Restructuring the form of REST API deployment to provide
for security of app's REST APIs and for consistency of
exception mappers and JSON writer.
Change-Id: Id318372bf62f82ed974355c05e7fe64e0fbfc0c5
diff --git a/utils/rest/src/main/java/org/onlab/rest/exceptions/AbstractMapper.java b/utils/rest/src/main/java/org/onlab/rest/exceptions/AbstractMapper.java
new file mode 100644
index 0000000..fa94c2d
--- /dev/null
+++ b/utils/rest/src/main/java/org/onlab/rest/exceptions/AbstractMapper.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright 2014-2015 Open Networking Laboratory
+ *
+ * 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
+ *
+ * http://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.onlab.rest.exceptions;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+
+import javax.ws.rs.core.Response;
+import javax.ws.rs.ext.ExceptionMapper;
+
+import static com.google.common.base.Strings.isNullOrEmpty;
+
+/**
+ * Base exception mapper implementation.
+ */
+public abstract class AbstractMapper<E extends Throwable> implements ExceptionMapper<E> {
+
+ /**
+ * Holds the current exception for use in subclasses.
+ */
+ protected Throwable error;
+
+ /**
+ * Returns the response status to be given when the exception occurs.
+ *
+ * @return response status
+ */
+ protected abstract Response.Status responseStatus();
+
+ @Override
+ public Response toResponse(E exception) {
+ error = exception;
+ return response(responseStatus(), exception).build();
+ }
+
+ /**
+ * Produces a response builder primed with the supplied status code
+ * and JSON entity with the status code and exception message.
+ *
+ * @param status response status
+ * @param exception exception to encode
+ * @return response builder
+ */
+ protected Response.ResponseBuilder response(Response.Status status,
+ Throwable exception) {
+ error = exception;
+ ObjectMapper mapper = new ObjectMapper();
+ String message = messageFrom(exception);
+ ObjectNode result = mapper.createObjectNode()
+ .put("code", status.getStatusCode())
+ .put("message", message);
+ return Response.status(status).entity(result.toString());
+ }
+
+ /**
+ * Produces a response message from the supplied exception. Either it will
+ * use the exception message, if there is one, or it will use the top
+ * stack-frame message.
+ *
+ * @param exception exception from which to produce a message
+ * @return response message
+ */
+ protected String messageFrom(Throwable exception) {
+ if (isNullOrEmpty(exception.getMessage())) {
+ StackTraceElement[] trace = exception.getStackTrace();
+ return trace.length == 0 ? "Unknown error" : trace[0].toString();
+ }
+ return exception.getMessage();
+ }
+
+}