springmvc采用formdata进行多文件上传

参考链接：https://www.cnblogs.com/kanyun/p/7159232.html

https://www.cnblogs.com/kanyun/p/7159232.html

因为项目是前后端分离，且跨域访问。采用form表单提交难以实现。故需要引入formdata，采用ajax提交。

参考地址中已经写的很详细了。这里只做个代码简化

前端代码：

<form enctype="multipart/form-data" id="formfile" class="upload-img">
<input  type="file" multiple="multiple" />
</form>

$(document).on("change", ".upload-img input:file", function() {
    var t_files = this.files;
    var data = new FormData();
    for (var i=0;i<t_files.length;i++){
        data.append('file',t_files[i]);
    }
    $.ajax({
        url : 'http://localhost:8080/YDplatform/apply/uploadScanFiles', //用于文件上传的服务器端请求地址
        type : 'post',
        processData: false, // 告诉jQuery不要去处理发送的数据
        contentType: false, // 告诉jQuery不要去设置Content-Type请求头
        data:data,
        cache: false
    }).done(function(data,status){
        var dataObj = jQuery.parseJSON(data);
        if(dataObj.state == -1){
            new Message().showMsg("上传图片出错");
        }else{
        }
    }).fail(function (res) {
    })
});

 后端代码：

@ResponseBody
	@RequestMapping(value = "uploadScanFiles", method = RequestMethod.POST)
	public HttpResponse uploadScanFiles(HttpServletRequest request,
			@RequestParam(value = "file", required = true) List<MultipartFile> files, String key, Long applyId,
			Long appId) throws Exception {
		if (null == files || 0 == files.size()) {
			throw BizException.create(Code.ParamError, "文件为空");
		}
		for (MultipartFile file : files) {
			System.out.println("文件名：" + file.getOriginalFilename() + "---contentType：" + file.getContentType());
		}
		return HttpResponse.OK();
	}

 注意：前端formdata的参数名和后台注解@RequestParam的value要对应上。后端接收参数里面除了文件以外，还有其它字段参数，也是可以用formdata来append的，这里就不改动了。

文件下载：

参考链接：https://blog.csdn.net/a447332241/article/details/78998239

前端代码：

ajax请求无法响应下载功能。因为response原因，一般请求浏览器是会处理服务器输出的response，例如生成png、文件下载等,然而ajax请求只是个“字符型”的请求，即请求的内容是以文本类型存放的。文件的下载是以二进制形式进行的，虽然可以读取到返回的response，但只是读取而已，是无法执行的，说白点就是js无法调用到浏览器的下载处理机制和程序。

推荐使用这种方式 自己构建表单进行提交

var form = $("<form>");
form.attr("style","display:none");
form.attr("target","");
form.attr("method","post");
form.attr("action",rootPath + "T_academic_essay/DownloadZipFile.do");
var input1 = $("<input>");
input1.attr("type","hidden");
input1.attr("name","strZipPath");
input1.attr("value",strZipPath);
$("body").append(form);
form.append(input1);
form.submit();
form.remove();

后端代码有两种方式，我采用的后者：

方式一：直接贴代码

@RequestMapping("/download")
		public String download( String fileName ,String filePath, HttpServletRequest request, HttpServletResponse response){
					 
			response.setContentType("text/html;charset=utf-8");
			try {
				request.setCharacterEncoding("UTF-8");
			} catch (UnsupportedEncodingException e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}
					
			java.io.BufferedInputStream bis = null;
			java.io.BufferedOutputStream bos = null;
		
			String downLoadPath = filePath;  //注意不同系统的分隔符
		//	String downLoadPath =filePath.replaceAll("/", "\\\\\\\\");   //replace replaceAll区别 *****  
			System.out.println(downLoadPath);
			
			try {
				long fileLength = new File(downLoadPath).length();
				response.setContentType("application/x-msdownload;");
				response.setHeader("Content-disposition", "attachment; filename=" + new String(fileName.getBytes("utf-8"), "ISO8859-1"));
				response.setHeader("Content-Length", String.valueOf(fileLength));
				bis = new BufferedInputStream(new FileInputStream(downLoadPath));
				bos = new BufferedOutputStream(response.getOutputStream());
				byte[] buff = new byte[2048];
				int bytesRead;
				while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
					bos.write(buff, 0, bytesRead);
				}
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				if (bis != null)
					try {
						bis.close();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				if (bos != null)
					try {
						bos.close();
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
			}
			return null;	
		}

 方式二：利用springmvc提供的ResponseEntity类型,使用它可以很方便地定义返回的HttpHeaders和HttpStatus。

RequestMapping("/download")  
	    public ResponseEntity<byte[]> export(String fileName,String filePath) throws IOException {  
	    	
	        HttpHeaders headers = new HttpHeaders();    
	        File file = new File(filePath);
	        
	        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);    
	        headers.setContentDispositionFormData("attachment", fileName);    
	       
	        return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),    
	                                              headers, HttpStatus.CREATED);    
	    }

 如果是多文件下载，则需要进行压缩处理：

参考链接：https://www.cnblogs.com/zeng1994/p/7862288.html文 

Controller:

@RequestMapping(value = "downloadPackage", method = RequestMethod.GET)
	public void downloadPackage2(HttpServletRequest request, @RequestParam(required = true) String key,
			Integer processType, Long applyId, HttpServletResponse response) throws Exception {
		String fileDir = applicationService.getPackagefileDirByProcessAndKey(applyId, key, processType);
		if (StringUtils.isBlank(fileDir)) {
			throw BizException.create(Code.NOTEXIST, "文件没找到！");
		}
		String rootPath = request.getSession().getServletContext().getRealPath("/");
		String tempFileName = rootPath + "/" + UUID.randomUUID().toString().replaceAll("-", "");
		File temDir = new File(tempFileName);
		if (!temDir.exists()) {
			temDir.mkdirs();
		}
		File resource = new File(fileDir);
		FileUtils.copyDirectory(resource, temDir);
		response.setContentType("application/zip");
		response.setHeader("Content-Disposition",
				"attachment; filename=package_" + System.currentTimeMillis() + ".zip");
		ZipUtils.toZip(temDir.getPath(), response.getOutputStream(), false);
		File[] listFiles = temDir.listFiles();
		for (int i = 0; i < listFiles.length; i++) {
			listFiles[i].delete();
		}
		temDir.delete();

	}

Utils:

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

/**
 * 
 * ZipUtils
 * 
 * @author ZENG.XIAO.YAN
 * 
 * @date 2017年11月19日 下午7:16:08
 * 
 * @version v1.0
 * 
 */

public class ZipUtils {

	private static final int BUFFER_SIZE = 2 * 1024;

	/**
	 * 
	 * 压缩成ZIP 方法1
	 * 
	 * @param srcDir
	 *            压缩文件夹路径
	 * 
	 * @param out
	 *            压缩文件输出流
	 * 
	 * @param KeepDirStructure
	 *            是否保留原来的目录结构,true:保留目录结构;
	 * 
	 *            false:所有文件跑到压缩包根目录下(注意：不保留目录结构可能会出现同名文件,会压缩失败)
	 * 
	 * @throws RuntimeException
	 *             压缩失败会抛出运行时异常
	 * 
	 */

	public static void toZip(String srcDir, OutputStream out, boolean KeepDirStructure) throws RuntimeException {
		long start = System.currentTimeMillis();
		ZipOutputStream zos = null;
		try {
			zos = new ZipOutputStream(out);
			File sourceFile = new File(srcDir);
			compress(sourceFile, zos, sourceFile.getName(), KeepDirStructure);
			long end = System.currentTimeMillis();
			System.out.println("压缩完成，耗时：" + (end - start) + " ms");
		} catch (Exception e) {
			throw new RuntimeException("zip error from ZipUtils", e);
		} finally {
			if (zos != null) {
				try {
					zos.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

	/**
	 * 
	 * 压缩成ZIP 方法2
	 * 
	 * @param srcFiles
	 *            需要压缩的文件列表
	 * 
	 * @param out
	 *            压缩文件输出流
	 * 
	 * @throws RuntimeException
	 *             压缩失败会抛出运行时异常
	 * 
	 */

	public static void toZip(List<File> srcFiles, OutputStream out) throws RuntimeException {

		long start = System.currentTimeMillis();

		ZipOutputStream zos = null;

		try {

			zos = new ZipOutputStream(out);

			for (File srcFile : srcFiles) {
				byte[] buf = new byte[BUFFER_SIZE];
				zos.putNextEntry(new ZipEntry(srcFile.getName()));
				int len;
				FileInputStream in = new FileInputStream(srcFile);
				while ((len = in.read(buf)) != -1) {
					zos.write(buf, 0, len);
				}
				zos.closeEntry();
				in.close();
			}
			long end = System.currentTimeMillis();
			System.out.println("压缩完成，耗时：" + (end - start) + " ms");
		} catch (Exception e) {
			throw new RuntimeException("zip error from ZipUtils", e);
		} finally {
			if (zos != null) {
				try {
					zos.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

	/**
	 * 
	 * 递归压缩方法
	 * 
	 * @param sourceFile
	 *            源文件
	 * 
	 * @param zos
	 *            zip输出流
	 * 
	 * @param name
	 *            压缩后的名称
	 * 
	 * @param KeepDirStructure
	 *            是否保留原来的目录结构,true:保留目录结构;
	 * 
	 *            false:所有文件跑到压缩包根目录下(注意：不保留目录结构可能会出现同名文件,会压缩失败)
	 * 
	 * @throws Exception
	 * 
	 */

	private static void compress(File sourceFile, ZipOutputStream zos, String name,

			boolean KeepDirStructure) throws Exception {

		byte[] buf = new byte[BUFFER_SIZE];

		if (sourceFile.isFile()) {

			// 向zip输出流中添加一个zip实体，构造器中name为zip实体的文件的名字

			zos.putNextEntry(new ZipEntry(name));

			// copy文件到zip输出流中

			int len;

			FileInputStream in = new FileInputStream(sourceFile);

			while ((len = in.read(buf)) != -1) {

				zos.write(buf, 0, len);

			}

			// Complete the entry

			zos.closeEntry();

			in.close();

		} else {

			File[] listFiles = sourceFile.listFiles();

			if (listFiles == null || listFiles.length == 0) {

				// 需要保留原来的文件结构时,需要对空文件夹进行处理

				if (KeepDirStructure) {

					// 空文件夹的处理

					zos.putNextEntry(new ZipEntry(name + "/"));

					// 没有文件，不需要文件的copy

					zos.closeEntry();

				}

			} else {

				for (File file : listFiles) {

					// 判断是否需要保留原来的文件结构

					if (KeepDirStructure) {

						// 注意：file.getName()前面需要带上父文件夹的名字加一斜杠,

						// 不然最后压缩包中就不能保留原来的文件结构,即：所有文件都跑到压缩包根目录下了

						compress(file, zos, name + "/" + file.getName(), KeepDirStructure);

					} else {

						compress(file, zos, file.getName(), KeepDirStructure);

					}

				}

			}

		}

	}

	public static void main(String[] args) throws Exception {

		/** 测试压缩方法1 */

		FileOutputStream fos1 = new FileOutputStream(new File("c:/mytest01.zip"));

		ZipUtils.toZip("D:/log", fos1, true);

		/** 测试压缩方法2 */

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

		fileList.add(new File("D:/Java/jdk1.7.0_45_64bit/bin/jar.exe"));

		fileList.add(new File("D:/Java/jdk1.7.0_45_64bit/bin/java.exe"));

		FileOutputStream fos2 = new FileOutputStream(new File("c:/mytest02.zip"));

		ZipUtils.toZip(fileList, fos2);

	}

}