GH-3085 Add Number and Boolean Spel converter

Refactor SpelConverter into an abstract class

Resolves #3085

Author: olegz

core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/config/SpelExpressionConverterConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2018 the original author or authors.
+ * Copyright 2015-2025 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.
@@ -16,8 +16,6 @@
 
 package org.springframework.cloud.stream.config;
 
-import java.beans.Introspector;
-
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -44,6 +42,7 @@
  *
  * @author Eric Bottard
  * @author Artem Bilan
+ * @author Oleg Zhurakousky
  */
 @Configuration(proxyBeanMethods = false)
 @Role(BeanDefinition.ROLE_INFRASTRUCTURE)
@@ -61,19 +60,19 @@ public class SpelExpressionConverterConfiguration {
 	@Bean
 	public static SpelPropertyAccessorRegistrar spelPropertyAccessorRegistrar() {
 		return new SpelPropertyAccessorRegistrar()
-				.add(Introspector
-						.decapitalize(JsonPropertyAccessor.class.getSimpleName()),
-						new JsonPropertyAccessor());
+				.add(new JsonPropertyAccessor());
 	}
 
 	@Bean
 	@ConfigurationPropertiesBinding
 	@IntegrationConverter
-	public Converter<Object, Expression> spelConverter(ConfigurableApplicationContext context) {
+	public Converter<String, Expression> spelConverter(ConfigurableApplicationContext context) {
 		SpelConverter converter = new SpelConverter();
 		ConfigurableConversionService cs = (ConfigurableConversionService) context.getBeanFactory().getConversionService();
 		if (cs != null) {
 			cs.addConverter(converter);
+			cs.addConverter(new NumberToStringSpelConverter());
+			cs.addConverter(new BooleanToStringSpelConverter());
 		}
 		return converter;
 	}
@@ -83,7 +82,30 @@ public Converter<Object, Expression> spelConverter(ConfigurableApplicationContex
 	 *
 	 * @author Eric Bottard
 	 */
-	public static class SpelConverter implements Converter<Object, Expression> {
+	public static class SpelConverter extends AbstractSpelConverter<String> {
+		@Override
+		public Expression convert(String source) {
+			return this.doConvert(source);
+		}
+	}
+
+	public static class NumberToStringSpelConverter extends AbstractSpelConverter<Number> {
+		@Override
+		public Expression convert(Number source) {
+			String value = source.toString();
+			return this.doConvert(value);
+		}
+	}
+
+	public static class BooleanToStringSpelConverter extends AbstractSpelConverter<Boolean> {
+		@Override
+		public Expression convert(Boolean source) {
+			String value = source.toString();
+			return this.doConvert(value);
+		}
+	}
+
+	public static abstract class AbstractSpelConverter<T> implements Converter<T, Expression> {
 
 		private SpelExpressionParser parser = new SpelExpressionParser();
 
@@ -92,12 +114,8 @@ public static class SpelConverter implements Converter<Object, Expression> {
 		@Lazy
 		private EvaluationContext evaluationContext;
 
-		@Override
-		public Expression convert(Object source) {
+		public Expression doConvert(String source) {
 			try {
-				if (!(source instanceof String)) {
-					source = String.valueOf(source); // see https://github.com/spring-cloud/spring-cloud-stream/issues/2989
-				}
 				Expression expression = this.parser.parseExpression((String) source);
 				if (expression instanceof SpelExpression) {
 					((SpelExpression) expression)
@@ -110,7 +128,5 @@ public Expression convert(Object source) {
 						"Could not convert '%s' into a SpEL expression", source), e);
 			}
 		}
-
 	}
-
 }

core/spring-cloud-stream/src/test/java/org/springframework/cloud/stream/config/SpelExpressionConverterConfigurationTests.java

@@ -31,6 +31,7 @@
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.PropertySource;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;
 import org.springframework.expression.PropertyAccessor;
@@ -47,8 +48,7 @@
  * @author Artem Bilan
  * @author Soby Chacko
  */
-@SpringBootTest(classes = SpelExpressionConverterConfigurationTests.Config.class, properties = {
-		"expression: a.b" })
+@SpringBootTest(classes = SpelExpressionConverterConfigurationTests.Config.class)
 class SpelExpressionConverterConfigurationTests {
 
 	@Autowired
@@ -77,13 +77,23 @@ void converterCorrectlyInstalled() {
 
 		assertThat(propertyAccessors)
 				.hasAtLeastOneElementOfType(JsonPropertyAccessor.class);
+		
+		Expression numberExpression = this.pojo.getNumberExpression();
+		assertThat(numberExpression.getValue()).isEqualTo(5);
+		
+		Expression booleanExpression = this.pojo.getBooleanExpression();
+		assertThat(booleanExpression.getValue()).isEqualTo(true);
 	}
 
 	@ConfigurationProperties
 	public static class Pojo {
 
 		private Expression expression;
 
+		private Expression numberExpression;
+
+		private Expression booleanExpression;
+
 		public Expression getExpression() {
 			return this.expression;
 		}
@@ -92,11 +102,28 @@ public void setExpression(Expression expression) {
 			this.expression = expression;
 		}
 
+		public Expression getNumberExpression() {
+			return numberExpression;
+		}
+
+		public void setNumberExpression(Expression numberExpression) {
+			this.numberExpression = numberExpression;
+		}
+
+		public Expression getBooleanExpression() {
+			return booleanExpression;
+		}
+
+		public void setBooleanExpression(Expression booleanExpression) {
+			this.booleanExpression = booleanExpression;
+		}
+
 	}
 
 	@Configuration
 	@EnableAutoConfiguration
 	@EnableConfigurationProperties(Pojo.class)
+	@PropertySource("classpath:/application.yml")
 	public static class Config implements BeanFactoryAware {
 
 		private BeanFactory beanFactory;