Hadoop 源码详解之​​RecordReader​​接口

1. 类释义

RecordReader reads <key, value> pairs from an InputSplit.
​​RecordReader​​ 从InputSplit中读取<key,value> pairs 。

RecordReader, typically, converts the byte-oriented view of the input, provided by the InputSplit, and presents a record-oriented view for the Mapper and Reducer tasks for processing. It thus assumes the responsibility of processing record boundaries and presenting the tasks with keys and values.
​​RecordReader​​转换输入面向字节的视图，由​​InputSplit​​提供，并且展示一个面向记录的视图给 ​​Mapper​​ 以及 ​​Reducer​​任务从而进行处理。它承担处理记录边界并且使用keys 和 values展示任务的责任。

2. 源码

@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class RecordReader<KEYIN, VALUEIN> implements Closeable {
  ...
}

3. 方法详解