From 26f3376b1bed8a305bc6bb2415c4fedf7f63784d Mon Sep 17 00:00:00 2001
From: freelansam <79205526+freelansam@users.noreply.github.com>
Date: Sun, 23 May 2021 21:44:50 +0530
Subject: [PATCH] BAEL-4791: Spring AliasFor Annotation (#10794)

---
 spring-core-5/pom.xml                         |  5 ++
 .../java/com/baeldung/aliasfor/MyMapping.java | 29 ++++++++
 .../aliasfor/MyMappingController.java         | 13 ++++
 .../baeldung/aliasfor/AliasForUnitTest.java   | 66 +++++++++++++++++++
 4 files changed, 113 insertions(+)
 create mode 100644 spring-core-5/src/main/java/com/baeldung/aliasfor/MyMapping.java
 create mode 100644 spring-core-5/src/main/java/com/baeldung/aliasfor/MyMappingController.java
 create mode 100644 spring-core-5/src/test/java/com/baeldung/aliasfor/AliasForUnitTest.java

diff --git a/spring-core-5/pom.xml b/spring-core-5/pom.xml
index 68229b80b8..1c2e80be44 100644
--- a/spring-core-5/pom.xml
+++ b/spring-core-5/pom.xml
@@ -19,6 +19,11 @@
             <artifactId>spring-boot-starter</artifactId>
             <version>${spring-boot-starter.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+            <version>${spring-boot-starter.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
diff --git a/spring-core-5/src/main/java/com/baeldung/aliasfor/MyMapping.java b/spring-core-5/src/main/java/com/baeldung/aliasfor/MyMapping.java
new file mode 100644
index 0000000000..05263297b5
--- /dev/null
+++ b/spring-core-5/src/main/java/com/baeldung/aliasfor/MyMapping.java
@@ -0,0 +1,29 @@
+package com.baeldung.aliasfor;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.core.annotation.AliasFor;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+
+@Target({ElementType.METHOD, ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@RequestMapping
+public @interface MyMapping {
+
+    @AliasFor(annotation = RequestMapping.class, attribute = "method")
+    RequestMethod[] action() default {};
+    
+    @AliasFor(annotation = RequestMapping.class, attribute = "path")
+    String[] value() default {};
+
+    @AliasFor(annotation = RequestMapping.class, attribute = "path")
+    String[] mapping() default {};
+    
+    @AliasFor(annotation = RequestMapping.class, attribute = "path")
+    String[] route() default {};
+
+}
diff --git a/spring-core-5/src/main/java/com/baeldung/aliasfor/MyMappingController.java b/spring-core-5/src/main/java/com/baeldung/aliasfor/MyMappingController.java
new file mode 100644
index 0000000000..c3dc2784f8
--- /dev/null
+++ b/spring-core-5/src/main/java/com/baeldung/aliasfor/MyMappingController.java
@@ -0,0 +1,13 @@
+package com.baeldung.aliasfor;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.RequestMethod;
+
+@Controller
+public class MyMappingController {
+
+    @MyMapping(action = RequestMethod.PATCH, route = "/test")
+    public void mappingMethod() {
+    }
+    
+}
diff --git a/spring-core-5/src/test/java/com/baeldung/aliasfor/AliasForUnitTest.java b/spring-core-5/src/test/java/com/baeldung/aliasfor/AliasForUnitTest.java
new file mode 100644
index 0000000000..449a55a6f8
--- /dev/null
+++ b/spring-core-5/src/test/java/com/baeldung/aliasfor/AliasForUnitTest.java
@@ -0,0 +1,66 @@
+package com.baeldung.aliasfor;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.forwardedUrl;
+
+import java.lang.reflect.Method;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.annotation.AnnotatedElementUtils;
+import org.springframework.core.annotation.AnnotationAttributes;
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = MyMappingController.class)
+public class AliasForUnitTest {
+
+    @Autowired
+    private ConfigurableApplicationContext context;
+
+    Class controllerClass;
+
+    @Before
+    public void setControllerBean() {
+        MyMappingController controllerBean = context.getBean(MyMappingController.class);
+        controllerClass = controllerBean.getClass();
+    }
+
+    @Test
+    public void givenComposedAnnotation_whenExplicitAlias_thenMetaAnnotationAttributeOverridden() {
+
+        for (Method method : controllerClass.getMethods()) {
+            if (method.isAnnotationPresent(MyMapping.class)) {
+                MyMapping annotation = AnnotationUtils.findAnnotation(method, MyMapping.class);
+                RequestMapping metaAnnotation = AnnotationUtils.findAnnotation(method, RequestMapping.class);
+
+                assertEquals(RequestMethod.PATCH, annotation.action()[0]);
+
+                assertEquals(0, metaAnnotation.method().length);
+            }
+        }
+    }
+
+    @Test
+    public void givenComposedAnnotation_whenImplictAlias_thenAttributesEqual() {
+        for (Method method : controllerClass.getMethods()) {
+            if (method.isAnnotationPresent(MyMapping.class)) {
+                MyMapping annotationOnBean = AnnotationUtils.findAnnotation(method, MyMapping.class);
+
+                assertTrue(annotationOnBean.mapping()[0].equals(annotationOnBean.route()[0]));
+                assertTrue(annotationOnBean.value()[0].equals(annotationOnBean.route()[0]));
+            }
+        }
+    }
+
+}