content: /*
   * Copyright (C) 2016 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 com.android.apksig.util;
  
  import com.android.apksig.internal.util.ByteBufferDataSource;
  import com.android.apksig.internal.util.FileChannelDataSource;
  import java.io.RandomAccessFile;
  import java.nio.ByteBuffer;
  import java.nio.channels.FileChannel;
  
  /**
   * Utility methods for working with {@link DataSource} abstraction.
   */
  public abstract class DataSources {
      private DataSources() {}
  
      /**
       * Returns a {@link DataSource} backed by the provided {@link ByteBuffer}. The data source
       * represents the data contained between the position and limit of the buffer. Changes to the
       * buffer's contents will be visible in the data source.
       */
      public static DataSource asDataSource(ByteBuffer buffer) {
          if (buffer == null) {
              throw new NullPointerException();
          }
          return new ByteBufferDataSource(buffer);
      }
  
      /**
       * Returns a {@link DataSource} backed by the provided {@link RandomAccessFile}. Changes to the
       * file, including changes to size of file, will be visible in the data source.
       */
      public static DataSource asDataSource(RandomAccessFile file) {
          return asDataSource(file.getChannel());
      }
  
      /**
       * Returns a {@link DataSource} backed by the provided region of the {@link RandomAccessFile}.
       * Changes to the file will be visible in the data source.
       */
      public static DataSource asDataSource(RandomAccessFile file, long offset, long size) {
          return asDataSource(file.getChannel(), offset, size);
      }
  
      /**
       * Returns a {@link DataSource} backed by the provided {@link FileChannel}. Changes to the
       * file, including changes to size of file, will be visible in the data source.
       */
      public static DataSource asDataSource(FileChannel channel) {
          if (channel == null) {
              throw new NullPointerException();
          }
          return new FileChannelDataSource(channel);
      }
  
      /**
       * Returns a {@link DataSource} backed by the provided region of the {@link FileChannel}.
       * Changes to the file will be visible in the data source.
       */
      public static DataSource asDataSource(FileChannel channel, long offset, long size) {
          if (channel == null) {
              throw new NullPointerException();
          }
          return new FileChannelDataSource(channel, offset, size);
      }
  }
  