2. Use commons upload to develop file upload function
1) . download the jar package and dependent package of Commons upload and add them to the project project
2) . modify the html form, and set the content code type of the form to multipart / form date
3) . write jsp or servlet to handle file upload and other form data
In the webContent directory, create a directory to save the uploaded file
4) . path to save the file on the server
Code implementation:
jsp page:
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<!-- To upload files, you must enctype Change to multipart/form-date -->
<form name="regForm" action="upLoadServlet" method="post" enctype="multipart/form-data">
<table width="500" align="center" border="1">
<tr>
<td colspan="2">User registration</td>
</tr>
<tr>
<td>Account number</td>
<td><input name="userName" type="text"></td>
</tr>
<tr>
<td>Password</td>
<td><input name="password" type="password"></td>
</tr>
<tr>
<td>Head portrait</td>
<td><input name="userHead" type="file"></td>
</tr>
<tr>
<td><input type="submit"></td>
<td><input type="reset"></td>
</tr>
</table>
</form>
</body>
</html>
upLoadServlet:
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
UserInfo userInfo=new UserInfo();//Use temporary variables to save the data uploaded by users
//1. Classify and manage the uploaded files
//Get the path of Uploads in the file system
String basePath=getServletContext().getRealPath("/uploads");
String tempPath=getServletContext().getRealPath("/temp");
Calendar calendar=Calendar.getInstance(Locale.CHINA);
String subPath=calendar.get(Calendar.YEAR)+"/"+calendar.get((Calendar.MONTH)+1);
System.out.println(basePath+"/"+subPath);
File file=new File(basePath+"/"+subPath);
if(!file.exists()){
file.mkdirs();//Create multi-level directory, create different file directories according to date changes, classify and save files
}
File file2=new File(tempPath);
if(!file2.exists()){
file.mkdirs();//Create if the directory is not changed
}
//2. File upload processing
//Document item factory class
DiskFileItemFactory factory = new DiskFileItemFactory();
factory.setSizeThreshold(5*1024); //Maximum cache
factory.setRepository(new File(tempPath));//Temporary file directory
//Set upload parameters
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setSizeMax(5*1024*1024);//Maximum file limit
try {
List<FileItem>items=upload.parseRequest(request);
for(FileItem fileItem:items){
if(fileItem.isFormField()){
//Text field processing
String filedName=fileItem.getFieldName();
System.out.println(filedName);
String value=fileItem.getString();
String str=new String(value.getBytes(Charset.forName("ISO-8859-1")),"UTF-8");
if("userName".equals(filedName)){
System.out.println("userName=="+str);
userInfo.setUserName(str);
}else if ("password".equals(filedName)) {
System.out.println("password=="+str);
userInfo.setPassword(str);
}
}else {
//Document processing
//Prevent exceptions when files are not uploaded
if(fileItem.getName()!=null&&fileItem.getName().trim().length()>3){
String fileName=fileItem.getName().toLowerCase();//Convert file names to lowercase
int beginIndex=fileName.lastIndexOf(".");
if(beginIndex!=-1){
System.out.println(beginIndex);
String fileType=fileName.substring(beginIndex);
System.out.println("fileType"+fileType);
//When the server renames, the UUID algorithm is used to generate a random file name, which is used to rename and upload the file
String randomFileName=UUID.randomUUID().toString().toLowerCase()+fileType;
System.out.println("randomFileName:"+randomFileName);
File uploadFile=new File(basePath+"/"+subPath,randomFileName);
System.out.println("uploadFile"+uploadFile.getAbsolutePath());
fileItem.write(uploadFile);//Perform upload
userInfo.setUserHead("uploads/"+subPath+"/"+randomFileName);
System.out.println("Relative path: "+userInfo.getUserHead());
fileItem.delete();//File uploaded successfully, delete temporary file
//This example passes the data to the success page for saving
request.getSession().setAttribute("userInfo", userInfo);
//3. Save or process the uploaded path
response.sendRedirect("success.jsp");
}
}else {
response.sendRedirect("Upload.jsp");
}
}
}
} catch (FileUploadException e) {
// TODO Auto-generated catch block
e.printStackTrace();Effect demonstration:
File read read through EL expression
Head image: < img SRC = "${userinfo. Userhead}" width = "100px" > when setting the picture size, you cannot set the width and height at the same time, otherwise it will be distorted