diff --git a/notes/Hadoop-MapReduce.md b/notes/Hadoop-MapReduce.md index b2169bf..7355533 100644 --- a/notes/Hadoop-MapReduce.md +++ b/notes/Hadoop-MapReduce.md @@ -149,7 +149,7 @@ public class WordCountMapper extends Mapper @@ -162,13 +162,13 @@ public class Mapper { + **KEYIN** : `mapping`输入key的类型,即每行的偏移量(每行第一个字符在整个文本中的位置),`Long`类型,对应Hadoop中的`LongWritable`类型; + **VALUEIN** : `mapping`输入value的类型,即每行数据;`String`类型,对应Hadoop中`Text`类型; + **KEYOUT** :`mapping`输出的key的类型,即每个单词;`String`类型,对应Hadoop中`Text`类型; -+ **VALUEOUT**:`mapping`输出value的类型,即每个单词出现的次数;这里用`int`类型,对应Hadoop中`IntWritable`类型。 ++ **VALUEOUT**:`mapping`输出value的类型,即每个单词出现的次数;这里用`int`类型,对应`IntWritable`类型。 ### 4.4 WordCountReducer -在Reduce中进程单词出现次数统计: +在Reduce中进行单词出现次数的统计: ```java public class WordCountReducer extends Reducer {