com.github.hetianyi.common.http.ResourceServant Maven / Gradle / Ivy
package com.github.hetianyi.common.http;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.StringUtils;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Path;
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.List;
/**
* 文件下载工具类，支持文件下载断点续传。
* 参考 StackOverflow
*
* @author Jason He
* @version 1.0.0
* @date 2019-12-27
*/
public abstract class ResourceServant {
private static final Logger log = LoggerFactory.getLogger(ResourceServant.class);
public static final int DEFAULT_BUFFER_SIZE = 20480; // ..bytes = 20KB.
public static final long DEFAULT_EXPIRE_TIME = 604800000L; // ..ms = 1 week.
public static final String MULTIPART_BOUNDARY = "MULTIPART_BYTERANGES";
/**
* 文件下载
* @param file
* @param request
* @param response
* @throws IOException
*/
protected void serveResource(File file,
boolean enableMimetype,
HttpServletRequest request,
HttpServletResponse response) throws IOException {
Path filepath = file.toPath();
if (!Files.exists(filepath)) {
log.error("File doesn't exist at URI : {}", filepath.toAbsolutePath().toString());
response.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
Long length = file.length();
String fileName = file.getName();
FileTime lastModifiedObj = Files.getLastModifiedTime(filepath);
if (StringUtils.isEmpty(fileName) || lastModifiedObj == null) {
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
return;
}
String ext = fileName.contains(".") ? fileName.substring(fileName.lastIndexOf(".") + 1) : "";
long lastModified = LocalDateTime.ofInstant(lastModifiedObj.toInstant(), ZoneId.of(ZoneOffset.systemDefault().getId())).toEpochSecond(ZoneOffset.UTC);
String contentType = enableMimetype ? Mimetypes.getMimetype(ext) : Mimetypes.DEFAULT_MIME_TYPE;
// 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 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";
}
if (log.isDebugEnabled()) {
log.debug("Content-Type : {}", contentType);
}
// Initialize response.
response.reset();
response.setBufferSize(DEFAULT_BUFFER_SIZE);
response.setHeader("Content-Type", contentType);
response.setHeader("Content-Disposition", disposition + ";filename=\"" + new String(fileName.getBytes(), "ISO-8859-1") + "\"");
if (log.isDebugEnabled()) {
log.debug("Content-Disposition : {}", disposition);
}
response.setHeader("Accept-Ranges", "bytes");
response.setHeader("ETag", new String(fileName.getBytes(), "ISO-8859-1"));
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.
log.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);
log.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) {
log.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 + "--");
}
}
}
}
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