glide是安卓上非常方便的图片加载工具，通过url等方式加载的图片会在本地缓存一份文件，glide并没有提供直接获取本地缓存的方法，以下方法可以直接获取glide在本地缓存的文件

• 添加DataCacheKey到自己的项目中

/**
 * A cache key for original source data + any requested signature.
 */
public class DataCacheKey implements Key  {

    private final Key sourceKey;
    private final Key signature;

    public DataCacheKey(Key sourceKey, Key signature) {
        this.sourceKey = sourceKey;
        this.signature = signature;
    }

    public Key getSourceKey() {
        return sourceKey;
    }

    @Override
    public boolean equals(Object o) {
        if (o instanceof DataCacheKey) {
            DataCacheKey other = (DataCacheKey) o;
            return sourceKey.equals(other.sourceKey) && signature.equals(other.signature);
        }
        return false;
    }

    @Override
    public int hashCode() {
        int result = sourceKey.hashCode();
        result = 31 * result + signature.hashCode();
        return result;
    }

    @Override
    public String toString() {
        return "DataCacheKey{"
                + "sourceKey=" + sourceKey
                + ", signature=" + signature
                + '}';
    }

    @Override
    public void updateDiskCacheKey(MessageDigest messageDigest) {
        sourceKey.updateDiskCacheKey(messageDigest);
        signature.updateDiskCacheKey(messageDigest);
    }
}

• 使用以下方法即可获得缓存文件

public static File getGlideCacheFile(Context context ,String id) {
        DataCacheKey dataCacheKey = new DataCacheKey(new GlideUrl(id), EmptySignature.obtain());
        SafeKeyGenerator safeKeyGenerator = new SafeKeyGenerator();
        String safeKey = safeKeyGenerator.getSafeKey(dataCacheKey);
        try {
            int cacheSize = 100 * 1000 * 1000;
            DiskLruCache diskLruCache = DiskLruCache.open(new File(context.getCacheDir(), DiskCache.Factory.DEFAULT_DISK_CACHE_DIR), 1, 1, cacheSize);
            DiskLruCache.Value value = diskLruCache.get(safeKey);
            if (value != null) {
                return value.getFile(0);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

glide4.8可以使用此方法获取本地图片缓存（支持glide4.0+）

来自Mr_Fingerling | github