Allow PropertySourcesPlaceholderConfigurer to customize PropertyResolver

spring-context/src/main/java/org/springframework/context/support/PropertySourcesPlaceholderConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -139,8 +139,7 @@ public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
 				// See https://github.com/spring-projects/spring-framework/issues/27947
 				if (this.ignoreUnresolvablePlaceholders &&
 						(this.environment instanceof ConfigurableEnvironment configurableEnvironment)) {
-					PropertySourcesPropertyResolver resolver =
-							new PropertySourcesPropertyResolver(configurableEnvironment.getPropertySources());
+					ConfigurablePropertyResolver resolver = createPropertyResolver(configurableEnvironment.getPropertySources());
 					resolver.setIgnoreUnresolvableNestedPlaceholders(true);
 					propertyResolver = resolver;
 				}
@@ -169,11 +168,19 @@ public String getProperty(String key) {
 				throw new BeanInitializationException("Could not load properties", ex);
 			}
 		}
-
-		processProperties(beanFactory, new PropertySourcesPropertyResolver(this.propertySources));
+		processProperties(beanFactory, createPropertyResolver(this.propertySources));
 		this.appliedPropertySources = this.propertySources;
 	}
 
+	/**
+	 * Factory method used to create the {@link ConfigurablePropertyResolver}
+	 * instance used by the placeholder configurer.
+	 * @since 6.0.8
+	 */
+	protected ConfigurablePropertyResolver createPropertyResolver(MutablePropertySources propertySources) {
+		return new PropertySourcesPropertyResolver(propertySources);
+	}
+
 	/**
 	 * Visit each bean definition in the given bean factory and attempt to replace ${...} property
 	 * placeholders with values from the given properties.

spring-context/src/test/java/org/springframework/context/support/PropertySourcesPlaceholderConfigurerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -30,12 +30,16 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.convert.support.DefaultConversionService;
+import org.springframework.core.env.ConfigurablePropertyResolver;
 import org.springframework.core.env.MutablePropertySources;
 import org.springframework.core.env.PropertySource;
+import org.springframework.core.env.PropertySources;
+import org.springframework.core.env.PropertySourcesPropertyResolver;
 import org.springframework.core.env.StandardEnvironment;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.core.testfixture.env.MockPropertySource;
+import org.springframework.lang.Nullable;
 import org.springframework.mock.env.MockEnvironment;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -430,6 +434,47 @@ public void optionalPropertyWithoutValue() {
 		assertThat(bf.getBean(OptionalTestBean.class).getName()).isEqualTo(Optional.empty());
 	}
 
+	@Test
+	void withCustomPropertyResolver() {
+		DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
+		beanFactory.registerBeanDefinition("testBean",
+				genericBeanDefinition(TestBean.class)
+						.addPropertyValue("name", "${my.name}")
+						.getBeanDefinition());
+
+		MockEnvironment env = new MockEnvironment();
+		env.setProperty("my.name", "myValue");
+
+		CustomPropertySourcesPlaceholderConfigurer configurer = new CustomPropertySourcesPlaceholderConfigurer();
+		configurer.setEnvironment(env);
+		configurer.setIgnoreUnresolvablePlaceholders(true);
+		configurer.postProcessBeanFactory(beanFactory);
+		assertThat(beanFactory.getBean(TestBean.class).getName()).isEqualTo("myValue-custom");
+	}
+
+	private static class CustomPropertySourcesPropertyResolver extends PropertySourcesPropertyResolver {
+
+		public CustomPropertySourcesPropertyResolver(PropertySources propertySources) {
+			super(propertySources);
+		}
+
+		@Override
+		@Nullable
+		public String getProperty(String key) {
+			return super.getProperty(key) + "-custom";
+		}
+
+	}
+
+	private static class CustomPropertySourcesPlaceholderConfigurer extends PropertySourcesPlaceholderConfigurer {
+
+		@Override
+		protected ConfigurablePropertyResolver createPropertyResolver(MutablePropertySources propertySources) {
+			return new CustomPropertySourcesPropertyResolver(propertySources);
+		}
+
+	}
+
 
 	private static class OptionalTestBean {