Struts 2文件上传：文件对象为空 [英] Struts 2 file upload : File object being null

问题描述

我试图使用Struts 2文件上传，但在我看来，它不工作。下面是我的代码。

UploadAction.java ：

  public class UploadAction extends ActionSupport {
 
 private file file; 
 private String orgFileName; 
 private String orgContentType; 
 $ b $ public void setUpload（File file）{
 this.file = file; 
} 
 
 public void setUploadContentType（String contentType）{
 this.orgContentType = contentType; 
} 
 public void setUploadFileName（String fileName）{
 this.orgFileName = fileName; 
 
 $ b @覆盖
 public String execute（）{
 if（file == null）
 {
 System.out.println （无文件....）; 
} 
 System.out.println（orgContentType）; 
 System.out.println（orgFileName）; 
回报SUCCESS; 
 
 
 
 $ b $ / code $ / pre 
 $ b $ p $ <$ c 
 $ b $ 
 <常数名称=struts.multipart.maxSize value =20971520/> 
< constant name =struts2.multipart.saveDirvalue =C：/ users / sabertooth / desktop / upload/> 
< include file =example.xml/> 
 
 <！ -   - 默认包的配置。 - > 
 < action name =uploadclass =UploadAction> 
 
< result name =success> /example/HelloWorld.jsp< / result> 
< / action> 
< / package> 
  
我也尝试设置struts2.multipart.saveDir属性，如上所见，但是当我读服务器日志我看到这一行
 无法找到`struts.multipart.saveDir`默认为`javax.servlet.dir` 
  
此文件对象为空，因为没有文件...在控制台上打印出来。 
我不知道这里有什么问题。
 
 
 编辑： 
 
 
 
  fileupload.jsp ：
 <％@ page contentType =text / htmlpageEncoding =UTF-8％> 
 <％@ taglib prefix =suri =/ struts-tags％> 
<！DOCTYPE html> 
< html> 
< head> 
< meta http-equiv =Content-Typecontent =text / html; charset = UTF-8> 
< title> JSP页< / title> 
< / head> 
< body> 
< h1>下方的上载档案< / h1> 
 < input type =filename =fileid =uploadfile/> 
< input type =submitid =submit/> 
< / s：form> 
 
< / body> 
< / html> 
  
 
 
解决方案
除了更改 saveDir （确实没有必要，也很危险），你没有遵循Action类中的约定：一个私有变量的名字必须和它的Getters和Setters的名字匹配。最后，在页面中，通过指向私有变量而不是指定者来匹配名称。更改为： 
 
 
  public class UploadAction extends ActionSupport {
 
 private文件上传; 
 private String uploadFileName; 
 private String uploadContentType; 
 
 public void setUpload（File upload）{
 this.upload = upload; 
 
 public void setUploadContentType（String uploadContentType）{
 this.uploadContentType = uploadContentType; 
 
 public void setUploadFileName（String uploadFileName）{
 this.uploadFileName = uploadFileName; 
 b 
 $ b @Override 
 public String execute（）{
 if（upload == null）
 {
 System.out.println （无文件....）; 
} 
 System.out.println（uploadContentType）; 
 System.out.println（uploadFileName）; 
回报SUCCESS; 
 
 
 
 
 $ JSP b 
 
 
 < s：form action =uploadmethod =postenctype =multipart / form-data> 
< input type =filename =uploadid =uploadfile/> 
< input type =submitid =submit/> 
< / s：form> 
  
 
I am trying to use Struts 2 file upload but it seems to me that its not working. Below is my code.

UploadAction.java:
public class UploadAction extends ActionSupport{

    private File file;
    private String orgFileName;
    private String orgContentType;

    public void setUpload(File file){
        this.file=file;
    }

    public void setUploadContentType(String contentType){
        this.orgContentType=contentType;
    }
    public void setUploadFileName(String fileName){
        this.orgFileName=fileName;
    }

    @Override
    public String execute(){
        if(file==null)
        {
            System.out.println("No file....");
        }
        System.out.println(orgContentType);
        System.out.println(orgFileName);
        return SUCCESS;
    }


}
struts.xml:
    <constant name="struts.multipart.maxSize" value="20971520" />
    <constant name="struts2.multipart.saveDir" value="C:/users/sabertooth/desktop/upload" />
    <include file="example.xml"/>

    <!-- Configuration for the default package. -->
    <package name="default" extends="struts-default">
        <action name="upload" class="UploadAction">

            <result name="success">/example/HelloWorld.jsp</result>
        </action>
    </package>
I am also trying to set struts2.multipart.saveDir property as you can see above but when I read the server logs I see this line
unable to find `struts.multipart.saveDir` defaulting to `javax.servlet.dir`
Also the file object is null as no file... gets printed out on console.
I can't figure out what is wrong here.

EDIT: 

fileupload.jsp:
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <h1>upload file below</h1>
        <s:form action="upload" method="post" enctype="multipart/form-data">
            <input type="file" name="file" id="uploadfile" />
            <input type="submit" id="submit" />
        </s:form>

    </body>
</html>

解决方案
Apart from changing the saveDir (really not necessary, and dangerous), your are not following the conventions in the Action class: the name of an private variable must match the names of its Getters and Setters; and finally, in page you are mismatching the name by pointing to the private variable, not the setter. Change it to:
public class UploadAction extends ActionSupport{

    private File   upload;
    private String uploadFileName;
    private String uploadContentType;

    public void setUpload(File upload){
        this.upload=upload;
    }
    public void setUploadContentType(String uploadContentType){
        this.uploadContentType=uploadContentType;
    }
    public void setUploadFileName(String uploadFileName){
        this.uploadFileName=uploadFileName;
    }

    @Override
    public String execute(){
        if(upload==null)
        {
            System.out.println("No file....");
        }
        System.out.println(uploadContentType);
        System.out.println(uploadFileName);
        return SUCCESS;
    }
}
JSP
<s:form action="upload" method="post" enctype="multipart/form-data">
    <input type="file" name="upload" id="uploadfile" />
    <input type="submit" id="submit" />
</s:form>


                        
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