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 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);}