使用 fileupload 组件完成文件的上传应用

1. 使用 fileupload 组件完成文件的上传应用

commons-dbutils-1.3.jar
commons-fileupload-1.2.1.jar

1). 需求:

> 在 upload.jsp 页面上使用 jQuery 实现 "新增一个附件", "删除附件". 但至少需要保留一个.

> 对文件的扩展名和文件的大小进行验证. 以下的规则是可配置的. 而不是写死在程序中的.

①文件的扩展名必须为 .pptx, docx, doc
   ② 每个文件的大小不能超过 1 M
   ③ 总的文件大小不能超过 5 M.

upload.properties

exts=pptx,docx,doc
file.max.size=1048576
total.file.max.size=5242880

> 若验证失败, 则在 upload.jsp 页面上显示错误消息:

① 若某一个文件不符合要求: xxx 文件扩展名不合法 或 xxx 文件大小超过 1 M
  ② 总的文件大小不能超过 5 M.

> 若验证通过, 则进行文件的上传操作

① 文件上传, 并给一个不能和其他文件重复的名字, 但扩展名不变
   ② 在对应的数据表中添加一条记录.
        id file_name file_path file_desc

FileUploadServlet.java

package com.aff.fileupload.app.servlet;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
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.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;mport com.aff.fileupload.app.bean.FileUploadBean;
import com.aff.fileupload.app.db.UploadFileDao;
import com.aff.fileupload.app.exception.InvalidExtNameException;
import com.aff.fileupload.app.utils.FileUploadAppProperties;
import com.aff.fileupload.app.utils.FileUtils;

@WebServlet("/app/fileuploadservlet")
public class FileUploadServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    private static final String FILE_PATH = "/WEB-INF/files/";

    private static final String TEMP_DIR = "d:\\tempDirectory";

    private UploadFileDao dao = new UploadFileDao();

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

        request.setCharacterEncoding("UTF-8");

        String path = null;

        // 获取 ServletFileUpload 对象.
        ServletFileUpload upload = getServletFileUpload();

        try {

            // 把需要上传的 FileItem 都放入到该 Map 中
            // 键: 文件的待存放的路径, 值: 对应的 FileItem 对象
            Map<String, FileItem> uploadFiles = new HashMap<String, FileItem>();

            // 解析请求, 得到 FileItem 的集合.
            List<FileItem> items = upload.parseRequest(request);

            // 1. 构建 FileUploadBean 的集合, 同时填充 uploadFiles
            List<FileUploadBean> beans = buildFileUploadBeans(items, uploadFiles);

            // 2. 校验扩展名:
            vaidateExtName(beans);

            // 3. 校验文件的大小: 在解析时, 已经校验了, 我们只需要通过异常得到结果.

            // 4. 进行文件的上传操作.
            upload(uploadFiles);

            // 5. 把上传的信息保存到数据库中
            saveBeans(beans);

            // 6. 删除临时文件夹的临时文件
            FileUtils.delAllFile(TEMP_DIR);

            path = "/app/success.jsp";

        } catch (Exception e) {
            e.printStackTrace();
            path = "/app/upload.jsp";
            request.setAttribute("message", e.getMessage());
        }

        request.getRequestDispatcher(path).forward(request, response);
    }

    private void saveBeans(List<FileUploadBean> beans) {
        dao.save(beans);
    }

    /**
     * 文件上传前的准备工作. 得到 filePath 和 InputStream
     *
     * @param uploadFiles
     * @throws IOException
     */
    private void upload(Map<String, FileItem> uploadFiles) throws IOException {
        for (Map.Entry<String, FileItem> uploadFile : uploadFiles.entrySet()) {
            String filePath = uploadFile.getKey();
            FileItem item = uploadFile.getValue();

            upload(filePath, item.getInputStream());
        }
    }

    /**
     * 文件上传的 IO 方法.
     *
     * @param filePath
     * @param inputStream
     * @throws IOException
     */
    private void upload(String filePath, InputStream inputStream) throws IOException {
        OutputStream out = new FileOutputStream(filePath);

        byte[] buffer = new byte[1024];
        int len = 0;

        while ((len = inputStream.read(buffer)) != -1) {
            out.write(buffer, 0, len);
        }

        inputStream.close();
        out.close();

        System.out.println(filePath);
    }

    /**
     * 校验扩展名是否合法
     *
     * @param beans:
     */
    private void vaidateExtName(List<FileUploadBean> beans) {
        String exts = FileUploadAppProperties.getInstance().getProperty("exts");
        List<String> extList = Arrays.asList(exts.split(","));
        System.out.println(extList);

        for (FileUploadBean bean : beans) {
            String fileName = bean.getFileName();
            System.out.println(fileName.indexOf("."));

            String extName = fileName.substring(fileName.lastIndexOf(".") + 1);
            System.out.println(extName);

            if (!extList.contains(extName)) {
                throw new InvalidExtNameException(fileName + "文件的扩展名不合法");
            }
        }
    }

    /**
     * 利用传入的 FileItem 的集合, 构建 FileUploadBean 的集合, 同时填充 uploadFiles
     *
     * FileUploadBean 对象封装了: id, fileName, filePath, fileDesc uploadFiles:
     * Map<String, FileItem> 类型, 存放文件域类型的 FileItem. 键: 待保存的文件的名字 ,值: FileItem 对象
     *
     * 构建过程: 1. 对传入 FileItem 的集合进行遍历. 得到 desc 的那个 Map. 键: desc 的
     * fieldName(desc1, desc2 ...). 值: desc 的那个输入的文本值
     *
     * 2. 对传入 FileItem 的集合进行遍历. 得到文件域的那些 FileItem 对象, 构建对应的 key (desc1 ....)
     * 来获取其 desc. 构建的 FileUploadBean 对象, 并填充 beans 和 uploadFiles
     *
     * @param items
     * @param uploadFiles
     * @return
     * @throws UnsupportedEncodingException
     */
    private List<FileUploadBean> buildFileUploadBeans(List<FileItem> items, Map<String, FileItem> uploadFiles)
            throws UnsupportedEncodingException {
        List<FileUploadBean> beans = new ArrayList<>();

        Map<String, String> descs = new HashMap<>();

        for (int i = 0; i < items.size(); i++) {
            FileItem item = items.get(i);

            if (item.isFormField()) {
                // desc1 或 desc2 ...
                String fieldName = item.getFieldName();
                String desc = item.getString("UTF-8");

                descs.put(fieldName, desc);
            }
        }

        for (int i = 0; i < items.size(); i++) {
            FileItem item = items.get(i);
            FileUploadBean bean = null;
            if (!item.isFormField()) {
                String fieldName = item.getFieldName();
                String descName = "desc" + fieldName.substring(fieldName.length() - 1);
                String desc = descs.get(descName);

                // 对应文件名
                String fileName = item.getName();
                String filePath = getFilePath(fileName);

                bean = new FileUploadBean(fileName, filePath, desc);
                beans.add(bean);

                uploadFiles.put(bean.getFilePath(), item);
            }
        }

        return beans;
    }

    /**
     * 根据跟定的文件名构建一个随机的文件名 1. 构建的文件的文件名的扩展名和给定的文件的扩展名一致 2. 利用 ServletContext 的
     * getRealPath 方法获取的绝对路径 3. 利用了 Random 和 当前的系统时间构建随机的文件的名字
     *
     * @param fileName
     * @return
     */
    private String getFilePath(String fileName) {
        String extName = fileName.substring(fileName.lastIndexOf("."));
        Random random = new Random();

        String filePath = getServletContext().getRealPath(FILE_PATH) + "\\" + System.currentTimeMillis()
                + random.nextInt(100000) + extName;
        return filePath;
    }

    /**
     * 构建 ServletFileUpload 对象 从配置文件中读取了部分属性, 用户设置约束. 该方法代码来源于文档.
     *
     * @return
     */
    private ServletFileUpload getServletFileUpload() {
        String fileMaxSize = FileUploadAppProperties.getInstance().getProperty("file.max.size");
        String totalFileMaxSize = FileUploadAppProperties.getInstance().getProperty("total.file.max.size");

        DiskFileItemFactory factory = new DiskFileItemFactory();

        factory.setSizeThreshold(1024 * 500);
        File tempDirectory = new File(TEMP_DIR);
        factory.setRepository(tempDirectory);

        ServletFileUpload upload = new ServletFileUpload(factory);

        upload.setSizeMax(Integer.parseInt(totalFileMaxSize));
        upload.setFileSizeMax(Integer.parseInt(fileMaxSize));

        return upload;
    }
}

upload.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript"
    src="${pageContext.request.contextPath }/scripts/jquery-1.12.3.js"></script>
<script type="text/javascript">

    $(function(){
        var i = 2;
        $("#addFile").click(function(){
            $(this).parent().parent().before("<tr class='file'><td>File"
                    + i + ":</td><td><input type='file' name='file"
                    + i + "'/></td></tr>"
                    + "<tr class='desc'><td>Desc"
                    + i + ":</td><td><input type='text' name='desc"
                    + i + "'/><button id='delete"
                    + i + "'>删除</button></td></tr>");
            i++;

            //获取新添加的删除按钮
            $("#delete" + (i-1)).click(function(){
                var $tr = $(this).parent().parent();
                $tr.prev("tr").remove();
                $tr.remove();

                //对 i 重写排序
                $(".file").each(function(index){
                    var n = index + 1;

                    $(this).find("td:first").text("File" + n);
                    $(this).find("td:last input").attr("name", "file" + n);
                });

                $(".desc").each(function(index){
                    var n = index + 1;

                    $(this).find("td:first").text("Desc" + n);
                    $(this).find("td:last input").attr("name", "desc" + n);
                });

                i = i - 1;
            });

            return false;
        });

    });

</script>

</head>
<body>

    <font color="red">${message }</font>
    <br><br>

    <form action="fileuploadservlet" method="post" enctype="multipart/form-data">

        <table>
            <tr class="file">
                <td>File1:</td>
                <td><input type="file" name="file1"/></td>
            </tr>
            <tr class="desc">
                <td>Desc1:</td>
                <td><input type="text" name="desc1"/></td>
            </tr>

            <tr>
                <td><input type="submit" id="submit" value="提交"/></td>
                <td><button id="addFile">新增一个附件</button></td>
            </tr>
        </table>

    </form>
</body>
</html>

FileUploadAppListener.java

package com.aff.fileupload.app.listener;

import java.io.IOException;
import java.io.InputStream;
import java.util.Map;
import java.util.Properties;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

import com.aff.fileupload.app.utils.FileUploadAppProperties;

@WebListener
public class FileUploadAppListener implements ServletContextListener {

    public FileUploadAppListener() {
    }

    public void contextInitialized(ServletContextEvent sce) {
        InputStream is = getClass().getClassLoader().getResourceAsStream("upload.properties");
        Properties properties = new Properties();

        try {
            properties.load(is);

            for (Map.Entry<Object, Object> prop : properties.entrySet()) {
                String propertyName = (String) prop.getKey();
                String propertyValue = (String) prop.getValue();

                FileUploadAppProperties.getInstance().addProperty(propertyName, propertyValue);

            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void contextDestroyed(ServletContextEvent sce) {
    }
}

UploadFileDao.java

package com.aff.fileupload.app.db;

import java.sql.Connection;
import java.util.List;

import com.aff.fileupload.app.bean.FileUploadBean;

public class UploadFileDao extends DAO<FileUploadBean> {

    public List<FileUploadBean> getFiles() {

        Connection conn = null;

        try {
            conn = JDBCUtils.getConnection();
            String sql = "SELECT id, file_name fileName, file_path filePath, " + "file_desc fileDesc FROM upload_files";
            return getForList(conn, sql);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtils.release(conn);
        }
        return null;
    }

    public void save(List<FileUploadBean> uploadFiles) {

        Connection conn = null;

        try {
            conn = JDBCUtils.getConnection();
            String sql = "INSERT INTO upload_files (file_name, file_path, file_desc) VALUES " + "(?, ?, ?)";
            for (FileUploadBean file : uploadFiles) {
                update(conn, sql, file.getFileName(), file.getFilePath(), file.getFileDesc());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtils.release(conn);
        }
    }
}

FileUploadBean.java

package com.aff.fileupload.app.bean;

public class FileUploadBean {

    private Integer id;
    private String fileName;
    private String filePath;
    private String fileDesc;
    public FileUploadBean() {
        super();
    }
    public FileUploadBean(String fileName, String filePath, String fileDesc) {
        super();
        this.fileName = fileName;
        this.filePath = filePath;
        this.fileDesc = fileDesc;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getFileName() {
        return fileName;
    }
    public void setFileName(String fileName) {
        this.fileName = fileName;
    }
    public String getFilePath() {
        return filePath;
    }
    public void setFilePath(String filePath) {
        this.filePath = filePath;
    }
    public String getFileDesc() {
        return fileDesc;
    }
    public void setFileDesc(String fileDesc) {
        this.fileDesc = fileDesc;
    }
}

目录

2. 如何修改小工具或框架的源代码 ?

1). 原则: 能不修改就不修改.

2). 修改的方法:

> 修改源代码, 替换 jar 包中对应的 class 文件. 
> 在本地新建相同的包, 和类, 在这个类中修改即可.

3. 文件的下载:

DownloadServlet.java

package com.aff.download.servlet;
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.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/downloadServlet")
public class DownloadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //I. 设置 contentType 响应头: 设置响应的类型是什么 ? 通知浏览器是个下载的文件
        response.setContentType("application/x-msdownload");

        String fileName = "文件下载.pptx";
        //II. 设置 Content-Disposition 响应头: 通知浏览器不再有浏览器来自行处理(或打开)要下载的文件, 
        //    而由用户手工完成
        response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));

        //III. 具体的文件: 可以调用 response.getOutputStream 的方式, 以 IO 流的方式发送给客户端.
        OutputStream out = response.getOutputStream();
        String pptFileName = "C:\\Users\\lz\\Desktop\\NEW\\PPT\\MAPP.pptx";

        InputStream in = new FileInputStream(pptFileName);

        byte[] buffer = new byte[1024];
        int len = 0;

        while ((len = in.read(buffer)) != -1) {
            out.write(buffer, 0, len);
        }
        in.close();
    }
}

download.jsp

<body>
    <!-- 静态下载 -->
    <a href="xyz.txt">download xyz.txt</a>
    <br>
    <br>
    <a href="test.jsp">download test.jsp</a>
    <br>
    <br>
    <a href="downloadServlet">DownLoad abcd.pptx</a>
</body>