java浏览器文件下载实例（附源码下载地址）

   最近开始学习java，尝试实现浏览器文件下载，使用IDEA15构建了Springboot maven工程。根据网上的资料做了比较多的尝试，也遇到了
许多问题，在此记录总结一下。由于是本地局域网的测试，所以代码中的文件的源目录都是直接写死的本地目录。

方式一：

 @RequestMapping("mydownload")
    public ResponseEntity<Object> download(HttpServletResponse response) throws IOException {
        String path = "D:\\111.ts";
        File file = new File(path);
        long size = file.length();
        //为了解决中文名称乱码问题 这里是设置文件下载后的名称
        String fileName = new String("000.ts".getBytes("UTF-8"), "iso-8859-1");
        response.reset();
        response.setHeader("Accept-Ranges", "bytes");
        //设置文件下载是以附件的形式下载
        response.setHeader("Content-disposition", String.format("attachment; filename=\"%s\"", fileName));
        response.addHeader("Content-Length", String.valueOf(size));

        ServletOutputStream sos = response.getOutputStream();
        FileInputStream in = new FileInputStream(file);
        BufferedOutputStream outputStream = new BufferedOutputStream(sos);
        byte[] b = new byte[1024];
        int i = 0;
        while ((i = in.read(b)) > 0) {
            outputStream.write(b, 0, i);
        }
        outputStream.flush();
        sos.close();
        outputStream.close();
        in.close();
        return new ResponseEntity<Object>(HttpStatus.OK);
    }

方式二：

    //文件下载相关代码  与上面的方法类似
    @RequestMapping("/download")
    public String downloadFile(HttpServletRequest request, HttpServletResponse response) {
        String fileName = "111.mov";
        if (fileName != null) {
            //当前是从该工程的WEB-INF//File//下获取文件(该目录可以在下面一行代码配置)
            String realPath = request.getServletContext().getRealPath(
                    "WEB-INF/File/");
            File file = new File(realPath, fileName);
            if (file.exists()) {
                // 设置强制下载不打开
                response.setContentType("application/force-download");
                // 设置文件名
                response.addHeader("Content-Disposition",
                        "attachment;fileName=" + fileName);
                byte[] buffer = new byte[1024];
                FileInputStream fis = null;
                BufferedInputStream bis = null;
                try {
                    fis = new FileInputStream(file);
                    bis = new BufferedInputStream(fis);
                    OutputStream os = response.getOutputStream();
                    int i = bis.read(buffer);
                    while (i != -1) {
                        os.write(buffer, 0, i);
                        i = bis.read(buffer);
                    }
                    System.out.println("success");
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if (bis != null) {
                        try {
                            bis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (fis != null) {
                        try {
                            fis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
        return null;
    }

方式三（在方式一的基础上加了下载进度和下载速度的简单实现）:

@Component
    @Scope("prototype")
    @RequestMapping("/downloadFile")
    public class DownloadActionc {
        @RequestMapping("downloadFiletest")
        public ResponseEntity<Object> download(HttpServletResponse response) throws IOException {
            String path = "D:\\abc.ts";
            File file = new File(path);
            String fileName = new String("test.ts".getBytes("UTF-8"), "iso-8859-1");
            long fileTotalsize = file.length();
            System.out.println("fileTotalsize = " + fileTotalsize);
            response.reset();
            response.setHeader("Accept-Ranges", "bytes");
            response.setHeader("Content-disposition", String.format("attachment; filename=\"%s\"", fileName));
            response.addHeader("Content-Length", String.valueOf(fileTotalsize));
            ServletOutputStream sos = response.getOutputStream();
            FileInputStream in = new FileInputStream(file);
            BufferedOutputStream outputStream = new BufferedOutputStream(sos);
            byte[] b = new byte[1024 * 2];//每次传输2K
            long filecomplateSize = 0L;
            double rateSpeed = 0;//速度
            long rateProcess = 0L;//进度
            int readSize = 0;
            int i = 0;
            int nbytes = 0;
            long startTime = System.nanoTime();
            //这里是下载进度和速度的简单实现 没有使用单独的线程进行速度计算
            while ((readSize = in.read(b)) > 0) {
                if (i % 20 == 0) {
                    startTime = System.nanoTime();
                }
                filecomplateSize = filecomplateSize + readSize;
                outputStream.write(b, 0, readSize);
                nbytes = readSize + nbytes;
                if (i % 20 == 19) {
                    rateProcess = filecomplateSize / fileTotalsize;
                    //时间差  System.nanoTime()的返回值精确度是毫微秒
                    double currentTime = (System.nanoTime() - startTime);
                    //将速度转化成比较通用的MB/S
                    rateSpeed = ((nbytes / currentTime) * 1000 * 1000 * 1000) / 1024 / 1024;
                    String strrateSpeed = String.format("%.2f", rateSpeed);
                    rateSpeed = Double.valueOf(strrateSpeed);
                    System.out.println(rateSpeed);
                    System.out.println(rateSpeed);
                    nbytes = 0;
                }
                i++;
            }
            outputStream.flush();
            outputStream.close();
            sos.close();
            in.close();
            return new ResponseEntity<Object>(HttpStatus.OK);
        }

     在做下载的测试学习中了解到，浏览器的下载的目标路径程序中是不能修改的，这是浏览器自己的安全机制，所以浏览器的文件下载
是下载到浏览器中设置的默认的下载路径中。

本人是Java开发的小白，若有问题请各位大神及时指正指教。

项目下载地址(仅作为参考或者测试)：http://download.youkuaiyun.com/detail/coding13/9801171