Hadoop计数器的应用以及数据清洗

package com.atguigu.mapreduce.weblog;import java.io.IOException;import org.apache.hadoop.io.LongWritable;import org.apache.hadoop.io.NullWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Mapper;public class LogMapper extends Mapper<LongWritable, Text, Text, NullWritable>{  Text k = new Text();  @Override  protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {   // 1 获取1行数据   String line = value.toString();   // 2 解析日志   boolean result = parseLog(line,context);   // 3 日志不合法退出   if (!result) {     return;   }   // 4 设置key   k.set(line);   // 5 写出数据   context.write(k, NullWritable.get());  }  // 2 解析日志  private boolean parseLog(String line, Context context) {   // 1 截取   String[] fields = line.split(" ");   // 2 日志长度大于11的为合法    if (fields.length > 11) {     // 系统计数器     context.getCounter("map", "true").increment(1);     return true;   }else {     context.getCounter("map", "false").increment(1);     return false;   }  }}

package com.atguigu.mapreduce.weblog;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.NullWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Job;import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;public class LogDriver {  public static void main(String[] args) throws Exception {// 输入输出路径需要根据自己电脑上实际的输入输出路径设置    args = new String[] { "e:/input/inputlog", "e:/output1" };   // 1 获取job信息   Configuration conf = new Configuration();   Job job = Job.getInstance(conf);   // 2 加载jar包   job.setJarByClass(LogDriver.class);   // 3 关联map   job.setMapperClass(LogMapper.class);   // 4 设置最终输出类型   job.setOutputKeyClass(Text.class);   job.setOutputValueClass(NullWritable.class);   // 设置reducetask个数为0   job.setNumReduceTasks(0);   // 5 设置输入和输出路径   FileInputFormat.setInputPaths(job, new Path(args[0]));   FileOutputFormat.setOutputPath(job, new Path(args[1]));   // 6 提交   job.waitForCompletion(true);  }}