9-文件上传和下载
apache commons类库jar包
一。文件上传
1.导入jar文件：commons-fileupload1.3.3.jar,commons-io.2.5.jar
2.页面：
<form action="upload" method="post" enctype="multipart/form-data">
<input type="file" name="files"><br>
<input type="text" name="miaoshu"><br>
<input type="submit" value="提交">
</form>
注意：form的method必须为post，form必须要有enctype="multipart/form-data"
input type=“file” 必须要有name属性，名字可以自定义
3.后台程序部分：
4.要在项目中创建一个文件夹来存放上传后的文件，在webcontent目录下创建upload
5.上传后的文件的路径，位于
D:\javaTools\eclipse\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\StudentManager\upload
实例1：
upload.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <base href="<%=basePath%>"/> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <form action="upload" method="post" enctype="multipart/form-data"> <input type="file" name="files"><br> <input type="text" name="miaoshu"><br> <input type="submit" value="提交"> </form> </body> ${mess} </html>
FileupLoadServlet.java
package com.control; import java.io.File; import java.io.IOException; import java.util.List; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; 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.FileItemFactory; import org.apache.commons.fileupload.FileUploadException; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; @WebServlet("/upload") public class FileupLoadServlet extends HttpServlet { @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { try { //创建一个请求解析工厂 FileItemFactory factory = new DiskFileItemFactory(); //根据解析工厂创建一个文件上传对象 ServletFileUpload upload = new ServletFileUpload(factory); //设置上传文件的总大小 4m upload.setSizeMax(4194304); //上传对象去解析请求，将请求中的所有表单元素全部打包成一个集合，文件和非文件都会打包进来 List<FileItem> files = upload.parseRequest(req); //获取项目中文件夹的绝对路径,用来存放上传的文件 String realPath = getServletContext().getRealPath("upload"); if(files!=null){ for (FileItem fi : files) { //fi.isFormField()判断该参数是不是一个普通的表单元素 if(fi.isFormField()){//是一个普通元素 //解决中文乱码问题 //fi.getFieldName() 获取表单的元素名 //fi.getString() 获取表单元素的值 System.out.println("name="+fi.getFieldName()+",value="+new String(fi.getString().getBytes("iso-8859-1"),"utf-8")); }else{//是一个文件 //构造客户端完整路径的文件对象，目的是为了获取该文件的文件名 File fullFile = new File(fi.getName()); //根据服务器的路径和文件名老构造要保存到服务器的文件对象 File savedFile = new File(realPath, fullFile.getName()); //将文件写入 fi.write(savedFile); } } } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } req.setAttribute("mess", "<script>alert('上传成功！')</script>"); req.getRequestDispatcher("upload.jsp").forward(req, resp); } }
实例2：
load.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE html> <html> <head> <base href="<%=basePath%>"/> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <a href="down">下载</a> </body> </html>
FileDownLoadServlet.java
package com.control; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.net.URLEncoder; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet("/down") public class FileDownLoadServlet extends HttpServlet{ @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //处理请求 //读取要下载的文件 File f = new File("d:/JavaEE课程体系.xlsx"); if(f.exists()){ FileInputStream fis = new FileInputStream(f); String filename=URLEncoder.encode(f.getName(),"utf-8"); //解决中文文件名下载后乱码的问题 byte[] b = new byte[fis.available()]; fis.read(b); resp.setCharacterEncoding("utf-8"); resp.setHeader("Content-Disposition","attachment; filename="+filename+""); //获取响应报文输出流对象 ServletOutputStream out =resp.getOutputStream(); //输出 out.write(b); out.flush(); out.close(); } } }
