Java 使用 jsp 和 servlet 上传多个文件

Uploading multiple files using jsp & servlets

提问by user3029610

I am currently working on a dynamic web application that I want the user to be able to upload multiple files at once for the application to use. I don't know how many files the user may upload at once; it could be 2 or it could 100+ files. I am new to JSP dynamic web applications and I have started with a single upload file but I am not really sure where to go from here. I've looked at few examples searching but I haven't been able to find exactly what I was looking for. This is what I have so far:

我目前正在开发一个动态 Web 应用程序，我希望用户能够一次上传多个文件供应用程序使用。我不知道用户一次可以上传多少个文件；它可能是 2 个，也可能是 100 多个文件。我是 JSP 动态 Web 应用程序的新手，我从一个上传文件开始，但我不确定从哪里开始。我查看了几个搜索示例，但一直无法找到我正在寻找的内容。这是我到目前为止：

Servlet:

小服务程序：

package Servlets;
import java.io.File;  
import java.io.IOException;  
import java.io.PrintWriter;  
import java.util.Iterator;   
import java.util.List;  
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
import org.apache.commons.fileupload.FileItem;  
import org.apache.commons.fileupload.FileItemFactory;  
import org.apache.commons.fileupload.FileUploadException;  
import org.apache.commons.fileupload.disk.DiskFileItemFactory;  
import org.apache.commons.fileupload.servlet.ServletFileUpload;  

public class UploadServlet extends HttpServlet 
{  

private static final long serialVersionUID = 1L;

    @Override  
      protected void doPost(HttpServletRequest request, HttpServletResponse response)  
          throws ServletException, IOException 
          {  
            boolean isMultipart = ServletFileUpload.isMultipartContent(request);  
            response.setContentType("text/html");  
            PrintWriter out = response.getWriter();  
            if (isMultipart) 
            {  
                // Create a factory for disk-based file items  
                FileItemFactory factory = new DiskFileItemFactory();  
                // Create a new file upload handler  
                ServletFileUpload upload = new ServletFileUpload(factory);  
                try 
                {  
                    // Parse the request  
                    List items = upload.parseRequest(request);  
                    Iterator iterator = items.iterator();  
                    while (iterator.hasNext()) 
                    {  
                        FileItem item = (FileItem) iterator.next();  
                        if (!item.isFormField())  
                        {  
                            String fileName = item.getName();      
                            String root = getServletContext().getRealPath("/");  
                            File path = new File(root + "/uploads");  
                            if (!path.exists())  
                            {  
                                boolean status = path.mkdirs();  
                            }  
                            File uploadedFile = new File(path + "/" + fileName);  
                            System.out.println(uploadedFile.getAbsolutePath());  
                        if(fileName!="")  
                            item.write(uploadedFile);  
                        else  
                        out.println("file not found");  
                        out.println("<h1>File Uploaded Successfully....:-)</h1>");  
                    }  
                    else  
                    {  
                        String abc = item.getString();  
                        out.println("<br><br><h1>"+abc+"</h1><br><br>");  
                    }  
                }  
            } 
            catch (FileUploadException e) 
            {  
            out.println(e);  
            } 
            catch (Exception e) 
            {  
            out.println(e);  
            }  
        }  
        else  
        {  
            out.println("Not Multipart");  
        }  
      }  
}

.JSP File:

.JSP 文件：

<form method="post" action="UploadServlet" enctype="multipart/form-data">
Select file to upload:
    <p><input type="file" name="dataFile" id="fileChooser" />&nbsp;
    <input type="submit" value="Upload" multiple="multiple" /></p>
</form>

I am looking for a way to upload multiple files instead of just one and show them in a list.

我正在寻找一种上传多个文件而不是一个文件并将它们显示在列表中的方法。

回答by Amadan

Oh... At the first glance, looks like a simple mistake. multipleis an attribute of file input, not of the submit button.

哦... 乍一看，似乎是一个简单的错误。multiple是文件输入的属性，而不是提交按钮的属性。

回答by Amadan

To upload a single file you should use a single tag with attribute type="file". To allow multiple files uploading, include more than one input tags with different values for the name attribute. The browser associates a Browse button with each of them.

要上传单个文件，您应该使用属性 type="file" 的单个标签。要允许上传多个文件，请为 name 属性包含多个具有不同值的输入标签。浏览器将浏览按钮与每个按钮相关联。

That is, use the below line multiple times:

也就是说，多次使用以下行：

<input type="file" name="dataFile" id="fileChooser" /><br><br>

Refer this link for details

详情请参阅此链接

I hope this helps.

我希望这有帮助。

回答by Mitul Maheshwari

i have upload multiple files using jsp /servlet. following is the code that i have used.

我使用jsp / servlet上传了多个文件。以下是我使用过的代码。

<form action="UploadFileServlet" method="post">
<input type="text" name="description" />
<input type="file" name="file" />
<input type="submit" />
</form>

on the other hand server side. use following code.

另一方面服务器端。使用以下代码。

    package com.abc..servlet;

import java.io.File;
---------
--------


/**
 * Servlet implementation class UploadFileServlet
 */
public class UploadFileServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public UploadFileServlet() {
        super();
        // TODO Auto-generated constructor stub
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.sendRedirect("../jsp/ErrorPage.jsp");
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub

            PrintWriter out = response.getWriter();
            HttpSession httpSession = request.getSession();
            String filePathUpload = (String) httpSession.getAttribute("path")!=null ? httpSession.getAttribute("path").toString() : "" ;

            String path1 =  filePathUpload;
            String filename = null;
            File path = null;
            FileItem item=null;


            boolean isMultipart = ServletFileUpload.isMultipartContent(request);

            if (isMultipart) {
                FileItemFactory factory = new DiskFileItemFactory();
                ServletFileUpload upload = new ServletFileUpload(factory);
                String FieldName = "";
                try {
                    List items = upload.parseRequest(request);
                    Iterator iterator = items.iterator();
                    while (iterator.hasNext()) {
                         item = (FileItem) iterator.next();

                            if (fieldname.equals("description")) {
                                description = item.getString();
                            }
                        }
                        if (!item.isFormField()) {
                            filename = item.getName();
                            path = new File(path1 + File.separator);
                            if (!path.exists()) {
                                boolean status = path.mkdirs();
                            }
                            /* START OF CODE FRO PRIVILEDGE*/

                            File uploadedFile = new File(path + Filename);  // for copy file
                            item.write(uploadedFile);
                            }
                        } else {
                            f1 = item.getName();
                        }

                    } // END OF WHILE 
                    response.sendRedirect("welcome.jsp");
                } catch (FileUploadException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                } 
            }   
    }

}

回答by Shirishkumar Bari

Check the FileUPload Using Servlet 3.0

使用 Servlet 3.0检查 FileUPload

It has a working code for uploading Single File Using Servlet3.0 As you can see code is now much simplified . And there is no dependancy on apache Library.

它有一个使用 Servlet3.0 上传单个文件的工作代码，正如您所看到的，代码现在大大简化了。并且不依赖 apache 库。

just use below index.html

只需在下面使用 index.html

<html>
<head></head>
<body>
<form action="FileUploadServlet" method="post" enctype="multipart/form-data">
Select File to Upload:<input type="file"  name="fileName" multiple="multiple"/>
<br>
<input type="submit" value="Upload"/>
</form>
</body>
</html>

Only change here is I have usedmultiple="multiple"attribute for input type File

这里唯一的变化是我使用multiple="multiple"了输入类型文件的属性

回答by s.nainwal

images.jsp

图像.jsp

选择文件：

storeimages.java servlet

storeimages.java servlet

public class storeimages extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException,
                                                   IOException {

String sav_dir=""; //this will be a folder inside
        //directory
        PrintWriter out =response.getWriter();

        //if you want u can give this at run time
         sav_dir="6022"; //in my case folder name is 6022 
         //you can alse set this at dynamic

        int flag = 0;

        //now set the path
        //this is the path where my images are stored
        //now u can see the code
 String savepath="K:/imageupload"+File.separator +sav_dir;   

 File file = new File(savepath);

 if(!file.exists()){

     file.mkdir();
 }

 String filename="";

 List<Part> fileParts = request.getParts().stream().
filter(part->"file".equals(part.getName())).collect(Collectors.
        toList());

for(Part filePart: fileParts){
    filename=Paths.get(filePart.getSubmittedFileName()).
    getFileName().toString();

    filePart.write(savepath+File.separator+filename);
    flag=1;


}
         if(flag==1){

             out.println("success");
         }

         else{

             out.println("try again");
         }

     //now save this and run the project
    }
}

回答by Joe9008

You only have to write multiple, because multiple is a boolean var and only defining it, it will be true to your tag. Example below:

你只需要写multiple，因为 multiple 是一个布尔变量并且只定义它，它对你的标签来说是真实的。下面的例子：

<input type="file" name="file" id="file" multiple/> 

This will let you choose multiple files at once. Good luck

这将让您一次选择多个文件。祝你好运

回答by user13417848

This is how I did. It will dynamically add and remove the field (multiple files). Validates it and on validation calls the action method i.e the servlet and store in the DB. ** html/jsp ** .jsp file

我就是这样做的。它将动态添加和删除字段（多个文件）。验证它并在验证时调用操作方法，即 servlet 并存储在数据库中。** html/jsp ** .jsp 文件

<div class="recent-work-pic">
<form id="upload_form" method="post" action="uploadFile" enctype="multipart/form-data" >
<input type="hidden" id="counter" value="1" >
<a href="javascript:void(0);" class="remove_fields"  id="add_fields">Add</a>
<div class="record"><input type="file" placeholder="Upload File" name="uploadFile_0" class="upload_input"></div>
<div id="add_field_div"></div>
<button type="submit" class="btn btn-read">Submit</button>
</form>
<p>${message}</p>
 </div>

jquery validation

jQuery 验证

<script>
$(document).ready(function(){
    $('#add_fields').click( function(){
        add_inputs()
    });

    $(document).on('click', '.remove_fields', function() {
        $(this).closest('.record').remove();
    });
    function add_inputs(){
        var counter = parseInt($('#counter').val());
        var html = '<div class="record"><input type="file" placeholder="Upload File" name="uploadFile_' + counter + '" class="upload_input"><a href="javascript:void(0);" class="remove_fields">Remove</a></div>';
        $('#add_field_div').append(html);
        $('#counter').val( counter + 1 );
    }
    $('form#upload_form').on('submit', function(event) {
        //Add validation rule for dynamically generated name fields
    $('.upload_input').each(function() {
        $(this).rules("add", 
            {
                required: true,
                messages: {
                    required: "File is required",
                }
            });
    });

});
$("#upload_form").validate();


});
</script>

servlet

小服务程序

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

//      KeycloakPrincipal principal = (KeycloakPrincipal) request.getUserPrincipal();


        PrintWriter writer = response.getWriter();
        Properties properties = new Properties();
        properties.load(this.getClass().getClassLoader().getResourceAsStream("/resources/datenBank.properties"));

        if (!ServletFileUpload.isMultipartContent(request)) {
            writer.println("Fehler: Form must has enctype=multipart/form-data.");
            writer.flush();
            return;
        }
        String message = null;
        InputStream inputStream = null;
        Connection dbConnection = null;

        String page = "";
        try {
            for (Part filePart : request.getParts()) {
                System.out.println("filePart" + filePart.getName() + "-----" + filePart.getSize());
                if (filePart != null && filePart.getSize() != 0) {
                    inputStream = filePart.getInputStream();

                    System.out.println("inputStream" + inputStream);
                     HttpSession session=request.getSession();  
                     session.setAttribute("username",request.getRemoteUser());  
                    Class.forName(properties.getProperty("driverClassName"));
                    dbConnection = DriverManager.getConnection(properties.getProperty("url"), properties.getProperty("username"), properties.getProperty("password"));
                    if (dbConnection != null) {

                            String sql = "INSERT INTO skl_lieferung (file_name, file_size, file_content,file_content_type, entry_time, user) values (?,?,?,?,?, ?)";
                            PreparedStatement statement = dbConnection.prepareStatement(sql);

                            if (inputStream != null) {
                                statement.setString(1, getFileName(filePart));
                                statement.setLong(2, filePart.getSize());
                                statement.setBlob(3, inputStream);
                                statement.setString(4, filePart.getContentType());
                            }

                            Calendar calendar = Calendar.getInstance();
                            java.sql.Date entryDate = new java.sql.Date(calendar.getTime().getTime());
                            statement.setDate(5, entryDate);
                            statement.setString(6, request.getRemoteUser());
                            //statement.setString(6, username);

                            int row = statement.executeUpdate();
                            if (row > 0) {
                                message = "Datei hochgeladen und in der Datenbank gespeichert";
                            }else {
                                message = "Fehler: Connection Problem";
                            }
                        }                   message = "Datei hochgeladen und in der Datenbank gespeichert";

                        }else {
                            page = "index.jsp";
                            System.out.println("cannot execute if condition");
                            message = "Das Upload-Feld darf nicht leer sein ";
                            RequestDispatcher dd = request.getRequestDispatcher(page);
                            dd.forward(request, response);
                            return;
                        }
                } 
            }catch (Exception exc) {
            page = "index.jsp";
            message = "Fehler: " + exc.getMessage();
            exc.printStackTrace();
        } finally {
            if (dbConnection != null) {
                try {
                    dbConnection.close();
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
                page = "index.jsp";
                request.setAttribute("message", message);
                RequestDispatcher dd = request.getRequestDispatcher(page);
                dd.forward(request, response);
            }
        }
    }

    private String getFileName(Part part) {
        for (String content : part.getHeader("content-disposition").split(";")) {
            if (content.trim().startsWith("filename")) {
                return content.substring(content.indexOf('=') + 1).trim().replace("\"", "");
            }
        }
        return null;
    }

I hope people find it useful!!

我希望人们觉得它有用！！