对比：hadoop版本1.x 新版，hadoop版本0.x 旧版
1.新api引用包一般是mapreduce ，旧版api引用的包一般是mapred
2.新api使用Job，旧版api使用JobConf
3.新api类的包名使用mapreduce，旧版api使用mapred
4.新api使用job.waitForCompletion(true)提交作业，旧版api使用JobClient.runJob(job);
5.新api:extends Mapper，旧版api:extends MapRedcueBase implements Mapper
6.新api:使用上下文Context ctx ctx.write()，旧版api:使用OutputCollector<>collector Reporter collector.collect();
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新版：
public class kpi extends Configured implements Tool
{
static class MyMapper extends Mapper<LongWritable, Text, Text, kpiwritable>
{
protected void map(LongWritable k1, Text v1, Context context)
context.write(k2, v2);
}
static class MyReducer extends Reducer<Text, kpiwritable, Text, kpiwritable>
{
protected void reduce(Text k2, java.lang.Iterable<kpiwritable> v2s, Context ctx)
context.write(k2, v2);
}
public int run(String[] arg0)
{Job job=new Job(conf,"kpi");
job.waitForCompletion(true);
return 0;
}
public static void main(String[] args) throws Exception
{
ToolRunner.run(new kpi(), args);
}
}
---------------------------------------------------------
旧版：
public class old_api
{
static class MyMapper extends MapReduceBase implements Mapper<LongWritable, Text, Text, LongWritable>{
public void map(LongWritable k1, Text v1,
OutputCollector<Text, LongWritable> collector, Reporter reporter){
collector.collect(new Text(word), new LongWritable(1));
}
}
static class MyReducer extends MapReduceBase implements Reducer<Text, LongWritable, Text, LongWritable>{
public void reduce(Text k2, Iterator<LongWritable> v2s,
OutputCollector<Text, LongWritable> collector, Reporter reporter){
collector.collect(k2, new LongWritable(times));
}
}
public static void main(String[] args) {
final JobConf job = new JobConf(conf , old_api.class);
JobClient.runJob(job);
}
}