首页 / 移动开发 / Android / Android开发之使用ExifInterface获取拍照后的图片属性

ExifInterface exif = new ExifInterface（file.getPath（））;String widthStr = exif.getAttribute（ExifInterface.TAG_IMAGE_WIDTH）;String heightStr = exif.getAttribute（ExifInterface.TAG_IMAGE_LENGTH）;......

/* * Copyright （C） 2007 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 （the "License"）; * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package android.media;import java.io.IOException;import java.text.ParsePosition;import java.text.SimpleDateFormat;import java.util.Date;import java.util.HashMap;import java.util.Map;import java.util.TimeZone;/** * This is a class for reading and writing Exif tags in a JPEG file. */public class ExifInterface {// The Exif tag names/** Type is int. */public static final String TAG_ORIENTATION = "Orientation";/** Type is String. */public static final String TAG_DATETIME = "DateTime";/** Type is String. */public static final String TAG_MAKE = "Make";/** Type is String. */public static final String TAG_MODEL = "Model";/** Type is int. */public static final String TAG_FLASH = "Flash";/** Type is int. */public static final String TAG_IMAGE_WIDTH = "ImageWidth";/** Type is int. */public static final String TAG_IMAGE_LENGTH = "ImageLength";/** String. Format is "num1/denom1,num2/denom2,num3/denom3". */public static final String TAG_GPS_LATITUDE = "GPSLatitude";/** String. Format is "num1/denom1,num2/denom2,num3/denom3". */public static final String TAG_GPS_LONGITUDE = "GPSLongitude";/** Type is String. */public static final String TAG_GPS_LATITUDE_REF = "GPSLatitudeRef";/** Type is String. */public static final String TAG_GPS_LONGITUDE_REF = "GPSLongitudeRef";/** Type is String. */public static final String TAG_GPS_TIMESTAMP = "GPSTimeStamp";/** Type is String. */public static final String TAG_GPS_DATESTAMP = "GPSDateStamp";/** Type is int. */public static final String TAG_WHITE_BALANCE = "WhiteBalance";/** Type is rational. */public static final String TAG_FOCAL_LENGTH = "FocalLength";/** Type is String. Name of GPS processing method used for location finding. */public static final String TAG_GPS_PROCESSING_METHOD = "GPSProcessingMethod";// Constants used for the Orientation Exif tag.public static final int ORIENTATION_UNDEFINED = 0;public static final int ORIENTATION_NORMAL = 1;public static final int ORIENTATION_FLIP_HORIZONTAL = 2; // left right reversed mirrorpublic static final int ORIENTATION_ROTATE_180 = 3;public static final int ORIENTATION_FLIP_VERTICAL = 4; // upside down mirrorpublic static final int ORIENTATION_TRANSPOSE = 5; // flipped about top-left <--> bottom-right axispublic static final int ORIENTATION_ROTATE_90 = 6; // rotate 90 cw to right itpublic static final int ORIENTATION_TRANSVERSE = 7; // flipped about top-right <--> bottom-left axispublic static final int ORIENTATION_ROTATE_270 = 8; // rotate 270 to right it// Constants used for white balancepublic static final int WHITEBALANCE_AUTO = 0;public static final int WHITEBALANCE_MANUAL = 1;private static SimpleDateFormat sFormatter;static {System.loadLibrary（"exif"）;sFormatter = new SimpleDateFormat（"yyyy:MM:dd HH:mm:ss"）;sFormatter.setTimeZone（TimeZone.getTimeZone（"UTC"））;}private String mFilename;private HashMap<String, String> mAttributes;private boolean mHasThumbnail;// Because the underlying implementation （jhead） uses static variables,// there can only be one user at a time for the native functions （and// they cannot keep state in the native code across function calls）. We// use sLock to serialize the accesses.private static Object sLock = new Object（）;/** * Reads Exif tags from the specified JPEG file. */public ExifInterface（String filename） throws IOException {mFilename = filename;loadAttributes（）;}/** * Returns the value of the specified tag or {@code null} if there * is no such tag in the JPEG file. * * @param tag the name of the tag. */public String getAttribute（String tag） {return mAttributes.get（tag）;}/** * Returns the integer value of the specified tag. If there is no such tag * in the JPEG file or the value cannot be parsed as integer, return * <var>defaultValue</var>. * * @param tag the name of the tag. * @param defaultValue the value to return if the tag is not available. */public int getAttributeInt（String tag, int defaultValue） {String value = mAttributes.get（tag）;if （value == null） return defaultValue;try {return Integer.valueOf（value）;} catch （NumberFormatException ex） {return defaultValue;}}/** * Returns the double value of the specified rational tag. If there is no * such tag in the JPEG file or the value cannot be parsed as double, return * <var>defaultValue</var>. * * @param tag the name of the tag. * @param defaultValue the value to return if the tag is not available. */public double getAttributeDouble（String tag, double defaultValue） {String value = mAttributes.get（tag）;if （value == null） return defaultValue;try {int index = value.indexOf（"/"）;if （index == -1） return defaultValue;double denom = Double.parseDouble（value.substring（index + 1））;if （denom == 0） return defaultValue;double num = Double.parseDouble（value.substring（0, index））;return num / denom;} catch （NumberFormatException ex） {return defaultValue;}}/** * Set the value of the specified tag. * * @param tag the name of the tag. * @param value the value of the tag. */public void setAttribute（String tag, String value） {mAttributes.put（tag, value）;}/** * Initialize mAttributes with the attributes from the file mFilename. * * mAttributes is a HashMap which stores the Exif attributes of the file. * The key is the standard tag name and the value is the tag"s value: e.g. * Model -> Nikon. Numeric values are stored as strings. * * This function also initialize mHasThumbnail to indicate whether the * file has a thumbnail inside. */private void loadAttributes（） throws IOException {// format of string passed from native C code:// "attrCnt attr1=valueLen value1attr2=value2Len value2..."// example:// "4 attrPtr ImageLength=4 1024Model=6 FooImageWidth=4 1280Make=3 FOO"mAttributes = new HashMap<String, String>（）;String attrStr;synchronized （sLock） {attrStr = getAttributesNative（mFilename）;}// get countint ptr = attrStr.indexOf（" "）;int count = Integer.parseInt（attrStr.substring（0, ptr））;// skip past the space between item count and the rest of the attributes++ptr;for （int i = 0; i < count; i++） {// extract the attribute nameint equalPos = attrStr.indexOf（"=", ptr）;String attrName = attrStr.substring（ptr, equalPos）;ptr = equalPos + 1; // skip past =// extract the attribute value lengthint lenPos = attrStr.indexOf（" ", ptr）;int attrLen = Integer.parseInt（attrStr.substring（ptr, lenPos））;ptr = lenPos + 1;// skip pas the space// extract the attribute valueString attrValue = attrStr.substring（ptr, ptr + attrLen）;ptr += attrLen;if （attrName.equals（"hasThumbnail"）） {mHasThumbnail = attrValue.equalsIgnoreCase（"true"）;} else {mAttributes.put（attrName, attrValue）;}}}/** * Save the tag data into the JPEG file. This is expensive because it involves * copying all the JPG data from one file to another and deleting the old file * and renaming the other. It"s best to use {@link #setAttribute（String,String）} * to set all attributes to write and make a single call rather than multiple * calls for each attribute. */public void saveAttributes（） throws IOException {// format of string passed to native C code:// "attrCnt attr1=valueLen value1attr2=value2Len value2..."// example:// "4 attrPtr ImageLength=4 1024Model=6 FooImageWidth=4 1280Make=3 FOO"StringBuilder sb = new StringBuilder（）;int size = mAttributes.size（）;if （mAttributes.containsKey（"hasThumbnail"）） {--size;}sb.append（size + " "）;for （Map.Entry<String, String> iter : mAttributes.entrySet（）） {String key = iter.getKey（）;if （key.equals（"hasThumbnail"）） {// this is a fake attribute not saved as an exif tagcontinue;}String val = iter.getValue（）;sb.append（key + "="）;sb.append（val.length（） + " "）;sb.append（val）;}String s = sb.toString（）;synchronized （sLock） {saveAttributesNative（mFilename, s）;commitChangesNative（mFilename）;}}/** * Returns true if the JPEG file has a thumbnail. */public boolean hasThumbnail（） {return mHasThumbnail;}/** * Returns the thumbnail inside the JPEG file, or {@code null} if there is no thumbnail. * The returned data is in JPEG format and can be decoded using * {@link android.graphics.BitmapFactory#decodeByteArray（byte[],int,int）} */public byte[] getThumbnail（） {synchronized （sLock） {return getThumbnailNative（mFilename）;}}/** * Stores the latitude and longitude value in a float array. The first element is * the latitude, and the second element is the longitude. Returns false if the * Exif tags are not available. */public boolean getLatLong（float output[]） {String latValue = mAttributes.get（ExifInterface.TAG_GPS_LATITUDE）;String latRef = mAttributes.get（ExifInterface.TAG_GPS_LATITUDE_REF）;String lngValue = mAttributes.get（ExifInterface.TAG_GPS_LONGITUDE）;String lngRef = 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）;return true;} else {return false;}}/** * Returns number of milliseconds since Jan. 1, 1970, midnight. * Returns -1 if the date time information if not available. * @hide */public long getDateTime（） {String dateTimeString = mAttributes.get（TAG_DATETIME）;if （dateTimeString == null） return -1;ParsePosition pos = new ParsePosition（0）;try {Date datetime = sFormatter.parse（dateTimeString, pos）;if （datetime == null） return -1;return datetime.getTime（）;} catch （IllegalArgumentException ex） {return -1;}}/** * Returns number of milliseconds since Jan. 1, 1970, midnight UTC. * Returns -1 if the date time information if not available. * @hide */public long getGpsDateTime（） {String date = mAttributes.get（TAG_GPS_DATESTAMP）;String time = mAttributes.get（TAG_GPS_TIMESTAMP）;if （date == null || time == null） return -1;String dateTimeString = date + " " + time;if （dateTimeString == null） return -1;ParsePosition pos = new ParsePosition（0）;try {Date datetime = sFormatter.parse（dateTimeString, pos）;if （datetime == null） return -1;return datetime.getTime（）;} catch （IllegalArgumentException ex） {return -1;}}private static float convertRationalLatLonToFloat（String rationalString, String ref） {try {String [] parts = rationalString.split（","）;String [] pair;pair = parts[0].split（"/"）;int degrees = （int） （Float.parseFloat（pair[0].trim（））/ Float.parseFloat（pair[1].trim（）））;pair = parts[1].split（"/"）;int minutes = （int） （（Float.parseFloat（pair[0].trim（））/ Float.parseFloat（pair[1].trim（））））;pair = parts[2].split（"/"）;float seconds = Float.parseFloat（pair[0].trim（））/ Float.parseFloat（pair[1].trim（））;float result = degrees + （minutes / 60F） + （seconds / （60F * 60F））;if （（ref.equals（"S"） || ref.equals（"W"））） {return -result;}return result;} catch （RuntimeException ex） {// if for whatever reason we can"t parse the lat long then return// nullreturn 0f;}}private native boolean appendThumbnailNative（String fileName,String thumbnailFileName）;private native void saveAttributesNative（String fileName,String compressedAttributes）;private native String getAttributesNative（String fileName）;private native void commitChangesNative（String fileName）;private native byte[] getThumbnailNative（String fileName）;}