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

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<String, Object> 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<Range> ranges = new ArrayList<Range>();

        // 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;
        }
    }
    
}

通过ProgressListener实现大文件上传时进度条的显示

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"/><!-- 20M ： Maximum size of a single uploaded file-->
    <property name="maxUploadSize" value="52428800"/><!-- 50M ： The maximum allowed size of a complete request-->
</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<FileItem> 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>

参考：
How to Implement HTTP byte-range requests in Spring MVC
Implementing HTTP byte-range requests in Spring MVC
FileServlet supporting resume and caching and GZIP

评论

2 楼 ausit 2015-12-13  

请问，函数在getFileUpload().setFileSizeMax(fileSizeMax);
在哪里 ？能分享个能跑的demo么，谢谢

1 楼 lis1314 2015-10-28  

mark!