Allow customization of SpEL method resolution

This change introduces a protected ReflectiveMethodResolver#getMethods,
allowing subclasses to specify additional static methods not
declared directly on the type being evaluated. These methods then become
candidates for filtering by any registered MethodFilters and ultimately
become available within for use within SpEL expressions.

Issue: SPR-9038

org.springframework.expression/src/main/java/org/springframework/expression/spel/support/ReflectiveMethodResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2011 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -90,7 +90,7 @@ public class ReflectiveMethodResolver implements MethodResolver {
 		try {
 			TypeConverter typeConverter = context.getTypeConverter();
 			Class<?> type = (targetObject instanceof Class ? (Class<?>) targetObject : targetObject.getClass());
-			Method[] methods = type.getMethods();
+			Method[] methods = getMethods(type);
 
 			// If a filter is registered for this type, call it
 			MethodFilter filter = (this.filters != null ? this.filters.get(type) : null);
@@ -197,4 +197,16 @@ public class ReflectiveMethodResolver implements MethodResolver {
 		}
 	}
 
+	/**
+	 * Return the set of methods for this type. The default implementation returns the
+	 * result of Class#getMethods for the given {@code type}, but subclasses may override
+	 * in order to alter the results, e.g. specifying static methods declared elsewhere.
+	 *
+	 * @param type the class for which to return the methods
+	 * @since 3.1.1
+	 */
+	protected Method[] getMethods(Class<?> type) {
+		return type.getMethods();
+	}
+
 }

org.springframework.expression/src/test/java/org/springframework/expression/spel/SpringEL300Tests.java

@@ -17,8 +17,10 @@
 package org.springframework.expression.spel;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
@@ -38,6 +40,7 @@ import org.springframework.expression.EvaluationException;
 import org.springframework.expression.Expression;
 import org.springframework.expression.ExpressionParser;
 import org.springframework.expression.MethodExecutor;
+import org.springframework.expression.MethodResolver;
 import org.springframework.expression.ParserContext;
 import org.springframework.expression.PropertyAccessor;
 import org.springframework.expression.TypedValue;
@@ -1137,6 +1140,41 @@ public class SpringEL300Tests extends ExpressionTestCase {
 		public Map<String, String> getFourthContext() {return fourthContext;}
 	}
 
+	/**
+	 * Test the ability to subclass the ReflectiveMethodResolver and change how it
+	 * determines the set of methods for a type.
+	 */
+	@Test
+	public void testCustomStaticFunctions_SPR9038() {
+		try {
+			ExpressionParser parser = new SpelExpressionParser();
+			StandardEvaluationContext context = new StandardEvaluationContext();
+			List<MethodResolver> methodResolvers = new ArrayList<MethodResolver>();
+			methodResolvers.add(new ReflectiveMethodResolver() {
+				@Override
+				protected Method[] getMethods(Class<?> type) {
+					try {
+						return new Method[] {
+								Integer.class.getDeclaredMethod("parseInt", new Class[] {
+										String.class, Integer.TYPE }) };
+					} catch (NoSuchMethodException e1) {
+						return new Method[0];
+					}
+				}
+			});
+
+			context.setMethodResolvers(methodResolvers);
+			org.springframework.expression.Expression expression =
+					parser.parseExpression("parseInt('-FF', 16)");
+
+			Integer result = expression.getValue(context, "", Integer.class);
+			assertEquals("Equal assertion failed: ", -255, result.intValue());
+		} catch (Exception e) {
+			e.printStackTrace();
+			fail("Unexpected exception: "+e.toString());
+		}
+	}
+
 }