Android Open Source - Android-Universal-Image-Loader Image Downloader

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License

The source code is released under:

Apache License

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Java Source Code

/*******************************************************************************
 * Copyright 2011-2013 Sergey Tarasevich
 *//from w ww.  ja v a  2  s  .  co  m
 * 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 com.nostra13.universalimageloader.core.download;

import com.nostra13.universalimageloader.core.DisplayImageOptions;

import java.io.IOException;
import java.io.InputStream;
import java.util.Locale;

/**
 * Provides retrieving of {@link InputStream} of image by URI.<br />
 * Implementations have to be thread-safe.
 *
 * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
 * @since 1.4.0
 */
public interface ImageDownloader {
  /**
   * Retrieves {@link InputStream} of image by URI.
   *
   * @param imageUri Image URI
   * @param extra    Auxiliary object which was passed to {@link DisplayImageOptions.Builder#extraForDownloader(Object)
   *                 DisplayImageOptions.extraForDownloader(Object)}; can be null
   * @return {@link InputStream} of image
   * @throws IOException                   if some I/O error occurs during getting image stream
   * @throws UnsupportedOperationException if image URI has unsupported scheme(protocol)
   */
  InputStream getStream(String imageUri, Object extra) throws IOException;

  /** Represents supported schemes(protocols) of URI. Provides convenient methods for work with schemes and URIs. */
  public enum Scheme {
    HTTP("http"), HTTPS("https"), FILE("file"), CONTENT("content"), ASSETS("assets"), DRAWABLE("drawable"), UNKNOWN("");

    private String scheme;
    private String uriPrefix;

    Scheme(String scheme) {
      this.scheme = scheme;
      uriPrefix = scheme + "://";
    }

    /**
     * Defines scheme of incoming URI
     *
     * @param uri URI for scheme detection
     * @return Scheme of incoming URI
     */
    public static Scheme ofUri(String uri) {
      if (uri != null) {
        for (Scheme s : values()) {
          if (s.belongsTo(uri)) {
            return s;
          }
        }
      }
      return UNKNOWN;
    }

    private boolean belongsTo(String uri) {
      return uri.toLowerCase(Locale.US).startsWith(uriPrefix);
    }

    /** Appends scheme to incoming path */
    public String wrap(String path) {
      return uriPrefix + path;
    }

    /** Removed scheme part ("scheme://") from incoming URI */
    public String crop(String uri) {
      if (!belongsTo(uri)) {
        throw new IllegalArgumentException(String.format("URI [%1$s] doesn't have expected scheme [%2$s]", uri, scheme));
      }
      return uri.substring(uriPrefix.length());
    }
  }
}

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