编写WordCount程序之一固定格式讲解
WordCount因果图 MapReduce中 map和reduce函数格式 MapReduce中,map和reduce函数遵循如下常规格式: map: (K1, V1) → list(K2, V2) reduce: (K2, list(V2)) → list(K3, V3) Mapper的基类: protected void map(KEY key, VALUE value, Context context) throws IOException, InterruptedException { } Reducer的基类: protected void reduce(KEY key, Iterable<VALUE> values, Context context) throws IOException, InterruptedException { } Context是上下文对象 代码模板 wordcount 代码 代码编写依据,也就是固定写法 input-->map--->reduce->output以下java代码实现此命令的功能bin/hdfs df...
