Struts 2文件上传：文件对象为null

  • Z时代
  • 2024-01-10
  • 分类：问答

我正在尝试使用Struts 2文件上传，但是在我看来，它不起作用。下面是我的代码。

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>

我也在尝试设置struts2.multipart.saveDir属性，如您在上面看到的，但是当我阅读服务器日志时，我看到了这一行

unable to find `struts.multipart.saveDir` defaulting to `javax.servlet.dir`

而且文件对象为null，因为没有文件…在控制台上打印出来。我无法弄清楚这里出了什么问题。

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>

回答：

除了更改saveDir（实际上是不必要和危险的）之外，您还没有遵循Action类中的约定：私有变量的名称必须与其Getter和Setter的名称匹配；最后，在页面中，您通过指向私有变量而不是setter来使名称不匹配。更改为：

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>

以上是 Struts 2文件上传：文件对象为null 的全部内容， 来源链接： utcz.com/qa/408022.html

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