如何使用Java从文件获取媒体类型(MIME类型)? 我已经尝试了JMimeMagic和Mime-Util。第一个给了我内存异常,第二个没有正确关闭其流。
你将如何探测文件以确定其实际类型(不仅基于扩展名)?
如何使用Java从文件获取媒体类型(MIME类型)? 我已经尝试了JMimeMagic和Mime-Util。第一个给了我内存异常,第二个没有正确关闭其流。
你将如何探测文件以确定其实际类型(不仅基于扩展名)?
我尝试了几种方法来解决这个问题,包括@Joshua Fox提到的第一种方法。但是有些方法不能识别常见的文件类型,比如PDF文件,而其他方法可能对伪造的文件不可靠(例如我曾将RAR文件的扩展名改为TIF并进行测试)。我找到的解决方法与@Joshua Fox表述的方式类似,就是使用MimeUtil2,具体做法如下:
MimeUtil2 mimeUtil = new MimeUtil2();
mimeUtil.registerMimeDetector("eu.medsea.mimeutil.detector.MagicMimeMimeDetector");
String mimeType = MimeUtil2.getMostSpecificMimeType(mimeUtil.getMimeTypes(file)).toString();
如果您正在使用Servlet,并且如果servlet上下文对您可用,您可以使用:
getServletContext().getMimeType( fileName );
getServletContext
是什么? - e-info128byte[] byteArray = ...
InputStream is = new BufferedInputStream(new ByteArrayInputStream(byteArray));
String mimeType = URLConnection.guessContentTypeFromStream(is);
你只需要一行代码就可以实现: MimetypesFileTypeMap().getContentType(new File("filename.ext"))。 以下是完整的Java 7测试代码:
import java.io.File;
import javax.activation.MimetypesFileTypeMap;
public class MimeTest {
public static void main(String a[]){
System.out.println(new MimetypesFileTypeMap().getContentType(
new File("/path/filename.txt")));
}
}
对于文件上传最好使用两层验证。
首先你可以检查 mimeType 并进行验证。
其次,您应该查看将文件的前4个字节转换为十六进制,然后将其与魔术数字进行比较。这将是一种非常安全的文件验证方式。
我找不到任何可以检查video/mp4
MIME类型的内容,所以我自己做了一个解决方案。
我注意到维基百科是错误的,00 00 00 18 66 74 79 70 69 73 6F 6D
文件签名是不正确的。第四个字节(18
)和所有mp4
文件中除了70
(不包括)以外的其他地方都会发生相当大的变化。
这段代码本质上是URLConnection.guessContentTypeFromStream
代码的复制/粘贴,但针对的是video/mp4
。
BufferedInputStream bis = new BufferedInputStream(new ByteArrayInputStream(content));
String mimeType = URLConnection.guessContentTypeFromStream(bis);
// Goes full barbaric and processes the bytes manually
if (mimeType == null){
// These ints converted in hex ar:
// 00 00 00 18 66 74 79 70 69 73 6F 6D
// which are the file signature (magic bytes) for .mp4 files
// from https://www.wikiwand.com/en/List_of_file_signatures
// just ctrl+f "mp4"
int[] mp4_sig = {0, 0, 0, 24, 102, 116, 121, 112};
bis.reset();
bis.mark(16);
int[] firstBytes = new int[8];
for (int i = 0; i < 8; i++) {
firstBytes[i] = bis.read();
}
// This byte doesn't matter for the file signature and changes
mp4_sig[3] = content[3];
bis.reset();
if (Arrays.equals(firstBytes, mp4_sig)){
mimeType = "video/mp4";
}
}
成功测试了10个不同的.mp4
文件。
编辑:这是一个有用的链接(如果仍然在线),您可以在其中找到许多类型的示例。我不拥有那些视频,也不知道谁拥有,但它们对于测试上述代码非常有用。
实际上,Apache Tika detector的Tika.detect(File)
是最佳选择,比Files.probeContentType(path)
更准确。
可以查看这个很好的快速参考,其中包含示例和代码样例。
File
、Path
或InputStream
数据源进行比较如果您复制代码,请记得给出来源。
-1
表示跳过比较该索引处的字节;-2
表示文件类型签名结束。这可以检测二进制格式,主要是图像,以及一些纯文本格式的变化(HTML、SVG、XML)。代码使用数据源头部的最多前 11 个“魔法”字节。欢迎进行优化和改进,使逻辑更简洁。import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Path;
import java.util.LinkedHashMap;
import java.util.Map;
import static com.keenwrite.io.MediaType.*;
import static java.lang.System.arraycopy;
public class StreamMediaType {
private static final int FORMAT_LENGTH = 11;
private static final int END_OF_DATA = -2;
private static final Map<int[], MediaType> FORMAT = new LinkedHashMap<>();
static {
//@formatter:off
FORMAT.put( ints( 0x3C, 0x73, 0x76, 0x67, 0x20 ), IMAGE_SVG_XML );
FORMAT.put( ints( 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A ), IMAGE_PNG );
FORMAT.put( ints( 0xFF, 0xD8, 0xFF, 0xE0 ), IMAGE_JPEG );
FORMAT.put( ints( 0xFF, 0xD8, 0xFF, 0xEE ), IMAGE_JPEG );
FORMAT.put( ints( 0xFF, 0xD8, 0xFF, 0xE1, -1, -1, 0x45, 0x78, 0x69, 0x66, 0x00 ), IMAGE_JPEG );
FORMAT.put( ints( 0x49, 0x49, 0x2A, 0x00 ), IMAGE_TIFF );
FORMAT.put( ints( 0x4D, 0x4D, 0x00, 0x2A ), IMAGE_TIFF );
FORMAT.put( ints( 0x47, 0x49, 0x46, 0x38 ), IMAGE_GIF );
FORMAT.put( ints( 0x8A, 0x4D, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A ), VIDEO_MNG );
FORMAT.put( ints( 0x25, 0x50, 0x44, 0x46, 0x2D, 0x31, 0x2E ), APP_PDF );
FORMAT.put( ints( 0x38, 0x42, 0x50, 0x53, 0x00, 0x01 ), IMAGE_PHOTOSHOP );
FORMAT.put( ints( 0x25, 0x21, 0x50, 0x53, 0x2D, 0x41, 0x64, 0x6F, 0x62, 0x65, 0x2D ), APP_EPS );
FORMAT.put( ints( 0x25, 0x21, 0x50, 0x53 ), APP_PS );
FORMAT.put( ints( 0xFF, 0xFB, 0x30 ), AUDIO_MP3 );
FORMAT.put( ints( 0x49, 0x44, 0x33 ), AUDIO_MP3 );
FORMAT.put( ints( 0x3C, 0x21 ), TEXT_HTML );
FORMAT.put( ints( 0x3C, 0x68, 0x74, 0x6D, 0x6C ), TEXT_HTML );
FORMAT.put( ints( 0x3C, 0x68, 0x65, 0x61, 0x64 ), TEXT_HTML );
FORMAT.put( ints( 0x3C, 0x62, 0x6F, 0x64, 0x79 ), TEXT_HTML );
FORMAT.put( ints( 0x3C, 0x48, 0x54, 0x4D, 0x4C ), TEXT_HTML );
FORMAT.put( ints( 0x3C, 0x48, 0x45, 0x41, 0x44 ), TEXT_HTML );
FORMAT.put( ints( 0x3C, 0x42, 0x4F, 0x44, 0x59 ), TEXT_HTML );
FORMAT.put( ints( 0x3C, 0x3F, 0x78, 0x6D, 0x6C, 0x20 ), TEXT_XML );
FORMAT.put( ints( 0xFE, 0xFF, 0x00, 0x3C, 0x00, 0x3f, 0x00, 0x78 ), TEXT_XML );
FORMAT.put( ints( 0xFF, 0xFE, 0x3C, 0x00, 0x3F, 0x00, 0x78, 0x00 ), TEXT_XML );
FORMAT.put( ints( 0x42, 0x4D ), IMAGE_BMP );
FORMAT.put( ints( 0x23, 0x64, 0x65, 0x66 ), IMAGE_X_BITMAP );
FORMAT.put( ints( 0x21, 0x20, 0x58, 0x50, 0x4D, 0x32 ), IMAGE_X_PIXMAP );
FORMAT.put( ints( 0x2E, 0x73, 0x6E, 0x64 ), AUDIO_BASIC );
FORMAT.put( ints( 0x64, 0x6E, 0x73, 0x2E ), AUDIO_BASIC );
FORMAT.put( ints( 0x52, 0x49, 0x46, 0x46 ), AUDIO_WAV );
FORMAT.put( ints( 0x50, 0x4B ), APP_ZIP );
FORMAT.put( ints( 0x41, 0x43, -1, -1, -1, -1, 0x00, 0x00, 0x00, 0x00, 0x00 ), APP_ACAD );
FORMAT.put( ints( 0xCA, 0xFE, 0xBA, 0xBE ), APP_JAVA );
FORMAT.put( ints( 0xAC, 0xED ), APP_JAVA_OBJECT );
//@formatter:on
}
private StreamMediaType() {
}
public static MediaType getMediaType( final Path path ) throws IOException {
return getMediaType( path.toFile() );
}
public static MediaType getMediaType( final java.io.File file )
throws IOException {
try( final var fis = new FileInputStream( file ) ) {
return getMediaType( fis );
}
}
public static MediaType getMediaType( final InputStream is )
throws IOException {
final var input = new byte[ FORMAT_LENGTH ];
final var count = is.read( input, 0, FORMAT_LENGTH );
if( count > 1 ) {
final var available = new byte[ count ];
arraycopy( input, 0, available, 0, count );
return getMediaType( available );
}
return UNDEFINED;
}
public static MediaType getMediaType( final byte[] data ) {
assert data != null;
final var source = new int[]{
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
for( int i = 0; i < source.length; i++ ) {
source[ i ] = data[ i ] & 0xFF;
}
for( final var key : FORMAT.keySet() ) {
int i = -1;
boolean matches = true;
while( ++i < FORMAT_LENGTH && key[ i ] != END_OF_DATA && matches ) {
matches = key[ i ] == source[ i ] || key[ i ] == -1;
}
if( matches ) {
return FORMAT.get( key );
}
}
return UNDEFINED;
}
private static int[] ints( final int... data ) {
final var magic = new int[ FORMAT_LENGTH ];
int i = -1;
while( ++i < data.length ) {
magic[ i ] = data[ i ];
}
while( i < FORMAT_LENGTH ) {
magic[ i++ ] = END_OF_DATA;
}
return magic;
}
}
MediaTypeExtension
中。它依赖于Apache的FilenameUtils类,因为它具有getExtension
函数。import java.io.File;
import java.io.IOException;
import java.nio.file.Path;
import static MediaType.TypeName.*;
import static MediaTypeExtension.getMediaType;
import static org.apache.commons.io.FilenameUtils.getExtension;
public enum MediaType {
APP_ACAD( APPLICATION, "acad" ),
APP_JAVA_OBJECT( APPLICATION, "x-java-serialized-object" ),
APP_JAVA( APPLICATION, "java" ),
APP_PS( APPLICATION, "postscript" ),
APP_EPS( APPLICATION, "eps" ),
APP_PDF( APPLICATION, "pdf" ),
APP_ZIP( APPLICATION, "zip" ),
FONT_OTF( "otf" ),
FONT_TTF( "ttf" ),
IMAGE_APNG( "apng" ),
IMAGE_ACES( "aces" ),
IMAGE_AVCI( "avci" ),
IMAGE_AVCS( "avcs" ),
IMAGE_BMP( "bmp" ),
IMAGE_CGM( "cgm" ),
IMAGE_DICOM_RLE( "dicom_rle" ),
IMAGE_EMF( "emf" ),
IMAGE_EXAMPLE( "example" ),
IMAGE_FITS( "fits" ),
IMAGE_G3FAX( "g3fax" ),
IMAGE_GIF( "gif" ),
IMAGE_HEIC( "heic" ),
IMAGE_HEIF( "heif" ),
IMAGE_HEJ2K( "hej2k" ),
IMAGE_HSJ2( "hsj2" ),
IMAGE_X_ICON( "x-icon" ),
IMAGE_JLS( "jls" ),
IMAGE_JP2( "jp2" ),
IMAGE_JPEG( "jpeg" ),
IMAGE_JPH( "jph" ),
IMAGE_JPHC( "jphc" ),
IMAGE_JPM( "jpm" ),
IMAGE_JPX( "jpx" ),
IMAGE_JXR( "jxr" ),
IMAGE_JXRA( "jxrA" ),
IMAGE_JXRS( "jxrS" ),
IMAGE_JXS( "jxs" ),
IMAGE_JXSC( "jxsc" ),
IMAGE_JXSI( "jxsi" ),
IMAGE_JXSS( "jxss" ),
IMAGE_KTX( "ktx" ),
IMAGE_KTX2( "ktx2" ),
IMAGE_NAPLPS( "naplps" ),
IMAGE_PNG( "png" ),
IMAGE_PHOTOSHOP( "photoshop" ),
IMAGE_SVG_XML( "svg+xml" ),
IMAGE_T38( "t38" ),
IMAGE_TIFF( "tiff" ),
IMAGE_WEBP( "webp" ),
IMAGE_WMF( "wmf" ),
IMAGE_X_BITMAP( "x-xbitmap" ),
IMAGE_X_PIXMAP( "x-xpixmap" ),
AUDIO_BASIC( AUDIO, "basic" ),
AUDIO_MP3( AUDIO, "mp3" ),
AUDIO_WAV( AUDIO, "x-wav" ),
VIDEO_MNG( VIDEO, "x-mng" ),
TEXT_HTML( TEXT, "html" ),
TEXT_MARKDOWN( TEXT, "markdown" ),
TEXT_PLAIN( TEXT, "plain" ),
TEXT_XHTML( TEXT, "xhtml+xml" ),
TEXT_XML( TEXT, "xml" ),
TEXT_YAML( TEXT, "yaml" ),
/*
* When all other lights go out.
*/
UNDEFINED( TypeName.UNDEFINED, "undefined" );
public enum TypeName {
APPLICATION,
AUDIO,
IMAGE,
TEXT,
UNDEFINED,
VIDEO
}
private final String mMediaType;
private final TypeName mTypeName;
private final String mSubtype;
MediaType( final String subtype ) {
this( IMAGE, subtype );
}
MediaType( final TypeName typeName, final String subtype ) {
mTypeName = typeName;
mSubtype = subtype;
mMediaType = typeName.toString().toLowerCase() + '/' + subtype;
}
public static MediaType valueFrom( final File file ) {
assert file != null;
return fromFilename( file.getName() );
}
public static MediaType fromFilename( final String filename ) {
assert filename != null;
return getMediaType( getExtension( filename ) );
}
public static MediaType valueFrom( final Path path ) {
assert path != null;
return valueFrom( path.toFile() );
}
public static MediaType valueFrom( String contentType ) {
if( contentType == null || contentType.isBlank() ) {
return UNDEFINED;
}
var i = contentType.indexOf( ';' );
contentType = contentType.substring(
0, i == -1 ? contentType.length() : i );
i = contentType.indexOf( '/' );
i = i == -1 ? contentType.length() : i;
final var type = contentType.substring( 0, i );
final var subtype = contentType.substring( i + 1 );
return valueFrom( type, subtype );
}
public static MediaType valueFrom(
final String type, final String subtype ) {
assert type != null;
assert subtype != null;
for( final var mediaType : values() ) {
if( mediaType.equals( type, subtype ) ) {
return mediaType;
}
}
return UNDEFINED;
}
public boolean equals( final String type, final String subtype ) {
assert type != null;
assert subtype != null;
return mTypeName.name().equalsIgnoreCase( type ) &&
mSubtype.equalsIgnoreCase( subtype );
}
public boolean isType( final TypeName typeName ) {
return mTypeName == typeName;
}
public String getSubtype() {
return mSubtype;
}
@Override
public String toString() {
return mMediaType;
}
}
MediaType
与其已知和常见/流行的文件扩展名相对应的地图。这允许根据文件扩展名进行双向查找。import static MediaType.*;
import static java.util.List.of;
public enum MediaTypeExtension {
MEDIA_APP_ACAD( APP_ACAD, of( "dwg" ) ),
MEDIA_APP_PDF( APP_PDF ),
MEDIA_APP_PS( APP_PS, of( "ps" ) ),
MEDIA_APP_EPS( APP_EPS ),
MEDIA_APP_ZIP( APP_ZIP ),
MEDIA_AUDIO_MP3( AUDIO_MP3 ),
MEDIA_AUDIO_BASIC( AUDIO_BASIC, of( "au" ) ),
MEDIA_AUDIO_WAV( AUDIO_WAV, of( "wav" ) ),
MEDIA_FONT_OTF( FONT_OTF ),
MEDIA_FONT_TTF( FONT_TTF ),
MEDIA_IMAGE_APNG( IMAGE_APNG ),
MEDIA_IMAGE_BMP( IMAGE_BMP ),
MEDIA_IMAGE_GIF( IMAGE_GIF ),
MEDIA_IMAGE_JPEG( IMAGE_JPEG,
of( "jpg", "jpe", "jpeg", "jfif", "pjpeg", "pjp" ) ),
MEDIA_IMAGE_PNG( IMAGE_PNG ),
MEDIA_IMAGE_PSD( IMAGE_PHOTOSHOP, of( "psd" ) ),
MEDIA_IMAGE_SVG( IMAGE_SVG_XML, of( "svg" ) ),
MEDIA_IMAGE_TIFF( IMAGE_TIFF, of( "tiff", "tif" ) ),
MEDIA_IMAGE_WEBP( IMAGE_WEBP ),
MEDIA_IMAGE_X_BITMAP( IMAGE_X_BITMAP, of( "xbm" ) ),
MEDIA_IMAGE_X_PIXMAP( IMAGE_X_PIXMAP, of( "xpm" ) ),
MEDIA_VIDEO_MNG( VIDEO_MNG, of( "mng" ) ),
MEDIA_TEXT_MARKDOWN( TEXT_MARKDOWN, of(
"md", "markdown", "mdown", "mdtxt", "mdtext", "mdwn", "mkd", "mkdown",
"mkdn" ) ),
MEDIA_TEXT_PLAIN( TEXT_PLAIN, of( "txt", "asc", "ascii", "text", "utxt" ) ),
MEDIA_TEXT_R_MARKDOWN( TEXT_R_MARKDOWN, of( "Rmd" ) ),
MEDIA_TEXT_R_XML( TEXT_R_XML, of( "Rxml" ) ),
MEDIA_TEXT_XHTML( TEXT_XHTML, of( "xhtml" ) ),
MEDIA_TEXT_XML( TEXT_XML ),
MEDIA_TEXT_YAML( TEXT_YAML, of( "yaml", "yml" ) ),
MEDIA_UNDEFINED( UNDEFINED, of( "undefined" ) );
private final MediaType mMediaType;
private final List<String> mExtensions;
MediaTypeExtension( final MediaType mediaType ) {
this( mediaType, of( mediaType.getSubtype() ) );
}
MediaTypeExtension(
final MediaType mediaType, final List<String> extensions ) {
assert mediaType != null;
assert extensions != null;
assert !extensions.isEmpty();
mMediaType = mediaType;
mExtensions = extensions;
}
public String getExtension() {
return mExtensions.get( 0 );
}
public static MediaTypeExtension valueFrom( final MediaType mediaType ) {
for( final var type : values() ) {
if( type.isMediaType( mediaType ) ) {
return type;
}
}
return MEDIA_UNDEFINED;
}
boolean isMediaType( final MediaType mediaType ) {
return mMediaType == mediaType;
}
static MediaType getMediaType( final String extension ) {
final var sanitized = sanitize( extension );
for( final var mediaType : MediaTypeExtension.values() ) {
if( mediaType.isType( sanitized ) ) {
return mediaType.getMediaType();
}
}
return UNDEFINED;
}
private boolean isType( final String sanitized ) {
for( final var extension : mExtensions ) {
if( extension.equalsIgnoreCase( sanitized ) ) {
return true;
}
}
return false;
}
private static String sanitize( final String extension ) {
return extension == null ? "" : extension.toLowerCase();
}
private MediaType getMediaType() {
return mMediaType;
}
}
// EXAMPLE -- Detect media type
//
final File image = new File( "filename.jpg" );
final MediaType mt = StreamMediaType.getMediaType( image );
// Tricky! The JPG could be a PNG in disguise.
if( mt.isType( MediaType.TypeName.IMAGE ) ) {
if( mt == MediaType.IMAGE_PNG ) {
// Nice try! Sneaky sneak.
}
}
// EXAMPLE -- Get typical media type file name extension
//
final String ext = MediaTypeExtension.valueFrom( MediaType.IMAGE_SVG_XML ).getExtension();
// EXAMPLE -- Get media type from HTTP request
//
final var url = new URL( "https://localhost/path/file.ext" );
final var conn = (HttpURLConnection) url.openConnection();
final var contentType = conn.getContentType();
MediaType mediaType = valueFrom( contentType );
// Fall back to stream detection probe
if( mediaType == UNDEFINED ) {
mediaType = StreamMediaType.getMediaType( conn.getInputStream() );
}
conn.disconnect();
图书馆简评:
用于测试的示例音频、视频和图像文件:
<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN" "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
<svg xmlns="http://www.w3.org/2000/svg">
<svg
标记之前可以插入任意长度的注释,使得检测变得非常困难。
<svg
。实际上,我最终使用从HTTP连接检索的Content-Type来获取SVG资源。 - Dave Jarvis<?xml...
并跳过它的挑战在于,在 <svg
根节点之前可能有注释。事实上,Adobe Illustrator 插入了一个长度不同的长注释。 :-( - E-Rizorg.springframework.web.multipart.MultipartFile
file.getContentType();