001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.config.store;
014
015import static org.apache.juneau.internal.StringUtils.*;
016
017import java.io.*;
018import java.util.concurrent.*;
019
020import org.apache.juneau.*;
021import org.apache.juneau.annotation.*;
022import org.apache.juneau.internal.*;
023
024/**
025 * Classpath-based storage location for configuration files.
026 *
027 * <p>
028 * Looks inside the JVM classpath for configuration files.
029 *
030 * <p>
031 * Configuration files retrieved from the classpath can be modified but not persisted.
032 */
033@ConfigurableContext
034public class ConfigClasspathStore extends ConfigStore {
035
036   //-------------------------------------------------------------------------------------------------------------------
037   // Configurable properties
038   //-------------------------------------------------------------------------------------------------------------------
039
040   static final String PREFIX = "ConfigClasspathStore";
041
042   //-------------------------------------------------------------------------------------------------------------------
043   // Predefined instances
044   //-------------------------------------------------------------------------------------------------------------------
045
046   /** Default memory store, all default values.*/
047   public static final ConfigClasspathStore DEFAULT = ConfigClasspathStore.create().build();
048
049
050   //-------------------------------------------------------------------------------------------------------------------
051   // Instance
052   //-------------------------------------------------------------------------------------------------------------------
053
054   /**
055    * Create a new builder for this object.
056    *
057    * @return A new builder for this object.
058    */
059   public static ConfigClasspathStoreBuilder create() {
060      return new ConfigClasspathStoreBuilder();
061   }
062
063   @Override /* Context */
064   public ConfigClasspathStoreBuilder builder() {
065      return new ConfigClasspathStoreBuilder(getPropertyStore());
066   }
067
068   private final ConcurrentHashMap<String,String> cache = new ConcurrentHashMap<>();
069
070   /**
071    * Constructor.
072    *
073    * @param ps The settings for this content store.
074    */
075   protected ConfigClasspathStore(PropertyStore ps) {
076      super(ps);
077   }
078
079   @Override /* ConfigStore */
080   public synchronized String read(String name) throws IOException {
081      String s = cache.get(name);
082      if (s != null)
083         return s;
084
085      ClassLoader cl = Thread.currentThread().getContextClassLoader();
086      try (InputStream in = cl.getResourceAsStream(name)) {
087         if (in != null)
088            cache.put(name, IOUtils.read(in, IOUtils.UTF8));
089      }
090      return emptyIfNull(cache.get(name));
091   }
092
093   @Override /* ConfigStore */
094   public synchronized String write(String name, String expectedContents, String newContents) throws IOException {
095
096      // This is a no-op.
097      if (isEquals(expectedContents, newContents))
098         return null;
099
100      String currentContents = read(name);
101
102      if (expectedContents != null && ! isEquals(currentContents, expectedContents))
103         return currentContents;
104
105      update(name, newContents);
106
107      return null;
108   }
109
110   @Override /* ConfigStore */
111   public synchronized boolean exists(String name) {
112      try {
113         return ! read(name).isEmpty();
114      } catch (IOException e) {
115         return false;
116      }
117   }
118
119   @Override /* ConfigStore */
120   public synchronized ConfigClasspathStore update(String name, String newContents) {
121      if (newContents == null)
122         cache.remove(name);
123      else
124         cache.put(name, newContents);
125      super.update(name, newContents);
126      return this;
127   }
128
129   /**
130    * No-op.
131    */
132   @Override /* Closeable */
133   public void close() throws IOException {
134      // No-op
135   }
136
137   //-----------------------------------------------------------------------------------------------------------------
138   // Other methods.
139   //-----------------------------------------------------------------------------------------------------------------
140
141   @Override /* Context */
142   public ObjectMap toMap() {
143      return super.toMap()
144         .append("ConfigClasspathStore", new DefaultFilteringObjectMap()
145         );
146   }
147}