hadoop通过Configuration类来保存配置信息 1、通过Configuration.addResource()来加载配置文件 2、通过Configuration.get***()来获取配置属性 1、创建一个新的Configuration实例时，会加载core-default.xml与core-site.xml，若还有其它配置，则调用addResource()继续添加。 package org.jediael.hadoopdemo; import org.apache.hadoop.conf.Configuration; public class ConfigurationDemo { public static void main(String[] args){ Configuration conf = new Configuration(); //conf.addResource("/opt/jediael/hadoop-1.2.1/conf/core-site.xml"); Configuration.addDefaultResource("mapred-default.xml"); //System.out.println(conf.get("fs.default.name")); System.out.println(conf.get("hadoop.tmp.dir")); System.out.println(conf.get("io.sort.mb")); } } 输出结果为： www:Downloads liaoliuqing$ hadoop jar hdemo.jar org.jediael.hadoopdemo.ConfigurationDemo hdfs://localhost:9000 /opt/tmp null 2、可以通过Configuration.addDefaultResource（）加载CLASSPATH下的内容，主要用于加载hdfs-default.xml hdfs-site.xml mapred-default.xm mapred-site.xml package org.jediael.hadoopdemo; import org.apache.hadoop.conf.Configuration; public class ConfigurationDemo { public static void main(String[] args){ Configuration conf = new Configuration(); //conf.addResource("/opt/jediael/hadoop-1.2.1/conf/core-site.xml"); Configuration.addDefaultResource("mapred-default.xml"); System.out.println(conf.get("fs.default.name")); System.out.println(conf.get("hadoop.tmp.dir")); System.out.println(conf.get("io.sort.mb")); } } 输出结果为： www:Downloads liaoliuqing$ hadoop jar hdemo.jar org.jediael.hadoopdemo.ConfigurationDemo hdfs://localhost:9000 /opt/tmp 100 若color.xml位于$HADOOP_HOME/conf package org.jediael.hadoopdemo; import org.apache.hadoop.conf.Configuration; public class ConfigurationDemo { public static void main(String[] args){ Configuration conf = new Configuration(); //conf.addResource("/opt/jediael/hadoop-1.2.1/conf/color.xml"); Configuration.addDefaultResource("color.xml"); Configuration.addDefaultResource("mapred-default.xml"); System.out.println(conf.get("fs.default.name")); System.out.println(conf.get("hadoop.tmp.dir")); System.out.println(conf.get("io.sort.mb")); System.out.println(conf.get("color")); } } 输出结果为： www:Downloads liaoliuqing$ hadoop jar hdemo.jar org.jediael.hadoopdemo.ConfigurationDemo hdfs://localhost:9000 /opt/tmp 100 yellow 若color.xml不位于$HADOOP_HOME/conf，则color的输出值为null。 3、conf.addResource（）与Configuration.addDefaultResource（）的区别
转载于:https://www.cnblogs.com/jinhong-lu/p/4559373.html
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