上传下载在web项目中应该是很常见的需求,能够熟练敲出代码实现是web开发人员必不可少的
下面简化的上传:
jsp页面的实现:
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <%@ taglib uri = "http://java.sun.com/jsp/jstl/core" prefix = "c" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP 'uploadfile.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <form action="<c:url value = '/UploadServlet1' />" method="post" enctype="multipart/form-data" > 用户名:<input type = "text" name = "username"> 上传照片:<input type = "file" name = "photo"> <input type = "submit" value="提交"> </form> </body> </html>
package cn.Lionel.servlet; import java.io.File; import java.io.IOException; 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.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; public class UploadServlet1 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); //创建工厂 DiskFileItemFactory factory = new DiskFileItemFactory() ; //通过工厂创建解析器 ServletFileUpload upload = new ServletFileUpload(factory); try { List<FileItem> list = upload.parseRequest(request); FileItem item1 = list.get(0); FileItem item2 = list.get(1); System.out.println("普通表单项:"+item1.getName()+"="+item1.getString("utf-8")); System.out.println("文件表单项:"); System.out.println("Content-Type"+item2.getContentType()); System.out.println("filename="+item2.getName()); System.out.println("size = "+item2.getSize()); item2.write(new File("d:\\1.jpg")); } catch (Exception e) { throw new RuntimeException() ; } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
下面是设置了缓存文件夹+文件打散
jsp页面跟上面差不多:
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <%@ taglib uri = "http://java.sun.com/jsp/jstl/core" prefix = "c" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP 'uploadfile.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <h1>${msg }</h1> <form action="<c:url value = '/UploadServlet2' />" method="post" enctype="multipart/form-data" > 用户名:<input type = "text" name = "username"> 上传照片:<input type = "file" name = "photo"> <input type = "submit" value="提交"> </form> </body> </html>
package cn.Lionel.servlet; import java.io.File; import java.io.IOException; 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.FileUploadBase; import org.apache.commons.fileupload.FileUploadException; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; public class UploadServlet3 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); //设置缓冲区和临时目录 DiskFileItemFactory factory = new DiskFileItemFactory(100,new File("e:\\temp")); ServletFileUpload upload = new ServletFileUpload(factory); //限制上传的文件大小 //upload.setFileSizeMax(200*1024) ; //限制整个表单的大小:upload.setSizeMax(); try { List<FileItem> list = upload.parseRequest(request); FileItem item = list.get(1); String filename = item.getName(); //处理有些浏览器返回的文件名是绝对路径 int index = filename.lastIndexOf("\\") ; if(index != -1) { filename = filename.substring(index+1); } int hashCode = filename.hashCode(); //把hash值转换为十六进制 String hex = Integer.toHexString(hashCode); String realPath = this.getServletContext().getRealPath( "WEB-INF/files"); File dirFile = new File(realPath + "/" + hex.charAt(0) + "/" + hex.charAt(1)); //创建目录链 dirFile.mkdirs(); String savename = uuid()+"_"+filename; File destFile = new File(dirFile,savename); item.write(destFile); }catch (FileUploadException e) { if(e instanceof FileUploadBase.FileSizeLimitExceededException) { request.setAttribute("msg", "您上传的文件超出200KiB!") ; request.getRequestDispatcher("/uploadfile2.jsp").forward(request, response) ; return ; } } catch (Exception e) { throw new RuntimeException(); } } private String uuid() { return UUID.randomUUID().toString().replace("-", "").toUpperCase(); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
说完了上传,该说下载了:
该事先依赖commons.io组件,直接访问servlet实现下载。要下载的文件需要改你自己项目中存在的文件。
package cn.Lionel.servlet; import java.io.FileInputStream; import java.io.IOException; import java.net.URLEncoder; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.io.IOUtils; import sun.misc.BASE64Encoder; public class DownloadServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset = utf-8"); String filename = "E:\\KuGou\\可米小子 - 青春纪念册.mp3"; //改为自己项目中存在的文件 //这种方法对部分字符仍存在乱码! //String dname = new String("青春纪念册.mp3".getBytes("utf-8"), "iso-8859-1"); //这种方法最常用!解决文件名乱码 String dname = filenameEncoding("青春纪念册.mp3",request); String contentType = this.getServletContext().getMimeType(filename); String contentDisposition = "attachment;filename="+dname; response.setHeader("Content-Type", contentType + ""); response.setHeader("Content-Disposition", contentDisposition); FileInputStream input = new FileInputStream(filename); ServletOutputStream out = response.getOutputStream(); IOUtils.copy(input, out); input.close(); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } public static String filenameEncoding(String filename, HttpServletRequest request) throws IOException { String agent = request.getHeader("User-Agent"); //获取浏览器 if (agent.contains("Firefox")) { BASE64Encoder base64Encoder = new BASE64Encoder(); filename = "=?utf-8?B?" + base64Encoder.encode(filename.getBytes("utf-8")) + "?="; } else if(agent.contains("MSIE")) { filename = URLEncoder.encode(filename, "utf-8"); } else { filename = URLEncoder.encode(filename, "utf-8"); } return filename; } }
能力有限。写博客只为了防止自己忘记,方便查找,如有错误,还望指出