5、SpingBoot文件上传、多文件上传、文件下载(断点续传)

文件上传

SpringBoot的文件上传相对比较简单，文件信息都包含在MultipartFile对象中，只要从中获取文件信息即可
不煽情，直接上代码吧，这个部分出门右拐“百度一下”一大堆

/*** 单文件上传* * @param name 携带的其他文本表单(可以省略)* @param file 文件内容* @return*/@RequestMapping(value = "/upload_single", method = RequestMethod.POST)public @ResponseBody String handleFileUpload(@RequestParam("name") String name,            @RequestParam("file") MultipartFile file) {    if (!file.isEmpty()) {        BufferedOutputStream out = null;        try {            byte[] bytes = file.getBytes();            out = new BufferedOutputStream(                        new FileOutputStream(new File(BASE_PATH + "\\" + name + "-" + file.getOriginalFilename())));            out.write(bytes);            return "You successfully uploaded " + name + " into " + name + "-uploaded !";        } catch (Exception e) {            return "You failed to upload " + name + " => " + e.getMessage();        } finally {            if (null != out) {                try {                    out.close();                } catch (IOException e) {                        e.printStackTrace();                }            }        }    } else {        return "You failed to upload " + name + " because the file was empty.";    }}

测试：

<p>单文件上传</p><form method="POST" enctype="multipart/form-data"        action="/upload_single">       File to upload: <input type="file" name="file"/><br />      Name: <input type="text" name="name"/>    <input type="submit"  value="单文件上传"/></form> 

多文件上传

多文件上传需要接收解析出MultipartHttpServletRequest对象中包含的文件信息

/*** 多文件上传，主要是使用了MultipartHttpServletRequest和MultipartFile* * @param name 携带的其他文本表单(可以省略)* @param request* @return*/@RequestMapping(value = "/upload", method = RequestMethod.POST)public @ResponseBody String handleFileUpload(HttpServletRequest request,@RequestParam("name") String name) {    List<MultipartFile> files = ((MultipartHttpServletRequest) request).getFiles("file");    System.out.println("name==>"+name);    MultipartFile file = null;    BufferedOutputStream out = null;    for (int i = 0; i < files.size(); ++i) {        file = files.get(i);        if (!file.isEmpty()) {            try {                byte[] bytes = file.getBytes();                out = new BufferedOutputStream(new FileOutputStream(new File(BASE_PATH + "\\" + file.getOriginalFilename())));                out.write(bytes);            } catch (Exception e) {                return "failed to upload " + i + " => " + e.getMessage();            } finally {                if (null != out) {                    try {                        out.close();                    } catch (IOException e) {                        e.printStackTrace();                    }                    out = null;                }            }        } else {            return "failed to upload " + i + " because the file was empty.";        }    }    return "upload successful";}

测试：

<p>多文件上传</p><form method="POST" enctype="multipart/form-data"        action="/upload">    Name: <input type="text" name="name"/>    <p>文件1：<input type="file" name="file" /></p>    <p>文件2：<input type="file" name="file" /></p>    <p><input type="submit" value="多文件上传" /></p></form>

文件下载（断点续传）

相对于上传在文件下载的处理上，需要自己处理HttpServletResponse中流的返回，这里直接上一个有断点续传的代码：

@RequestMapping(value = "/download", method = RequestMethod.GET)public void getDownload(String name, HttpServletRequest request, HttpServletResponse response) {        // Get your file stream from wherever.        String fullPath = "D:\\upload_test\\" + name;        File downloadFile = new File(fullPath);        ServletContext context = request.getServletContext();        // get MIME type of the file        String mimeType = context.getMimeType(fullPath);        if (mimeType == null) {            // set to binary type if MIME mapping not found            mimeType = "application/octet-stream";        }        // set content attributes for the response        response.setContentType(mimeType);        // response.setContentLength((int) downloadFile.length());        // set headers for the response        String headerKey = "Content-Disposition";        String headerValue = String.format("attachment; filename=\"%s\"", downloadFile.getName());        response.setHeader(headerKey, headerValue);        // 解析断点续传相关信息        response.setHeader("Accept-Ranges", "bytes");        long downloadSize = downloadFile.length();        long fromPos = 0, toPos = 0;        if (request.getHeader("Range") == null) {            response.setHeader("Content-Length", downloadSize + "");        } else {            // 若客户端传来Range，说明之前下载了一部分，设置206状态(SC_PARTIAL_CONTENT)            response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);            String range = request.getHeader("Range");            String bytes = range.replaceAll("bytes=", "");            String[] ary = bytes.split("-");            fromPos = Long.parseLong(ary[0]);            if (ary.length == 2) {                toPos = Long.parseLong(ary[1]);            }            int size;            if (toPos > fromPos) {                size = (int) (toPos - fromPos);            } else {                size = (int) (downloadSize - fromPos);            }            response.setHeader("Content-Length", size + "");            downloadSize = size;        }        // Copy the stream to the response's output stream.        RandomAccessFile in = null;        OutputStream out = null;        try {            in = new RandomAccessFile(downloadFile, "rw");            // 设置下载起始位置            if (fromPos > 0) {                in.seek(fromPos);            }            // 缓冲区大小            int bufLen = (int) (downloadSize < 2048 ? downloadSize : 2048);            byte[] buffer = new byte[bufLen];            int num;            int count = 0; // 当前写到客户端的大小            out = response.getOutputStream();            while ((num = in.read(buffer)) != -1) {                out.write(buffer, 0, num);                count += num;                //处理最后一段，计算不满缓冲区的大小                if (downloadSize - count < bufLen) {                    bufLen = (int) (downloadSize-count);                    if(bufLen==0){                        break;                    }                    buffer = new byte[bufLen];                }            }            response.flushBuffer();        } catch (IOException e) {            e.printStackTrace();        } finally {            if (null != out) {                try {                    out.close();                } catch (IOException e) {                    e.printStackTrace();                }            }            if (null != in) {                try {                    in.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }}

该部分本人直接在Android客户端上测试：
下载代码：

public static boolean downLoadFile(String url, int from, int to,String savePath) {    try {        URL link = new URL(url);        HttpURLConnection conn = (HttpURLConnection) link.openConnection();        // 设置断点续传的开始位置        if (to != 0) {                conn.setRequestProperty("Range", "bytes=" + from + "-" + to);        }else{            conn.setRequestProperty("Range", "bytes=" + from + "-");        }        Log.e("m_tag", "code:" + conn.getResponseCode());        if (conn.getResponseCode() == 206) {            RandomAccessFile file = new RandomAccessFile(savePath, "rw");            file.seek(from);            InputStream in = conn.getInputStream();            byte[] buffer = new byte[1024];            int num;            while ((num = in.read(buffer)) > 0) {                file.write(buffer, 0, num);            }            file.close();            in.close();            return true;        }    } catch (Exception e) {        // TODO Auto-generated catch block        e.printStackTrace();    }    return false;}

Activity中运用：

class MyTask extends AsyncTask<Object, Integer, Object> {        @Override        protected Object doInBackground(Object... params) {                String uri = (String) params[0];                int from = (Integer) params[1];                int to = (Integer) params[2];                String savePath = (String) params[3];                return HttpUtil.downLoadFile(uri, from, to, savePath);        }        @Override        protected void onPostExecute(Object result) {            // TODO Auto-generated method stub            super.onPostExecute(result);            tvRes.setText(result.toString());        }}//这里用两个按钮点击模拟分段，第一个按钮下载0-50B，第二个从50B下载到末尾...省略其他部分...case R.id.btn_part_01:    new MyTask().execute("http://192.168.2.183:8080/download?name=11.jpg",0, 50, "/mnt/sdcard/pic_123.jpg");break;case R.id.btn_part_02:    new MyTask().execute("http://192.168.2.183:8080/download?name=11.jpg",50, 0, "/mnt/sdcard/pic_123.jpg");break;...省略其他部分...

[附]

文件上传时相对路径配置

以上的上传文件可以保存到服务器端的D:\upload_test但是对于这个路径，客户端如果想要使用一个相对路径来访问的话，需要做以下配置：

1、在application.properties中声明一个变量描述该地址

#图片上传存储路径imagesPath=file:/D:/upload_test/

2、定义一个配置文件可以将该绝对路径映射到一个/images的相对路径上

package com.example.demo.config;import org.apache.log4j.spi.LoggerFactory;import org.springframework.beans.factory.annotation.Value;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;@Configurationpublic class FileConfig extends WebMvcConfigurerAdapter {    @Value("${imagesPath}")     private String mImagesPath;    @Override    public void addResourceHandlers(ResourceHandlerRegistry registry) {        if (mImagesPath.equals("") || mImagesPath.equals("${imagesPath}")) {            String imagesPath = FileConfig.class.getClassLoader().getResource("").getPath();            if (imagesPath.indexOf(".jar") > 0) {                imagesPath = imagesPath.substring(0, imagesPath.indexOf(".jar"));            } else if (imagesPath.indexOf("classes") > 0) {                imagesPath = "file:" + imagesPath.substring(0, imagesPath.indexOf("classes"));            }            imagesPath = imagesPath.substring(0, imagesPath.lastIndexOf("/")) + "/images/";            mImagesPath = imagesPath;        }        System.out.println("imagesPath=" + mImagesPath);        registry.addResourceHandler("/images/**").addResourceLocations(mImagesPath);        super.addResourceHandlers(registry);    }}

这样之后对于服务器上D:\upload_test\1.jpg这个图片可以在客户端直接使用http://127.0.0.1:8080/images/1.jpg这个路径就可以访问了