JavaWeb多文件上传及zip打包下载

项目中经常会使用到文件上传及下载的功能。本篇文章总结场景在JavaWeb环境下，多文件上传及批量打包下载功能，包括前台及后台部分。 
首先明确一点： 
无法通过页面的无刷新ajax请求，直接发下载、上传请求。上传和下载，均需要在整页请求的基础上实现。项目中一般通过构建form表单形式实现这一功能。

一、多文件上传

项目需求为实现多图片上传功能。参考测试了网上找到的众多插件方法后，决定选用Jquery原始上传方案。以下按步骤贴出具体代码。

1、HTML部分（可省略使用js构建）

<form id="uploadForm" method="post" enctype="multipart/form-data">

    <input type="file" hidden name="fileImage" multiple/>

    <a href="javascript:void(0);" id="fileSubmit" onclick="uploadFileMulti()">上传资料</a>

</form>

有几点说明： 
1. form中 enctype=”multipart/form-data” 
2. 例中使用标签，构建submit

2、JS部分

var formData = new FormData($("#uploadForm")[0]);

formData.append("foldName", "datumList");      //设置父级文件夹名称

formData.append("oderCode", selfOrderCode);

formData.append("datumType", datumType);

$.ajax({

    type: "POST",

    data: formData,

    url: "order/datumList/batchInsertDatumLists",

    contentType: false,

    processData: false,

    success: function (result) {

        if (result.success) {

            //清空框文件内容

            $("#fileImage").val("");

            var obj = document.getElementById('fileImage');

            obj.outerHTML = obj.outerHTML;

            refreshDatumList();

            showSuccessToast(result.message);

        } else {

            showWarningToast(result.message);

        }

    },

    error: function () {

        showErrorToast('请求失败！')

    }

}); 

以上有几点说明： 
 1. var formData = new FormData($(“#uploadForm”)[0]); 
 2. 使用 formData.append(“oderCode”, selfOrderCode); 添加其他参数

Java后台

MultipartHttpServletRequest mRequest = (MultipartHttpServletRequest) request; List<MultipartFile> files = mRequest.getFiles("fileImage");

以上有几点说明： 
 1. 获取MultipartHttpServletRequest，对应file标签的name

二、文件批量下载

本项目中，需求为批量下载某一批次文件。使用zip在服务器压缩文件，之后将文件下载到客户机。 
网上查询，使用Java自带的文件输出类不能解决压缩文件中文件名乱码的问题。解决方法：使用ant.jar包，创建压缩文件时，可以设置文件的编码格式，文件名乱码的问题就解决了。

HTML部分（可省略使用js构建）

<form id="uploadForm" method="post" enctype="multipart/form-data">

    <div class="product-dl">

        <input type="hidden" name="orderCode"/>

        <input type="hidden" name="datumType"/>

        <a href="javascript:void(0);" class="btn" onclick="batchDatumListDownLoad()">批量下载</a>

    </div>

</form>

JS部分

//批量下载

function batchDatumListDownLoad() {

    var param = {};

    param.datumType = $("#datumTypeQ").val();

    if (param.datumType == -1) {

        param.datumType = null;     //查询所有

    }

    param.orderCode = selfOrderCode;

    $("#uploadForm input[name=orderCode]").val(param.orderCode);

    $("#uploadForm input[name=datumType]").val(param.datumType);

    var form = $("#uploadForm")[0];

    form.action = "order/datumList/batchDownLoadDatumList";

    form.method = "post";

    form.submit();//表单提交

}

后台部分

public void batchDownLoadDatumList(DatumListVo datumListVo, HttpServletResponse response) {

    try {

        //查询文件列表

        List<DatumListVo> voList = datumListService.queryDatumLists(datumListVo);

        //压缩文件

        List<File> files = new ArrayList<>();

        for (DatumListVo vo : voList) {

            File file = new File(vo.getDatumUrl());

            files.add(file);

        }

        String fileName = datumListVo.getOrderCode() + "_" + datumListVo.getDatumType() + ".zip";

        //在服务器端创建打包下载的临时文件

        String globalUploadPath = "";

        String osName = System.getProperty("os.name");

        if (osName.toLowerCase().indexOf("windows") >= 0) {

            globalUploadPath = GlobalKeys.getString(GlobalKeys.WINDOWS_UPLOAD_PATH);

        } else if (osName.toLowerCase().indexOf("linux") >= 0 || osName.toLowerCase().indexOf("mac") >= 0) {

            globalUploadPath = GlobalKeys.getString(GlobalKeys.LINUX_UPLOAD_PATH);

        }

        String outFilePath = globalUploadPath + File.separator + fileName;

        File file = new File(outFilePath);

        //文件输出流

        FileOutputStream outStream = new FileOutputStream(file);

        //压缩流

        ZipOutputStream toClient = new ZipOutputStream(outStream);

        //设置压缩文件内的字符编码，不然会变成乱码

        toClient.setEncoding("GBK");

        ZipUtil.zipFile(files, toClient);

        toClient.close();

        outStream.close();

        ZipUtil.downloadZip(file, response);

    } catch (Exception e) {

        e.printStackTrace();

    }

}

其中ZipUtil.java

/**

 * 压缩文件列表中的文件

 *

 * @param files

 * @param outputStream

 * @throws IOException

 */

public static void zipFile(List files, ZipOutputStream outputStream) throws IOException, ServletException {

    try {

        int size = files.size();

        //压缩列表中的文件

        for (int i = 0; i < size; i++) {

            File file = (File) files.get(i);

            try {

                zipFile(file, outputStream);

            } catch (Exception e) {

                continue;

            }

        }

    } catch (Exception e) {

        throw e;

    }

}

/**

 * 将文件写入到zip文件中

 *

 * @param inputFile

 * @param outputstream

 * @throws Exception

 */

public static void zipFile(File inputFile, ZipOutputStream outputstream) throws IOException, ServletException {

    try {

        if (inputFile.exists()) {

            if (inputFile.isFile()) {

                FileInputStream inStream = new FileInputStream(inputFile);

                BufferedInputStream bInStream = new BufferedInputStream(inStream);

                ZipEntry entry = new ZipEntry(inputFile.getName());

                outputstream.putNextEntry(entry);

                final int MAX_BYTE = 10 * 1024 * 1024;    //最大的流为10M

                long streamTotal = 0;                      //接受流的容量

                int streamNum = 0;                      //流需要分开的数量

                int leaveByte = 0;                      //文件剩下的字符数

                byte[] inOutbyte;                          //byte数组接受文件的数据

                streamTotal = bInStream.available();                        //通过available方法取得流的最大字符数

                streamNum = (int) Math.floor(streamTotal / MAX_BYTE);    //取得流文件需要分开的数量

                leaveByte = (int) streamTotal % MAX_BYTE;                //分开文件之后,剩余的数量

                if (streamNum > 0) {

                    for (int j = 0; j < streamNum; ++j) {

                        inOutbyte = new byte[MAX_BYTE];

                        //读入流,保存在byte数组

                        bInStream.read(inOutbyte, 0, MAX_BYTE);

                        outputstream.write(inOutbyte, 0, MAX_BYTE);  //写出流

                    }

                }

                //写出剩下的流数据

                inOutbyte = new byte[leaveByte];

                bInStream.read(inOutbyte, 0, leaveByte);

                outputstream.write(inOutbyte);

                outputstream.closeEntry();     //Closes the current ZIP entry and positions the stream for writing the next entry

                bInStream.close();    //关闭

                inStream.close();

            }

        } else {

            throw new ServletException("文件不存在！");

        }

    } catch (IOException e) {

        throw e;

    }

}

/**

 * 下载打包的文件

 *

 * @param file

 * @param response

 */

public static void downloadZip(File file, HttpServletResponse response) {

    try {

        // 以流的形式下载文件。

        BufferedInputStream fis = new BufferedInputStream(new FileInputStream(file.getPath()));

        byte[] buffer = new byte[fis.available()];

        fis.read(buffer);

        fis.close();

        // 清空response

        response.reset();

        OutputStream toClient = new BufferedOutputStream(response.getOutputStream());

        response.setContentType("application/octet-stream");

        response.setHeader("Content-Disposition", "attachment;filename=" + file.getName());

        toClient.write(buffer);

        toClient.flush();

        toClient.close();

        file.delete();        //将生成的服务器端文件删除

    } catch (IOException ex) {

        ex.printStackTrace();

    }

}

以上基本满足文件上传下载所需

DEMO下载地址：https://dwz.cn/fgXtRtnu