#1321 - Introduced MvcLink to ease Link creation from MvcUriComponentsBuilders.

We now ease Link creation from MvcUriComponentsBuilder controller method references via MvcLink.of(…).

src/main/java/org/springframework/hateoas/server/mvc/MvcLink.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2020 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.hateoas.server.mvc;
+
+import static org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder.*;
+
+import java.util.function.Supplier;
+
+import org.springframework.hateoas.Link;
+import org.springframework.hateoas.LinkRelation;
+import org.springframework.util.Assert;
+import org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder;
+
+/**
+ * Syntactic sugar to create {@link Link} instances from {@link MvcUriComponentsBuilder} invocations.
+ *
+ * @author Oliver Drotbohm
+ */
+public class MvcLink {
+
+	/**
+	 * Creates a new {@link Link} from the given {@link MvcUriComponentsBuilder} invocation.
+	 *
+	 * @param invocation must not be {@literal null}.
+	 * @param relation must not be {@literal null}.
+	 * @return
+	 */
+	public static Link of(Object invocation, LinkRelation relation) {
+
+		Assert.notNull(invocation, "MethodInvocation must not be null!");
+		Assert.notNull(relation, "Link relation must not be null!");
+
+		return Link.of(fromMethodCall(invocation).toUriString(), relation);
+	}
+
+	/**
+	 * Creates a new {@link Link} from the given lazy {@link MvcUriComponentsBuilder} invocation.
+	 *
+	 * @param invocation must not be {@literal null}.
+	 * @param relation must not be {@literal null}.
+	 * @return
+	 */
+	public static Link of(Supplier<Object> invocation, LinkRelation relation) {
+
+		Assert.notNull(invocation, "MethodInvocation must not be null!");
+		Assert.notNull(relation, "Link relation must not be null!");
+
+		return Link.of(fromMethodCall(invocation.get()).toUriString(), relation);
+	}
+}

src/test/java/org/springframework/hateoas/server/mvc/MvcLinkUnitTests.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2020 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.hateoas.server.mvc;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder.*;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.hateoas.IanaLinkRelations;
+import org.springframework.hateoas.TestUtils;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+
+/**
+ * Unit tests for {@link MvcLink}.
+ *
+ * @author Oliver Drotbohm
+ */
+class MvcLinkUnitTests extends TestUtils {
+
+	@Test
+	void createsLinkPointingToController() {
+
+		Object invocation = on(MyController.class).get("4711");
+		String expected = "http://localhost/4711";
+
+		assertThat(MvcLink.of(invocation, IanaLinkRelations.SELF).getHref()).isEqualTo(expected);
+		assertThat(MvcLink.of(() -> invocation, IanaLinkRelations.SELF).getHref()).isEqualTo(expected);
+	}
+
+	static class MyController {
+
+		@RequestMapping("/{id}")
+		HttpEntity<?> get(@PathVariable String id) {
+			return ResponseEntity.ok().build();
+		}
+	}
+}