SimpleEvaluationContext.Builder withMethodResolvers/withInstanceMethods

Includes DataBindingMethodResolver as ReflectiveMethodResolver subclass.

Issue: SPR-16588

spring-expression/src/main/java/org/springframework/expression/EvaluationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -41,6 +41,11 @@ public interface EvaluationContext {
 	 */
 	TypedValue getRootObject();
 
+	/**
+	 * Return a list of accessors that will be asked in turn to read/write a property.
+	 */
+	List<PropertyAccessor> getPropertyAccessors();
+
 	/**
 	 * Return a list of resolvers that will be asked in turn to locate a constructor.
 	 */
@@ -52,9 +57,10 @@ public interface EvaluationContext {
 	List<MethodResolver> getMethodResolvers();
 
 	/**
-	 * Return a list of accessors that will be asked in turn to read/write a property.
+	 * Return a bean resolver that can look up beans by name.
 	 */
-	List<PropertyAccessor> getPropertyAccessors();
+	@Nullable
+	BeanResolver getBeanResolver();
 
 	/**
 	 * Return a type locator that can be used to find types, either by short or
@@ -78,12 +84,6 @@ public interface EvaluationContext {
 	 */
 	OperatorOverloader getOperatorOverloader();
 
-	/**
-	 * Return a bean resolver that can look up beans by name.
-	 */
-	@Nullable
-	BeanResolver getBeanResolver();
-
 	/**
 	 * Set a named variable within this evaluation context to a specified value.
 	 * @param name variable to set

spring-expression/src/main/java/org/springframework/expression/spel/support/DataBindingMethodResolver.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2002-2018 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.expression.spel.support;
+
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.List;
+
+import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.expression.AccessException;
+import org.springframework.expression.EvaluationContext;
+import org.springframework.expression.MethodExecutor;
+import org.springframework.lang.Nullable;
+
+/**
+ * A {@link org.springframework.expression.MethodResolver} variant for data binding
+ * purposes, using reflection to access instance methods on a given target object.
+ *
+ * <p>This accessor does not resolve static methods and also no technical methods
+ * on {@code java.lang.Object} or {@code java.lang.Class}.
+ * For unrestricted resolution, choose {@link ReflectiveMethodResolver} instead.
+ *
+ * @author Juergen Hoeller
+ * @since 4.3.15
+ * @see #forInstanceMethodInvocation()
+ * @see DataBindingPropertyAccessor
+ */
+public class DataBindingMethodResolver extends ReflectiveMethodResolver {
+
+	private DataBindingMethodResolver() {
+		super();
+	}
+
+	@Override
+	@Nullable
+	public MethodExecutor resolve(EvaluationContext context, Object targetObject, String name,
+			List<TypeDescriptor> argumentTypes) throws AccessException {
+
+		if (targetObject instanceof Class) {
+			throw new IllegalArgumentException("DataBindingMethodResolver does not support Class targets");
+		}
+		return super.resolve(context, targetObject, name, argumentTypes);
+	}
+
+	@Override
+	protected boolean isCandidateForInvocation(Method method, Class<?> targetClass) {
+		if (Modifier.isStatic(method.getModifiers())) {
+			return false;
+		}
+		Class<?> clazz = method.getDeclaringClass();
+		return (clazz != Object.class && clazz != Class.class && !ClassLoader.class.isAssignableFrom(targetClass));
+	}
+
+
+	/**
+	 * Create a new data-binding method resolver for instance method resolution.
+	 */
+	public static DataBindingMethodResolver forInstanceMethodInvocation() {
+		return new DataBindingMethodResolver();
+	}
+
+}

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

@@ -20,8 +20,6 @@ import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.lang.reflect.Proxy;
 import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.LinkedHashSet;
@@ -82,6 +80,12 @@ public class ReflectiveMethodResolver implements MethodResolver {
 	}
 
 
+	/**
+	 * Register a filter for methods on the given type.
+	 * @param type the type to filter on
+	 * @param filter the corresponding method filter,
+	 * or {@code null} to clear any filter for the given type
+	 */
 	public void registerMethodFilter(Class<?> type, @Nullable MethodFilter filter) {
 		if (this.filters == null) {
 			this.filters = new HashMap<>();
@@ -94,7 +98,6 @@ public class ReflectiveMethodResolver implements MethodResolver {
 		}
 	}
 
-
 	/**
 	 * Locate a method on a type. There are three kinds of match that might occur:
 	 * <ol>
@@ -112,13 +115,13 @@ public class ReflectiveMethodResolver implements MethodResolver {
 		try {
 			TypeConverter typeConverter = context.getTypeConverter();
 			Class<?> type = (targetObject instanceof Class ? (Class<?>) targetObject : targetObject.getClass());
-			List<Method> methods = new ArrayList<>(getMethods(type, targetObject));
+			ArrayList<Method> methods = new ArrayList<>(getMethods(type, targetObject));
 
 			// If a filter is registered for this type, call it
 			MethodFilter filter = (this.filters != null ? this.filters.get(type) : null);
 			if (filter != null) {
 				List<Method> filtered = filter.filter(methods);
-				methods = (filtered instanceof ArrayList ? filtered : new ArrayList<>(filtered));
+				methods = (filtered instanceof ArrayList ? (ArrayList<Method>) filtered : new ArrayList<>(filtered));
 			}
 
 			// Sort methods into a sensible order
@@ -126,7 +129,7 @@ public class ReflectiveMethodResolver implements MethodResolver {
 				methods.sort((m1, m2) -> {
 					int m1pl = m1.getParameterCount();
 					int m2pl = m2.getParameterCount();
-					// varargs methods go last
+					// vararg methods go last
 					if (m1pl == m2pl) {
 						if (!m1.isVarArgs() && m2.isVarArgs()) {
 							return -1;
@@ -218,7 +221,7 @@ public class ReflectiveMethodResolver implements MethodResolver {
 		}
 	}
 
-	private Collection<Method> getMethods(Class<?> type, Object targetObject) {
+	private Set<Method> getMethods(Class<?> type, Object targetObject) {
 		if (targetObject instanceof Class) {
 			Set<Method> result = new LinkedHashSet<>();
 			// Add these so that static methods are invocable on the type: e.g. Float.valueOf(..)
@@ -236,12 +239,24 @@ public class ReflectiveMethodResolver implements MethodResolver {
 			Set<Method> result = new LinkedHashSet<>();
 			// Expose interface methods (not proxy-declared overrides) for proper vararg introspection
 			for (Class<?> ifc : type.getInterfaces()) {
-				Collections.addAll(result, getMethods(ifc));
+				Method[] methods = getMethods(ifc);
+				for (Method method : methods) {
+					if (isCandidateForInvocation(method, type)) {
+						result.add(method);
+					}
+				}
 			}
 			return result;
 		}
 		else {
-			return Arrays.asList(getMethods(type));
+			Set<Method> result = new LinkedHashSet<>();
+			Method[] methods = getMethods(type);
+			for (Method method : methods) {
+				if (isCandidateForInvocation(method, type)) {
+					result.add(method);
+				}
+			}
+			return result;
 		}
 	}
 
@@ -257,4 +272,17 @@ public class ReflectiveMethodResolver implements MethodResolver {
 		return type.getMethods();
 	}
 
+	/**
+	 * Determine whether the given {@code Method} is a candidate for method resolution
+	 * on an instance of the given target class.
+	 * <p>The default implementation considers any method as a candidate, even for
+	 * static methods sand non-user-declared methods on the {@link Object} base class.
+	 * @param method the Method to evaluate
+	 * @param targetClass the concrete target class that is being introspected
+	 * @since 4.3.15
+	 */
+	protected boolean isCandidateForInvocation(Method method, Class<?> targetClass) {
+		return true;
+	}
+
 }

spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectivePropertyAccessor.java

@@ -421,7 +421,8 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
 	}
 
 	/**
-	 * Determine whether the given {@code Method} is a candidate for property access.
+	 * Determine whether the given {@code Method} is a candidate for property access
+	 * on an instance of the given target class.
 	 * <p>The default implementation considers any method as a candidate, even for
 	 * non-user-declared properties on the {@link Object} base class.
 	 * @param method the Method to evaluate

spring-expression/src/main/java/org/springframework/expression/spel/support/SimpleEvaluationContext.java

@@ -92,6 +92,8 @@ public class SimpleEvaluationContext implements EvaluationContext {
 
 	private final List<PropertyAccessor> propertyAccessors;
 
+	private final List<MethodResolver> methodResolvers;
+
 	private final TypeConverter typeConverter;
 
 	private final TypeComparator typeComparator = new StandardTypeComparator();
@@ -101,8 +103,11 @@ public class SimpleEvaluationContext implements EvaluationContext {
 	private final Map<String, Object> variables = new HashMap<>();
 
 
-	private SimpleEvaluationContext(List<PropertyAccessor> accessors, @Nullable TypeConverter converter) {
+	private SimpleEvaluationContext(List<PropertyAccessor> accessors, List<MethodResolver> resolvers,
+			@Nullable TypeConverter converter) {
+
 		this.propertyAccessors = accessors;
+		this.methodResolvers = resolvers;
 		this.typeConverter = (converter != null ? converter : new StandardTypeConverter());
 	}
 
@@ -119,6 +124,10 @@ public class SimpleEvaluationContext implements EvaluationContext {
 		return TypedValue.NULL;
 	}
 
+	/**
+	 * Return the specified {@link PropertyAccessor} delegates, if any.
+	 * @see #forPropertyAccessors
+	 */
 	@Override
 	public List<PropertyAccessor> getPropertyAccessors() {
 		return this.propertyAccessors;
@@ -134,16 +143,17 @@ public class SimpleEvaluationContext implements EvaluationContext {
 	}
 
 	/**
-	 * Return a single {@link ReflectiveMethodResolver}.
+	 * Return the specified {@link MethodResolver} delegates, if any.
+	 * @see Builder#withMethodResolvers
 	 */
 	@Override
 	public List<MethodResolver> getMethodResolvers() {
-		return Collections.emptyList();
+		return this.methodResolvers;
 	}
 
 	/**
-	 * {@code SimpleEvaluationContext} does not support use of bean references.
-	 * @return Always returns {@code null}
+	 * {@code SimpleEvaluationContext} does not support the use of bean references.
+	 * @return always {@code null}
 	 */
 	@Override
 	@Nullable
@@ -164,6 +174,8 @@ public class SimpleEvaluationContext implements EvaluationContext {
 	/**
 	 * The configured {@link TypeConverter}.
 	 * <p>By default this is {@link StandardTypeConverter}.
+	 * @see Builder#withTypeConverter
+	 * @see Builder#withConversionService
 	 */
 	@Override
 	public TypeConverter getTypeConverter() {
@@ -203,6 +215,7 @@ public class SimpleEvaluationContext implements EvaluationContext {
 	 * delegates: typically a custom {@code PropertyAccessor} specific to a use case
 	 * (e.g. attribute resolution in a custom data structure), potentially combined with
 	 * a {@link DataBindingPropertyAccessor} if property dereferences are needed as well.
+	 * @param accessors the accessor delegates to use
 	 * @see DataBindingPropertyAccessor#forReadOnlyAccess()
 	 * @see DataBindingPropertyAccessor#forReadWriteAccess()
 	 */
@@ -242,13 +255,46 @@ public class SimpleEvaluationContext implements EvaluationContext {
 	 */
 	public static class Builder {
 
-		private final List<PropertyAccessor> propertyAccessors;
+		private final List<PropertyAccessor> accessors;
+
+		private List<MethodResolver> resolvers = Collections.emptyList();
 
 		@Nullable
 		private TypeConverter typeConverter;
 
 		public Builder(PropertyAccessor... accessors) {
-			this.propertyAccessors = Arrays.asList(accessors);
+			this.accessors = Arrays.asList(accessors);
+		}
+
+		/**
+		 * Register the specified {@link MethodResolver} delegates for
+		 * a combination of property access and method resolution.
+		 * @param resolvers the resolver delegates to use
+		 * @see #withInstanceMethods()
+		 * @see SimpleEvaluationContext#forPropertyAccessors
+		 */
+		public Builder withMethodResolvers(MethodResolver... resolvers) {
+			for (MethodResolver resolver : resolvers) {
+				if (resolver.getClass() == ReflectiveMethodResolver.class) {
+					throw new IllegalArgumentException("SimpleEvaluationContext is not designed for use with a plain " +
+							"ReflectiveMethodResolver. Consider using DataBindingMethodResolver or a custom subclass.");
+				}
+			}
+			this.resolvers = Arrays.asList(resolvers);
+			return this;
+		}
+
+		/**
+		 * Register a {@link DataBindingMethodResolver} for instance method invocation purposes
+		 * (i.e. not supporting static methods) in addition to the specified property accessors,
+		 * typically in combination with a {@link DataBindingPropertyAccessor}.
+		 * @see #withMethodResolvers
+		 * @see SimpleEvaluationContext#forReadOnlyDataBinding()
+		 * @see SimpleEvaluationContext#forReadWriteDataBinding()
+		 */
+		public Builder withInstanceMethods() {
+			this.resolvers = Collections.singletonList(DataBindingMethodResolver.forInstanceMethodInvocation());
+			return this;
 		}
 
 		/**
@@ -276,7 +322,7 @@ public class SimpleEvaluationContext implements EvaluationContext {
 		}
 
 		public SimpleEvaluationContext build() {
-			return new SimpleEvaluationContext(this.propertyAccessors, this.typeConverter);
+			return new SimpleEvaluationContext(this.accessors, this.resolvers, this.typeConverter);
 		}
 	}
 

spring-expression/src/test/java/org/springframework/expression/spel/PropertyAccessTests.java

@@ -32,7 +32,7 @@ import org.springframework.expression.PropertyAccessor;
 import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.standard.SpelExpression;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
-import org.springframework.expression.spel.support.DataBindingPropertyAccessor;
+import org.springframework.expression.spel.support.SimpleEvaluationContext;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
 import org.springframework.expression.spel.testresources.Person;
 
@@ -186,22 +186,38 @@ public class PropertyAccessTests extends AbstractExpressionTests {
 
 	@Test
 	public void standardGetClassAccess() {
-		Expression expr = parser.parseExpression("'a'.class.getName()");
-		assertEquals(String.class.getName(), expr.getValue());
+		assertEquals(String.class.getName(), parser.parseExpression("'a'.class.name").getValue());
 	}
 
 	@Test(expected = SpelEvaluationException.class)
 	public void noGetClassAccess() {
-		Expression expr = parser.parseExpression("'a'.class.getName()");
-		StandardEvaluationContext context = new StandardEvaluationContext();
-		context.setPropertyAccessors(Collections.singletonList(DataBindingPropertyAccessor.forReadWriteAccess()));
-		expr.getValue(context);
+		EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
+
+		parser.parseExpression("'a'.class.name").getValue(context);
+	}
+
+	@Test
+	public void propertyReadOnly() {
+		EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
+
+		Expression expr = parser.parseExpression("name");
+		Person target = new Person("p1");
+		assertEquals("p1", expr.getValue(context, target));
+		target.setName("p2");
+		assertEquals("p2", expr.getValue(context, target));
+
+		try {
+			parser.parseExpression("name='p3'").getValue(context, target);
+			fail("Should have thrown SpelEvaluationException");
+		}
+		catch (SpelEvaluationException ex) {
+			// expected
+		}
 	}
 
 	@Test
 	public void propertyReadWrite() {
-		StandardEvaluationContext context = new StandardEvaluationContext();
-		context.setPropertyAccessors(Collections.singletonList(DataBindingPropertyAccessor.forReadWriteAccess()));
+		EvaluationContext context = SimpleEvaluationContext.forReadWriteDataBinding().build();
 
 		Expression expr = parser.parseExpression("name");
 		Person target = new Person("p1");
@@ -218,18 +234,26 @@ public class PropertyAccessTests extends AbstractExpressionTests {
 		assertEquals("p4", expr.getValue(context, target));
 	}
 
-	@Test(expected = SpelEvaluationException.class)
-	public void propertyReadOnly() {
-		StandardEvaluationContext context = new StandardEvaluationContext();
-		context.setPropertyAccessors(Collections.singletonList(DataBindingPropertyAccessor.forReadOnlyAccess()));
+	@Test
+	public void propertyAccessWithoutMethodResolver() {
+		EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().build();
 
-		Expression expr = parser.parseExpression("name");
 		Person target = new Person("p1");
-		assertEquals("p1", expr.getValue(context, target));
-		target.setName("p2");
-		assertEquals("p2", expr.getValue(context, target));
+		try {
+			parser.parseExpression("name.substring(1)").getValue(context, target);
+			fail("Should have thrown SpelEvaluationException");
+		}
+		catch (SpelEvaluationException ex) {
+			// expected
+		}
+	}
 
-		parser.parseExpression("name='p3'").getValue(context, target);
+	@Test
+	public void propertyAccessWithInstanceMethodResolver() {
+		EvaluationContext context = SimpleEvaluationContext.forReadOnlyDataBinding().withInstanceMethods().build();
+
+		Person target = new Person("p1");
+		assertEquals("1", parser.parseExpression("name.substring(1)").getValue(context, target));
 	}