webserver/src/main/java/org/nanohttpd/webserver/SimpleWebServer.java
Response serveFile(String uri, Map<String, String> header, File file, String mime) {
        Response res;
        try {
            // Calculate etag
            String etag = Integer.toHexString((file.getAbsolutePath() + file.lastModified() + "" + file.length()).hashCode());

            // Support (simple) skipping:
            long startFrom = 0;
            long endAt = -1;
            String range = header.get("range");
            if (range != null) {
                if (range.startsWith("bytes=")) {
                    range = range.substring("bytes=".length());
                    int minus = range.indexOf('-');
                    try {
                        if (minus > 0) {
                            startFrom = Long.parseLong(range.substring(0, minus));
                            endAt = Long.parseLong(range.substring(minus + 1));
                        }
                    } catch (NumberFormatException ignored) {
                    }
                }
            }

            // get if-range header. If present, it must match etag or else we
            // should ignore the range request
            String ifRange = header.get("if-range");
            boolean headerIfRangeMissingOrMatching = (ifRange == null || etag.equals(ifRange));

            String ifNoneMatch = header.get("if-none-match");
            boolean headerIfNoneMatchPresentAndMatching = ifNoneMatch != null && ("*".equals(ifNoneMatch) || ifNoneMatch.equals(etag));

            // Change return code and add Content-Range header when skipping is
            // requested
            long fileLen = file.length();

            if (headerIfRangeMissingOrMatching && range != null && startFrom >= 0 && startFrom < fileLen) {
                // range request that matches current etag
                // and the startFrom of the range is satisfiable
                if (headerIfNoneMatchPresentAndMatching) {
                    // range request that matches current etag
                    // and the startFrom of the range is satisfiable
                    // would return range from file
                    // respond with not-modified
                    res = newFixedLengthResponse(Status.NOT_MODIFIED, mime, "");
                    res.addHeader("ETag", etag);
                } else {
                    if (endAt < 0) {
                        endAt = fileLen - 1;
                    }
                    long newLen = endAt - startFrom + 1;
                    if (newLen < 0) {
                        newLen = 0;
                    }

                    FileInputStream fis = new FileInputStream(file);
                    fis.skip(startFrom);

                    res = Response.newFixedLengthResponse(Status.PARTIAL_CONTENT, mime, fis, newLen);
                    res.addHeader("Accept-Ranges", "bytes");
                    res.addHeader("Content-Length", "" + newLen);
                    res.addHeader("Content-Range", "bytes " + startFrom + "-" + endAt + "/" + fileLen);
                    res.addHeader("ETag", etag);
                }
            } else {

                if (headerIfRangeMissingOrMatching && range != null && startFrom >= fileLen) {
                    // return the size of the file
                    // 4xx responses are not trumped by if-none-match
                    res = newFixedLengthResponse(Status.RANGE_NOT_SATISFIABLE, NanoHTTPD.MIME_PLAINTEXT, "");
                    res.addHeader("Content-Range", "bytes */" + fileLen);
                    res.addHeader("ETag", etag);
                } else if (range == null && headerIfNoneMatchPresentAndMatching) {
                    // full-file-fetch request
                    // would return entire file
                    // respond with not-modified
                    res = newFixedLengthResponse(Status.NOT_MODIFIED, mime, "");
                    res.addHeader("ETag", etag);
                } else if (!headerIfRangeMissingOrMatching && headerIfNoneMatchPresentAndMatching) {
                    // range request that doesn't match current etag
                    // would return entire (different) file
                    // respond with not-modified

                    res = newFixedLengthResponse(Status.NOT_MODIFIED, mime, "");
                    res.addHeader("ETag", etag);
                } else {
                    // supply the file
                    res = newFixedFileResponse(file, mime);
                    res.addHeader("Content-Length", "" + fileLen);
                    res.addHeader("ETag", etag);
                }
            }
        } catch (IOException ioe) {
            res = getForbiddenResponse("Reading file failed.");
        }

        return res;
    }
Response serveFile(String uri, Map<String, String> header, File file, String mime) {
        Response res;
        try {
            // Calculate etag
            String etag = Integer.toHexString((file.getAbsolutePath() + file.lastModified() + "" + file.length()).hashCode());

            // Support (simple) skipping:
            long startFrom = 0;
            long endAt = -1;
            String range = header.get("range");
            if (range != null) {
                if (range.startsWith("bytes=")) {
                    range = range.substring("bytes=".length());
                    int minus = range.indexOf('-');
                    try {
                        if (minus > 0) {
                            startFrom = Long.parseLong(range.substring(0, minus));
                            endAt = Long.parseLong(range.substring(minus + 1));
                        }
                    } catch (NumberFormatException ignored) {
                    }
                }
            }

            // get if-range header. If present, it must match etag or else we
            // should ignore the range request
            String ifRange = header.get("if-range");
            boolean headerIfRangeMissingOrMatching = (ifRange == null || etag.equals(ifRange));

            String ifNoneMatch = header.get("if-none-match");
            boolean headerIfNoneMatchPresentAndMatching = ifNoneMatch != null && ("*".equals(ifNoneMatch) || ifNoneMatch.equals(etag));

            // Change return code and add Content-Range header when skipping is
            // requested
            long fileLen = file.length();

            if (headerIfRangeMissingOrMatching && range != null && startFrom >= 0 && startFrom < fileLen) {
                // range request that matches current etag
                // and the startFrom of the range is satisfiable
                if (headerIfNoneMatchPresentAndMatching) {
                    // range request that matches current etag
                    // and the startFrom of the range is satisfiable
                    // would return range from file
                    // respond with not-modified
                    res = newFixedLengthResponse(Status.NOT_MODIFIED, mime, "");
                    res.addHeader("ETag", etag);
                } else {
                    if (endAt < 0) {
                        endAt = fileLen - 1;
                    }
                    long newLen = endAt - startFrom + 1;
                    if (newLen < 0) {
                        newLen = 0;
                    }

                    FileInputStream fis = new FileInputStream(file);
                    fis.skip(startFrom);

                    res = Response.newFixedLengthResponse(Status.PARTIAL_CONTENT, mime, fis, newLen);
                    res.addHeader("Accept-Ranges", "bytes");
                    res.addHeader("Content-Length", "" + newLen);
                    res.addHeader("Content-Range", "bytes " + startFrom + "-" + endAt + "/" + fileLen);
                    res.addHeader("ETag", etag);
                }
            } else {

                if (headerIfRangeMissingOrMatching && range != null && startFrom >= fileLen) {
                    // return the size of the file
                    // 4xx responses are not trumped by if-none-match
                    res = newFixedLengthResponse(Status.RANGE_NOT_SATISFIABLE, NanoHTTPD.MIME_PLAINTEXT, "");
                    res.addHeader("Content-Range", "bytes */" + fileLen);
                    res.addHeader("ETag", etag);
                } else if (range == null && headerIfNoneMatchPresentAndMatching) {
                    // full-file-fetch request
                    // would return entire file
                    // respond with not-modified
                    res = newFixedLengthResponse(Status.NOT_MODIFIED, mime, "");
                    res.addHeader("ETag", etag);
                } else if (!headerIfRangeMissingOrMatching && headerIfNoneMatchPresentAndMatching) {
                    // range request that doesn't match current etag
                    // would return entire (different) file
                    // respond with not-modified

                    res = newFixedLengthResponse(Status.NOT_MODIFIED, mime, "");
                    res.addHeader("ETag", etag);
                } else {
                    // supply the file
                    res = newFixedFileResponse(file, mime);
                    res.addHeader("Content-Length", "" + fileLen);
                    res.addHeader("ETag", etag);
                }
            }
        } catch (IOException ioe) {
            res = getForbiddenResponse("Reading file failed.");
        }

        return res;
    }
Serves file from homeDir and its' subdirectories (only). Uses only URI,
ignores all headers and HTTP parameters.