[Japi-cvs] SF.net SVN: japi: [132] trunk/src/app/net/sf/japi/util/Registry.java

[<chr...@us...>]

Revision: 132
Author:   christianhujer
Date:     2006-07-09 04:42:07 -0700 (Sun, 09 Jul 2006)
ViewCVS:  http://svn.sourceforge.net/japi/?rev=132&view=rev

Log Message:
-----------
Added Registry class.

Added Paths:
-----------
    trunk/src/app/net/sf/japi/util/Registry.java
Added: trunk/src/app/net/sf/japi/util/Registry.java
===================================================================
--- trunk/src/app/net/sf/japi/util/Registry.java	                        (rev 0)
+++ trunk/src/app/net/sf/japi/util/Registry.java	2006-07-09 11:42:07 UTC (rev 132)
@@ -0,0 +1,92 @@
+package net.sf.japi.util;
+
+import java.util.ArrayList;
+import static java.util.Arrays.asList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.PropertyResourceBundle;
+import java.net.URL;
+import java.io.IOException;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * A Registry is a class that allows registration of instances of classes that implement a certain interface.
+ * The Registry automatically scans classloaders, resource bundles, environment variables and system properties for looking up these classes.
+ * All that a Registry needs to know for that is a property key name.
+ * <p />
+ * @note This has nothing to do with MS Windows Registry.
+ * @author <a href="mailto:ch...@ri...">Christian Hujer</a>
+ */
+public class Registry<T> {
+
+    /** The registered instances of T. */
+    private List<T> instances = new ArrayList<T>();
+
+    private String[] prefixes = { "", "META-INF/services/" };
+
+    /**
+     * Create a Registry.
+     * @param keyname Key name
+     * @param classLoadersToUse optional classloaders to use in the search
+     */
+    public Registry(@NotNull final String keyname, @Nullable final Iterable<ClassLoader> classLoadersToUse) {
+        final List<String> stringsWithClassNames = new ArrayList<String>();
+        stringsWithClassNames.add(System.getProperty(keyname));
+        stringsWithClassNames.add(System.getenv(keyname));
+        final Set<ClassLoader> classLoaders = new HashSet<ClassLoader>();
+        for (final ClassLoader classLoader : classLoadersToUse) {
+            classLoaders.add(classLoader);
+        }
+        // Add own class loader, add context class loader
+        while (classLoaders.remove(null));
+        for (final ClassLoader classLoader : classLoaders) {
+            for (final String prefix : prefixes) {
+                try {
+                    for (final URL url : Collections.list(classLoader.getResources(prefix + keyname))) {
+                        stringsWithClassNames.add(new PropertyResourceBundle(url.openStream()).getString(keyname));
+                    }
+                } catch (final IOException e) {
+                    e.printStackTrace();
+                }
+            }
+        }
+        while (stringsWithClassNames.remove(null)); // remove entries that eventually are null
+        final Set<String> classNames = new HashSet<String>();
+        for (final String stringWithClassNames : stringsWithClassNames) {
+            classNames.addAll(asList(stringWithClassNames.split("[^.\\P{javaJavaIdentifierPart}]+")));
+        }
+        for (final String className : classNames) {
+            try {
+                add(((Class<? extends T>) Class.forName(className)).newInstance());
+            } catch (final ClassCastException e) {
+                e.printStackTrace();
+            } catch (final InstantiationException e) {
+                e.printStackTrace();
+            } catch (final IllegalAccessException e) {
+                e.printStackTrace();
+            } catch (final ClassNotFoundException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    /**
+     * Add an instance.
+     * @param t Instance to add
+     */
+    protected void add(@NotNull final T t) {
+        instances.add(t);
+    }
+
+    /**
+     * Get all registered instances.
+     * @return all registered instances
+     */
+    public List<T> getInstances() {
+        return Collections.unmodifiableList(instances);
+    }
+
+} // class Registry


Property changes on: trunk/src/app/net/sf/japi/util/Registry.java
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