org.apache.htrace.core.JavaPropertyConfiguration.java Source code

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Here is the source code for org.apache.htrace.core.JavaPropertyConfiguration.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.htrace.core;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.util.Iterator;
import java.util.LinkedList;

/**
 * This is an implementation of HTraceConfiguration which draws its properties
 * from global Java Properties.
 */
public final class JavaPropertyConfiguration extends HTraceConfiguration {
    private static final Log LOG = LogFactory.getLog(JavaPropertyConfiguration.class);

    public static class Builder {
        final LinkedList<String> prefixes;

        public Builder() {
            prefixes = new LinkedList<String>();
            prefixes.add("htrace.");
        }

        public Builder clearPrefixes() {
            prefixes.clear();
            return this;
        }

        public Builder addPrefix(String prefix) {
            prefixes.add(prefix);
            return this;
        }

        JavaPropertyConfiguration build() {
            return new JavaPropertyConfiguration(prefixes);
        }
    }

    private final String[] prefixes;

    private JavaPropertyConfiguration(LinkedList<String> prefixes) {
        this.prefixes = new String[prefixes.size()];
        int i = 0;
        for (Iterator<String> it = prefixes.descendingIterator(); it.hasNext();) {
            this.prefixes[i++] = it.next();
        }
    }

    @Override
    public String get(String key) {
        for (String prefix : prefixes) {
            String val = System.getProperty(prefix + key);
            if (val != null) {
                return val;
            }
        }
        return null;
    }

    @Override
    public String get(String key, String defaultValue) {
        String val = get(key);
        return (val != null) ? val : defaultValue;
    }
}