Support matrix variable (#260)

* support for matrix variable

* support for matrix variable Fixes gh-117

* unit tests for matrix variable

* Correct JavaDoc fixes gh-117

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/annotation/MatrixVariableParameterProcessor.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2013-2019 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.cloud.openfeign.annotation;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Method;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import feign.MethodMetadata;
+
+import org.springframework.cloud.openfeign.AnnotatedParameterProcessor;
+import org.springframework.web.bind.annotation.MatrixVariable;
+
+import static feign.Util.checkState;
+import static feign.Util.emptyToNull;
+
+/**
+ * {@link MatrixVariable} annotation processor.
+ *
+ * Can expand maps or single objects. Values are assigned from the objects {@code toString()}
+ * method.
+ *
+ * @author Matt King
+ * @see AnnotatedParameterProcessor
+ */
+public class MatrixVariableParameterProcessor implements AnnotatedParameterProcessor {
+
+	private static final Class<MatrixVariable> ANNOTATION = MatrixVariable.class;
+
+	@Override
+	public Class<? extends Annotation> getAnnotationType() {
+		return ANNOTATION;
+	}
+
+	@Override
+	public boolean processArgument(AnnotatedParameterContext context,
+			Annotation annotation, Method method) {
+		int parameterIndex = context.getParameterIndex();
+		Class<?> parameterType = method.getParameterTypes()[parameterIndex];
+		MethodMetadata data = context.getMethodMetadata();
+		String name = ANNOTATION.cast(annotation).value();
+
+		checkState(emptyToNull(name) != null,
+				"MatrixVariable annotation was empty on param %s.",
+				context.getParameterIndex());
+
+		context.setParameterName(name);
+
+		if (Map.class.isAssignableFrom(parameterType)) {
+			data.indexToExpander().put(parameterIndex, this::expandMap);
+		}
+		else {
+			data.indexToExpander().put(parameterIndex,
+					object -> ";" + name + "=" + object.toString());
+		}
+
+		return true;
+	}
+
+	private String expandMap(Object object) {
+		Map<String, Object> paramMap = (Map) object;
+
+		return paramMap.keySet().stream()
+				.map(key -> ";" + key + "=" + paramMap.get(key).toString())
+				.collect(Collectors.joining());
+	}
+
+}

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/support/SpringMvcContract.java

@@ -36,6 +36,7 @@ import feign.Param;
 import feign.Request;
 
 import org.springframework.cloud.openfeign.AnnotatedParameterProcessor;
+import org.springframework.cloud.openfeign.annotation.MatrixVariableParameterProcessor;
 import org.springframework.cloud.openfeign.annotation.PathVariableParameterProcessor;
 import org.springframework.cloud.openfeign.annotation.QueryMapParameterProcessor;
 import org.springframework.cloud.openfeign.annotation.RequestHeaderParameterProcessor;
@@ -355,6 +356,7 @@ public class SpringMvcContract extends Contract.BaseContract
 
 		List<AnnotatedParameterProcessor> annotatedArgumentResolvers = new ArrayList<>();
 
+		annotatedArgumentResolvers.add(new MatrixVariableParameterProcessor());
 		annotatedArgumentResolvers.add(new PathVariableParameterProcessor());
 		annotatedArgumentResolvers.add(new RequestParamParameterProcessor());
 		annotatedArgumentResolvers.add(new RequestHeaderParameterProcessor());

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/support/SpringMvcContractTests.java

@@ -23,6 +23,7 @@ import java.time.LocalDateTime;
 import java.time.format.DateTimeFormatter;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -45,6 +46,7 @@ import org.springframework.util.MultiValueMap;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.MatrixVariable;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
@@ -523,6 +525,35 @@ public class SpringMvcContractTests {
 		this.contract.parseAndValidateMetadata(method.getDeclaringClass(), method);
 	}
 
+	@Test
+	public void testMatrixVariable_MapParam() throws Exception {
+		Method method = TestTemplate_MatrixVariable.class
+				.getDeclaredMethod("matrixVariable", Map.class);
+		MethodMetadata data = this.contract
+				.parseAndValidateMetadata(method.getDeclaringClass(), method);
+
+		Map<String, String> testMap = new HashMap<>();
+		testMap.put("param", "value");
+
+		assertThat(data.template().method()).isEqualTo("GET");
+		assertThat(data.template().url()).isEqualTo("/matrixVariable/{params}");
+		assertThat(";param=value")
+				.isEqualTo(data.indexToExpander().get(0).expand(testMap));
+	}
+
+	@Test
+	public void testMatrixVariable_ObjectParam() throws Exception {
+		Method method = TestTemplate_MatrixVariable.class
+				.getDeclaredMethod("matrixVariableObject", Object.class);
+		MethodMetadata data = this.contract
+				.parseAndValidateMetadata(method.getDeclaringClass(), method);
+
+		assertThat(data.template().method()).isEqualTo("GET");
+		assertThat(data.template().url()).isEqualTo("/matrixVariableObject/{param}");
+		assertThat(";param=value")
+				.isEqualTo(data.indexToExpander().get(0).expand("value"));
+	}
+
 	@Test
 	public void testAddingTemplatedParameterWithTheSameKey()
 			throws NoSuchMethodException {
@@ -639,6 +670,16 @@ public class SpringMvcContractTests {
 
 	}
 
+	public interface TestTemplate_MatrixVariable {
+
+		@RequestMapping(path = "/matrixVariable/{params}")
+		String matrixVariable(@MatrixVariable("params") Map<String, Object> params);
+
+		@RequestMapping(path = "/matrixVariableObject/{param}")
+		String matrixVariableObject(@MatrixVariable("param") Object object);
+
+	}
+
 	@JsonAutoDetect
 	@RequestMapping("/advanced")
 	public interface TestTemplate_Advanced {