Question

我从webstie https://www.mkyong.com/struts/struts-file-upload-example/引用了关于strust上传文件的文章，但我不明白一些问题。我希望得到帮助。为什么要使用Action Form类？我明白这是javabean？和代码

Private FormFile file;

Public FormFile getFile () {
Return file;
}

Public void setFile (FormFile file) {
This.file = file;
}

为要调用的文件创建getter setter方法???

我不明白这个命令：

FileUploadForm fileUploadForm = (FileUploadForm) form;

FormFile file = fileUploadForm.getFile ();

任何人都可以帮我解释上面的命令行。

Fos.flush ();据我所知，它用于删除FileOutStream上的数据并准备读取数据。期待帮助

行动表格

package com.mkyong.common.form;

import javax.servlet.http.HttpServletRequest;

import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;
import org.apache.struts.upload.FormFile;

public class FileUploadForm extends ActionForm{

    private FormFile file;

    public FormFile getFile() {
        return file;
    }

    public void setFile(FormFile file) {
        this.file = file;
    }

    @Override
    public ActionErrors validate(ActionMapping mapping,
       HttpServletRequest request) {

        ActionErrors errors = new ActionErrors();

        if( getFile().getFileSize()== 0){
           errors.add("common.file.err",
            new ActionMessage("error.common.file.required"));
           return errors;
        }

        //only allow textfile to upload
        if(!"text/plain".equals(getFile().getContentType())){
            errors.add("common.file.err.ext",
             new ActionMessage("error.common.file.textfile.only"));
            return errors;
        }

            //file size cant larger than 10kb
        System.out.println(getFile().getFileSize());
        if(getFile().getFileSize() > 10240){ //10kb
           errors.add("common.file.err.size",
            new ActionMessage("error.common.file.size.limit", 10240));
           return errors;
        }

        return errors;
    }
}

动作

package com.mkyong.common.action;

import java.io.File;
import java.io.FileOutputStream;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.upload.FormFile;

import com.mkyong.common.form.FileUploadForm;

public class FileUploadAction extends Action{

    @Override
    public ActionForward execute(ActionMapping mapping, ActionForm form,
        HttpServletRequest request, HttpServletResponse response)
        throws Exception {

        FileUploadForm fileUploadForm = (FileUploadForm)form;

        FormFile file = fileUploadForm.getFile();

        //Get the servers upload directory real path name
        String filePath =
               getServlet().getServletContext().getRealPath("/") +"upload";

        //create the upload folder if not exists
        File folder = new File(filePath);
        if(!folder.exists()){
            folder.mkdir();
        }

        String fileName = file.getFileName();

        if(!("").equals(fileName)){

            System.out.println("Server path:" +filePath);
            File newFile = new File(filePath, fileName);

            if(!newFile.exists()){
              FileOutputStream fos = new FileOutputStream(newFile);
              fos.write(file.getFileData());
              fos.flush();
              fos.close();
            }

            request.setAttribute("uploadedFilePath",newFile.getAbsoluteFile());
            request.setAttribute("uploadedFileName",newFile.getName());
        }
        return mapping.findForward("success");
    }
}

Answer 1

任何人都可以帮我解释上面的命令行。

内联

/** 
 * This would case the ActionForm object named form to 
 * FileUploadForm which is its sub-class's object
 */
FileUploadForm fileUploadForm = (FileUploadForm) form;

 /** 
  * This uses the getter for  the field `private FormFile file;`
  * in the FileUploadForm class definition to create a FormFile object
  */
 FormFile file = fileUploadForm.getFile ();

此外，共享代码中fos.flush()上方的行：

fos.write(file.getFileData()); 
// This writes to output stream using the file data from the FormFile object we got previously

在strust 1中询问formfile

1 个答案: