1. 编写文件上传Servlet
1 public class FileUpload1 extends HttpServlet {
2 @Override
3 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
4
5 InputStream in = null;
6 OutputStream out = null;
7
8 // 获取上传文件目录
9 String savePath = this.getServletContext().getRealPath("/WEB-INF/upload");
10
11 try {
12 // 使用默认配置创建解析器工厂
13 DiskFileItemFactory factory = new DiskFileItemFactory();
14 // 获取解析器
15 ServletFileUpload upload = new ServletFileUpload(factory);
16 upload.setProgressListener(new ProgressListener() {
17 @Override
18 public void update(long l, long l1, int i) {
19 System.out.println("文件大小为：" + l1 + ",当前已处理：" + l);
20 }
21 });
22 // 解决上传文件名的中文乱码问题
23 upload.setHeaderEncoding("UTF-8");
24 // 上传表单是否为multipart/form-data类型
25 if (!upload.isMultipartContent(request)) {
26 return;
27 }
28 // 解析request的输入流
29 List<FileItem> fileItemList = upload.parseRequest(request);
30 // 迭代list集合
31 for (FileItem fileItem : fileItemList) {
32 if (fileItem.isFormField()) {
33 // 普通字段
34 String name = fileItem.getFieldName();
35 // 调用getString重载方法, 解决上传数据的中文乱码问题
36 String value = fileItem.getString("UTF-8");
37 System.out.println(name + "=" + value);
38 } else {
39 // 上传文件
40 // 获取上传文件名
41 String fileName = fileItem.getName();
42 // input:file没有指定上传文件时, 结束本次循环并继续下一次循环
43 if(fileName == null && fileName.trim().equals("")) {
44 continue;
45 }
46 fileName = fileName.substring(fileName.lastIndexOf("\\")+1);
47 // 使用UUID作为上传文件的名称
48 fileName = makeFileName(fileName);
49 // 获取输入流
50 in = fileItem.getInputStream();
51
52 // 上传文件名若不存在, 则先创建
53 File savePathDir = new File(savePath);
54 if (!savePathDir.exists()) {
55 savePathDir.mkdir();
56 }
57
58 // 使用hash算法产生当前上传图片的随机目录
59 String currentFileSavePath = makePath(savePath, fileName);
60
61 // 获取输出流
62 out = new FileOutputStream(currentFileSavePath + "\\" + fileName);
63 int len = 0;
64 byte[] buffer = new byte[1024];
65 while((len=in.read(buffer)) > 0) {
66 out.write(buffer, 0, len);
67 }
68 }
69 }
70 } catch (Exception e) {
71 e.printStackTrace();
72 } finally {
73 if (in != null) {
74 in.close();
75 }
76 if (out != null) {
77 out.close();
78 }
79 }
80
81 }
82 public String makeFileName(String fileName) {
83 return UUID.randomUUID().toString() + "_" + fileName;
84 }
85 public String makePath(String savePath, String fileName) {
86 // 根据文件名产生int型hashcode, 32位二进制
87 int hashcode = fileName.hashCode();
88 // 获取第4位 0-15
89 int dir1 = hashcode&0xf;
90 // 获取第5-8位 0-15
91 int dir2 = (hashcode&0xf0)>>4;
92 // 凭借随机目录
93 String dir = savePath + "\\" + dir1 + "\\" + dir2; // upload\2\4
94 // 若目录不存在时, 创建目录
95 File file = new File(dir);
96 if(!file.exists()) {
97 file.mkdirs();
98 }
99 return dir;
100 }
101
102 @Override
103 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
104 doGet(req, resp);
105 }
106 }
2. 编写获取所有下载文件名称Servlet
1 /**
2 * Created by IntelliJ IDEA.
3 *
4 * @Auther: ShaoHsiung
5 * @Date: 2018/8/26 16:26
6 * @Title:
7 * @Description: 列出网站所有下载文件
8 */
9 public class ListFileServlet extends HttpServlet {
10 @Override
11 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
12
13 // 获取下载目录路径
14 String filePath = this.getServletContext().getRealPath("/WEB-INF/upload");
15 // 创建存储文件下载路径的Map集合
16 Map filePathMap = new HashMap();
17 // 将下载目录中所有文件名称存储到Map集合中
18 listFile(new File(filePath), filePathMap);
19 // 存储数据后跳转
20 request.setAttribute("map", filePathMap);
21 request.getRequestDispatcher("/listfile.jsp").forward(request, response);
22 }
23
24 /**
25 * 将下载目录中所有文件名称存储到Map集合中
26 * @param file 下载目录
27 * @param filePathMap Map集合
28 */
29 private void listFile(File file, Map filePathMap) {
30 if(!file.isFile()) {
31 // 文件为目录时
32 File[] files = file.listFiles();
33 for (File f : files) {
34 // 递归调用
35 listFile(f, filePathMap);
36 }
37 } else {
38 // 9349249849-88343-8344_阿_凡_达.avi 处理结果为: 阿_凡_达.avi
39 String realName = file.getName().substring(file.getName().indexOf("_")+1);
40 // 9349249849-88343-8344_阿_凡_达.avi -> 阿_凡_达.avi
41 filePathMap.put(file.getName(), realName);
42 }
43 }
44
45 @Override
46 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
47 doGet(req, resp);
48 }
49 }
3. 处理文件下载请求Servlet
1 public class FileDownload extends HttpServlet {
2 @Override
3 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
4
5 // 获取下载文件名称的key
6 String filename = request.getParameter("filename"); //23239283-92489-dfsd_阿凡达.avi
7 // 解决get请求的中文乱码问题
8 filename = new String(filename.getBytes("iso8859-1"),"UTF-8");
9 // 获取下载目录
10 String path = makePath(filename,this.getServletContext().getRealPath("/WEB-INF/upload"));
11 // 获取下载文件
12 File file = new File(path + "\\" + filename);
13 // 下载文件不存在时
14 if(!file.exists()){
15 request.setAttribute("message", "您要下载的资源已被删除！！");
16 request.getRequestDispatcher("/message.jsp").forward(request, response);
17 return;
18 }
19 // 获取下载文件名称 阿凡达.avi
20 String realname = filename.substring(filename.indexOf("_") + 1);
21 // 通知浏览器以下载方式打开, 不同浏览器可能不同
22 response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(realname, "UTF-8"));
23 // 下载文件
24 FileInputStream in = new FileInputStream(path + "\\" + filename);
25 OutputStream out = response.getOutputStream();
26 byte buffer[] = new byte[1024];
27 int len = 0;
28 while((len=in.read(buffer))>0){
29 out.write(buffer, 0, len);
30 }
31 in.close();
32 out.close();
33
34 }
35
36 /**
37 * 根据文件名称产生随机目录并将下载路径与随机目录拼接
38 * @param filename 文件名称
39 * @param savePath 下载路径
40 * @return 下载路径与随机目录拼接结果
41 */
42 private String makePath(String filename,String savePath){
43
44 int hashcode = filename.hashCode();
45 int dir1 = hashcode&0xf; //0--15
46 int dir2 = (hashcode&0xf0)>>4; //0-15
47
48 String dir = savePath + "\\" + dir1 + "\\" + dir2; //upload\2\3 upload\3\5
49 File file = new File(dir);
50 if(!file.exists()){
51 file.mkdirs();
52 }
53 return dir;
54 }
55
56 @Override
57 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
58 doGet(req, resp);
59 }
60 }
4. 配置web.xml
1 <!-- 文件上传 --> 2 <servlet> 3 <servlet-name>FileUpload1</servlet-name> 4 <servlet-class>fileupload.FileUpload1</servlet-class> 5 </servlet> 6 <servlet-mapping> 7 <servlet-name>FileUpload1</servlet-name> 8 <url-pattern>/servlet/FileUpload1</url-pattern> 9 </servlet-mapping> 10 11 <!--文件下载--> 12 <servlet> 13 <servlet-name>ListFileServlet</servlet-name> 14 <servlet-class>fileupload.ListFileServlet</servlet-class> 15 </servlet> 16 <servlet-mapping> 17 <servlet-name>ListFileServlet</servlet-name> 18 <url-pattern>/servlet/ListFileServlet</url-pattern> 19 </servlet-mapping> 20 <servlet> 21 <servlet-name>FileDownload</servlet-name> 22 <servlet-class>fileupload.FileDownload</servlet-class> 23 </servlet> 24 <servlet-mapping> 25 <servlet-name>FileDownload</servlet-name> 26 <url-pattern>/servlet/FileDownload</url-pattern> 27 </servlet-mapping>
5. 编写获取文件名称JSP
1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
2 <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
3
4 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
5 <html>
6 <head>
7 <title>My JSP ‘listfile.jsp‘ starting page</title>
8 </head>
9
10 <body>
11
12 <c:forEach var="me" items="${map}">
13 <c:url value="/servlet/FileDownload" var="downurl">
14 <c:param name="filename" value="${me.key}"></c:param>
15 </c:url>
16 ${me.value } <a href="${downurl}">下载</a> <br/>
17 </c:forEach>
18
19 </body>
20 </html>
6. 编写文件上传JSP
1 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
2 <html>
3 <head>
4 <title>演示文件上传</title>
5 </head>
6 <body>
7 <form action="${pageContext.request.contextPath}/servlet/FileUpload1" method="post" enctype="multipart/form-data">
8 用户名: <input type="text" name="username"/><br/>
9 文件1: <input type="file" name="file1"/><br/>
10 文件2: <input type="file" name="file1"/><br/>
11 <input type="submit"/>
12 </form>
13 </body>
14 </html>
7. 效果演示
在浏览器中访问http://localhost:8080/servlet/ListFileServlet
原文地址：https://www.cnblogs.com/shaohsiung/p/9537835.html
时间： 2024-08-29 04:09:29