org.onlab.rest.exceptions.AbstractMapper Maven / Gradle / Ivy
/*
* Copyright 2015-present Open Networking Foundation
*
* 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 implements ExceptionMapper {
/**
* 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();
}
}