Android开发之使用ExifInterface获取拍照后的图片属性
本文实例讲述了Android开发之使用ExifInterface获取拍照后的图片属性。分享给大家供大家参考，具体如下：
ExifInterfaceexif=newExifInterface(file.getPath()); StringwidthStr=exif.getAttribute(ExifInterface.TAG_IMAGE_WIDTH); StringheightStr=exif.getAttribute(ExifInterface.TAG_IMAGE_LENGTH); ......
/*
*Copyright(C)2007TheAndroidOpenSourceProject
*
*LicensedundertheApacheLicense,Version2.0(the"License");
*youmaynotusethisfileexceptincompliancewiththeLicense.
*YoumayobtainacopyoftheLicenseat
*
*http://www.apache.org/licenses/LICENSE-2.0
*
*Unlessrequiredbyapplicablelaworagreedtoinwriting,software
*distributedundertheLicenseisdistributedonan"ASIS"BASIS,
*WITHOUTWARRANTIESORCONDITIONSOFANYKIND,eitherexpressorimplied.
*SeetheLicenseforthespecificlanguagegoverningpermissionsand
*limitationsundertheLicense.
*/
packageandroid.media;
importjava.io.IOException;
importjava.text.ParsePosition;
importjava.text.SimpleDateFormat;
importjava.util.Date;
importjava.util.HashMap;
importjava.util.Map;
importjava.util.TimeZone;
/**
*ThisisaclassforreadingandwritingExiftagsinaJPEGfile.
*/
publicclassExifInterface{
//TheExiftagnames
/**Typeisint.*/
publicstaticfinalStringTAG_ORIENTATION="Orientation";
/**TypeisString.*/
publicstaticfinalStringTAG_DATETIME="DateTime";
/**TypeisString.*/
publicstaticfinalStringTAG_MAKE="Make";
/**TypeisString.*/
publicstaticfinalStringTAG_MODEL="Model";
/**Typeisint.*/
publicstaticfinalStringTAG_FLASH="Flash";
/**Typeisint.*/
publicstaticfinalStringTAG_IMAGE_WIDTH="ImageWidth";
/**Typeisint.*/
publicstaticfinalStringTAG_IMAGE_LENGTH="ImageLength";
/**String.Formatis"num1/denom1,num2/denom2,num3/denom3".*/
publicstaticfinalStringTAG_GPS_LATITUDE="GPSLatitude";
/**String.Formatis"num1/denom1,num2/denom2,num3/denom3".*/
publicstaticfinalStringTAG_GPS_LONGITUDE="GPSLongitude";
/**TypeisString.*/
publicstaticfinalStringTAG_GPS_LATITUDE_REF="GPSLatitudeRef";
/**TypeisString.*/
publicstaticfinalStringTAG_GPS_LONGITUDE_REF="GPSLongitudeRef";
/**TypeisString.*/
publicstaticfinalStringTAG_GPS_TIMESTAMP="GPSTimeStamp";
/**TypeisString.*/
publicstaticfinalStringTAG_GPS_DATESTAMP="GPSDateStamp";
/**Typeisint.*/
publicstaticfinalStringTAG_WHITE_BALANCE="WhiteBalance";
/**Typeisrational.*/
publicstaticfinalStringTAG_FOCAL_LENGTH="FocalLength";
/**TypeisString.NameofGPSprocessingmethodusedforlocationfinding.*/
publicstaticfinalStringTAG_GPS_PROCESSING_METHOD="GPSProcessingMethod";
//ConstantsusedfortheOrientationExiftag.
publicstaticfinalintORIENTATION_UNDEFINED=0;
publicstaticfinalintORIENTATION_NORMAL=1;
publicstaticfinalintORIENTATION_FLIP_HORIZONTAL=2;//leftrightreversedmirror
publicstaticfinalintORIENTATION_ROTATE_180=3;
publicstaticfinalintORIENTATION_FLIP_VERTICAL=4;//upsidedownmirror
publicstaticfinalintORIENTATION_TRANSPOSE=5;//flippedabouttop-left<-->bottom-rightaxis
publicstaticfinalintORIENTATION_ROTATE_90=6;//rotate90cwtorightit
publicstaticfinalintORIENTATION_TRANSVERSE=7;//flippedabouttop-right<-->bottom-leftaxis
publicstaticfinalintORIENTATION_ROTATE_270=8;//rotate270torightit
//Constantsusedforwhitebalance
publicstaticfinalintWHITEBALANCE_AUTO=0;
publicstaticfinalintWHITEBALANCE_MANUAL=1;
privatestaticSimpleDateFormatsFormatter;
static{
System.loadLibrary("exif");
sFormatter=newSimpleDateFormat("yyyy:MM:ddHH:mm:ss");
sFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
}
privateStringmFilename;
privateHashMap<String,String>mAttributes;
privatebooleanmHasThumbnail;
//Becausetheunderlyingimplementation(jhead)usesstaticvariables,
//therecanonlybeoneuseratatimeforthenativefunctions(and
//theycannotkeepstateinthenativecodeacrossfunctioncalls).We
//usesLocktoserializetheaccesses.
privatestaticObjectsLock=newObject();
/**
*ReadsExiftagsfromthespecifiedJPEGfile.
*/
publicExifInterface(Stringfilename)throwsIOException{
mFilename=filename;
loadAttributes();
}
/**
*Returnsthevalueofthespecifiedtagor{@codenull}ifthere
*isnosuchtagintheJPEGfile.
*
*@paramtagthenameofthetag.
*/
publicStringgetAttribute(Stringtag){
returnmAttributes.get(tag);
}
/**
*Returnstheintegervalueofthespecifiedtag.Ifthereisnosuchtag
*intheJPEGfileorthevaluecannotbeparsedasinteger,return
*<var>defaultValue</var>.
*
*@paramtagthenameofthetag.
*@paramdefaultValuethevaluetoreturnifthetagisnotavailable.
*/
publicintgetAttributeInt(Stringtag,intdefaultValue){
Stringvalue=mAttributes.get(tag);
if(value==null)returndefaultValue;
try{
returnInteger.valueOf(value);
}catch(NumberFormatExceptionex){
returndefaultValue;
}
}
/**
*Returnsthedoublevalueofthespecifiedrationaltag.Ifthereisno
*suchtagintheJPEGfileorthevaluecannotbeparsedasdouble,return
*<var>defaultValue</var>.
*
*@paramtagthenameofthetag.
*@paramdefaultValuethevaluetoreturnifthetagisnotavailable.
*/
publicdoublegetAttributeDouble(Stringtag,doubledefaultValue){
Stringvalue=mAttributes.get(tag);
if(value==null)returndefaultValue;
try{
intindex=value.indexOf("/");
if(index==-1)returndefaultValue;
doubledenom=Double.parseDouble(value.substring(index+1));
if(denom==0)returndefaultValue;
doublenum=Double.parseDouble(value.substring(0,index));
returnnum/denom;
}catch(NumberFormatExceptionex){
returndefaultValue;
}
}
/**
*Setthevalueofthespecifiedtag.
*
*@paramtagthenameofthetag.
*@paramvaluethevalueofthetag.
*/
publicvoidsetAttribute(Stringtag,Stringvalue){
mAttributes.put(tag,value);
}
/**
*InitializemAttributeswiththeattributesfromthefilemFilename.
*
*mAttributesisaHashMapwhichstorestheExifattributesofthefile.
*Thekeyisthestandardtagnameandthevalueisthetag'svalue:e.g.
*Model->Nikon.Numericvaluesarestoredasstrings.
*
*ThisfunctionalsoinitializemHasThumbnailtoindicatewhetherthe
*filehasathumbnailinside.
*/
privatevoidloadAttributes()throwsIOException{
//formatofstringpassedfromnativeCcode:
//"attrCntattr1=valueLenvalue1attr2=value2Lenvalue2..."
//example:
//"4attrPtrImageLength=41024Model=6FooImageWidth=41280Make=3FOO"
mAttributes=newHashMap<String,String>();
StringattrStr;
synchronized(sLock){
attrStr=getAttributesNative(mFilename);
}
//getcount
intptr=attrStr.indexOf('');
intcount=Integer.parseInt(attrStr.substring(0,ptr));
//skippastthespacebetweenitemcountandtherestoftheattributes
++ptr;
for(inti=0;i<count;i++){
//extracttheattributename
intequalPos=attrStr.indexOf('=',ptr);
StringattrName=attrStr.substring(ptr,equalPos);
ptr=equalPos+1;//skippast=
//extracttheattributevaluelength
intlenPos=attrStr.indexOf('',ptr);
intattrLen=Integer.parseInt(attrStr.substring(ptr,lenPos));
ptr=lenPos+1;//skippasthespace
//extracttheattributevalue
StringattrValue=attrStr.substring(ptr,ptr+attrLen);
ptr+=attrLen;
if(attrName.equals("hasThumbnail")){
mHasThumbnail=attrValue.equalsIgnoreCase("true");
}else{
mAttributes.put(attrName,attrValue);
}
}
}
/**
*SavethetagdataintotheJPEGfile.Thisisexpensivebecauseitinvolves
*copyingalltheJPGdatafromonefiletoanotheranddeletingtheoldfile
*andrenamingtheother.It'sbesttouse{@link#setAttribute(String,String)}
*tosetallattributestowriteandmakeasinglecallratherthanmultiple
*callsforeachattribute.
*/
publicvoidsaveAttributes()throwsIOException{
//formatofstringpassedtonativeCcode:
//"attrCntattr1=valueLenvalue1attr2=value2Lenvalue2..."
//example:
//"4attrPtrImageLength=41024Model=6FooImageWidth=41280Make=3FOO"
StringBuildersb=newStringBuilder();
intsize=mAttributes.size();
if(mAttributes.containsKey("hasThumbnail")){
--size;
}
sb.append(size+"");
for(Map.Entry<String,String>iter:mAttributes.entrySet()){
Stringkey=iter.getKey();
if(key.equals("hasThumbnail")){
//thisisafakeattributenotsavedasanexiftag
continue;
}
Stringval=iter.getValue();
sb.append(key+"=");
sb.append(val.length()+"");
sb.append(val);
}
Strings=sb.toString();
synchronized(sLock){
saveAttributesNative(mFilename,s);
commitChangesNative(mFilename);
}
}
/**
*ReturnstrueiftheJPEGfilehasathumbnail.
*/
publicbooleanhasThumbnail(){
returnmHasThumbnail;
}
/**
*ReturnsthethumbnailinsidetheJPEGfile,or{@codenull}ifthereisnothumbnail.
*ThereturneddataisinJPEGformatandcanbedecodedusing
*{@linkandroid.graphics.BitmapFactory#decodeByteArray(byte[],int,int)}
*/
publicbyte[]getThumbnail(){
synchronized(sLock){
returngetThumbnailNative(mFilename);
}
}
/**
*Storesthelatitudeandlongitudevalueinafloatarray.Thefirstelementis
*thelatitude,andthesecondelementisthelongitude.Returnsfalseifthe
*Exiftagsarenotavailable.
*/
publicbooleangetLatLong(floatoutput[]){
StringlatValue=mAttributes.get(ExifInterface.TAG_GPS_LATITUDE);
StringlatRef=mAttributes.get(ExifInterface.TAG_GPS_LATITUDE_REF);
StringlngValue=mAttributes.get(ExifInterface.TAG_GPS_LONGITUDE);
StringlngRef=mAttributes.get(ExifInterface.TAG_GPS_LONGITUDE_REF);
if(latValue!=null&&latRef!=null&&lngValue!=null&&lngRef!=null){
output[0]=convertRationalLatLonToFloat(latValue,latRef);
output[1]=convertRationalLatLonToFloat(lngValue,lngRef);
returntrue;
}else{
returnfalse;
}
}
/**
*ReturnsnumberofmillisecondssinceJan.1,1970,midnight.
*Returns-1ifthedatetimeinformationifnotavailable.
*@hide
*/
publiclonggetDateTime(){
StringdateTimeString=mAttributes.get(TAG_DATETIME);
if(dateTimeString==null)return-1;
ParsePositionpos=newParsePosition(0);
try{
Datedatetime=sFormatter.parse(dateTimeString,pos);
if(datetime==null)return-1;
returndatetime.getTime();
}catch(IllegalArgumentExceptionex){
return-1;
}
}
/**
*ReturnsnumberofmillisecondssinceJan.1,1970,midnightUTC.
*Returns-1ifthedatetimeinformationifnotavailable.
*@hide
*/
publiclonggetGpsDateTime(){
Stringdate=mAttributes.get(TAG_GPS_DATESTAMP);
Stringtime=mAttributes.get(TAG_GPS_TIMESTAMP);
if(date==null||time==null)return-1;
StringdateTimeString=date+''+time;
if(dateTimeString==null)return-1;
ParsePositionpos=newParsePosition(0);
try{
Datedatetime=sFormatter.parse(dateTimeString,pos);
if(datetime==null)return-1;
returndatetime.getTime();
}catch(IllegalArgumentExceptionex){
return-1;
}
}
privatestaticfloatconvertRationalLatLonToFloat(
StringrationalString,Stringref){
try{
String[]parts=rationalString.split(",");
String[]pair;
pair=parts[0].split("/");
intdegrees=(int)(Float.parseFloat(pair[0].trim())
/Float.parseFloat(pair[1].trim()));
pair=parts[1].split("/");
intminutes=(int)((Float.parseFloat(pair[0].trim())
/Float.parseFloat(pair[1].trim())));
pair=parts[2].split("/");
floatseconds=Float.parseFloat(pair[0].trim())
/Float.parseFloat(pair[1].trim());
floatresult=degrees+(minutes/60F)+(seconds/(60F*60F));
if((ref.equals("S")||ref.equals("W"))){
return-result;
}
returnresult;
}catch(RuntimeExceptionex){
//ifforwhateverreasonwecan'tparsethelatlongthenreturn
//null
return0f;
}
}
privatenativebooleanappendThumbnailNative(StringfileName,
StringthumbnailFileName);
privatenativevoidsaveAttributesNative(StringfileName,
StringcompressedAttributes);
privatenativeStringgetAttributesNative(StringfileName);
privatenativevoidcommitChangesNative(StringfileName);
privatenativebyte[]getThumbnailNative(StringfileName);
}
更多关于Android开发相关内容感兴趣的读者可查看本站专题：《Android开发入门与进阶教程》及《Android图形与图像处理技巧总结》
希望本文所述对大家Android程序设计有所帮助。