Provide optional SimpleBeanInfoFactory for better introspection performance

Closes gh-29330

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/CachedIntrospectionResults.java

@@ -97,8 +97,6 @@ public final class CachedIntrospectionResults {
 	 */
 	public static final String IGNORE_BEANINFO_PROPERTY_NAME = "spring.beaninfo.ignore";
 
-	private static final PropertyDescriptor[] EMPTY_PROPERTY_DESCRIPTOR_ARRAY = {};
-
 
 	private static final boolean shouldIntrospectorIgnoreBeaninfoClasses =
 			SpringProperties.getFlag(IGNORE_BEANINFO_PROPERTY_NAME);
@@ -422,7 +420,7 @@ PropertyDescriptor getPropertyDescriptor(String name) {
 	}
 
 	PropertyDescriptor[] getPropertyDescriptors() {
-		return this.propertyDescriptors.values().toArray(EMPTY_PROPERTY_DESCRIPTOR_ARRAY);
+		return this.propertyDescriptors.values().toArray(PropertyDescriptorUtils.EMPTY_PROPERTY_DESCRIPTOR_ARRAY);
 	}
 
 	private PropertyDescriptor buildGenericTypeAwarePropertyDescriptor(Class<?> beanClass, PropertyDescriptor pd) {

spring-beans/src/main/java/org/springframework/beans/PropertyDescriptorUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -17,9 +17,13 @@
 package org.springframework.beans;
 
 import java.beans.IntrospectionException;
+import java.beans.Introspector;
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Method;
+import java.util.Collection;
 import java.util.Enumeration;
+import java.util.Map;
+import java.util.TreeMap;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
@@ -32,6 +36,91 @@
  */
 abstract class PropertyDescriptorUtils {
 
+	public static final PropertyDescriptor[] EMPTY_PROPERTY_DESCRIPTOR_ARRAY = {};
+
+
+	/**
+	 * Simple introspection algorithm for basic set/get/is accessor methods,
+	 * building corresponding JavaBeans property descriptors for them.
+	 * <p>This just supports the basic JavaBeans conventions, without indexed
+	 * properties or any customizers, and without other BeanInfo metadata.
+	 * For standard JavaBeans introspection, use the JavaBeans Introspector.
+	 * @param beanClass the target class to introspect
+	 * @return a collection of property descriptors
+	 * @throws IntrospectionException from introspecting the given bean class
+	 * @since 5.3.24
+	 * @see SimpleBeanInfoFactory
+	 * @see java.beans.Introspector#getBeanInfo(Class)
+	 */
+	public static Collection<PropertyDescriptor> determineBasicProperties(Class<?> beanClass) throws IntrospectionException {
+		Map<String, PropertyDescriptor> pdMap = new TreeMap<>();
+
+		for (Method method : beanClass.getMethods()) {
+			String methodName = method.getName();
+
+			boolean setter;
+			int nameIndex;
+			if (methodName.startsWith("set") && method.getParameterCount() == 1) {
+				setter = true;
+				nameIndex = 3;
+			}
+			else if (methodName.startsWith("get") && method.getParameterCount() == 0 && method.getReturnType() != Void.TYPE) {
+				setter = false;
+				nameIndex = 3;
+			}
+			else if (methodName.startsWith("is") && method.getParameterCount() == 0 && method.getReturnType() == boolean.class) {
+				setter = false;
+				nameIndex = 2;
+			}
+			else {
+				continue;
+			}
+
+			String propertyName = Introspector.decapitalize(methodName.substring(nameIndex));
+			if (propertyName.isEmpty()) {
+				continue;
+			}
+
+			PropertyDescriptor pd = pdMap.get(propertyName);
+			if (pd != null) {
+				if (setter) {
+					if (pd.getWriteMethod() == null ||
+							pd.getWriteMethod().getParameterTypes()[0].isAssignableFrom(method.getParameterTypes()[0])) {
+						try {
+							pd.setWriteMethod(method);
+						}
+						catch (IntrospectionException ex) {
+							// typically a type mismatch -> ignore
+						}
+					}
+				}
+				else {
+					if (pd.getReadMethod() == null ||
+							(pd.getReadMethod().getReturnType() == method.getReturnType() && method.getName().startsWith("is"))) {
+						try {
+							pd.setReadMethod(method);
+						}
+						catch (IntrospectionException ex) {
+							// typically a type mismatch -> ignore
+						}
+					}
+				}
+			}
+			else {
+				pd = new BasicPropertyDescriptor(propertyName, beanClass);
+				if (setter) {
+					pd.setWriteMethod(method);
+				}
+				else {
+					pd.setReadMethod(method);
+				}
+				pdMap.put(propertyName, pd);
+			}
+		}
+
+		return pdMap.values();
+	}
+
 	/**
 	 * See {@link java.beans.FeatureDescriptor}.
 	 */
@@ -173,4 +262,46 @@ public static boolean equals(PropertyDescriptor pd, PropertyDescriptor otherPd)
 				pd.isBound() == otherPd.isBound() && pd.isConstrained() == otherPd.isConstrained());
 	}
 
+
+	/**
+	 * PropertyDescriptor for {@link #determineBasicProperties(Class)},
+	 * not performing any early type determination for
+	 * {@link #setReadMethod}/{@link #setWriteMethod}.
+	 * @since 5.3.24
+	 */
+	private static class BasicPropertyDescriptor extends PropertyDescriptor {
+
+		@Nullable
+		private Method readMethod;
+
+		@Nullable
+		private Method writeMethod;
+
+		public BasicPropertyDescriptor(String propertyName, Class<?> beanClass) throws IntrospectionException {
+			super(propertyName, beanClass, null, null);
+		}
+
+		@Override
+		public void setReadMethod(@Nullable Method readMethod) {
+			this.readMethod = readMethod;
+		}
+
+		@Override
+		@Nullable
+		public Method getReadMethod() {
+			return this.readMethod;
+		}
+
+		@Override
+		public void setWriteMethod(@Nullable Method writeMethod) {
+			this.writeMethod = writeMethod;
+		}
+
+		@Override
+		@Nullable
+		public Method getWriteMethod() {
+			return this.writeMethod;
+		}
+	}
+
 }

spring-beans/src/main/java/org/springframework/beans/SimpleBeanInfoFactory.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2002-2022 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
+ *
+ *      https://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.beans;
+
+import java.beans.BeanInfo;
+import java.beans.IntrospectionException;
+import java.beans.PropertyDescriptor;
+import java.beans.SimpleBeanInfo;
+import java.util.Collection;
+
+import org.springframework.core.Ordered;
+import org.springframework.lang.NonNull;
+
+/**
+ * {@link BeanInfoFactory} implementation that bypasses the standard {@link java.beans.Introspector}
+ * for faster introspection, reduced to basic property determination (as commonly needed in Spring).
+ *
+ * <p>To be configured via a {@code META-INF/spring.factories} file with the following content,
+ * overriding other custom {@code org.springframework.beans.BeanInfoFactory} declarations:
+ * {@code org.springframework.beans.BeanInfoFactory=org.springframework.beans.SimpleBeanInfoFactory}
+ *
+ * <p>Ordered at {@code Ordered.LOWEST_PRECEDENCE - 1} to override {@link ExtendedBeanInfoFactory}
+ * (registered by default in 5.3) if necessary while still allowing other user-defined
+ * {@link BeanInfoFactory} types to take precedence.
+ *
+ * @author Juergen Hoeller
+ * @since 5.3.24
+ * @see ExtendedBeanInfoFactory
+ * @see CachedIntrospectionResults
+ */
+public class SimpleBeanInfoFactory implements BeanInfoFactory, Ordered {
+
+	@Override
+	@NonNull
+	public BeanInfo getBeanInfo(Class<?> beanClass) throws IntrospectionException {
+		Collection<PropertyDescriptor> pds = PropertyDescriptorUtils.determineBasicProperties(beanClass);
+		return new SimpleBeanInfo() {
+			@Override
+			public PropertyDescriptor[] getPropertyDescriptors() {
+				return pds.toArray(PropertyDescriptorUtils.EMPTY_PROPERTY_DESCRIPTOR_ARRAY);
+			}
+		};
+	}
+
+	@Override
+	public int getOrder() {
+		return Ordered.LOWEST_PRECEDENCE - 1;
+	}
+
+}