload.parseRequest(request);  #request有值，但items却为null

原因：

    web.xml中的过滤器：     <filter>        <filter-name>struts2</filter-name>        <filter-class>                org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter        </filter-class>      </filter>      <filter-mapping>        <filter-name>struts2</filter-name>        <url-pattern>/*</url-pattern>      </filter-mapping>

struts2过滤时，会改变request的类型，由HttpServletRequest变成MultiPartRequestWrapper

解决：

第一步：加一个类

    public class RequestParseWrapper extends JakartaMultiPartRequest {    public void parse(HttpServletRequest servletRequest, String saveDir) throws IOException {    }    }

第二步：struts.xml配置文件加如下

    <!-- upload filt httpreqest process-->    <bean type="org.apache.struts2.dispatcher.multipart.MultiPartRequest" name="myRequestParser" class="com.dirsir.base.frame.RequestParseWrapper" scope="default" optional="true" />    <constant name="struts.multipart.handler" value="myRequestParser" />

这样配置之后引来了问题二。

问题二：action中通过getUpload()获取jsp页面中的表单数据<input type="file" name="upload"/>得到的files为空

    jsp中：<input type="file" name="upload"/>    action中：List<File> files = getUpload();   #files为空

原因：

struts2的过滤器：StrutsPrepareAndExecuteFilter源代码解析

由于重写了RequestParseWrapper 类，并把里面的内容置为空，影响了action中对file类型的表单数据“upload”的获取。

解决：

在action中采用HttpServletRequest的方式获取“upload”，即：

    private HttpServletRequest request;    FileItemFactory factory = new DiskFileItemFactory();    ServletFileUpload upload = new ServletFileUpload(factory);    List items = upload.parseRequest(request); 

然后再对items进行分情况处理。

注意：action中获得HttpServletRequest四种方式

    import javax.servlet.http.HttpServletRequest;    import org.apache.struts2.ServletActionContext;    import org.apache.struts2.interceptor.RequestAware;    import org.apache.struts2.interceptor.ServletRequestAware;    import com.opensymphony.xwork2.ActionContext;    import com.opensymphony.xwork2.ActionSupport;    /**     * 在action中获得HttpServletRequest四种方式     */    public class Login extends ActionSupport implements ServletRequestAware,RequestAware{     private HttpServletRequest req1=null;     private HttpServletRequest req2=null;     private HttpServletRequest req3=null;     private HttpServletRequest req4=null;     public String execute(){      HttpServletRequest req2 = ServletActionContext.getRequest();      req4 = (HttpServletRequest) ActionContext.getContext().get(org.apache.struts2.StrutsStatics.HTTP_REQUEST);      return "success";     }     public void setServletRequest(HttpServletRequest request) {      req1=request;     }     public void setRequest(Map<String, Object> request) {      req3 = (HttpServletRequest) request;     }    }