Fixing Problems with ClassCast Exception - TRUNK-4053(cherry picked f…

…rom commit 1850c17)
openmrs · Sep 2, 2013 · 5a15636 · 5a15636
1 parent 07e19c3
commit 5a15636
Showing 1 changed file with 39 additions and 1 deletion.
diff --git a/api/src/main/java/org/openmrs/module/ModuleClassLoader.java b/api/src/main/java/org/openmrs/module/ModuleClassLoader.java
@@ -30,6 +30,7 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Enumeration;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
@@ -67,6 +68,12 @@ public class ModuleClassLoader extends URLClassLoader {
 
 	private Set<String> additionalPackages = new LinkedHashSet<String>();
 
+	/**
+	 * Holds a list of all classes for this classloader so that they can be cleaned up.
+	 * This is also used to fix: https://tickets.openmrs.org/browse/TRUNK-4053
+	 */
+	private Map<String, Class<?>> loadedClasses = new HashMap<String, Class<?>>();
+
 	/**
 	 * @param module Module
 	 * @param urls resources "managed" by this class loader
@@ -387,6 +394,8 @@ public void dispose() {
 		requiredModules = null;
 		awareOfModules = null;
 		//resourceLoader = null;
+
+		loadedClasses.clear();
 	}
 
 	/**
@@ -405,6 +414,19 @@ public void setProbeParentLoaderLast(final boolean value) {
 	@Override
 	protected Class<?> loadClass(final String name, final boolean resolve) throws ClassNotFoundException {
 		Class<?> result = null;
+
+		//if this class was already loaded by some other class loader, do not load it again.
+		Collection<ModuleClassLoader> classLoaders = ModuleFactory.getModuleClassLoaders();
+		for (ModuleClassLoader classLoader : classLoaders) {
+			if (classLoader == this)
+				continue;
+
+			result = classLoader.getClassIfLoaded(name);
+			if (result != null) {
+				return result;
+			}
+		}
+
 		if (probeParentLoaderLast) {
 			try {
 				result = loadClass(name, resolve, this, null);
@@ -430,8 +452,14 @@ protected Class<?> loadClass(final String name, final boolean resolve) throws Cl
 			}
 		}
 
-		if (result != null)
+		if (result != null) {
+			//add only if this is its class loader
+			if (result.getClassLoader() == this) {
+				loadedClasses.put(name, result);
+			}
+
 			return result;
+		}
 
 		throw new ClassNotFoundException(name);
 	}
@@ -568,6 +596,16 @@ protected Class<?> loadClass(final String name, final boolean resolve, final Mod
 		return result;
 	}
 
+	/**
+	 * Gets a class instance if it was already loaded by this class loader.
+	 * 
+	 * @param name String path and name of the class to load.
+	 * @return the class instance if it was already loaded, else null.
+	 */
+	public Class<?> getClassIfLoaded(final String name) {
+		return loadedClasses.get(name);
+	}
+
 	/**
 	 * Checking the given class's visibility in this module
 	 *