INT-670 added support for SpEL expressions in parameter-level @Payload annotations on a Gateway

spring-integration-core/src/main/java/org/springframework/integration/handler/ArgumentArrayMessageMapper.java

@@ -115,6 +115,10 @@ public class ArgumentArrayMessageMapper implements InboundMessageMapper<Object[]
 
 	private final Expression payloadExpression;
 
+	private final Map<String, Expression> parameterPayloadExpressions = new HashMap<String, Expression>();
+
+	private final StandardEvaluationContext staticEvaluationContext = new StandardEvaluationContext();
+
 	private volatile BeanResolver beanResolver;
 
 
@@ -138,6 +142,7 @@ public class ArgumentArrayMessageMapper implements InboundMessageMapper<Object[]
 					return beanFactory.getBean(beanName);
 				}
 			};
+			this.staticEvaluationContext.setBeanResolver(beanResolver);
 		}
 	}
 
@@ -173,12 +178,14 @@ public class ArgumentArrayMessageMapper implements InboundMessageMapper<Object[]
 					if (messageOrPayload != null) {
 						this.throwExceptionForMultipleMessageOrPayloadParameters(methodParameter);
 					}
-					if (((Payload) annotation).value().length() != 0) {
-						throw new MessagingException(
-								"The Payload annotation does not support an expression when mapping to a Message.");
+					String expression = ((Payload) annotation).value();
+					if (!StringUtils.hasText(expression)) {
+						messageOrPayload = argumentValue;
+					}
+					else {
+						messageOrPayload = this.evaluatePayloadExpression(expression, argumentValue);
 					}
 					foundPayloadAnnotation = true;
-					messageOrPayload = argumentValue;
 				}
 				else if (annotation.annotationType().equals(Header.class)) {
 					Header headerAnnotation = (Header) annotation;
@@ -227,6 +234,15 @@ public class ArgumentArrayMessageMapper implements InboundMessageMapper<Object[]
 		return builder.build();
 	}
 
+	private Object evaluatePayloadExpression(String expressionString, Object argumentValue) {
+		Expression expression = this.parameterPayloadExpressions.get(expressionString);
+		if (expression == null) {
+			expression = PARSER.parseExpression(expressionString);
+			this.parameterPayloadExpressions.put(expressionString, expression);
+		}
+		return expression.getValue(this.staticEvaluationContext, argumentValue);
+	}
+
 	private Annotation findMappingAnnotation(Annotation[] annotations) {
 		if (annotations == null || annotations.length == 0) {
 			return null;

spring-integration-core/src/test/java/org/springframework/integration/gateway/GatewayProxyMessageMappingTests.java

@@ -144,6 +144,35 @@ public class GatewayProxyMessageMappingTests {
 		assertEquals("FOO!!!", result.getPayload());
 	}
 
+	@Test
+	public void payloadAnnotationWithExpression() throws Exception {
+		gateway.payloadAnnotationWithExpression("foo");
+		Message<?> result = channel.receive(0);
+		assertNotNull(result);
+		assertEquals("FOO", result.getPayload());
+	}
+
+	@Test
+	public void payloadAnnotationWithExpressionUsingBeanResolver() throws Exception {
+		GenericApplicationContext context = new GenericApplicationContext();
+		RootBeanDefinition gatewayDefinition = new RootBeanDefinition(GatewayProxyFactoryBean.class);
+		gatewayDefinition.getPropertyValues().add("defaultRequestChannel", channel);
+		gatewayDefinition.getPropertyValues().add("serviceInterface", TestGateway.class);
+		context.registerBeanDefinition("testGateway", gatewayDefinition);
+		context.registerBeanDefinition("testBean", new RootBeanDefinition(TestBean.class));
+		context.refresh();
+		TestGateway gateway = context.getBean("testGateway", TestGateway.class);
+		gateway.payloadAnnotationWithExpressionUsingBeanResolver("foo");
+		gateway.payloadAnnotationWithExpressionUsingBeanResolver("bar");
+		Message<?> fooResult = channel.receive(0);
+		assertNotNull(fooResult);
+		assertEquals(324, fooResult.getPayload());
+		Message<?> barResult = channel.receive(0);
+		assertNotNull(barResult);
+		assertEquals(309, barResult.getPayload());
+		assertNull(channel.receive(0));
+	}
+
 	@Test(expected = MessagingException.class)
 	public void twoMapsWithoutAnnotations() {
 		Map<String, Object> map1 = new HashMap<String, Object>();
@@ -168,11 +197,6 @@ public class GatewayProxyMessageMappingTests {
 		gateway.payloadAndHeadersAnnotationsOnSameParameter(new HashMap<String, Object>());
 	}
 
-	@Test(expected = MessagingException.class)
-	public void payloadWithExpression() throws Exception {
-		gateway.payloadWithExpression("test");
-	}
-
 
 	public static interface TestGateway {
 
@@ -192,6 +216,10 @@ public class GatewayProxyMessageMappingTests {
 		@Payload("@testBean.exclaim(#args[0])")
 		void payloadAnnotationAtMethodLevelUsingBeanResolver(String s);
 
+		void payloadAnnotationWithExpression(@Payload("toUpperCase()") String s);
+
+		void payloadAnnotationWithExpressionUsingBeanResolver(@Payload("@testBean.sum(#this)") String s);
+
 		// invalid
 		void twoMapsWithoutAnnotations(Map<String, Object> m1, Map<String, Object> m2);
 
@@ -204,9 +232,6 @@ public class GatewayProxyMessageMappingTests {
 		// invalid
 		void payloadAndHeadersAnnotationsOnSameParameter(@Payload @Headers Map<String, Object> map);
 
-		// invalid
-		void payloadWithExpression(@Payload("oops") String s);
-
 	}
 
 
@@ -215,6 +240,14 @@ public class GatewayProxyMessageMappingTests {
 		public String exclaim(String s) {
 			return s.toUpperCase() + "!!!";
 		}
+
+		public int sum(String s) {
+			int sum = 0;
+			for (byte b : s.getBytes()) {
+				sum += b;
+			}
+			return sum;
+		}
 	}
 
 }