content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.aliyun.odps.io;
  
  import java.io.IOException;
  
  /**
   * InputBlobWritable表示ODPS表或分区中列类型为blob的输入接口. 该接口只能用于
   * {@link com.aliyun.odps.mapreduce.Mapper}从 {@link com.aliyun.odps.Record}
   * 中读取blob类型的列.
   * <p>
   * 用法示例：
   *
   * <pre>
   * &#064;Override
   * public void map(LongWritable key, Record value,
   *     MapContext&lt;KEYOUT, VALUEOUT&gt; context) throws IOException {
   *   InputBlobWritable blob = value.get(0);
   *   BlobDataInputStream in = blob.getInputStream();
   *   long length = in.getLength();
   *   // 使用in.read从blob中读取
   *   in.close();
   * }
   * </pre>
   *
   * 从上面的示例看出, 从{@link com.aliyun.odps.Record}获得InputBlobWritable接口,
   * 调用InputBlobWritable的getInputStream获得BlobDataInputStream后, 即可读出数据.
   * </p>
   */
  public interface InputBlobWritable extends WritableComparable {
  
    /**
     * getInputStream方法获取可以读取blob的{@link BlobDataInputStream}接口
     *
     * @return blob列对应的{@link BlobDataInputStream}
     * @throws IOException
     */
    public BlobDataInputStream getInputStream() throws IOException;
  
    /**
     * getLength方法获取blob的总字节数
     *
     * @return blob列的字节数
     * @throws IOException
     */
    public long getLength() throws IOException;
  
  }
  