Struts2 Fileupload giving null file in the action class

问题

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

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;
 }

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.

I am executing the application in debug mode and gave this

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

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

回答1:

1. Interceptor configuration is wrong

FileUploadStack is:

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

then what you're really defining is:

    <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>

Using

two times the fileUpload interceptor
applying your limitations on maximumSize and allowedTypes only to the second.

Just do

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

2. File attributes are wrong

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

In your case:

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

You can find a full example on this question.

3. You are printing the File instead of the filename

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

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

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:.

来源：https://stackoverflow.com/questions/33696901/struts2-fileupload-giving-null-file-in-the-action-class

标签

java

jsp

file-upload

struts2

interceptorstack