在Hadoop中，使用configuration的时候，首先自动加载了默认的配置文件，比如core-default.xml、core-default.xml资源文件，代码如下：
static{ //print deprecation warning if hadoop-site.xml is found in classpath ClassLoader cL = Thread.currentThread().getContextClassLoader(); if (cL == null) { cL = Configuration.class.getClassLoader(); } if(cL.getResource("hadoop-site.xml")!=null) { LOG.warn("DEPRECATED: hadoop-site.xml found in the classpath. " "Usage of hadoop-site.xml is deprecated. Instead use core-site.xml, " "mapred-site.xml and hdfs-site.xml to override properties of " "core-default.xml, mapred-default.xml and hdfs-default.xml " "respectively"); } addDefaultResource("core-default.xml"); addDefaultResource("core-site.xml"); }
建立一个良好的Hadoop框架，势必会用很多自己写的资源文件，hadoop对xml支持好于对properties文件的支持，hadoop中的配置文件几乎都是是用xml写成的。那么如何加载自有的xml资源文件，使其成为全局的Configuration呢？
hadoop jar ‘你的jar包’ 之后跟随着一个-conf的命令，加载自有资源，靠的就是这个命令，ok，不废话了，上代码：
package com.ecom.asillin.utils;
import org.apache.hadoop.conf.Configuration;
/** * Created with IntelliJ IDEA. * User: asilin * Date: 14-10-23 * Time: 上午10:17 * To change this template use File | Settings | File Templates. */ public class ConfigurationUtils {
//静态类单例 private static class Singleton{ public static ConfigurationUtils instance = new ConfigurationUtils(); }
private ConfigurationUtils(){}
public static ConfigurationUtils getInstance(){ return Singleton.instance; }
//添加资源 public static Configuration create(){ Configuration conn = new Configuration(); addSources(conn); return conn; }
//添加默认资源 -conf 之后的资源 private static Configuration addSources(Configuration conn){ conn.addResource("你的xml文件名称，带有.xml,不要忘记"); return conn; } }
ok 现在完整的运行命令就是： hadoop jar ‘a.jar’ -conf ‘yourself.xml’
