com.github.gaoyangthu.core.hbase.ConfigurationUtils.java Source code

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Here is the source code for com.github.gaoyangthu.core.hbase.ConfigurationUtils.java

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/*
 * Copyright 2011-2013 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.github.gaoyangthu.core.hbase;

import java.util.Enumeration;
import java.util.Map;
import java.util.Properties;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapred.JobConf;

/**
 * Reusable utility class for common {@link org.apache.hadoop.conf.Configuration} operations.
 * 
 * @author Costin Leau
 */
public abstract class ConfigurationUtils {

    /**
     * Adds the specified properties to the given {@link org.apache.hadoop.conf.Configuration} object.
     * 
     * @param configuration configuration to manipulate. Should not be null.
     * @param properties properties to add to the configuration. May be null.
     */
    public static void addProperties(Configuration configuration, Properties properties) {
        if (configuration == null) {
            return;
        }
        if (properties != null) {
            Enumeration<?> props = properties.propertyNames();
            while (props.hasMoreElements()) {
                String key = props.nextElement().toString();
                configuration.set(key, properties.getProperty(key));
            }
        }
    }

    /**
     * Creates a new {@link org.apache.hadoop.conf.Configuration} based on the given arguments.
     * 
     * @param original initial configuration to read from. May be null. 
     * @param properties properties object to add to the newly created configuration. May be null.
     * @return newly created configuration based on the input parameters.
     */
    public static Configuration createFrom(Configuration original, Properties properties) {
        Configuration cfg = null;
        if (original != null) {
            cfg = (original instanceof JobConf ? new JobConf(original) : new Configuration(original));
        } else {
            cfg = new JobConf();
        }
        addProperties(cfg, properties);
        return cfg;
    }

    /**
     * Creates a new {@link org.apache.hadoop.mapred.JobConf} based on the given arguments. Identical to
     * {@link #createFrom(org.apache.hadoop.conf.Configuration, java.util.Properties)} but forces the use of
     * {@link org.apache.hadoop.mapred.JobConf}.
     * 
     * @param original initial configuration to read from. May be null. 
     * @param properties properties object to add to the newly created configuration. May be null.
     * @return newly created configuration based on the input parameters.
     */
    public static JobConf createFrom(JobConf original, Properties properties) {
        return (JobConf) createFrom((Configuration) original, properties);
    }

    /**
     * Returns a static {@link java.util.Properties} copy of the given configuration.
     * 
     * @param configuration Hadoop configuration
     */
    public static Properties asProperties(Configuration configuration) {
        Properties props = new Properties();

        if (configuration != null) {
            for (Map.Entry<String, String> entry : configuration) {
                props.setProperty(entry.getKey(), entry.getValue());
            }
        }

        return props;
    }

    /**
     * Creates a new {@link org.apache.hadoop.conf.Configuration} by merging the given configurations.
     * Ordering is important - the second configuration overriding values in the first.
     * 
     * @param one configuration to read from. May be null.
     * @param two configuration to read from. May be null.
     * @return the result of merging the two configurations.
     */
    public static Configuration merge(Configuration one, Configuration two) {
        if (one == null) {
            if (two == null) {
                return new JobConf();
            }
            return new JobConf(two);
        }

        Configuration c = new JobConf(one);

        if (two == null) {
            return c;
        }

        for (Map.Entry<String, String> entry : two) {
            c.set(entry.getKey(), entry.getValue());
        }

        return c;
    }

}