Allow use of '&' prefix to access factory bean in SpEL

Prior to this change SpEL did not have an syntactic
construct enabling easy access to a FactoryBean. With this
change it is now possible to use &foo in an expression when
the factory bean should be returned.

Issue: SPR-9511

spring-context/src/test/java/org/springframework/context/expression/FactoryBeanAccessTests.java

@@ -0,0 +1,129 @@
+/*
+ * Copyright 2002-2016 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.context.expression;
+
+import org.junit.Test;
+import org.springframework.beans.factory.BeanIsNotAFactoryException;
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.context.expression.FactoryBeanAccessTests.SimpleBeanResolver.Boat;
+import org.springframework.context.expression.FactoryBeanAccessTests.SimpleBeanResolver.CarFactoryBean;
+import org.springframework.context.support.StaticApplicationContext;
+import org.springframework.expression.AccessException;
+import org.springframework.expression.EvaluationContext;
+import org.springframework.expression.Expression;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
+
+import static org.junit.Assert.*;
+
+/**
+ * Unit tests for expressions accessing beans and factory beans.
+ *
+ * @author Andy Clement
+ */
+public class FactoryBeanAccessTests {
+
+	@Test
+	public void factoryBeanAccess() { // SPR9511
+		StandardEvaluationContext context = new StandardEvaluationContext();
+		context.setBeanResolver(new SimpleBeanResolver());
+		Expression expr = new SpelExpressionParser().parseRaw("@car.colour");
+		assertEquals("red", expr.getValue(context));
+		expr = new SpelExpressionParser().parseRaw("&car.class.name");
+		assertEquals(CarFactoryBean.class.getName(), expr.getValue(context));
+
+		expr = new SpelExpressionParser().parseRaw("@boat.colour");
+		assertEquals("blue",expr.getValue(context));
+		expr = new SpelExpressionParser().parseRaw("&boat.class.name");
+		try {
+			assertEquals(Boat.class.getName(), expr.getValue(context));
+			fail("Expected BeanIsNotAFactoryException");
+		} catch (BeanIsNotAFactoryException binafe) {
+			// success
+		}
+		
+		// No such bean
+		try {
+			expr = new SpelExpressionParser().parseRaw("@truck");
+			assertEquals("red", expr.getValue(context));
+			fail("Expected NoSuchBeanDefinitionException");
+		}
+		catch (NoSuchBeanDefinitionException nsbde) {
+			// success
+		}
+
+		// No such factory bean
+		try {
+			expr = new SpelExpressionParser().parseRaw("&truck");
+			assertEquals(CarFactoryBean.class.getName(), expr.getValue(context));
+			fail("Expected NoSuchBeanDefinitionException");
+		}
+		catch (NoSuchBeanDefinitionException nsbde) {
+			// success
+		}
+	}
+
+	static class SimpleBeanResolver
+			implements org.springframework.expression.BeanResolver {
+
+		static class Car {
+
+			public String getColour() {
+				return "red";
+			}
+		}
+
+		static class CarFactoryBean implements FactoryBean<Car> {
+
+			public Car getObject() {
+				return new Car();
+			}
+
+			public Class<Car> getObjectType() {
+				return Car.class;
+			}
+
+			public boolean isSingleton() {
+				return false;
+			}
+
+		}
+
+		static class Boat {
+
+			public String getColour() {
+				return "blue";
+			}
+
+		}
+
+		StaticApplicationContext ac = new StaticApplicationContext();
+
+		public SimpleBeanResolver() {
+			ac.registerSingleton("car", CarFactoryBean.class);
+			ac.registerSingleton("boat", Boat.class);
+		}
+
+		@Override
+		public Object resolve(EvaluationContext context, String beanName)
+				throws AccessException {
+			return ac.getBean(beanName);
+		}
+	}
+
+}