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：
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 mirror public static final int ORIENTATION_ROTATE_180 = 3; public static final int ORIENTATION_FLIP_VERTICAL = 4; // upside down mirror public static final int ORIENTATION_TRANSPOSE = 5; // flipped about top-left <--> bottom-right axis public static final int ORIENTATION_ROTATE_90 = 6; // rotate 90 cw to right it public static final int ORIENTATION_TRANSVERSE = 7; // flipped about top-right <--> bottom-left axis public static final int ORIENTATION_ROTATE_270 = 8; // rotate 270 to right it // Constants used for white balance public 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 count int 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 name int equalPos = attrStr.indexOf('=', ptr); String attrName = attrStr.substring(ptr, equalPos); ptr = equalPos + 1; // skip past = // extract the attribute value length int lenPos = attrStr.indexOf(' ', ptr); int attrLen = Integer.parseInt(attrStr.substring(ptr, lenPos)); ptr = lenPos + 1; // skip pas the space // extract the attribute value String 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 tag continue; } 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 // null return 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); }
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》
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