#313 - Assert compatibility with JSONPath 0.9 and 1.2.

We now reflectively invoke the JSONPath.compile(…) method as the method signature has changed but we need to stay compatible with 0.9 to allow the Spring Data Evans release train to upgrade to 0.17 without a major third-party dependency upgrade.

Copied the reflective method lookup from Spring's JsonPathExpectationsHelper.

Related ticket: #297, #305.

src/main/java/org/springframework/hateoas/core/JsonPathLinkDiscoverer.java

@@ -17,6 +17,8 @@ package org.springframework.hateoas.core;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.lang.reflect.Array;
+import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -28,6 +30,7 @@ import org.springframework.hateoas.Link;
 import org.springframework.hateoas.LinkDiscoverer;
 import org.springframework.http.MediaType;
 import org.springframework.util.Assert;
+import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
 
 import com.jayway.jsonpath.InvalidPathException;
@@ -40,6 +43,29 @@ import com.jayway.jsonpath.JsonPath;
  */
 public class JsonPathLinkDiscoverer implements LinkDiscoverer {
 
+	private static Method compileMethod;
+	private static Object emptyFilters;
+
+	static {
+
+		// Reflective bridging between JsonPath 0.9.x and 1.x
+		for (Method candidate : JsonPath.class.getMethods()) {
+
+			if (candidate.getName().equals("compile")) {
+
+				Class<?>[] paramTypes = candidate.getParameterTypes();
+
+				if (paramTypes.length == 2 && paramTypes[0].equals(String.class) && paramTypes[1].isArray()) {
+					compileMethod = candidate;
+					emptyFilters = Array.newInstance(paramTypes[1].getComponentType(), 0);
+					break;
+				}
+			}
+		}
+
+		Assert.state(compileMethod != null, "Unexpected JsonPath API - no compile(String, ...) method found");
+	}
+
 	private final String pathTemplate;
 	private final MediaType mediaType;
 
@@ -119,7 +145,7 @@ public class JsonPathLinkDiscoverer implements LinkDiscoverer {
 	 * @return
 	 */
 	private JsonPath getExpression(String rel) {
-		return JsonPath.compile(String.format(pathTemplate, rel));
+		return (JsonPath) ReflectionUtils.invokeMethod(compileMethod, null, String.format(pathTemplate, rel), emptyFilters);
 	}
 
 	/**