接着上一篇讲：

Jsp+Servlet实现文件上传下载（一）--文件上传 点击打开链接

本章来实现一下上传文件列表展示，同时优化了一下第一章中的代码。

废话少说，上代码

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mysql创建附件表

DROP TABLE tbl_accessory;

CREATE TABLE tbl_accessory
(
  id  INT AUTO_INCREMENT PRIMARY KEY,
  file_name VARCHAR(500),
  file_size DOUBLE(10,2),
  file_ext_name  VARCHAR(100),
  file_path  VARCHAR(2000)
)
;

SELECT * FROM tbl_accessory;

DELETE FROM tbl_accessory;

创建附件实体类

package entity.upload;

/**
 * 附件实体类
 *
 * @author xusucheng
 * @create 2017-12-29
 **/
public class EntityAccessory {
    private int id;
    private String fileName;
    private double fileSize;
    private String file_ext_name;
    private String filePath;

    public int getId() {
        return id;
    }

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

    public String getFileName() {
        return fileName;
    }

    public void setFileName(String fileName) {
        this.fileName = fileName;
    }

    public double getFileSize() {
        return fileSize;
    }

    public void setFileSize(double fileSize) {
        this.fileSize = fileSize;
    }

    public String getFile_ext_name() {
        return file_ext_name;
    }

    public void setFile_ext_name(String file_ext_name) {
        this.file_ext_name = file_ext_name;
    }

    public String getFilePath() {
        return filePath;
    }

    public void setFilePath(String filePath) {
        this.filePath = filePath;
    }
}

创建DBUtil工具类

package util;

import java.sql.*;
import java.io.InputStream;
import java.util.Properties;

/**
 * 数据库工具类
 *
 * @author xusucheng
 * @create 2017-11-18
 **/
public class DBUtil {
    //定义链接所需要的变量
    private static Connection con = null;
    private static PreparedStatement ps = null;
    private static ResultSet rs = null;

    //定义链接数据库所需要的参数
    private static String url = "";
    private static String username = "";
    private static String driver="";
    private static String password="";

    //定义读取配置文件所需要的变量
    private static Properties pp = null;
    private static InputStream fis = null;

    /**
     * 加载驱动
     */
    static {
        try {
            //从dbinfo.properties配置文件中读取配置信息
            pp = new Properties();
            fis = DBUtil.class.getClassLoader().getResourceAsStream("db.properties");

            pp.load(fis);
            url = pp.getProperty("url");
            username = pp.getProperty("username");
            driver=pp.getProperty("driver");
            password=pp.getProperty("password");

            //加载驱动
            Class.forName(driver);

        } catch (Exception e) {
            System.out.println("驱动加载失败！");
            e.printStackTrace();
        } finally {
            try {
                fis.close();
            } catch (Exception e) {
                e.printStackTrace();
            }

            fis = null; //垃圾回收自动处理
        }

    }

    /**
     * 得到Connection链接
     * @return Connection
     */
    public static Connection getConnection() {

        try {
            //建立连接
            con = DriverManager.getConnection(url, username, password);

        } catch (Exception e) {
            System.out.println("数据库链接失败！");
            e.printStackTrace();
        }

        return con;
    }

    /*public DBUtil(String sql){
        try {
            ps = getConnection().prepareStatement(sql);//准备执行语句
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void close() {
        try {
            con.close();
            ps.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }*/

    /**
     * 统一的资源关闭函数
     * @param rs
     * @param ps
     * @param con
     */
    public static void close(ResultSet rs,Statement ps, Connection con){

        if(rs != null) {
            try {
                rs.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        if(ps != null) {
            try {
                ps.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        if(con != null) {
            try {
                con.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

}

创建附件实体DAO类

package dao.upload;

import entity.upload.EntityAccessory;
import util.DBUtil;

import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * 附件上传DAO
 *
 * @author xusucheng
 * @create 2017-12-29
 **/
public class AccessoryDao {
    public static void add(EntityAccessory entity) {
        Connection conn = DBUtil.getConnection();
        String sql = "insert into tbl_accessory(file_name,file_size,file_ext_name,file_path) values(?,?,?,?)";
        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1, entity.getFileName());
            ps.setDouble(2, entity.getFileSize());
            ps.setString(3, entity.getFile_ext_name());
            ps.setString(4, entity.getFilePath());
            ps.execute();
            //conn.commit();

            DBUtil.close(null, ps, conn);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static List<EntityAccessory> list() {
        Connection conn = DBUtil.getConnection();
        String sql = "select id,file_name,file_size,file_ext_name,file_path from tbl_accessory";
        List<EntityAccessory> accessoryList = new ArrayList<>();
        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ResultSet rs = ps.executeQuery();

            while (rs.next()) {
                EntityAccessory entity = new EntityAccessory();
                entity.setId(rs.getInt("id"));
                entity.setFileName(rs.getString("file_name"));
                entity.setFileSize(new BigDecimal(rs.getDouble("file_size") / 1024).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue());
                entity.setFile_ext_name(rs.getString("file_ext_name"));
                entity.setFilePath(rs.getString("file_path"));
                accessoryList.add(entity);
            }

            DBUtil.close(rs, ps, conn);
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return accessoryList;

    }

    public static void remove(int id) {
        Connection conn = DBUtil.getConnection();
        String sql = "delete from tbl_accessory where id=?";
        try {
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1,id);
            ps.execute();
            //conn.commit(); mysql默认开启了autocommit

            DBUtil.close(null,ps,conn);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

创建list.jsp列表页面

<html>
<head>
    <title>上传文件列表</title>
</head>
<body>

<h3>文件列表</h3>
<table class="acclist_tab" border="1" bordercolor="#000000" cellspacing="0" cellpadding="2" style="border-collapse:collapse;">
    <tr>
        <th>文件名</th>
        <th>文件大小（KB）</th>
        <th>操作</th>
    </tr>
    <c:if test="${not empty accessoryList}">
        <c:forEach items="${accessoryList}" var="acc">
            <tr>
                <td>${acc.fileName}</td>
                <td>${acc.fileSize}</td>
                <td><a href="">删除</a></td>
            </tr>
        </c:forEach>
    </c:if>
</table>
</body>
</html>

创建展示列表Servlet:listUploadedFilesServlet

package servlet.upload;

import dao.upload.AccessoryDao;
import entity.upload.EntityAccessory;

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.IOException;
import java.util.List;

/**
 * 返回已上传文件列表
 *
 * @author xusucheng
 * @create 2017-12-29
 **/

@WebServlet("/listUploadedFiles")
public class listUploadedFilesServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取文件列表
        List<EntityAccessory> accessoryList = AccessoryDao.list();
        request.setAttribute("accessoryList", accessoryList);

        request.getRequestDispatcher("pages/upload/list.jsp").forward(request, response);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

增加error.jsp显示上传失败信息

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
    <title>上传错误页面</title>
</head>
<body>

<h3>上传失败：</h3>
<c:if test="${not empty errorMessage}">
    <%--<input type="text" id="errorMessage" value="${errorMessage}" style="color:red;" disabled="disabled">--%>
    <h4 style="color: red;">${errorMessage}</h4>
</c:if>


</body>
</html>

优化了第一章中的上传控制器

package servlet.upload;

import dao.upload.AccessoryDao;
import entity.upload.EntityAccessory;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadBase;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.ProgressListener;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

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.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Calendar;
import java.util.Iterator;
import java.util.List;
import java.util.UUID;

/**
 * 处理文件上传
 *
 * @author xusucheng
 * @create 2017-12-27
 **/
@WebServlet("/UploadServlet")
public class UploadServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置文件上传基本路径
        String savePath = this.getServletContext().getRealPath("/WEB-INF/uploadFiles");
        //设置临时文件路径
        String tempPath = this.getServletContext().getRealPath("/WEB-INF/tempFiles");
        File tempFile = new File(tempPath);
        if (!tempFile.exists()) {
            tempFile.mkdir();
        }

        //定义异常消息
        String errorMessage = "";
        //创建file items工厂
        DiskFileItemFactory factory = new DiskFileItemFactory();
        //设置缓冲区大小
        factory.setSizeThreshold(1024 * 100);
        //设置临时文件路径
        factory.setRepository(tempFile);
        //创建文件上传处理器
        ServletFileUpload upload = new ServletFileUpload(factory);
        //监听文件上传进度
        ProgressListener progressListener = new ProgressListener() {
            public void update(long pBytesRead, long pContentLength, int pItems) {
                System.out.println("正在读取文件： " + pItems);
                if (pContentLength == -1) {
                    System.out.println("已读取： " + pBytesRead + " 剩余0");
                } else {
                    System.out.println("文件总大小：" + pContentLength + " 已读取：" + pBytesRead);
                }
            }
        };
        upload.setProgressListener(progressListener);

        //解决上传文件名的中文乱码
        upload.setHeaderEncoding("UTF-8");
        //判断提交上来的数据是否是上传表单的数据
        if (!ServletFileUpload.isMultipartContent(request)) {
            //按照传统方式获取数据
            return;
        }

        //设置上传单个文件的大小的最大值，目前是设置为1024*1024字节，也就是1MB
        //upload.setFileSizeMax(1024 * 1024);
        //设置上传文件总量的最大值，最大值=同时上传的多个文件的大小的最大值的和，目前设置为10MB
        upload.setSizeMax(1024 * 1024 * 10);

        try {
            //使用ServletFileUpload解析器解析上传数据，解析结果返回的是一个List<FileItem>集合，每一个FileItem对应一个Form表单的输入项
            List<FileItem> items = upload.parseRequest(request);
            Iterator<FileItem> iterator = items.iterator();
            while (iterator.hasNext()) {
                FileItem item = iterator.next();

                //判断jsp提交过来的是不是文件
                if (item.isFormField()) {
                    errorMessage = "请提交文件！";
                    break;
                } else {
                    //文件名
                    String fileName = item.getName();
                    if (fileName == null || fileName.trim() == "") {
                        System.out.println("文件名为空！");
                    }
                    //处理不同浏览器提交的文件名带路径问题
                    fileName = fileName.substring(fileName.lastIndexOf("\\") + 1);
                    //文件大小
                    Long fileSize = item.getSize();
                    //文件扩展名
                    String fileExtension = fileName.substring(fileName.lastIndexOf(".") + 1);
                    //判断扩展名是否合法
                    if (!validExtension(fileExtension)) {
                        errorMessage = "上传文件非法！";
                        item.delete();
                        break;
                    }
                    //获得文件输入流
                    InputStream in = item.getInputStream();
                    //得到保存文件的名称
                    String saveFileName = createFileName(fileName);
                    //得到文件保存路径
                    String realFilePath = createRealFilePath(savePath, saveFileName);
                    //创建文件输出流
                    FileOutputStream out = new FileOutputStream(realFilePath);
                    //创建缓冲区
                    byte buffer[] = new byte[1024];
                    int len = 0;
                    while ((len = in.read(buffer)) > 0) {
                        //写文件
                        out.write(buffer, 0, len);
                    }
                    //关闭输入流
                    in.close();
                    //关闭输出流
                    out.close();
                    //删除临时文件
                    item.delete();
                    //将上传文件信息保存到附件表中 
                    EntityAccessory entity = new EntityAccessory();
                    entity.setFileName(fileName);
                    entity.setFileSize(fileSize);
                    entity.setFile_ext_name(fileExtension);
                    entity.setFilePath(realFilePath);
                    AccessoryDao.add(entity);
                }

            }

        } catch (FileUploadBase.FileSizeLimitExceededException e) {
            e.printStackTrace();
            errorMessage = "单个文件超出最大值！！！";
        } catch (FileUploadBase.SizeLimitExceededException e) {
            e.printStackTrace();
            errorMessage = "上传文件的总的大小超出限制的最大值！！！";
        } catch (FileUploadException e) {
            e.printStackTrace();
            errorMessage = "文件上传失败！！！";
        } finally {
            if (!"".equals(errorMessage)) {
                request.setAttribute("errorMessage", errorMessage);
                request.getRequestDispatcher("pages/upload/error.jsp").forward(request, response);
            } else {
                response.sendRedirect("listUploadedFiles");
            }

        }

    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    private boolean validExtension(String fileExtension) {
        String[] exts = {"jpg", "txt", "doc", "pdf"};
        for (int i = 0; i < exts.length; i++) {
            if (fileExtension.equals(exts[i])) {
                return true;
            }

        }

        return false;
    }

    private String createFileName(String fileName) {
        return UUID.randomUUID().toString() + "_" + fileName;
    }

    /**
     * 根据基本路径和文件名称生成真实文件路径，基本路径\\年\\月\\fileName
     *
     * @param basePath
     * @param fileName
     * @return
     */
    private String createRealFilePath(String basePath, String fileName) {
        Calendar today = Calendar.getInstance();
        String year = String.valueOf(today.get(Calendar.YEAR));
        String month = String.valueOf(today.get(Calendar.MONTH) + 1);


        String upPath = basePath + File.separator + year + File.separator + month + File.separator;
        File uploadFolder = new File(upPath);
        if (!uploadFolder.exists()) {
            uploadFolder.mkdirs();
        }

        String realFilePath = upPath + fileName;

        return realFilePath;
    }
}

测试效果截图

下集预告

实现附件删除功能！