This article is divided into two aspects to explain:
1. Java implements dynamic upload of multiple files
2. Solve file renaming problem java
For your reference, the specific content is as follows
1. Dynamically upload multiple files
<form name="xx" action="<c:url value='/Up3Servlet'//>" method="post" enctype="multipart/form-data"> <table id="tb"> <tr> <td> File: </td> <td> <input type="file" name="file"> <button onclick="_del(this);">Delete</button> </td> </tr> </table> <br/> <input type="button" onclick="_submit();" value="upload"> <input onclick="_add();" type="button" value="Add"> </form> </body> <script type="text/javascript"> function _add(){ var tb = document.getElementById("tb"); //Write a line var tr = tb.insertRow(); //Write column var td = tr.insertCell(); //Write data td.innerHTML="File:"; //Declare a new td var td2 = tr.insertCell(); //Write an input td2.innerHTML='<input type="file" name="file"/><button onclick="_del(this);">Delete</button>'; } function _del(btn){ var tr = btn.parentNode.parentNode; //alert(tr.tagName); //get the subscript of tr in the table var index = tr.rowIndex; //Delete var tb = document.getElementById("tb"); tb.deleteRow(index); } function _submit(){ //Transtraverse all files var files = document.getElementsByName("file"); if(files.length==0){ alert("No file that can be uploaded"); return false; } for(var i=0;i<files.length;i++){ if(files[i].value==""){ alert(""+(i+1)+"files cannot be empty"); return false; } } document.forms['xx'].submit(); } </script></html>Iterate through all files to upload
2. Solve the problem of duplicate file name
package cn.hx.servlet;import java.io.File;import java.io.IOException;import java.io.PrintWriter;import java.util.ArrayList;import java.util.List;import java.util.UUID;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.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;import org.apache.commons.io.FileUtils;public class UpImgServlet extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); String path = getServletContext().getRealPath("/up"); DiskFileItemFactory disk = new DiskFileItemFactory(1024*10,new File("d:/a")); ServletFileUpload up = new ServletFileUpload(disk); try{ List<FileItem> list = up.parseRequest(request); //Receive only images*.jpg-iamge/jpege.,bmp/imge/bmp,png, List<String> imgs = new ArrayList<String>(); for(FileItem file :list){ if(file.getContentType().contains("image/")){ String fileName = file.getName(); fileName = fileName.substring(fileName.lastIndexOf("//")+1); //Get extension String extName = fileName.substring(fileName.lastIndexOf("."));//.jpg //UUID String uuid = UUID.randomUUID().toString().replace("-", ""); //New name String newName = uuid+extName; //UUID is used to generate a new folder name, so that it will not cause the duplicate name FileUtils.copyInputStreamToFile(file.getInputStream(), new File(path+"/"+newName)); //Put to list imgs.add(newName); } file.delete(); } request.setAttribute("imgs",imgs); request.getRequestDispatcher("/jsps/imgs.jsp").forward(request, response); }catch(Exception e){ e.printStackTrace(); } }}The above implements Java multi-file uploading, which solves the problem of file duplicate names. I hope it will be helpful to everyone's learning.