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| |
| Config Stores |
| |
| <p> |
| Configuration files are stored in entities called Stores. |
| </p> |
| <p> |
| The methods that need to be implemented on a store are: |
| </p> |
| <ul class='javatree'> |
| <li class='jac'>{@link oaj.config.store.ConfigStore} |
| <ul> |
| <li class='jm'>{@link oaj.config.store.ConfigStore#read(String) read(String)} - Read a config file. |
| <li class='jm'>{@link oaj.config.store.ConfigStore#write(String,String,String) write(String,String,String)} - Write a config file. |
| <li class='jm'>{@link oaj.config.store.ConfigStore#update(String,String) update(String,String)} - Update the contents of a config file. |
| </ul> |
| </ul> |
| <p> |
| Read is self-explanatory: |
| </p> |
| <p class='bpcode w800'> |
| <jk>public</jk> String read(String name) { |
| <jc>// Return the contents of the specified configuration.</jc> |
| } |
| </p> |
| <p> |
| Write is slightly trickier: |
| </p> |
| <p class='bpcode w800'> |
| <jk>public</jk> String write(String name, String oldContents, String newContents) { |
| |
| <jc>// If the old contents match the current stored contents, the new contents will get stored, |
| // and the method returns null indicating success. |
| |
| // If the old contents DO NOT match the current stored contents (i.e. it was modified in some way), |
| // the new contents are NOT stored, and the method returns the current stored contents. |
| |
| // If the old contents are null, then just always write the new contents.</jc> |
| } |
| </p> |
| <p> |
| The update method is called whenever the stored file gets modified externally: |
| </p> |
| <p class='bpcode w800'> |
| <jk>public</jk> String update(String name, String newContents) { |
| <jc>// Do something with the updated contents.</jc> |
| } |
| </p> |
| <p> |
| Two configuration stores are provided by default: |
| </p> |
| <ul class='javatree'> |
| <li class='jc'>{@link oaj.config.store.ConfigFileStore} - File-system storage. |
| <li class='jc'>{@link oaj.config.store.ConfigMemoryStore} - In-memory storage. |
| </ul> |
| <p> |
| The store is defined on the <c>Config</c> object via the following setting: |
| </p> |
| <ul class='javatree'> |
| <li class='jf'>{@link oaj.config.Config#CONFIG_store} |
| </ul> |
| |
| <h5 class='figure'>Example:</h5> |
| <p class='bpcode w800'> |
| <jc>// Create a config with in-memory storage.</jc> |
| Config c = Config.<jsm>create</jsm>(<js>"MyConfig.cfg"</js>).store(ConfigMemoryStore.<jsf>DEFAULT</jsf>).build(); |
| </p> |
| <p> |
| The default store used is {@link oaj.config.store.ConfigFileStore#DEFAULT} which defines |
| the execution directory as the file system directory to store and retrieve files. |
| </p> |