MapReduce项目书写

• 导入相关jar包
• 写一个job类

job类的部分代码：

public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {        Configuration conf = new Configuration();        Job job =Job.getInstance(conf,"Pv");        job.setJarByClass(PvUvJob.class);        Path in =new Path("/user/input/pv");        Path out =new Path("/user/output/pv");        FileInputFormat.addInputPath(job,in);        FileOutputFormat.setOutputPath(job,out);        job.setInputFormatClass(TextInputFormat.class);        job.setOutputFormatClass(TextOutputFormat.class);        job.setMapperClass(PvUvMap.class);        job.setReducerClass(PvUvReduce.class);        job.setMapOutputKeyClass(Text.class);        job.setMapOutputValueClass(IntWritable.class);        job.setOutputKeyClass(Text.class);        job.setOutputValueClass(NullWritable.class);        job.waitForCompletion(true);    }

一个map类：

IntWritable one = new IntWritable(1);    @Override    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {        String[] line =value.toString().split("/t");        String url = line[28];        context.write(new Text(url),one);    }

reduce类

protected void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {        int sum = 0;        for (IntWritable value: values){            sum+=value.get();        }        context.write(new Text(key+"====>"+sum),NullWritable.get());    }