JavaWeb实现文件上传功能

文件上传需要2个包：

commons-io：下载

commons-fileupload：下载

前端的jsp页面

注意：文件上传的type=file 是以表单的显示进行提交的必须要有这句

enctype="multipart/form-data"

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10 <form action="register.do" enctype="multipart/form-data" method="post">
11 <input type="file" name="pic"/>//文件上传框
12 <input type="submit"/>//提交按钮 
13 </form>
14 </body>
15 </html>

写一个serlvet servlert需要与前台表单提交的地址一致

 1 package com.it;
 2 
 3 import java.io.File;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 import java.io.InputStream;
 7 import java.util.Date;
 8 import java.util.List;
 9 
10 import javax.servlet.ServletException;
11 import javax.servlet.annotation.WebServlet;
12 import javax.servlet.http.HttpServlet;
13 import javax.servlet.http.HttpServletRequest;
14 import javax.servlet.http.HttpServletResponse;
15 
16 import org.apache.commons.fileupload.FileItem;
17 import org.apache.commons.fileupload.FileUploadException;
18 import org.apache.commons.fileupload.disk.DiskFileItemFactory;
19 import org.apache.commons.fileupload.servlet.ServletFileUpload;
20 
21 
22 @WebServlet("/register.do")
23 public class RegisterServlet extends HttpServlet {
24     private static final long serialVersionUID = 1L;
25     
26     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
27         //1
28         DiskFileItemFactory factory=new DiskFileItemFactory();
29         //2
30         ServletFileUpload upload=new ServletFileUpload(factory);
31         //利用文件
32         try {
33             List<FileItem> list=upload.parseRequest(request);
34             for(FileItem fi:list){
35                 //如果是普通
36                 if(fi.isFormField()){
37                     System.out.println(fi.getFieldName()+" "+fi.getString("UTF-8"));
38                 }else{
39                     //判断图片的类型
40                     if(fi.getName().endsWith(".jpg") || fi.getName().endsWith(".png")) {
41                         long ti=new Date().getTime();
42                         int wz=fi.getName().lastIndexOf(".");
43                         String pricn=fi.getName().substring(wz+1);
44                         System.out.println("后缀名："+pricn);
45                         String pna=ti+"."+pricn;//图片名字设置时间戳
46                         System.out.println("图片名："+pna);
47                         InputStream in=fi.getInputStream();
48                         File f=new File("D:/pictures/test/"+pna);//输出的位置
49                         FileOutputStream out=new FileOutputStream(f);
50                         byte[] b= new byte[1024];
51                         int len;
52                         while((len=in.read(b))>-1){
53                             out.write(b,0,len);
54                         }
55                         out.close();
56                         in.close();
57                     }else {
58                         System.out.println("文件传入错误！");
59                     }
60                 }
61             }
62         } catch (FileUploadException e) {
63             
64             e.printStackTrace();
65         }
66         
67     }
68 
69 
70     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
71         doGet(request, response);
72     }
73 
74 }