Java Web总结十八之二上传下载和数据库结合

1、up.sql

use mydb3;
drop table if exists up;
create table if not exists up(
 id int primary key auto_increment,
 username varchar(20) not null,
 realFileName varchar(40) not null,
 uuidFileName varchar(80) not null
);

2、UpDao.java

package com.gnnuit.web.updownload.dao;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;

import com.gnnuit.web.updownload.domain.Up;
import com.gnnuit.web.updownload.util.JdbcUtil;


public class UpDao {
    // 增加Up对象
    public void addUp(Up up) throws SQLException {
        QueryRunner runner = new QueryRunner();
        String sql = "insert into up(username,realFileName,uuidFileName) values(?,?,?)";
        runner.update(
                JdbcUtil.getMySqlConnection(),
                sql,
                new Object[] { up.getUsername(), up.getRealFileName(),
                        up.getUuidFileName() });
    }

    // 查询所有的Up对象
    public List<Up> findAllUp() throws SQLException {
        List<Up> upList = new ArrayList<Up>();
        QueryRunner runner = new QueryRunner(JdbcUtil.getDataSource());
        String sql = "select * from up";
        upList = (List<Up>) runner
                .query(sql, new BeanListHandler<Up>(Up.class));
        return upList;
    }

    // 根据UUID文件名查询唯一的Up对象
    public Up findUpByUuidFileName(String uuidFileName) throws SQLException {
        Up up = null;
        QueryRunner runner = new QueryRunner(JdbcUtil.getDataSource());
        String sql = "select * from up where uuidFileName = ?";
        up = (Up) runner
                .query(sql, new BeanHandler<Up>(Up.class), uuidFileName);
        return up;
    }
}

3、Up.java

package com.gnnuit.web.updownload.domain;

public class Up {
    private int id;
    private String username;
    private String realFileName;
    private String uuidFileName;

    public Up() {
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getRealFileName() {
        return realFileName;
    }

    public void setRealFileName(String realFileName) {
        this.realFileName = realFileName;
    }

    public String getUuidFileName() {
        return uuidFileName;
    }

    public void setUuidFileName(String uuidFileName) {
        this.uuidFileName = uuidFileName;
    }
}

4、User.java

package com.gnnuit.web.updownload.domain;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.fileupload.FileItem;

//封装上传文件的内容
public class User {
    // 上传用户
    private String username;
    // 上传的文件
    private List<FileItem> upfileList = new ArrayList<FileItem>();

    public User() {
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public List<FileItem> getUpfileList() {
        return upfileList;
    }

    public void setUpfileList(List<FileItem> upfileList) {
        this.upfileList = upfileList;
    }
}

5、JdbcUtil.java

package com.gnnuit.web.updownload.util;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import com.mchange.v2.c3p0.ComboPooledDataSource;

//JDBC工具类：关闭流和取得连接
public final class JdbcUtil {
    private static ComboPooledDataSource dataSource;
    private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
    static {
        dataSource = new ComboPooledDataSource();
    }

    // 取得数据源
    public static ComboPooledDataSource getDataSource() {
        return dataSource;
    }

    // 取得连接
    public static Connection getMySqlConnection() throws SQLException {
        Connection conn = tl.get();
        if (conn == null) {
            conn = dataSource.getConnection();
            tl.set(conn);
        }
        return conn;
    }

    // 关闭连接
    public static void close(Connection conn) throws SQLException {
        if (conn != null) {
            conn.close();
        }
    }

    public static void close(PreparedStatement pstmt) throws SQLException {
        if (pstmt != null) {
            pstmt.close();
        }
    }

    public static void close(ResultSet rs) throws SQLException {
        if (rs != null) {
            rs.close();
        }
    }

    public static void begin() throws SQLException {
        Connection conn = getMySqlConnection();
        conn.setAutoCommit(false);
    }

    public static void commit() throws SQLException {
        Connection conn = getMySqlConnection();
        conn.commit();
    }

    public static void rollback() throws SQLException {
        Connection conn = getMySqlConnection();
        conn.rollback();
    }

    public static void closeConnection() throws SQLException {
        Connection conn = getMySqlConnection();
        close(conn);
        tl.remove();
    }
}

6、UploadUtil.java

package com.gnnuit.web.updownload.util;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;
import java.util.UUID;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import com.gnnuit.web.exception.NoUpfileException;
import com.gnnuit.web.updownload.domain.Up;
import com.gnnuit.web.updownload.domain.User;

public final class UploadUtil {

    // 取得上传使用的临时和真实目录
    public static final String tempPath = "/WEB-INF/temp";
    public static final String uploadPath = "/WEB-INF/upload";

    // 取得真实文件名
    public static String getRealFileName(String realFileName) {
        int index = realFileName.lastIndexOf("\\");
        if (index >= 0) {
            // IE6浏览器
            realFileName = realFileName.substring(index + 1);
        }
        return realFileName;
    }

    // 取得upload/目录下的分散目录
    public static String makeUuidFilePath(String uploadPath, String uuidFileName) {
        String uuidFilePath = null;
        int code = uuidFileName.hashCode();// 8
        int dir1 = code & 0xF;// 3
        int dir2 = code >> 4 & 0xF;// A
        File file = new File(uploadPath + "/" + dir1 + "/" + dir2);
        // 如果该目录未存在
        if (!file.exists()) {
            // 一次性创建N层目录
            file.mkdirs();
        }
        uuidFilePath = file.getPath();
        return uuidFilePath;
    }

    // 取得uuid文件名
    public static String makeUuidFileName(String realFileName) {
        return UUID.randomUUID().toString() + "_" + realFileName;
    }

    // 文件复制
    public static void doSave(InputStream is, String uuidFileName,
            String uuidFilePath) {
        OutputStream os = null;
        try {
            os = new FileOutputStream(uuidFilePath + "/" + uuidFileName);
            byte[] buf = new byte[1024];
            int len = 0;
            while ((len = is.read(buf)) > 0) {
                os.write(buf, 0, len);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (os != null) {
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    // 将上传文件封装成JavaBean对象中
    public static User doUpload(HttpServletRequest request, List<Up> upList)
            throws Exception {
        User user = new User();
        // 创建上传文件工厂
        DiskFileItemFactory factory = new DiskFileItemFactory();
        // 设置内存中缓存区的大小，默认10K
        factory.setSizeThreshold(100 * 1024);
        // 设置上传文件临时存放的目录
        String tempPath = request.getSession().getServletContext()
                .getRealPath(UploadUtil.tempPath);
        factory.setRepository(new File(tempPath));
        // 创建上传文件对象[核心]
        ServletFileUpload upload = new ServletFileUpload(factory);
        // 设置上传文件的中文编码方式
        upload.setHeaderEncoding("UTF-8");
        // 客户端上传文件是否使用MIME协议，
        boolean flag = ServletFileUpload.isMultipartContent(request);
        if (!flag) {
            // 不是以MIME协议上传文件
            throw new ServletException();
        } else {
            /*
             * 是以MIME协议上传的文件，解析request中的所有上传内容每个内容封装成一个对象FileItem，
             * FileItem代表普通字段和上传字段二类
             */
            List<FileItem> fileItemList = upload.parseRequest(request);
            for (FileItem fileItem : fileItemList) {
                if (fileItem.isFormField()) {
                    // 必定是普通字段
                    String fieldName = fileItem.getFieldName();
                    String fieldValue = fileItem.getString("UTF-8");
                    user.setUsername(fieldValue);
                } else {
                    // 必定是上传字段

                    // 如果无上传文件
                    if (fileItem.getSize() == 0) {
                        throw new NoUpfileException();
                    }

                    String realFileName = UploadUtil.getRealFileName(fileItem
                            .getName());

                    /*
                     * 只能上传JPG文件 if(!realFileName.endsWith("JPG")){ throw new
                     * UpfileTypeException(); }
                     */

                    /*
                     * 只有上传<=200K的文件 if(fileItem.getSize() > 200 * 1024){ throw
                     * new UpfileSizeException(); }
                     */

                    // 封装到JavaBean
                    user.getUpfileList().add(fileItem);

                    // 封装N个Up对象
                    Up up = new Up();
                    up.setRealFileName(realFileName);
                    up.setUuidFileName(UploadUtil
                            .makeUuidFileName(realFileName));
                    up.setUsername(user.getUsername());
                    upList.add(up);

                }
            }// end of for loop
        }
        return user;
    }

    public static void doSave(User user, String uploadPath, List<Up> upList)
            throws Exception {
        // 取得该用户上传的所有文件集合
        List<FileItem> fileItemList = user.getUpfileList();
        // 迭代每个文件，并上传
        int index = 0;
        for (FileItem fileItem : fileItemList) {
            // 取得输入流
            InputStream is = fileItem.getInputStream();
            // 取得真实文件名
            String realFileName = fileItem.getName();
            realFileName = UploadUtil.getRealFileName(realFileName);
            // 取得UUID文件名
            // String uuidFileName = UploadUtil.makeUuidFileName(realFileName);
            String uuidFileName = upList.get(index).getUuidFileName();
            // 取得UUID文件路径
            String uuidFilePath = UploadUtil.makeUuidFilePath(uploadPath,
                    uuidFileName);
            // 保存
            UploadUtil.doSave(is, uuidFileName, uuidFilePath);
            // 删除临时文件
            fileItem.delete();
            index++;
        }

    }
}

7、UpService.java

package com.gnnuit.web.updownload.service;

import java.sql.SQLException;
import java.util.List;

import com.gnnuit.web.updownload.dao.UpDao;
import com.gnnuit.web.updownload.domain.Up;

public class UpService {
    private UpDao upDao = new UpDao();

    public void addUps(List<Up> upList) throws Exception {
        for (Up up : upList) {
            try {
                upDao.addUp(up);
            } catch (SQLException e) {
                e.printStackTrace();
                throw new Exception();
            }
        }
    }

    public List<Up> findAllUp() throws Exception {
        try {
            return upDao.findAllUp();
        } catch (SQLException e) {
            e.printStackTrace();
            throw new Exception();
        }
    }

    public Up findUpByUuidFileName(String uuidFileName) throws Exception {
        try {
            return upDao.findUpByUuidFileName(uuidFileName);
        } catch (SQLException e) {
            e.printStackTrace();
            throw new Exception();
        }
    }
}

8、UploadServlet.java

package com.gnnuit.web.updownload.upload;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.gnnuit.web.updownload.domain.Up;
import com.gnnuit.web.updownload.domain.User;
import com.gnnuit.web.updownload.exception.NoUpfileException;
import com.gnnuit.web.updownload.exception.UpfileSizeException;
import com.gnnuit.web.updownload.exception.UpfileTypeException;
import com.gnnuit.web.updownload.service.UpService;
import com.gnnuit.web.updownload.util.JdbcUtil;
import com.gnnuit.web.updownload.util.UploadUtil;

public class UploadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        try {

            String uploadPath = this.getServletContext().getRealPath(
                    UploadUtil.uploadPath);
            List<Up> upList = new ArrayList<Up>();
            User user = UploadUtil.doUpload(request, upList);

            // 事务开始
            JdbcUtil.begin();

            // 写入表
            UpService upService = new UpService();
            upService.addUps(upList);

            // int i = 10/0;

            // 写入硬盘
            UploadUtil.doSave(user, uploadPath, upList);

            // 事务提交
            JdbcUtil.commit();

            request.setAttribute("message", "上传文件成功");
            request.getRequestDispatcher("/WEB-INF/message.jsp").forward(
                    request, response);
        } catch (UpfileSizeException e) {
            e.printStackTrace();
            request.setAttribute("message",
                    "<font color='green'>上传文件大小限制在200K以内</font>");
            request.getRequestDispatcher("/WEB-INF/message.jsp").forward(
                    request, response);
        } catch (UpfileTypeException e) {
            e.printStackTrace();
            request.setAttribute("message",
                    "<font color='red'>只能上传JPG格式的文件</font>");
            request.getRequestDispatcher("/WEB-INF/message.jsp").forward(
                    request, response);
        } catch (NoUpfileException e) {
            e.printStackTrace();
            request.setAttribute("message", "<font color='blue'>无上传文件</font>");
            request.getRequestDispatcher("/WEB-INF/message.jsp").forward(
                    request, response);
        } catch (Exception e) {
            // 事务回滚
            try {
                JdbcUtil.rollback();
                JdbcUtil.commit();
            } catch (Exception e1) {
                e1.printStackTrace();
            }
            // 事务提交
            e.printStackTrace();
            request.setAttribute("message", "上传文件失败");
            request.getRequestDispatcher("/WEB-INF/message.jsp").forward(
                    request, response);
        } finally {
            // 关闭Connection对象，并分离线程
            try {
                JdbcUtil.closeConnection();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

9、DownloadServlet.java

package com.gnnuit.web.updownload.download;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.gnnuit.web.updownload.domain.Up;
import com.gnnuit.web.updownload.service.UpService;
import com.gnnuit.web.util.UploadUtil;

//下载文件到本地[DB版]
public class DownloadServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        // 取得uuid文件名并进行URL解码
        String uuidFileName = request.getParameter("uuidFileName");
        byte[] buf = uuidFileName.getBytes("ISO8859-1");
        uuidFileName = new String(buf, "UTF-8");

        try {
            // 根据UUID文件名查询Up对象
            UpService upService = new UpService();
            Up up = upService.findUpByUuidFileName(uuidFileName);

            // 向浏览器输出以下载方式打开文件
            response.setHeader("content-disposition", "attachment;filename="
                    + URLEncoder.encode(up.getRealFileName(), "UTF-8"));

            // 真正下载
            String uploadPath = this.getServletContext().getRealPath(
                    UploadUtil.uploadPath);
            String uuidFilePath = UploadUtil.makeUuidFilePath(uploadPath,
                    uuidFileName);
            InputStream is = new FileInputStream(uuidFilePath + "/"
                    + uuidFileName);
            OutputStream os = response.getOutputStream();
            int len = 0;
            buf = new byte[1024];
            while ((len = is.read(buf)) > 0) {
                os.write(buf, 0, len);
            }
            is.close();
            os.close();
        } catch (Exception e) {
            e.printStackTrace();
            request.setAttribute("message", "下载文件失败");
            request.getRequestDispatcher("/WEB-INF/message.jsp").forward(
                    request, response);
        }
    }
}

10、ListFileServlet.java

package com.gnnuit.web.updownload.download;

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 com.gnnuit.web.updownload.domain.Up;
import com.gnnuit.web.updownload.service.UpService;

//显示可供下载的文件列表[DB版]
public class ListFileServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        try {
            UpService upService = new UpService();
            List<Up> upList = upService.findAllUp();
            request.setAttribute("upList", upList);
            request.getRequestDispatcher("/WEB-INF/list.jsp").forward(request,
                    response);
        } catch (Exception e) {
            e.printStackTrace();
            request.setAttribute("message", "显示可供下载文件失败");
            request.getRequestDispatcher("/WEB-INF/message.jsp").forward(
                    request, response);
        }
    }
}

11、NoUpfileException.java

package com.gnnuit.web.updownload.exception;

public class NoUpfileException extends Exception {

    private static final long serialVersionUID = 1L;

}

12、UpfileSizeException.java

package com.gnnuit.web.updownload.exception;

public class UpfileSizeException extends Exception {

    private static final long serialVersionUID = 1L;

}

13、UpfileTypeException.java

package com.gnnuit.web.updownload.exception;

public class UpfileTypeException extends Exception {

    private static final long serialVersionUID = 1L;

}

14、c3p0-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="user">root</property>
        <property name="password">root</property>
        <property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/mydb3</property>
    </default-config>
</c3p0-config>

15、upload.jsp

<%@ page language="java" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
      <script type="text/javascript">
          //全局变量
          var time = 0;
          function addLine(addButton){
              //创建内部div对象
              var divElement = document.createElement("div");
              //创建input对象[file类型]
              var inputElement1 = document.createElement("input");
              inputElement1.type="file";
              inputElement1.name="upfile";
              //创建input对象[button类型]
              var inputElement2 = document.createElement("input");
              inputElement2.type="button";
              inputElement2.value="删除";
              //对删除按钮添加事件监听
              inputElement2.onclick=function(){
                  //取得该按钮所在行的直接父元素
                  var divElement = this.parentNode.parentNode;
                  //通过父元素删除直接子元素
                  divElement.removeChild(this.parentNode);
                  time--;
                  if(time < 5){
                      //按钮生效
                      addButton.disabled=false;
                      //addButton.style.visibility="visible";
                  }
              };
              //依次将file类型和button类型的input对象加入到内部div对象中
              divElement.appendChild(inputElement1);
              divElement.appendChild(inputElement2);
              //再次内部div对象加入到外部div对象
              var outDivElement = document.getElementById("outDiv");
              outDivElement.appendChild(divElement);
              time++;
              if(time == 5){
                  //将按钮失效
                  addButton.disabled=true;
                  //addButton.style.visibility="hidden";
              }    
          }
      </script>
  </head>
  <body>
      <form 
          action="${pageContext.request.contextPath}/UploadServlet" 
          method="POST"
          enctype="multipart/form-data">
          <table border="1" align="center">
              <caption>文件上传</caption>
              <tr>
                  <th>上传用户</th>
                  <td><input type="text" name="username"/></td>
              </tr>
              <tr>
                  <th></th>
                  <td>
                      <div id="outDiv">
                          <%--
                          <div>
                            <input type="file" name="upfile"/>
                            <input type="button" value="删除"/>                              
                          </div>
                          --%>
                      </div>
                  </td>
              </tr>
              <tr>
                  <th></th>
                  <td>
                      <input 
                          type="button" 
                          value="添加上传文件"
                          onclick="addLine(this)"
                      />
                  </td>
              </tr>
              <tr>
                  <td colspan="2" align="center">
                      <input type="submit" value="上传"/>
                      <a href="${pageContext.request.contextPath}/ListFileServlet">
                          显示下载文件
                      </a>
                  </td>
              </tr>
          </table>
      </form>
  </body>
</html>

16、download.jsp

<%@ 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>
  
  <body>
    <table align="center" border="1">
        <tr>
            <th>文件列表</th>
            <th>操作</th>
        </tr>
        <c:forEach var="entry" items="${map }">
            <tr>
                <td>${entry.value }</td>
                <td>
                    <c:url var="myURL" value="/DownLoadServlet">
                        <c:param name="fileName" value="${entry.key }"></c:param>
                    </c:url>
                    <a href="${myURL }" >下载</a>
                </td>
            </tr>
        </c:forEach>
    </table>
  </body>
</html>

17、list.jsp

<%@ page language="java" 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>
  <body>
      <table border="1" align="center">
          <caption>下载文件列表</caption>
          <tr>
              <th>文件名</th>
              <th>操作</th>
          </tr>
          <c:forEach var="up" items="${requestScope.upList}">
              <tr>
                  <td>${up.realFileName}</td>    
                  <td>
                      <c:url var="myURL" value="/DownloadServlet">
                          <c:param name="uuidFileName" value="${up.uuidFileName}"/>
                      </c:url>
                      <a  href="${myURL}" 
                          style="text-decoration:none">
                          下载
                      </a>
                  </td>
              </tr>
          </c:forEach>
      </table>
  </body>
</html>

18、message.jsp

<%@ page language="java" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <body>
      ${message}<br/>
      <a href="${pageContext.request.contextPath}/upload.jsp">
          返回
      </a>
  </body>
</html>

19、web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    id="WebApp_ID" version="3.0">
    <display-name>day18</display-name>
    <servlet>
        <servlet-name>Upload</servlet-name>
        <servlet-class>com.gnnuit.web.servlet.upload.Upload</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>Upload</servlet-name>
        <url-pattern>/Upload</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>UploadServlet</servlet-name>
        <servlet-class>com.gnnuit.web.updownload.upload.UploadServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>ListFileServlet</servlet-name>
        <servlet-class>com.gnnuit.web.updownload.download.ListFileServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>DownloadServlet</servlet-name>
        <servlet-class>com.gnnuit.web.updownload.download.DownloadServlet</servlet-class>
    </servlet>



    <servlet-mapping>
        <servlet-name>UploadServlet</servlet-name>
        <url-pattern>/UploadServlet</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>ListFileServlet</servlet-name>
        <url-pattern>/ListFileServlet</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>DownloadServlet</servlet-name>
        <url-pattern>/DownloadServlet</url-pattern>
    </servlet-mapping>

    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>
</web-app>