1.x: add shorter RxJavaPlugin class lookup approach.

Author: akarnokd

src/main/java/rx/plugins/RxJavaPlugins.java

@@ -15,6 +15,7 @@
  */
 package rx.plugins;
 
+import java.util.*;
 import java.util.concurrent.atomic.AtomicReference;
 
 /**
@@ -26,7 +27,22 @@
  * property names)</li>
  * <li>default implementation</li>
  * </ol>
- *
+ * <p>In addition to the {@code rxjava.plugin.[simple classname].implementation} system properties,
+ * you can define two system property:<br>
+ * <pre><code>
+ * rxjava.plugin.[index].class}
+ * rxjava.plugin.[index].impl}
+ * </code></pre>
+ * 
+ * Where the {@code .class} property contains the simple classname from above and the {@code .impl}
+ * contains the fully qualified name of the implementation class. The {@code [index]} can be
+ * any short string or number of your chosing. For example, you can now define a custom 
+ * {@code RxJavaErrorHandler} via two system property:
+ * <pre><code>
+ * rxjava.plugin.1.class=RxJavaErrorHandler
+ * rxjava.plugin.1.impl=some.package.MyRxJavaErrorHandler
+ * </code></pre>
+ * 
  * @see <a href="https://github.com/ReactiveX/RxJava/wiki/Plugins">RxJava Uncyclo: Plugins</a>
  */
 public class RxJavaPlugins {
@@ -64,13 +80,12 @@ public static RxJavaPlugins getInstance() {
      * <p>
      * Override the default by calling {@link #registerErrorHandler(RxJavaErrorHandler)} or by setting the
      * property {@code rxjava.plugin.RxJavaErrorHandler.implementation} with the full classname to load.
-     * 
      * @return {@link RxJavaErrorHandler} implementation to use
      */
     public RxJavaErrorHandler getErrorHandler() {
         if (errorHandler.get() == null) {
             // check for an implementation from System.getProperty first
-            Object impl = getPluginImplementationViaProperty(RxJavaErrorHandler.class);
+            Object impl = getPluginImplementationViaProperty(RxJavaErrorHandler.class, System.getProperties());
             if (impl == null) {
                 // nothing set via properties so initialize with default 
                 errorHandler.compareAndSet(null, DEFAULT_ERROR_HANDLER);
@@ -112,7 +127,7 @@ public void registerErrorHandler(RxJavaErrorHandler impl) {
     public RxJavaObservableExecutionHook getObservableExecutionHook() {
         if (observableExecutionHook.get() == null) {
             // check for an implementation from System.getProperty first
-            Object impl = getPluginImplementationViaProperty(RxJavaObservableExecutionHook.class);
+            Object impl = getPluginImplementationViaProperty(RxJavaObservableExecutionHook.class, System.getProperties());
             if (impl == null) {
                 // nothing set via properties so initialize with default 
                 observableExecutionHook.compareAndSet(null, RxJavaObservableExecutionHookDefault.getInstance());
@@ -141,15 +156,42 @@ public void registerObservableExecutionHook(RxJavaObservableExecutionHook impl)
         }
     }
 
-    private static Object getPluginImplementationViaProperty(Class<?> pluginClass) {
-        String classSimpleName = pluginClass.getSimpleName();
+    /* test */ static Object getPluginImplementationViaProperty(Class<?> pluginClass, Properties props) {
+        final String classSimpleName = pluginClass.getSimpleName();
         /*
          * Check system properties for plugin class.
          * <p>
          * This will only happen during system startup thus it's okay to use the synchronized
          * System.getProperties as it will never get called in normal operations.
          */
-        String implementingClass = System.getProperty("rxjava.plugin." + classSimpleName + ".implementation");
+        
+        final String pluginPrefix = "rxjava.plugin.";
+        
+        String defaultKey = pluginPrefix + classSimpleName + ".implementation";
+        String implementingClass = props.getProperty(defaultKey);
+
+        if (implementingClass == null) {
+            final String classSuffix = ".class";
+            final String implSuffix = ".impl";
+    
+            for (Map.Entry<Object, Object> e : props.entrySet()) {
+                String key = e.getKey().toString();
+                if (key.startsWith(pluginPrefix) && key.endsWith(classSuffix)) {
+                    String value = e.getValue().toString();
+                    
+                    if (classSimpleName.equals(value)) {
+                        String index = key.substring(0, key.length() - classSuffix.length()).substring(pluginPrefix.length());
+                        
+                        String implKey = pluginPrefix + index + implSuffix;
+                        
+                        implementingClass = props.getProperty(implKey);
+                        
+                        break;
+                    }
+                }
+            }
+        }
+
         if (implementingClass != null) {
             try {
                 Class<?> cls = Class.forName(implementingClass);
@@ -165,9 +207,9 @@ private static Object getPluginImplementationViaProperty(Class<?> pluginClass) {
             } catch (IllegalAccessException e) {
                 throw new RuntimeException(classSimpleName + " implementation not able to be accessed: " + implementingClass, e);
             }
-        } else {
-            return null;
         }
+
+        return null;
     }
 
     /**
@@ -183,7 +225,7 @@ private static Object getPluginImplementationViaProperty(Class<?> pluginClass) {
     public RxJavaSchedulersHook getSchedulersHook() {
         if (schedulersHook.get() == null) {
             // check for an implementation from System.getProperty first
-            Object impl = getPluginImplementationViaProperty(RxJavaSchedulersHook.class);
+            Object impl = getPluginImplementationViaProperty(RxJavaSchedulersHook.class, System.getProperties());
             if (impl == null) {
                 // nothing set via properties so initialize with default
                 schedulersHook.compareAndSet(null, RxJavaSchedulersHook.getDefaultInstance());

src/test/java/rx/plugins/RxJavaPluginsTest.java

@@ -15,21 +15,12 @@
  */
 package rx.plugins;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
-
-import java.util.Calendar;
-import java.util.Collections;
-import java.util.Date;
+import static org.junit.Assert.*;
+
+import java.util.*;
 import java.util.concurrent.TimeUnit;
 
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.*;
 
 import rx.Observable;
 import rx.Subscriber;
@@ -251,4 +242,24 @@ private static String getFullClassNameForTestClass(Class<?> cls) {
         return RxJavaPlugins.class.getPackage()
                                   .getName() + "." + RxJavaPluginsTest.class.getSimpleName() + "$" + cls.getSimpleName();
     }
+    
+    @Test
+    public void testShortPluginDiscovery() {
+        Properties props = new Properties();
+        
+        props.setProperty("rxjava.plugin.1.class", "Map");
+        props.setProperty("rxjava.plugin.1.impl", "java.util.HashMap");
+
+        props.setProperty("rxjava.plugin.xyz.class", "List");
+        props.setProperty("rxjava.plugin.xyz.impl", "java.util.ArrayList");
+
+        
+        Object o = RxJavaPlugins.getPluginImplementationViaProperty(Map.class, props);
+        
+        assertTrue("" + o, o instanceof HashMap);
+        
+        o = RxJavaPlugins.getPluginImplementationViaProperty(List.class, props);
+        
+        assertTrue("" + o, o instanceof ArrayList);
+    }
 }