在 maven 中使用了 commons-fileupload，使用方法:

（一）上傳

1-1.前端介面

<form action="" enctype="multipart/form-data" class="modifyall"
            method="post" id="uploadForm">
            <input type="file" name="file" id="file"
                style="display: inline-block" class="po"> 
　　　　　　  <
 
input type="submit" class="layui-btn layui-btn-sm "
                value="上傳" id="fileUpload">
 </form>

1-2.js

function fileUpload() {
    var URL = root + "/teacher/teacherUpload";
    var data = new FormData($('#uploadForm')[0]);
    $.ajax({
        url : URL,
        type : "post",
        data : data,
        async : 
 
false,
        cache : false,
        processData : false,
        contentType : false,
        success : function(data) {
　　　　　　//返回資料型別為 String 
            if (data == "ok") {
                location.reload();
            }
            if (data == "min") {
　　　　　　//如果檔案大小小於最小上傳值，返回 "min",並將最小值的大小儲存在 session 中，通過<input type="hidden"> 和 id 獲取最小值
                
 
var min = $("#min").val();
                alert("檔案必須大於" + min);
                location.reload();
            }
            if (data == "max") {
　　　　　　//同最小值
                alert("檔案必須小於" + max);
                location.reload();
            }
        },
        error : function(data) {
            alert("操作失敗");
        }
    });
}

1-3.Controller@ResponseBody    @RequestMapping("/teacherUpload")

public String upload(MultipartFile file, HttpServletRequest request, HttpServletRequest reponse)
            throws IOException {
        PageData pd = this.getPageData();

        // 根據考試 id 獲取考試資訊
        String testid = pd.getString("testid");
        List<PageData> list = this.teacherFacade.selectTestById(testid);
        List<PageData> system = this.teacherFacade.selectSystem();
        /*
         * 檔案大小檢測
         */
        long filesize = file.getSize();
        long minSize = (long) system.get(0).get("file_minsize");
        long maxSize = (long) system.get(0).get("file_maxsize");

        // 檔案小於最小值或大於最大值;
        if (minSize > filesize) {
            session.setAttribute("min", minSize + "Byte");
            return "min";
        }
        if (maxSize < filesize) {
            session.setAttribute("max", maxSize + "Byte");
            return "max";
        }

        // 儲存路徑為考試名 
        String path = request.getSession().getServletContext()
                .getRealPath("/ExamSystem/" + list.get(0).getString("testname"));
        System.out.println("path>>" + path);

        String fileName = file.getOriginalFilename();
        // 將檔名加入到資料庫
        pd.put("submit", fileName);
        this.teacherFacade.updateaddfile(pd);
        System.out.println("fileName>>" + fileName);

        File dir = new File(path, fileName);
        System.out.println("dir.exists()>>" + dir.exists());
        if (!dir.exists()) {
            dir.mkdirs();
        }
        System.out.println("dir.exists()>>" + dir.exists());
//        MultipartFile自帶的解析方法
        file.transferTo(dir);

        return "ok";
    }

（二）下載

2-1 前端

<form action="downTest" name="form3" id="form3" method="post"><!-- action 是請求對映的地址 -->
    <input type="submit" class="test_down" value="下載檢視" />
</form>

2-2 Controller

@ResponseBody
    @RequestMapping("/downTest")
    private void down(HttpServletRequest request, HttpServletResponse response) throws IOException {

        // 根據考試 id 獲取考試資訊
        // list = this.studentFacade.selectTestById(testid);
        ServletContext application = request.getSession().getServletContext();
        List<PageData> list = (List<PageData>) application.getAttribute("RunTest");
        System.out.println(list);
        if (list != null) {
            String path = request.getServletContext().getRealPath("/") + "ExamSystem/"
                    + list.get(0).getString("testname") + "/";
            System.out.println(path);
            String fileName = list.get(0).getString("submit");
            fileName = new String(fileName.getBytes(), "ISO8859-1");//解決無法下載中文的問題
            //System.out.println(path + fileName);
            File file = new File(path + fileName);
            //System.out.println(file);
            if (file != null) {
                //System.out.println("檔案的名字：" + fileName);
                response.addHeader("content-disposition", "attachment;filename=" + fileName);
                FileUtils.copyFile(file, response.getOutputStream());
            }

        }
    }

下載是會有中文名無法顯示的問題，程式碼中加入 

fileName = new String(fileName.getBytes(), "ISO8859-1");

（三）打包為 zip 下載 (原文地址沒找到...)

3-1 前端 

<a  id="downloadInfo" href="downZip?testid=${test.get('testid')}"
title="打包下載">打包下載</a>

3-2 Controller

@ResponseBody
    @RequestMapping("/downZip")
    public void downZip(HttpServletRequest request, HttpServletRequest reponse) throws IOException {

        PageData pd = this.getPageData();
        //response.setContentType("application/x-msdownload;");
        // System.out.println(pd);
        String testid = pd.getString("testid");
        System.out.println(testid);
        List<PageData> list = new ArrayList<PageData>();
        if (this.teacherFacade.selectTestById(testid) != null) {
            // 歸檔考試
            pd.put("test_signal", "3");
            this.teacherFacade.updateSignal(pd);
            list = this.teacherFacade.selectTestById(testid);
        }

        if (list != null) {

            try {

                String testName = list.get(0).getString("testname");
                String sourcePath = request.getServletContext().getRealPath("/") + "ExamSystem/" + testName;
                System.out.println(sourcePath);
                String zipName = testName + ".zip";
                zipName = new String(zipName.getBytes(), "ISO8859-1");
                System.out.println(zipName);
                String zipPath = request.getServletContext().getRealPath("/") + "ExamSystem/" + zipName;
                File file = new File(sourcePath);// 要被壓縮的資料夾
                File zipFile = new File(zipPath);
                ZipOutputStream zipOut = new ZipOutputStream(new FileOutputStream(zipFile));
                if (file.isDirectory()) {
                    File[] files = file.listFiles();
                    for (File fileSec : files) {
                        ZipUtil.recursionZip(zipOut, fileSec, "");
                    }
                }
                zipOut.close();

                if (zipFile != null) {
                    System.out.println("檔案的名字：" + zipName);
                    response.addHeader("content-disposition", "attachment;filename=" + zipName);
                    FileUtils.copyFile(zipFile, response.getOutputStream());
                }
            } catch (Exception e) {
                e.printStackTrace();
            }

        }
    }

3-3 工具類

package com.ssm.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class ZipUtil {

    /*
     * 檔案壓縮
     */
    public static void recursionZip(ZipOutputStream zipOut, File file, String baseDir) throws Exception {
        if (file.isDirectory()) {
            File[] files = file.listFiles();
            for (File fileSec : files) {
                recursionZip(zipOut, fileSec, baseDir + file.getName() + File.separator);
            }
        } else {
            byte[] buf = new byte[1024];
            InputStream input = new FileInputStream(file);
            zipOut.putNextEntry(new ZipEntry(baseDir + file.getName()));
            int len;
            while ((len = input.read(buf)) != -1) {
                zipOut.write(buf, 0, len);
            }
            input.close();
        }
    }
}

（四）刪除資料夾下的所有內容  原文地址

4-1 獲取檔案地址

String sourcePath = request.getSession().getServletContext().getRealPath("/") + "ExamSystem/"
                        + testName;

4-2 刪除資料夾下所有內容

File sourceFile = new File(sourcePath);
if (sourceFile.exists()) {                                        
    DeleteFolderUtil.deleteFile(sourceFile);
}

4-3 工具類

package com.ssm.util;

import java.io.File;

public class DeleteFolderUtil {
    /*
     * 刪除資料夾下所有內容
     */
    public static void deleteFile(File file) {
        if (file.isDirectory()) {
            File[] files = file.listFiles();
            for (int i = 0; i < files.length; i++) {
                deleteFile(files[i]);
            }
        }
        file.delete();
    }

}