com.redpill_linpro.springframework.beans.factory.config.EtcdPlaceholderConfigurer.java Source code

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Here is the source code for com.redpill_linpro.springframework.beans.factory.config.EtcdPlaceholderConfigurer.java

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/*
 * Copyright 2002-2012 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.redpill_linpro.springframework.beans.factory.config;

import java.util.Properties;

import jetcd.EtcdClient;
import jetcd.EtcdClientFactory;
import jetcd.EtcdException;

import org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Required;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;

/**
 * Subclass of PropertyPlaceholderConfigurer that supports loading properties 
 * from a etcd key-value store.
 *
 * <p>Tries to resolve placeholders as keys in the given base directory. Default is no directory.
 * </p>
 *
 * @author Pontus Ullgren
 * @see #setServerUrl
 * @see #setBaseDirectory
 */
public class EtcdPlaceholderConfigurer extends PropertyPlaceholderConfigurer implements InitializingBean {

    private EtcdClient client;
    private String serverUrl;
    private String baseDirectory = "";

    /**
     * Set the URL to the etcd server
     */
    public void setServerUrl(String serverUrl) {
        this.client = EtcdClientFactory.newInstance(serverUrl);
    }

    /**
     * Sets the base directory to used to resolve the 
     * placeholders.
     */
    public void setBaseDirectory(String baseDirectory) {
        if (baseDirectory != null && !baseDirectory.endsWith("/")) {
            baseDirectory += baseDirectory + "/";
        }
        this.baseDirectory = baseDirectory;
    }

    /**
     */
    @Override
    public void afterPropertiesSet() {
        if (this.client == null) {
            throw new IllegalArgumentException("serverUrl is required");
        }
    }

    /**
     * This implementation tries to resolve placeholders first by querying the etcd server,
     * then in the passed-in properties.
     */
    @Override
    protected String resolvePlaceholder(String placeholder, Properties props) {
        String value = null;
        if (this.client == null) {
            this.client = createEtcdClient();
        }
        try {
            value = this.client.get(this.baseDirectory + placeholder);
        } catch (Exception e) {
            // Ignore any error so we can check in passed-in properties
        }
        if (value == null) {
            value = props.getProperty(placeholder);
        }
        return value;
    }

    /** Used to set a EtcdClient when running unit tests
     */
    protected void setEtcdClient(EtcdClient client) {
        this.client = client;
    }

    /** Creates a new EtcdClient using the provided serverUrl
      */
    private EtcdClient createEtcdClient() {
        return EtcdClientFactory.newInstance(this.serverUrl);
    }
}