used URLClassLoader instead of changing java.class.path to dynamicall…

…y load plugin jars (Lighthouse unclebob#63)

src/fitnesse/components/PluginsClassLoader.java

@@ -0,0 +1,53 @@
+package fitnesse.components;
+
+import java.io.File;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+
+
+public class PluginsClassLoader {
+
+    protected String pluginsDirectory = "plugins";
+
+    public void addPluginsToClassLoader() {
+        File pluginsDir = new File(pluginsDirectory);
+        if (pluginsDir.exists()) {
+            for (File plugin : pluginsDir.listFiles()) {
+                if (plugin.getName().endsWith("jar")) {
+                    addFile(plugin);
+                }
+            }
+        }
+    }
+
+
+    public void addFile(File plugin) {
+        try {
+            addURL(plugin.toURI().toURL());
+        } catch (MalformedURLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+
+    public void addURL(URL url) {
+        URLClassLoader sysloader = (URLClassLoader) ClassLoader.getSystemClassLoader();
+        Class sysclass = URLClassLoader.class;
+        try {
+            Method method = sysclass.getDeclaredMethod("addURL", new Class[]{URL.class});
+            method.setAccessible(true);
+            method.invoke(sysloader, url);
+        } catch (NoSuchMethodException nsme) {
+            throw new RuntimeException("Error, could not add URL to system classloader", nsme);
+        } catch (InvocationTargetException ite) {
+            throw new RuntimeException("Error, could not add URL to system classloader", ite);
+        } catch (IllegalAccessException iae) {
+            throw new RuntimeException("Error, could not add URL to system classloader", iae);
+        }
+    }
+
+
+}

src/fitnesse/components/PluginsClassLoaderTest.java

@@ -0,0 +1,51 @@
+package fitnesse.components;
+
+import static org.junit.Assert.*;
+import org.junit.Test;
+
+
+public class PluginsClassLoaderTest {
+
+    @Test
+    public void whenPluginsDirectoryDoesNotExist() {
+        try {
+            PluginsClassLoader pluginsClassLoader = new PluginsClassLoader();
+            pluginsClassLoader.pluginsDirectory = "nonExistingPluginsDirectory";
+            pluginsClassLoader.addPluginsToClassLoader();
+            assertTrue("didn't cause exception", true);
+        } catch (Exception e) {
+            fail("if exception occurs when plugins directory does not exist");
+        }
+    }
+
+    @Test
+    public void addPluginsToClassLoader() {
+        String[] dynamicClasses = new String[]{"fitnesse.testing.PluginX", "fitnesse.testing.PluginY"};
+        assertLoadingClassCausesException(dynamicClasses);
+        new PluginsClassLoader().addPluginsToClassLoader();
+        assertLoadingClassWorksNow(dynamicClasses);
+    }
+
+    private void assertLoadingClassWorksNow(String... dynamicClasses) {
+        for (String dynamicClass : dynamicClasses) {
+            try {
+                Class<?> dynamicallyLoadedClass = Class.forName(dynamicClass);
+                assertEquals(dynamicClass, dynamicallyLoadedClass.getName());
+            } catch (ClassNotFoundException e) {
+                fail(e.getMessage());
+            }
+        }
+    }
+
+    private void assertLoadingClassCausesException(String... dynamicClasses) {
+        for (String dynamicClass : dynamicClasses) {
+            try {
+                Class.forName(dynamicClass);
+                fail("plugins are not yet added to the classloader");
+            } catch (ClassNotFoundException e) {
+                assertEquals(dynamicClass, e.getMessage());
+            }
+        }
+    }
+
+}

src/fitnesseMain/FitNesseMain.java

@@ -2,6 +2,7 @@
 
 import java.io.File;
 
+import fitnesse.components.PluginsClassLoader;
 import util.CommandLine;
 import fitnesse.Arguments;
 import fitnesse.ComponentFactory;
@@ -35,6 +36,7 @@ public static void main(String[] args) throws Exception {
   }
 
   private static void launchFitNesse(Arguments arguments) throws Exception {
+    loadPlugins();
     FitNesseContext context = loadContext(arguments);
     VelocityFactory.makeVelocityFactory(context);
     Updater updater = null;
@@ -46,6 +48,10 @@ private static void launchFitNesse(Arguments arguments) throws Exception {
     updateAndLaunch(arguments, context, fitnesse);
   }
 
+  private static void loadPlugins() {
+    new PluginsClassLoader().addPluginsToClassLoader();
+  }
+
   static void updateAndLaunch(Arguments arguments, FitNesseContext context,
       FitNesse fitnesse) throws Exception {
     if (!arguments.isOmittingUpdates())