Storing application settings in a property file

This is not a totally necessary class, but it doesn't abstract loading text from a properties file. For example if you need to store application specific settings or even localizations you can use this class to access it using flexible paths (dot notation or directory path style). Here is how to use it: Properties props = PropertyLoader.loadProperties("/some/package/Config.properties"); String val = props.getProperty(key); package mypackage;

import java.util.ResourceBundle; import java.util.Properties; import java.io.InputStream; import java.util.Locale; import java.util.Enumeration;

public class PropertyLoader { /** Creates a new instance of PropertyLoader */ public PropertyLoader() { } /** * Looks up a resource named 'name' in the classpath. The resource must map * to a file with .properties extention. The name is assumed to be absolute * and can use either "/" or "." for package segment separation with an * optional leading "/" and optional ".properties" suffix. Thus, the * following names refer to the same resource: * <pre> * some.pkg.Resource * some.pkg.Resource.properties * some/pkg/Resource * some/pkg/Resource.properties * /some/pkg/Resource * /some/pkg/Resource.properties * </pre> * * @param name classpath resource name [may not be null] * @param loader classloader through which to load the resource [null * is equivalent to the application loader] * * @return resource converted to java.util.Properties [may be null if the * resource was not found and THROW_ON_LOAD_FAILURE is false] * @throws IllegalArgumentException if the resource was not found and * THROW_ON_LOAD_FAILURE is true */ public static Properties loadProperties (String name, ClassLoader loader) { if (name == null) throw new IllegalArgumentException ("null input: name"); if (name.startsWith ("/")) name = name.substring (1); if (name.endsWith (SUFFIX)) name = name.substring (0, name.length () - SUFFIX.length ()); Properties result = null; InputStream in = null; try { if (loader == null) loader = ClassLoader.getSystemClassLoader (); if (LOAD_AS_RESOURCE_BUNDLE) { name = name.replace ('/', '.'); // Throws MissingResourceException on lookup failures: final ResourceBundle rb = ResourceBundle.getBundle (name, Locale.getDefault (), loader); result = new Properties (); for (Enumeration keys = rb.getKeys (); keys.hasMoreElements ();) { final String key = (String) keys.nextElement (); final String value = rb.getString (key); result.put (key, value); } } else { name = name.replace ('.', '/'); if (! name.endsWith (SUFFIX)) name = name.concat (SUFFIX); // Returns null on lookup failures: in = loader.getResourceAsStream (name); if (in != null) { result = new Properties (); result.load (in); // Can throw IOException } } } catch (Exception e) { result = null; } finally { if (in != null) try { in.close (); } catch (Throwable ignore) {} } if (THROW_ON_LOAD_FAILURE && (result == null)) { throw new IllegalArgumentException ("could not load [" + name + "]"+ " as " + (LOAD_AS_RESOURCE_BUNDLE ? "a resource bundle" : "a classloader resource")); } return result; } public static Properties loadProperties (final String name) { return loadProperties (name, Thread.currentThread ().getContextClassLoader ()); } private static final boolean THROW_ON_LOAD_FAILURE = true; private static final boolean LOAD_AS_RESOURCE_BUNDLE = true; // if true localization and caching is used. private static final String SUFFIX = ".properties"; }