Struts2 Fileupload 在动作类中给出空文件 [英] Struts2 Fileupload giving null file in the action class

问题描述

我正在尝试使用 struts2 fileUpload 拦截器在我的 Web 应用程序中实现文件上传过程.以下是我在

I am trying to implement the file upload process in my web application using struts2 fileUpload interceptor. below is my code in

index.jsp

<tags:form action="fileUpload" method="post" enctype="multipart/form-data">
   <tags:file name="fileUpload" label="Choose File"/>
   <tags:submit value="Upload"/>     
</tags:form> 

struts.xml

<action name="fileUpload" class="com.hibernate.action.FileUploadAction">
    <interceptor-ref name="fileUploadStack"/>
    <interceptor-ref name="fileUpload">
        <param name="maximumSize">1024000</param>
        <param name="allowedTypes">application/pdf</param>
    </interceptor-ref>
    <result name="success">/viewChapters.jsp</result>
</action>

FileUploadAction.java

FileUploadAction.java

public class FileUploadAction extends ActionSupport
{
private File fileUpload;
private String contentType;
private String fileName;
private String destPath;
/// setter and getter methods
 public String execute()
{
    destPath="C:\WebPortal_testing";
    try
    {
        System.out.println("Source File Name:"+fileUpload);
        System.out.println("Destination File Name:"+fileName);

        File destFile= new File(destPath,fileName);
        FileUtils.copyFile(fileUpload, destFile);
    }
    catch(IOException exception)
    {
        exception.printStackTrace();
        return ERROR;
    }
    return SUCCESS;
 }

当我在 index.jsp 页面中选择一个 pdf 文件并单击上传按钮时，它会为操作类的 fileUpload 字段提供空值.

when I select a pdf file in the index.jsp page and click on upload button it is giving null value to the fileUpload field of the action class.

我正在调试模式下执行应用程序并给出了这个

I am executing the application in debug mode and gave this

System.out.println("Source File Name:"+fileUpload);

检查它返回的内容，我得到空值.

to check what it is returning and I am getting null.

推荐答案

1.拦截器配置错误

FileUploadStack 是:

<!-- Sample file upload stack -->
<interceptor-stack name="fileUploadStack">
    <interceptor-ref name="fileUpload"/>
    <interceptor-ref name="basicStack"/>
</interceptor-stack>

那么你真正定义的是:

    <interceptor-ref name="fileUpload"/>
    <interceptor-ref name="basicStack"/>
    <interceptor-ref name="fileUpload">
        <param name="maximumSize">1024000</param>
        <param name="allowedTypes">application/pdf</param>
    </interceptor-ref>

使用

• 文件上传拦截器的两倍
• 仅将您对 maximumSize 和 allowedTypes 的限制应用于第二个.

做吧

<interceptor-ref name="fileUploadStack">
    <param name="fileUpload.maximumSize">1024000</param>
    <param name="fileUpload.allowedTypes">application/pdf</param>
</interceptor-ref>

<小时>

<强>2.文件属性错误

内容类型和文件名属性必须以文件属性名开头.

Content type and file name attributes must start with the File attribute name.

在你的情况下:

private File fileUpload;
private String fileUploadContentType;
private String fileUploadFileName;

您可以在 this question 上找到完整示例.

You can find a full example on this question.

3.您正在打印文件而不是文件名

System.out.println("Source File Name:"+fileUpload);

那是文件，而不是文件名，顺便说一句，文件名是在另一个变量中传递的.

That is the file, not the filename, and btw the filename is passed in the other variable.

修复此问题并重试.另请注意，当全世界都在使用 <s: 时，使用 作为前缀是不安全的.这样做没有任何好处，只有并发症.只需使用 <s:.

Fix this and retry. Also note that is not safe to use <tags: as prefix when the whole world is using <s:. There's no gain in doing that, only complications. Just use <s:.

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