Android 图片Exif 信息读取和写入

1. 信息读取.
   传统方法引用Android 原生接口

    ExifInterface mExifInterface = new ExifInterface(PATH);
     //For example
     String flash = mExifInterface.getAttribute(ExifInterface.TAG_FLASH);
     String iso = mExifInterface.getAttribute(ExifInterface.TAG_ISO_SPEED_RATINGS);
     String orientation = mExifInterface.getAttribute(ExifInterface.TAG_ORIENTATION);

2. 引用3rd jar来实现信息读取
   在build.gradle里面加入 compile 'com.drewnoakes:metadata-extractor:2.11.0'

    private static void readPic(File jpegFile) {
    com.drew.metadata.Metadata metadata;
    try {
    metadata = JpegMetadataReader.readMetadata(jpegFile);
    Iterator<Directory> it = metadata.getDirectories().iterator();
    while (it.hasNext()) {
    Directory exif = it.next();
    Iterator<com.drew.metadata.Tag> tags = exif.getTags().iterator();
    while (tags.hasNext()) {
    com.drew.metadata.Tag tag = tags.next();
    android.util.Log.d("Exif tag", "tag ======== " + tag);
    }
    }
    } catch (JpegProcessingException e) {
            e.printStackTrace();
    } catch (IOException e) {
            e.printStackTrace();
    }
    }

3. 信息写入

传统方法引用google 原生接口
和上面的一样
mExifInterface.setAttribute(ExifInterface.TAG_ORIENTATION, "1254"); 
mExifInterface.saveAttributes(); // 这个地方一定要调用保存。否则保存不了.

4. 引用3rd jar来实现信息写入
   下载 commons-imaging-1.0-SNAPSHOT.jar, 这个方法的好处是如果图片里面没有字段. 比如orientation 没有，但是
   还可以写入. 场景: 比如你把多张图片合成之后，生成的新的图片里面没有了信息, 那么你就可以重新写入信息.

    private static void writePic(String srcJpeg) {
    File file = new File(srcJpeg);
    try {
    这个类在这里下载
    //https://github.com/skypx/JpegMetadate
    JpegInfo inJpegInfo = new JpegInfo(file);
   try {
        inJpegInfo.set(TiffTagConstants.TIFF_TAG_MAKE, "SKY");
        inJpegInfo.set(ExifTagConstants.EXIF_TAG_ISO, (short)30);
        inJpegInfo.set(ExifTagConstants.EXIF_TAG_APERTURE_VALUE, new RationalNumber(2,4));
        inJpegInfo.set(ExifTagConstants.EXIF_TAG_FLASH, (short) ExifTagConstants.FLASH_VALUE_OFF);
        rewriteInplace(inJpegInfo, file);
    } catch (ImageWriteException e) {
            e.printStackTrace();
    }  catch (ImageReadException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
   

   }

    private static final String SUFFIX_TEMP_FILE = ".rewrite-exif";
    private static void rewriteInplace(JpegInfo exif, File file) throws
       IOException, ImageReadException, ImageWriteException {
    final long lastModified = file.lastModified();
   
    File tempFile = File.createTempFile(
            file.getName(), SUFFIX_TEMP_FILE, file.getParentFile());
    final FileOutputStream out = new FileOutputStream(tempFile);
    boolean success = false;
    try {
        try {
            exif.rewrite(file, out, true);
            out.flush();
        } finally {
            out.close();
        }
        success = tempFile.renameTo(file);
        if (success) {
            if (!file.setLastModified(lastModified)) {
                Log.w("TAG", "Failed to set last modified time to " + file.getAbsolutePath());
            }
        } else {
            throw new IOException("Could not replace file " + file);
        }
    } finally {
        if (!success) {
            if (!tempFile.delete()) {
                Log.w("TAG","Could not delete temporary file " + tempFile.getAbsolutePath());
            }
        }
    }
   

   }