org.springframework.cloud.zookeeper.config.ZookeeperPropertySourceLocator.java Source code

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Here is the source code for org.springframework.cloud.zookeeper.config.ZookeeperPropertySourceLocator.java

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/*
 * Copyright 2013-2015 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 org.springframework.cloud.zookeeper.config;

import javax.annotation.PreDestroy;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.curator.framework.CuratorFramework;
import org.springframework.cloud.bootstrap.config.PropertySourceLocator;
import org.springframework.core.env.CompositePropertySource;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;
import org.springframework.core.env.PropertySource;
import org.springframework.util.ReflectionUtils;

/**
 * Zookeeper provides a <a href="http://zookeeper.apache.org/doc/current/zookeeperOver.html#sc_dataModelNameSpace">hierarchical namespace</a> that allows
 * clients to store arbitrary data, such as configuration data.  Spring Cloud Zookeeper Config is an alternative to the
 * <a href="https://github.com/spring-cloud/spring-cloud-config">Config Server and Client</a>.  Configuration is loaded into the Spring Environment during
 * the special "bootstrap" phase.  Configuration is stored in the {@code /config} namespace by default.  Multiple
 * {@code PropertySource} instances are created based on the application's name and the active profiles that mimicks the Spring Cloud Config
 * order of resolving properties.  For example, an application with the name "testApp" and with the "dev" profile will have the following property sources
 * created:
 *
 * <pre>{@code
 * config/testApp,dev
 * config/testApp
 * config/application,dev
 * config/application
 * }</pre>
 *
 * </p>
 * The most specific property source is at the top, with the least specific at the
 * bottom.  Properties is the {@code config/application} namespace are applicable to all applications
 * using zookeeper for configuration.  Properties in the {@code config/testApp} namespace are only available
 * to the instances of the service named "testApp".
 *
 * @author Spencer Gibb
 * @since 1.0.0
 */
public class ZookeeperPropertySourceLocator implements PropertySourceLocator {

    private ZookeeperConfigProperties properties;

    private CuratorFramework curator;

    private List<String> contexts;

    private static final Log log = LogFactory.getLog(ConfigWatcher.class);

    public ZookeeperPropertySourceLocator(CuratorFramework curator, ZookeeperConfigProperties properties) {
        this.curator = curator;
        this.properties = properties;
    }

    public List<String> getContexts() {
        return this.contexts;
    }

    @Override
    public PropertySource<?> locate(Environment environment) {
        if (environment instanceof ConfigurableEnvironment) {
            ConfigurableEnvironment env = (ConfigurableEnvironment) environment;
            String appName = env.getProperty("spring.application.name");
            List<String> profiles = Arrays.asList(env.getActiveProfiles());

            String root = this.properties.getRoot();
            this.contexts = new ArrayList<>();

            String defaultContext = root + "/" + this.properties.getDefaultContext();
            this.contexts.add(defaultContext);
            addProfiles(this.contexts, defaultContext, profiles);

            StringBuilder baseContext = new StringBuilder(root);
            if (!appName.startsWith("/")) {
                baseContext.append("/");
            }
            baseContext.append(appName);
            this.contexts.add(baseContext.toString());
            addProfiles(this.contexts, baseContext.toString(), profiles);

            CompositePropertySource composite = new CompositePropertySource("zookeeper");

            Collections.reverse(this.contexts);

            for (String propertySourceContext : this.contexts) {
                try {
                    PropertySource propertySource = create(propertySourceContext);
                    composite.addPropertySource(propertySource);
                    // TODO: howto call close when /refresh
                } catch (Exception e) {
                    if (this.properties.isFailFast()) {
                        ReflectionUtils.rethrowRuntimeException(e);
                    } else {
                        log.warn("Unable to load zookeeper config from " + propertySourceContext, e);
                    }
                }
            }

            return composite;
        }
        return null;
    }

    @PreDestroy
    public void destroy() {
    }

    private PropertySource<CuratorFramework> create(String context) {
        return new ZookeeperPropertySource(context, this.curator);
    }

    private void addProfiles(List<String> contexts, String baseContext, List<String> profiles) {
        for (String profile : profiles) {
            contexts.add(baseContext + this.properties.getProfileSeparator() + profile);
        }
    }
}