文章目录

• 一、 实验目的：
• 二、实验要求：
• 三、实验内容：
• • 1、单文件上传
  • 2、多文件上传
  • 3、上传文件的大小限定
  • 4、实现文件的下载功能，并解决下载乱码问题

一、 实验目的：

掌握Servlet的HttpServletRequest对文件上传的支持；
能够理解文件上传的原理，掌握文件上传与下载的步骤

二、实验要求：

1. 基于Servlet的文件上传。
2. 文件的下载。
3. 熟练使用MYEclipse开发

三、实验内容：

1、单文件上传

uploadHttpOne.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java"  pageEncoding="utf-8"%>





文件描述：
请选择文件：

UploadHttpOneServlst.java

package servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;@MultipartConfig(maxFileSize = 10 * 1024 * 1024)
@WebServlet("/uploadHttpOneServlst")
public class UploadHttpOneServlst extends HttpServlet {private static final long serialVersionUID = 1L;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();request.setCharacterEncoding("UTF-8");Part part = request.getPart("resPath");String filediscription = request.getParameter("filediscription");out.println("输入的文件描述：" + filediscription + "
");File uploadFileDir = new File(getServletContext().getRealPath("/uploadFiles"));if (!uploadFileDir.exists()) {uploadFileDir.mkdir();}String oldName = MyUtil.getFileName(part);out.println("上传文件的原始名：" + oldName + "
");out.println("上传文件的大小：" + part.getSize() + "
");if (oldName != null) {part.write(uploadFileDir + File.separator + oldName);}out.println("文件上传到：" + uploadFileDir + File.separator + oldName + "
");}
}

MyUtil.java

package servlet;import javax.servlet.http.Part;public class MyUtil {public static String getFileName(Part part) {if (part == null)return null;String fileName = part.getHeader("content-disposition");if (fileName.lastIndexOf("=") + 2 == fileName.length() - 1)return null;return fileName.substring(fileName.lastIndexOf("=") + 2, fileName.length() - 1);}
}

运行结果：

2、多文件上传

UploadHttpMultiServlst.java

package servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Collection;@MultipartConfig
@WebServlet("/uploadHttpMultiServlst")
public class UploadHttpMultiServlst extends HttpServlet {private static final long serialVersionUID = 1L;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();request.setCharacterEncoding("UTF-8");String filediscription1 = request.getParameter("filediscription1");out.println("输入的文件1描述：" + filediscription1 + "
");String filediscription2 = request.getParameter("filediscription2");out.println("输入的文件2描述：" + filediscription2 + "
");File uploadFileDir = new File(getServletContext().getRealPath("/uploadFiles"));if (!uploadFileDir.exists()) {uploadFileDir.mkdir();}Collection parts = request.getParts();for (Part part : parts) {if (part == null || !part.getName().contains("resPat")) {continue;}String oldName = MyUtil.getFileName(part);out.println("上传文件的原始名：" + oldName + "
");out.println("上传文件的大小：" + part.getSize() + "
");if (oldName != null) {part.write(uploadFileDir + File.separator + oldName);}out.println("文件上传到：" + uploadFileDir + File.separator + oldName + "
");}}
}

MyUtil.java

package servlet;import javax.servlet.http.Part;public class MyUtil {public static String getFileName(Part part) {if (part == null)return null;String fileName = part.getHeader("content-disposition");if (fileName.lastIndexOf("=") + 2 == fileName.length() - 1)return null;return fileName.substring(fileName.lastIndexOf("=") + 2, fileName.length() - 1);}
}

UploadHttpMultiServlst.jsp

<%@ page contentType="text/html;charset=UTF-8" 
language="java" pageEncoding="utf-8" %>





文件1描述：
请选择文件1：
文件2描述：
请选择文件2：

运行结果：

3、上传文件的大小限定

对多文件上传实例文件大小进行限定！
仅仅在UploadHttpMultiServlst.Java中加上限制条件——@MultipartConfig(maxFileSize = 10 * 1024 * 1024)//设置上传文件的最大值为10MB,其他代码不用变！
UploadHttpMultiServlst.Java

package servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Collection;@MultipartConfig(maxFileSize = 10 * 1024 * 1024)//设置上传文件的最大值为10MB
@WebServlet("/uploadHttpMultiServlst")
public class UploadHttpMultiServlst extends HttpServlet {private static final long serialVersionUID = 1L;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();request.setCharacterEncoding("UTF-8");String filediscription1 = request.getParameter("filediscription1");out.println("输入的文件1描述：" + filediscription1 + "
");String filediscription2 = request.getParameter("filediscription2");out.println("输入的文件2描述：" + filediscription2 + "
");File uploadFileDir = new File(getServletContext().getRealPath("/uploadFiles"));if (!uploadFileDir.exists()) {uploadFileDir.mkdir();}Collection parts = request.getParts();for (Part part : parts) {if (part == null || !part.getName().contains("resPat")) {continue;}String oldName = MyUtil.getFileName(part);out.println("上传文件的原始名：" + oldName + "
");out.println("上传文件的大小：" + part.getSize() + "
");if (oldName != null) {part.write(uploadFileDir + File.separator + oldName);}out.println("文件上传到：" + uploadFileDir + File.separator + oldName + "
");}}
}

运行结果：
当其中一个文件大小大于10MB时，无法上传文件数据：



当文件小于10MB时，能够正常上传：

4、实现文件的下载功能，并解决下载乱码问题

实验代码和运行结果如下：
导包：
ShowDownServlet.java

package servlet;import javax.servlet.RequestDispatcher;
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 java.io.File;
import java.io.IOException;@WebServlet("/showDownServlet")
public class ShowDownServlet extends HttpServlet {private static final long serialVersionUID = 1L;protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request, response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//指定从服务器uploadFiles目录中下载文件File downLoadFileDir = new File(getServletContext().getRealPath("/uploadFiles"));//获得目录中的文件File[] list = downLoadFileDir.listFiles();request.setAttribute("fileList", list);RequestDispatcher dis = request.getRequestDispatcher("showInfo.jsp");dis.forward(request, response);}
}

MyUtil.java

package servlet;import javax.servlet.http.Part;
import java.io.UnsupportedEncodingException;public class MyUtil {public static String getFileName(Part part) {if (part == null)return null;String fileName = part.getHeader("content-disposition");if (fileName.lastIndexOf("=") + 2 == fileName.length() - 1)return null;return fileName.substring(fileName.lastIndexOf("=") + 2, fileName.length() - 1);}//处理乱码问题public static String toUTF8String(String str) {StringBuffer sb = new StringBuffer();int len = str.length();for (int i = 0; i < len; i++) {char c = str.charAt(i);if (c >= 0 && c <= 255) {sb.append(c);} else {byte b[];try {b = Character.toString(c).getBytes("UTF-8");} catch (UnsupportedEncodingException e) {e.printStackTrace();b = null;}for (int j = 0; j < b.length; j++) {int k = b[j];if (k < 0) {k &= 255;}sb.append("&" + Integer.toHexString(k).toUpperCase());}}}return sb.toString();}}

DownloadServlet.java

package servlet;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;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;@WebServlet("/downloadServlet")
public class DownloadServlet extends HttpServlet {private static final long serialVersionUID = 1L;protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {File downLoadFileDir = new File(getServletContext().getRealPath("/uploadFiles"));String aFileName = null;FileInputStream in = null;ServletOutputStream out = null;try {aFileName = request.getParameter("resPath");response.setHeader("Content-Type", "application/x-msdownload");response.setHeader("Content-Dissposition", "attachment;filename=" + MyUtil.toUTF8String(aFileName));in = new FileInputStream(downLoadFileDir + File.separator + aFileName);out = response.getOutputStream();out.flush();int aRead = 0;byte b[] = new byte[1024];while ((aRead = in.read(b)) != -1 & in != null) {out.write(b, 0, aRead);}out.flush();in.close();out.close();} catch (Throwable e) {e.printStackTrace();}}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}
}

showInfo.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" pageEncoding="utf-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>





文件名称
下载课件
${afile.name}
下载

运行结果：