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See the License for the * 011// * specific language governing permissions and limitations under the License. * 012// *************************************************************************************************************************** 013package org.apache.juneau.config.store; 014 015import java.io.*; 016import java.util.*; 017import java.util.concurrent.*; 018 019import org.apache.juneau.*; 020import org.apache.juneau.annotation.*; 021import org.apache.juneau.config.internal.*; 022 023/** 024 * Represents a storage location for configuration files. 025 * 026 * <p> 027 * Content stores require two methods to be implemented: 028 * <ul class='javatree'> 029 * <li class='jm'>{@link #read(String)} - Retrieve a config file. 030 * <li class='jm'>{@link #write(String,String,String)} - ConfigStore a config file. 031 * </ul> 032 */ 033@ConfigurableContext 034public abstract class ConfigStore extends Context implements Closeable { 035 036 //------------------------------------------------------------------------------------------------------------------- 037 // Configurable properties 038 //------------------------------------------------------------------------------------------------------------------- 039 040 static final String PREFIX = "ConfigStore"; 041 042 //------------------------------------------------------------------------------------------------------------------- 043 // Instance 044 //------------------------------------------------------------------------------------------------------------------- 045 046 private final ConcurrentHashMap<String,Set<ConfigStoreListener>> listeners = new ConcurrentHashMap<>(); 047 private final ConcurrentHashMap<String,ConfigMap> configMaps = new ConcurrentHashMap<>(); 048 049 /** 050 * Constructor. 051 * 052 * @param ps The settings for this content store. 053 */ 054 protected ConfigStore(PropertyStore ps) { 055 super(ps, false); 056 } 057 058 /** 059 * Returns the contents of the configuration file. 060 * 061 * @param name The config file name. 062 * @return 063 * The contents of the configuration file. 064 * <br>A blank string if the config does not exist. 065 * <br>Never <jk>null</jk>. 066 * @throws IOException Thrown by underlying stream. 067 */ 068 public abstract String read(String name) throws IOException; 069 070 /** 071 * Saves the contents of the configuration file if the underlying storage hasn't been modified. 072 * 073 * @param name The config file name. 074 * @param expectedContents The expected contents of the file. 075 * @param newContents The new contents. 076 * @return 077 * If <jk>null</jk>, then we successfully stored the contents of the file. 078 * <br>Otherwise the contents of the file have changed and we return the new contents of the file. 079 * @throws IOException Thrown by underlying stream. 080 */ 081 public abstract String write(String name, String expectedContents, String newContents) throws IOException; 082 083 /** 084 * Checks whether the configuration with the specified name exists in this store. 085 * 086 * @param name The config name. 087 * @return <jk>true</jk> if the configuration with the specified name exists in this store. 088 */ 089 public abstract boolean exists(String name); 090 091 /** 092 * Registers a new listener on this store. 093 * 094 * @param name The configuration name to listen for. 095 * @param l The new listener. 096 * @return This object (for method chaining). 097 */ 098 public synchronized ConfigStore register(String name, ConfigStoreListener l) { 099 name = resolveName(name); 100 Set<ConfigStoreListener> s = listeners.get(name); 101 if (s == null) { 102 s = Collections.synchronizedSet(Collections.newSetFromMap(new IdentityHashMap<ConfigStoreListener,Boolean>())); 103 listeners.put(name, s); 104 } 105 s.add(l); 106 return this; 107 } 108 109 /** 110 * Unregisters a listener from this store. 111 * 112 * @param name The configuration name to listen for. 113 * @param l The listener to unregister. 114 * @return This object (for method chaining). 115 */ 116 public synchronized ConfigStore unregister(String name, ConfigStoreListener l) { 117 name = resolveName(name); 118 Set<ConfigStoreListener> s = listeners.get(name); 119 if (s != null) 120 s.remove(l); 121 return this; 122 } 123 124 /** 125 * Returns a map file containing the parsed contents of a configuration. 126 * 127 * @param name The configuration name. 128 * @return 129 * The parsed configuration. 130 * <br>Never <jk>null</jk>. 131 * @throws IOException Thrown by underlying stream. 132 */ 133 public synchronized ConfigMap getMap(String name) throws IOException { 134 name = resolveName(name); 135 ConfigMap cm = configMaps.get(name); 136 if (cm != null) 137 return cm; 138 cm = new ConfigMap(this, name); 139 ConfigMap cm2 = configMaps.putIfAbsent(name, cm); 140 if (cm2 != null) 141 return cm2; 142 register(name, cm); 143 return cm; 144 } 145 146 /** 147 * Called when the physical contents of a config file have changed. 148 * 149 * <p> 150 * Triggers calls to {@link ConfigStoreListener#onChange(String)} on all registered listeners. 151 * 152 * @param name The config name (e.g. the filename without the extension). 153 * @param contents The new contents. 154 * @return This object (for method chaining). 155 */ 156 public synchronized ConfigStore update(String name, String contents) { 157 name = resolveName(name); 158 Set<ConfigStoreListener> s = listeners.get(name); 159 if (s != null) 160 for (ConfigStoreListener l : listeners.get(name)) 161 l.onChange(contents); 162 return this; 163 } 164 165 /** 166 * Convenience method for updating the contents of a file with lines. 167 * 168 * @param name The config name (e.g. the filename without the extension). 169 * @param contentLines The new contents. 170 * @return This object (for method chaining). 171 */ 172 public synchronized ConfigStore update(String name, String...contentLines) { 173 name = resolveName(name); 174 StringBuilder sb = new StringBuilder(); 175 for (String l : contentLines) 176 sb.append(l).append('\n'); 177 return update(name, sb.toString()); 178 } 179 180 /** 181 * Subclasses can override this method to convert config names to internal forms. 182 * 183 * <p> 184 * For example, the {@link ConfigFileStore} class can take in both <js>"MyConfig"</js> and <js>"MyConfig.cfg"</js> 185 * as names that both resolve to <js>"MyConfig.cfg"</js>. 186 * 187 * @param name The name to resolve. 188 * @return The resolved name. 189 */ 190 protected String resolveName(String name) { 191 return name; 192 } 193 194 /** 195 * Unused. 196 */ 197 @Override /* Context */ 198 public final Session createSession(SessionArgs args) { 199 throw new NoSuchMethodError(); 200 } 201 202 /** 203 * Unused. 204 */ 205 @Override /* Context */ 206 public final SessionArgs createDefaultSessionArgs() { 207 throw new NoSuchMethodError(); 208 } 209 210 //----------------------------------------------------------------------------------------------------------------- 211 // Other methods. 212 //----------------------------------------------------------------------------------------------------------------- 213 214 @Override /* Context */ 215 public ObjectMap toMap() { 216 return super.toMap() 217 .append("ConfigStore", new DefaultFilteringObjectMap() 218 ); 219 } 220}