Hadoop辅助类Tool和ToolRunner

来源：互联网发布：sql 删除重复数据编辑：程序博客网时间：2024/06/16 10:04

Tool的实现，用来打印所有Configuration中对象中所有属性的键值对：

import java.util.Map.Entry;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.conf.Configured;import org.apache.hadoop.util.Tool;import org.apache.hadoop.util.ToolRunner;public class ConfigurationPrinter extends Configured implements Tool {   static {    Configuration.addDefaultResource("hdfs-default.xml");    Configuration.addDefaultResource("hdfs-site.xml");    Configuration.addDefaultResource("mapred-default.xml");    Configuration.addDefaultResource("mapred-site.xml");  }  @Override  public int run(String[] args) throws Exception {    Configuration conf = getConf();    for (Entry entry: conf) {      System.out.printf("%s=%s\n", entry.getKey(), entry.getValue());    }    return 0;  }   public static void main(String[] args) throws Exception {    int exitCode = ToolRunner.run(new ConfigurationPrinter(), args);    System.exit(exitCode);  }}

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