Spring MVC大文件的断点续传（File Transfer Resume）

Spring MVC大文件的断点续传（File Transfer Resume）

博客分类： 
• Java

 

根据 HTTP/1.1 协议，客户端可以获取 response 资源的一部分，以便由于在通信中断后还能够继续前一次的请求，常见的场景包括 大文件下载、 视频播放的前进/后退等。 

以下是一个Byte-Range请求的具体HTTP信息： 

引用

【Status Code】 
206 Partial Content （出错时416） 

【Request Headers】 
Range:bytes=19448183- 

【Response Headers】 
Accept-Ranges:bytes 
Content-Length:58 
Content-Range:bytes 19448183-19448240/19448241 
Content-Type:video/mp4

详细说明可以参考HTTP/1.1（ RFC 2616）的以下部分： 

• 3.12 Range Units
• 14.5 Accept-Ranges
• 14.16 Content-Range
• 14.27 If-Range
• 14.35 Range

以下是一次请求的处理链： 
(0)Client Request -> (1)Web Server -> (2）Servlet Container -> (3）Web Framework -> (4) Your Code 

• Web Server： 一般遵循HTTP/1.1 协议都支持Byte-Range请求，比如Apache、Ngnix
• Servlet Container：大部分也支持，比如Tomcat的DefaultServlet.java
• Web Framework： Spring4.2开始支持，具体可以查看ResourceHttpRequestHandler.java

截止到第三步都是针对static resources的，如果你想经过逻辑处理后再动态返回resource的话，就到了第四步，也就是在自己写的代码里相应Byte-Range请求。 

可以通过 Spring MVC 的 XmlViewResolver中注册一个自定义的View，在Controller中返回该View来实现。 

 ModelAndView mv = new ModelAndView("byteRangeViewRender");
 mv.addObject("file", new File("C:\\RenSanNing\\xxx.mp4"));
 mv.addObject("contentType", "video/mp4");
 return mv;

这样具体的Byte-Range请求处理都将会在ByteRangeViewRender中进行。ByteRangeViewRender的具体实现可以参考Tomcat的DefaultServlet.java和Spring的ResourceHttpRequestHandler.java。 

以下是一个写好的View： 

 public class ByteRangeViewRender extends AbstractView {

     // Constants ----------------------------------------------------------------------------------

     private static final int DEFAULT_BUFFER_SIZE = 20480; // ..bytes = 20KB.
     private static final long DEFAULT_EXPIRE_TIME = 604800000L; // ..ms = 1 week.
     private static final String MULTIPART_BOUNDARY = "MULTIPART_BYTERANGES";

     @Override
     protected void renderMergedOutputModel(Map objectMap,
             HttpServletRequest request, HttpServletResponse response)
             throws Exception {

         File file = (File) objectMap.get("file");
         if (file == null || !file.exists()) {
             response.sendError(HttpServletResponse.SC_NOT_FOUND);
             return;
         }

         String contentType = (String) objectMap.get("contentType");

         String fileName = file.getName();
         long length = file.length();
         long lastModified = file.lastModified();
         String eTag = fileName + "_" + length + "_" + lastModified;
         long expires = System.currentTimeMillis() + DEFAULT_EXPIRE_TIME;

         // Validate request headers for caching ---------------------------------------------------

         // If-None-Match header should contain "*" or ETag. If so, then return 304.
         String ifNoneMatch = request.getHeader("If-None-Match");
         if (ifNoneMatch != null && matches(ifNoneMatch, fileName)) {
             response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
             response.setHeader("ETag", eTag); // Required in 304.
             response.setDateHeader("Expires", expires); // Postpone cache with 1 week.
             return;
         }

         // If-Modified-Since header should be greater than LastModified. If so, then return 304.
         // This header is ignored if any If-None-Match header is specified.
         long ifModifiedSince = request.getDateHeader("If-Modified-Since");
         if (ifNoneMatch == null && ifModifiedSince != -1 && ifModifiedSince + 1000 > lastModified) {
             response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
             response.setHeader("ETag", eTag); // Required in 304.
             response.setDateHeader("Expires", expires); // Postpone cache with 1 week.
             return;
         }

         // Validate request headers for resume ----------------------------------------------------

         // If-Match header should contain "*" or ETag. If not, then return 412.
         String ifMatch = request.getHeader("If-Match");
         if (ifMatch != null && !matches(ifMatch, fileName)) {
             response.sendError(HttpServletResponse.SC_PRECONDITION_FAILED);
             return;
         }

         // If-Unmodified-Since header should be greater than LastModified. If not, then return 412.
         long ifUnmodifiedSince = request.getDateHeader("If-Unmodified-Since");
         if (ifUnmodifiedSince != -1 && ifUnmodifiedSince + 1000 <= lastModified) {
             response.sendError(HttpServletResponse.SC_PRECONDITION_FAILED);
             return;
         }

         // Validate and process range -------------------------------------------------------------

         // Prepare some variables. The full Range represents the complete file.
         Range full = new Range(0, length - 1, length);
         List ranges = new ArrayList();

         // Validate and process Range and If-Range headers.
         String range = request.getHeader("Range");
         if (range != null) {

             // Range header should match format "bytes=n-n,n-n,n-n...". If not, then return 416.
             if (!range.matches("^bytes=\\d*-\\d*(,\\d*-\\d*)*$")) {
                 response.setHeader("Content-Range", "bytes */" + length); // Required in 416.
                 response.sendError(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                 return;
             }

             String ifRange = request.getHeader("If-Range");
             if (ifRange != null && !ifRange.equals(eTag)) {
                 try {
                     long ifRangeTime = request.getDateHeader("If-Range"); // Throws IAE if invalid.
                     if (ifRangeTime != -1 && ifRangeTime + 1000 < lastModified) {
                         ranges.add(full);
                     }
                 } catch (IllegalArgumentException ignore) {
                     ranges.add(full);
                 }
             }

             // If any valid If-Range header, then process each part of byte range.
             if (ranges.isEmpty()) {
                 for (String part : range.substring(6).split(",")) {
                     // Assuming a file with length of 100, the following examples returns bytes at:
                     // 50-80 (50 to 80), 40- (40 to length=100), -20 (length-20=80 to length=100).
                     long start = sublong(part, 0, part.indexOf("-"));
                     long end = sublong(part, part.indexOf("-") + 1, part.length());

                     if (start == -1) {
                         start = length - end;
                         end = length - 1;
                     } else if (end == -1 || end > length - 1) {
                         end = length - 1;
                     }

                     // Check if Range is syntactically valid. If not, then return 416.
                     if (start > end) {
                         response.setHeader("Content-Range", "bytes */" + length); // Required in 416.
                         response.sendError(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                         return;
                     }

                     // Add range.
                     ranges.add(new Range(start, end, length));
                 }
             }
         }

         // Prepare and initialize response --------------------------------------------------------

         // Get content type by file name and set content disposition.
         String disposition = "inline";

         // If content type is unknown, then set the default value.
         // For all content types, see: http://www.w3schools.com/media/media_mimeref.asp
         // To add new content types, add new mime-mapping entry in web.xml.
         if (contentType == null) {
             contentType = "application/octet-stream";
         } else if (!contentType.startsWith("image")) {
             // Else, expect for images, determine content disposition. If content type is supported by
             // the browser, then set to inline, else attachment which will pop a 'save as' dialogue.
             String accept = request.getHeader("Accept");
             disposition = accept != null && accepts(accept, contentType) ? "inline" : "attachment";
         }

         // Initialize response.
         response.reset();
         response.setBufferSize(DEFAULT_BUFFER_SIZE);
         response.setHeader("Content-Disposition", disposition + ";filename=\"" + fileName + "\"");
         response.setHeader("Accept-Ranges", "bytes");
         response.setHeader("ETag", eTag);
         response.setDateHeader("Last-Modified", lastModified);
         response.setDateHeader("Expires", expires);

         // Send requested file (part(s)) to client ------------------------------------------------

         // Prepare streams.
         RandomAccessFile input = null;
         OutputStream output = null;

         try {
             // Open streams.
             input = new RandomAccessFile(file, "r");
             output = response.getOutputStream();

             if (ranges.isEmpty() || ranges.get(0) == full) {

                 // Return full file.
                 Range r = full;
                 response.setContentType(contentType);
                 response.setHeader("Content-Range", "bytes " + r.start + "-" + r.end + "/" + r.total);
                 response.setHeader("Content-Length", String.valueOf(r.length));

                 copy(input, output, r.start, r.length);

             } else if (ranges.size() == 1) {

                 // Return single part of file.
                 Range r = ranges.get(0);
                 response.setContentType(contentType);
                 response.setHeader("Content-Range", "bytes " + r.start + "-" + r.end + "/" + r.total);
                 response.setHeader("Content-Length", String.valueOf(r.length));
                 response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT); // 206.

                 // Copy single part range.
                 copy(input, output, r.start, r.length);

             } else {

                 // Return multiple parts of file.
                 response.setContentType("multipart/byteranges; boundary=" + MULTIPART_BOUNDARY);
                 response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT); // 206.

                 // Cast back to ServletOutputStream to get the easy println methods.
                 ServletOutputStream sos = (ServletOutputStream) output;

                 // Copy multi part range.
                 for (Range r : ranges) {
                     // Add multipart boundary and header fields for every range.
                     sos.println();
                     sos.println("--" + MULTIPART_BOUNDARY);
                     sos.println("Content-Type: " + contentType);
                     sos.println("Content-Range: bytes " + r.start + "-" + r.end + "/" + r.total);

                     // Copy single part range of multi part range.
                     copy(input, output, r.start, r.length);
                 }

                 // End with multipart boundary.
                 sos.println();
                 sos.println("--" + MULTIPART_BOUNDARY + "--");
             }
         } finally {
             close(output);
             close(input);
         }

     }

     // Helpers (can be refactored to public utility class) ----------------------------------------

     private void close(Closeable resource) {
         if (resource != null) {
             try {
                 resource.close();
             } catch (IOException ignore) {
             }
         }
     }

     private void copy(RandomAccessFile input, OutputStream output, long start, long length) throws IOException {
         byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
         int read;

         try {
             if (input.length() == length) {
                 // Write full range.
                 while ((read = input.read(buffer)) > 0) {
                     output.write(buffer, 0, read);
                 }
             } else {
                 input.seek(start);
                 long toRead = length;

                 while ((read = input.read(buffer)) > 0) {
                     if ((toRead -= read) > 0) {
                         output.write(buffer, 0, read);
                     } else {
                         output.write(buffer, 0, (int) toRead + read);
                         break;
                     }
                 }
             }
         } catch (IOException ignore) {
         }
     }

     private long sublong(String value, int beginIndex, int endIndex) {
         String substring = value.substring(beginIndex, endIndex);
         return (substring.length() > 0) ? Long.parseLong(substring) : -1;
     }

     private boolean accepts(String acceptHeader, String toAccept) {
         String[] acceptValues = acceptHeader.split("\\s*(,|;)\\s*");
         Arrays.sort(acceptValues);
         return Arrays.binarySearch(acceptValues, toAccept) > -1
             || Arrays.binarySearch(acceptValues, toAccept.replaceAll("/.*$", "/*")) > -1
             || Arrays.binarySearch(acceptValues, "*/*") > -1;
     }

     private boolean matches(String matchHeader, String toMatch) {
         String[] matchValues = matchHeader.split("\\s*,\\s*");
         Arrays.sort(matchValues);
         return Arrays.binarySearch(matchValues, toMatch) > -1
             || Arrays.binarySearch(matchValues, "*") > -1;
     }

     // Inner classes ------------------------------------------------------------------------------

     protected class Range {
         long start;
         long end;
         long length;
         long total;

         public Range(long start, long end, long total) {
             this.start = start;
             this.end = end;
             this.length = end - start + 1;
             this.total = total;
         }
     }

 }

大文件上传时显示进度条 

1）application-context.xml 

 <bean id="multipartResolver" class="com.rensanning.test.core.fileupload.CustomMultipartResolver">
     <property name="defaultEncoding" value="UTF-8"/>
     <property name="fileSizeMax" value="20971520"/>
     <property name="maxUploadSize" value="52428800"/>
 bean>

2）CustomMultipartResolver.java 

 public class CustomMultipartResolver extends CommonsMultipartResolver {

     @Autowired
     private CustomProgressListener progressListener;

     public void setFileUploadProgressListener(CustomProgressListener progressListener){
         this.progressListener = progressListener;
     }

     public void setFileSizeMax(long fileSizeMax) {
         getFileUpload().setFileSizeMax(fileSizeMax);
     }

     @Override
     public MultipartParsingResult parseRequest(HttpServletRequest request) throws MultipartException {
         String encoding = determineEncoding(request);
         FileUpload fileUpload = prepareFileUpload(encoding);

         progressListener.setSession(request.getSession());
         fileUpload.setProgressListener(progressListener);

         try {
             List fileItems = ((ServletFileUpload) fileUpload).parseRequest(request);
             return parseFileItems(fileItems, encoding);
         }
         catch (FileUploadBase.SizeLimitExceededException ex) {
             throw new MaxUploadSizeExceededException(fileUpload.getSizeMax(), ex);
         }
         catch (FileUploadBase.FileSizeLimitExceededException ex) {
             throw new MaxUploadSizeExceededException(fileUpload.getFileSizeMax(), ex);
         }
         catch (FileUploadException ex) {
             throw new MultipartException("Could not parse multipart servlet request", ex);
         }
     }

 }

3）CustomProgressListener.java 

 @Component
 public class CustomProgressListener implements ProgressListener {

     private HttpSession session;

     public void setSession(HttpSession session){
         this.session = session;
         ProgressInfo ps = new ProgressInfo();
         this.session.setAttribute(Constants.SESSION_KEY_UPLOAD_PROGRESS_INFO, ps);
     }

     @Override
     public void update(long pBytesRead, long pContentLength, int pItems) {
         ProgressInfo ps = (ProgressInfo) session.getAttribute(Constants.SESSION_KEY_UPLOAD_PROGRESS_INFO);
         ps.setBytesRead(pBytesRead);
         ps.setContentLength(pContentLength);
         ps.setItemSeq(pItems);
     }

 }

4）ProgressInfo.java 

 public class ProgressInfo {
     private long bytesRead;
     private long contentLength;
     private int itemSeq;

     public long getBytesRead() {
         return bytesRead;
     }
     public void setBytesRead(long bytesRead) {
         this.bytesRead = bytesRead;
     }
     public long getContentLength() {
         return contentLength;
     }
     public void setContentLength(long contentLength) {
         this.contentLength = contentLength;
     }
     public int getItemSeq() {
         return itemSeq;
     }
     public void setItemSeq(int itemSeq) {
         this.itemSeq = itemSeq;
     }
 }

5）Controller 

 @ResponseBody
 @RequestMapping(value = "admin/common/getProgress.do", method = RequestMethod.GET)
 public String getProgress(HttpServletRequest request, HttpServletResponse response) {
     if (request.getSession().getAttribute(Constants.SESSION_KEY_UPLOAD_PROGRESS_INFO) == null) {
         return "";
     }
     ProgressInfo ps = (ProgressInfo) request.getSession().getAttribute(Constants.SESSION_KEY_UPLOAD_PROGRESS_INFO);
     Double percent = 0d;
     if (ps.getContentLength() != 0L) {
         percent = (double) ps.getBytesRead() / (double) ps.getContentLength() * 1.0d;
         if (percent != 0d) {
             DecimalFormat df = new DecimalFormat("0.00");
             percent = Double.parseDouble(df.format(percent));
         }
     }
     int pp = (int)(percent * 100);
     return String.valueOf(pp);
 }

6）JSP 

 <div class="control-group" id="progressbar" style="display:none;">
   <div class="progress progress-striped active">
     <div class="bar" id="progressbardata" style="width: 0;">div>
   div>
 div>

 <script language="javascript">
 function upload() {
     $('#uploadForm').submit();
     var interval = setInterval(function() {
         $.ajax({
              dataType : "json",
              url : "<%=request.getContextPath()%>/admin/common/getProgress.do",
              contentType : "application/json; charset=utf-8",
              type : "GET",
              success : function(data, stats) {
                 if(data) {
                     $('#progressbar').show();
                     console.log(data);
                     if (data == '100') {
                        clearInterval(interval);
                     } else {
                         $('#progressbardata').width(data+'%');
                     }
                 }
              }
         });
     }, 100);
 }
 script>