下载Excel 模板，使用java下载 springMVC实现文件上传和下载

pom.xml

关键jar包如下：

<!-- 文件上传 -->
    <dependency>
        <groupId>commons-fileupload</groupId>
        <artifactId>commons-fileupload</artifactId>
        <version>1.3.3</version>
    </dependency>
    <!-- apache poi -->
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>3.17</version>
    </dependency>

其中, commons-fileupload 适用于文件上传和下载的jar包, poi-ooxml 是支持操作excel文件的jar包.

spring-web.xml

需要在spring的配置文件中配置上传文件的解析器.

<!-- 4: 文件上传解析器 -->
    <bean id="multipartResolver"
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- 设定默认编码 -->
        <property name="defaultEncoding" value="UTF-8"/>
        <!-- 设定文件上传的最大值为5MB, 5*1024*1024 = 5242880 -->
        <property name="maxUploadSize" value="5242880"/>
        <!-- 设定文件上传时写入内存的最大值, 如果小于这个参数不会生成临时文件, 默认为10240 -->
        <property name="maxInMemorySize" value="40960"/>
        <!-- 上传文件的临时路径 -->
        <property name="uploadTempDir" value="upload/temp/"/>
        <!-- 延迟文件解析 -->
        <property name="resolveLazily" value="true" />
    </bean>

单个excel文件上传

前端代码(使用thymeleaf模板引擎)

<div>
    <p>单个excel文件上传</p>
    <form th:action="@{/excel/import}" method="post" enctype="multipart/form-data">
        <input type="file" name="excelFile"/>
        <input type="submit" value="导入单个excel文件"/>
    </form>
</div>

 还可以使用 直接请求 后台controller 的方法： 

window.location.href = 请求后台的路径

后端代码

这里使用了 POIUtil 工具类解析excel文件, 传送门

 /**
     * * 从web页面导入单个excel文件
     *
     * @param excelFile 上传的excel文件
     * @param request   Request对象
     * @return 内容
     * @throws IOException
     */
    @PostMapping("/excel/import")
    @ResponseBody
    public List<ExcelUserInfo> importExcel(@RequestParam("excelFile") MultipartFile excelFile, HttpServletRequest request) throws IOException {

        // 1: 转存文件
        if (!excelFile.isEmpty()) {
            /**
             * 这里的getRealPath("/")是打包之后的项目的根目录。
             * 也就是 target项目名-1.0-SNAPSHOT
             */
            String storePath = request.getSession().getServletContext().getRealPath("/") + "upload/temp/";
            excelFile.transferTo(new File(storePath + excelFile.getOriginalFilename()));
        }

        // 2: 解析excel数据
        List<String[]> excelData = POIUtil.readExcelFile(excelFile, 1);

        List<ExcelUserInfo> userInfoList = new ArrayList<>();
        for (String[] arr : excelData) {
            ExcelUserInfo userInfo = new ExcelUserInfo();
            userInfo.setId(Integer.valueOf(arr[0]));
            userInfo.setName(arr[1]);
            userInfo.setAge(Integer.valueOf(arr[2]));
            userInfoList.add(userInfo);
        }
        // 3: 输出excel数据
        return userInfoList;
    }

多个excel文件上传

前端代码(使用thymeleaf模板引擎)

div>
    <p>多个excel文件上传</p>
    <form th:action="@{/excel/multiImport}" method="post" enctype="multipart/form-data">
        <div>
            <input type="file" name="excelFiles"/>
        </div>
        <div>
            <input type="file" name="excelFiles"/>
        </div>
        <input type="submit" value="导入多个excel文件"/>
    </form>
</div>

后端代码

 /**
     * 从web页面导入多个excel文件
     *
     * @param excelFiles excel文件数组
     * @param request    Request对象
     * @return 内容
     */
    @PostMapping("/excel/multiImport")
    @ResponseBody
    public Map<String, List<ExcelUserInfo>> importMultiExcel(@RequestParam("excelFiles") MultipartFile[] excelFiles, HttpServletRequest request) throws IOException {
        if (excelFiles == null) {
            throw new RuntimeException("excel files can not be null");
        }

        // 1: 转存文件
        if (excelFiles != null && excelFiles.length > 0) {
            String storePath = request.getSession().getServletContext().getRealPath("/") + "upload/temp/";
            for (MultipartFile excelFile : excelFiles) {
                excelFile.transferTo(new File(storePath + excelFile.getOriginalFilename()));
            }
        }

        // 2: 解析文件
        Map<String, List<ExcelUserInfo>> fileMap = new LinkedHashMap<>();
        for (MultipartFile excelFile : excelFiles) {
            List<String[]> excelData = POIUtil.readExcelFile(excelFile, 1);
            List<ExcelUserInfo> userInfoList = new ArrayList<>();
            for (String[] arr : excelData) {
                ExcelUserInfo userInfo = new ExcelUserInfo();
                userInfo.setId(Integer.valueOf(arr[0]));
                userInfo.setName(arr[1]);
                userInfo.setAge(Integer.valueOf(arr[2]));
                userInfoList.add(userInfo);
            }
            fileMap.put(excelFile.getOriginalFilename(), userInfoList);
        }
        // 3: 返回数据
        return fileMap;
    }

带参数上传excel文件

前端代码(使用thymeleaf模板引擎)

<div>
    <p>带参数上传excel文件</p>
    <form th:action="@{/excel/importWithParams}" method="post" enctype="multipart/form-data">
        <div>
            作者:<input type="text" name="author"/>
        </div>
        <div>
            描述:<input type="text" name="desc"/>
        </div>
        <input type="file" name="excelFile"/>
        <input type="submit" value="导入单个excel文件"/>
    </form>
</div>

后端代码

  /**
     * 带参数上传excel文件
     *
     * @param author    作者
     * @param desc      描述
     * @param excelFile excel文件
     * @param request   Request对象
     * @return 内容
     * @throws IOException
     */
    @PostMapping("/excel/importWithParams")
    @ResponseBody
    public Map<String, Object> importExcelFileWithParams(@RequestParam("author") String author,
                                                         @RequestParam("desc") String desc,
                                                         @RequestParam("excelFile") MultipartFile excelFile,
                                                         HttpServletRequest request) throws IOException {
        // 1: 转存文件
        if (!excelFile.isEmpty()) {
            /**
             * 这里的getRealPath("/")是打包之后的项目的根目录。
             * 也就是 target项目名-1.0-SNAPSHOT
             */
            String storePath = request.getSession().getServletContext().getRealPath("/") + "upload/temp/";
            excelFile.transferTo(new File(storePath + excelFile.getOriginalFilename()));
        }

        // 2: 解析excel数据
        List<String[]> excelData = POIUtil.readExcelFile(excelFile, 1);

        List<ExcelUserInfo> userInfoList = new ArrayList<>();
        for (String[] arr : excelData) {
            ExcelUserInfo userInfo = new ExcelUserInfo();
            userInfo.setId(Integer.valueOf(arr[0]));
            userInfo.setName(arr[1]);
            userInfo.setAge(Integer.valueOf(arr[2]));
            userInfoList.add(userInfo);
        }
        // 3: 输出excel数据
        Map<String, Object> resultMap = new LinkedHashMap<>();
        resultMap.put("author", author);
        resultMap.put("desc", desc);
        resultMap.put("excelContent", userInfoList);
        return resultMap;
    }

下载excel文件

前端代码(使用thymeleaf模板引擎)

<div>
    <p>下载excel文件</p>
    <input type="button" value="下载excel文件" onclick="downloadExcelFile()"/>
</div>

<script>
    // 下载excel文件
    function downloadExcelFile() {
        window.location.href = "/ss/excel/download";
    }
</script>

后端代码

 /**
     * 下载服务器中的excel文件
     *
     * @param request  Request对象
     * @param response Response对象
     * @return
     */
    @GetMapping("/excel/download")
    public String downloadExcelFile(HttpServletRequest request, HttpServletResponse response) {
        // 1: 找到excel文件
        String storePath = request.getSession().getServletContext().getRealPath("/") + "upload/temp/";
        String fileName = "userInfo1.xlsx";

        File file = new File(storePath + fileName);
        if (!file.exists()) {
            throw new RuntimeException("file do not exist");
        }
        InputStream inputStream = null;
        ServletOutputStream servletOutputStream = null;
        // 重置response
        response.reset();
        //设置http头信息的内容
        response.setCharacterEncoding("utf-8");
        response.setContentType("application/vnd.ms-excel");
        response.addHeader("Content-Disposition", "attachment;filename="" + fileName + """);
        int fileLength = (int) file.length();
        response.setContentLength(fileLength);

        try {
            if (fileLength != 0) {
                inputStream = new FileInputStream(file);
                byte[] buf = new byte[4096];
                // 创建输出流
                servletOutputStream = response.getOutputStream();
                int readLength;
                // 读取文件内容并输出到response的输出流中
                while ((readLength = inputStream.read(buf)) != -1) {
                    servletOutputStream.write(buf, 0, readLength);
                }
            }
        } catch (IOException e) {
            throw new RuntimeException("download file error");
        } finally {
            try {
                // 关闭ServletOutputStream
                if (servletOutputStream != null) {
                    servletOutputStream.flush();
                    servletOutputStream.close();
                }
                // 关闭InputStream
                if (inputStream != null) {
                    inputStream.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

创建并下载excel文件

后端代码

 /**
     * 创建并下载excel文件
     *
     * @param request  请求
     * @param response 响应
     * @return
     */
    @GetMapping("/excel/createAndDownload")
    public String createAndDownloadExcelFile(HttpServletRequest request, HttpServletResponse response) {
        // 查询数据
        List<ExcelUserInfo> userInfoList = this.getData();
        // 组装输入参数
        List<String> attributes = Arrays.asList("编号", "姓名", "年龄");
        List<List<String>> data = new ArrayList<>();
        for (ExcelUserInfo excelUserInfo : userInfoList) {
            List<String> rowInfo = new ArrayList<>();
            rowInfo.add(String.valueOf(excelUserInfo.getId()));
            rowInfo.add(excelUserInfo.getName());
            rowInfo.add(String.valueOf(excelUserInfo.getAge()));
            data.add(rowInfo);
        }
        // 生成workbook
        Workbook workbook = POIUtil.createExcelFile(attributes, data, POIUtil.XLS);
        if (workbook == null) {
            throw new RuntimeException("create excel file error");
        }

        // 输出到临时文件
        String storePath = request.getSession().getServletContext().getRealPath("/") + "upload/temp/";
        String fileName = "userInfo-" + (new Date()).getTime() + "." + POIUtil.XLS;
        FileOutputStream fout = null;
        try {
            fout = new FileOutputStream(storePath + fileName);
            workbook.write(fout);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (fout != null) {
                    fout.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        // 找到文件并下载
        File file = new File(storePath + fileName);
        if (!file.exists()) {
            throw new RuntimeException("file do not exist");
        }
        InputStream inputStream = null;
        ServletOutputStream servletOutputStream = null;
        // 重置response
        response.reset();
        //设置http头信息的内容
        response.setCharacterEncoding("utf-8");
        response.setContentType("application/vnd.ms-excel");
        response.addHeader("Content-Disposition", "attachment;filename="" + fileName + """);
        int fileLength = (int) file.length();
        response.setContentLength(fileLength);

        try {
            if (fileLength != 0) {
                inputStream = new FileInputStream(file);
                byte[] buf = new byte[4096];
                // 创建输出流
                servletOutputStream = response.getOutputStream();
                int readLength;
                // 读取文件内容并输出到response的输出流中
                while ((readLength = inputStream.read(buf)) != -1) {
                    servletOutputStream.write(buf, 0, readLength);
                }
            }
        } catch (IOException e) {
            throw new RuntimeException("download file error");
        } finally {
            try {
                // 关闭ServletOutputStream
                if (servletOutputStream != null) {
                    servletOutputStream.flush();
                    servletOutputStream.close();
                }
                // 关闭InputStream
                if (inputStream != null) {
                    inputStream.close();
                }
                // 删除临时文件
                file.delete();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }


    /**
     * 模拟从数据库中查询出数据
     *
     * @return 数据
     */
    private List<ExcelUserInfo> getData() {
        List<ExcelUserInfo> userInfoList = new ArrayList<>();
        for (int i = 1; i <= 5; i++) {
            ExcelUserInfo userInfo = new ExcelUserInfo();
            userInfo.setId(i);
            userInfo.setName("导出的用户_" + i);
            userInfo.setAge(20 + i);
            userInfoList.add(userInfo);
        }
        return userInfoList;
    }