在使用Spring/SpringBoot做文件服务（对外提供文件流下载等）的时候，如果是音频视频，最好是提供断点续传功能，这样能可以支持客户端软件的断点续传功能，或者更好的音视频播放的播放、拖动等功能。
实现
- 实现方法1
新版本的Spring或者SpringBoot是直接支持的，示例如下：
// 也可以是video/* 或者下载文件application/octet-stream
@GetMapping(value = "/audio/some.mp3", produces = "audio/*")
public ResponseEntity<FileSystemResource> serveMediaFile() {
File file = new File("/path/to/file");
return ResponseEntity.ok().body(new FileSystemResource(file));
}
- 实现方法2
有开发者已经写好了相关的工具类，无论在什么框架中都能使用
请出我们的工具类：MultipartFileSender.java 如下
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.FileTime;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* @author Terry E-mail: yaoxinghuo at 126 dot com
* @date 2022/8/24 16:05
* @description
* taken from: https://github.com/davinkevin/Podcast-Server/blob/d927d9b8cb9ea1268af74316cd20b7192ca92da7/src/main/java/lan/dk/podcastserver/utils/multipart/MultipartFileSender.java
*/
@Slf4j
public class MultipartFileSender {
private final Logger logger = LoggerFactory.getLogger(MultipartFileSender.class);
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";
Path filepath;
HttpServletRequest request;
HttpServletResponse response;
public MultipartFileSender() {
}
public static MultipartFileSender fromPath(Path path) {
return new MultipartFileSender().setFilepath(path);
}
public static MultipartFileSender fromFile(File file) {
return new MultipartFileSender().setFilepath(file.toPath());
}
public static MultipartFileSender fromURIString(String uri) {
return new MultipartFileSender().setFilepath(Paths.get(uri));
}
//** internal setter **//
private MultipartFileSender setFilepath(Path filepath) {
this.filepath = filepath;
return this;
}
public MultipartFileSender with(HttpServletRequest httpRequest) {
request = httpRequest;
return this;
}
public MultipartFileSender with(HttpServletResponse httpResponse) {
response = httpResponse;
return this;
}
public void serveResource() throws Exception {
if (response == null || request == null) {
return;
}
if (!Files.exists(filepath)) {
logger.error("File doesn't exist at URI : {}", filepath.toAbsolutePath().toString());
response.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
Long length = Files.size(filepath);
String fileName = filepath.getFileName().toString();
FileTime lastModifiedObj = Files.getLastModifiedTime(filepath);
if (StringUtils.isEmpty(fileName) || lastModifiedObj == null) {
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
return;
}
long lastModified = LocalDateTime.ofInstant(lastModifiedObj.toInstant(), ZoneId.of(ZoneOffset.systemDefault().getId())).toEpochSecond(ZoneOffset.UTC);
String contentType = "video/mp4";
// 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 && HttpUtils.matches(ifNoneMatch, fileName)) {
response.setHeader("ETag", fileName); // Required in 304.
response.sendError(HttpServletResponse.SC_NOT_MODIFIED);
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.setHeader("ETag", fileName); // Required in 304.
response.sendError(HttpServletResponse.SC_NOT_MODIFIED);
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 && !HttpUtils.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<>();
// 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(fileName)) {
try {
long ifRangeTime = request.getDateHeader("If-Range"); // Throws IAE if invalid.
if (ifRangeTime != -1) {
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 = Range.sublong(part, 0, part.indexOf("-"));
long end = Range.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 && HttpUtils.accepts(accept, contentType) ? "inline" : "attachment";
}
logger.debug("Content-Type : {}", contentType);
// Initialize response.
response.reset();
response.setBufferSize(DEFAULT_BUFFER_SIZE);
response.setHeader("Content-Type", contentType);
response.setHeader("Content-Disposition", disposition + ";filename=\"" + fileName + "\"");
logger.debug("Content-Disposition : {}", disposition);
response.setHeader("Accept-Ranges", "bytes");
response.setHeader("ETag", fileName);
response.setDateHeader("Last-Modified", lastModified);
response.setDateHeader("Expires", System.currentTimeMillis() + DEFAULT_EXPIRE_TIME);
// Send requested file (part(s)) to client ------------------------------------------------
// Prepare streams.
try (InputStream input = new BufferedInputStream(Files.newInputStream(filepath));
OutputStream output = response.getOutputStream()) {
if (ranges.isEmpty() || ranges.get(0) == full) {
// Return full file.
logger.info("Return full file");
response.setContentType(contentType);
response.setHeader("Content-Range", "bytes " + full.start + "-" + full.end + "/" + full.total);
response.setHeader("Content-Length", String.valueOf(full.length));
Range.copy(input, output, length, full.start, full.length);
} else if (ranges.size() == 1) {
// Return single part of file.
Range r = ranges.get(0);
logger.info("Return 1 part of file : from ({}) to ({})", r.start, r.end);
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.
Range.copy(input, output, length, 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) {
logger.info("Return multi part of file : from ({}) to ({})", r.start, r.end);
// 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.
Range.copy(input, output, length, r.start, r.length);
}
// End with multipart boundary.
sos.println();
sos.println("--" + MULTIPART_BOUNDARY + "--");
}
}
}
private static class Range {
long start;
long end;
long length;
long total;
/**
* Construct a byte range.
* @param start Start of the byte range.
* @param end End of the byte range.
* @param total Total length of the byte source.
*/
public Range(long start, long end, long total) {
this.start = start;
this.end = end;
this.length = end - start + 1;
this.total = total;
}
public static long sublong(String value, int beginIndex, int endIndex) {
String substring = value.substring(beginIndex, endIndex);
return (substring.length() > 0) ? Long.parseLong(substring) : -1;
}
private static void copy(InputStream input, OutputStream output, long inputSize, long start, long length) throws IOException {
byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
int read;
if (inputSize == length) {
// Write full range.
while ((read = input.read(buffer)) > 0) {
output.write(buffer, 0, read);
output.flush();
}
} else {
input.skip(start);
long toRead = length;
while ((read = input.read(buffer)) > 0) {
if ((toRead -= read) > 0) {
output.write(buffer, 0, read);
output.flush();
} else {
output.write(buffer, 0, (int) toRead + read);
output.flush();
break;
}
}
}
}
}
private static class HttpUtils {
/**
* Returns true if the given accept header accepts the given value.
* @param acceptHeader The accept header.
* @param toAccept The value to be accepted.
* @return True if the given accept header accepts the given value.
*/
public static 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;
}
/**
* Returns true if the given match header matches the given value.
* @param matchHeader The match header.
* @param toMatch The value to be matched.
* @return True if the given match header matches the given value.
*/
public static 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;
}
}
}
在Controller中调用：
@GetMapping(value = "/audio/{mediaId}.{ext}", produces = MediaType.APPLICATION_OCTET_STREAM_VALUE)
public void serveFile(HttpServletRequest request, HttpServletResponse response) throws Exception {
File file = new File("/path/to/file");
MultipartFileSender.fromFile(file)
.with(request)
.with(response)
.serveResource();
}
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