com.wealdtech.jersey.providers.HttpExceptionMapper.java Source code

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Here is the source code for com.wealdtech.jersey.providers.HttpExceptionMapper.java

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/*
 * Copyright 2012 - 2014 Weald Technology Trading Limited
 *
 * 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 com.wealdtech.jersey.providers;

import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.ResponseBuilder;
import javax.ws.rs.ext.ExceptionMapper;
import javax.ws.rs.ext.Provider;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.wealdtech.WealdError;
import com.wealdtech.errors.ErrorInfo;
import com.wealdtech.jackson.ObjectMapperFactory;
import com.wealdtech.jersey.exceptions.HttpException;

/**
 * Convert Weald HTTP exceptions in to a suitable JSON response for clients.
 */
@Provider
public class HttpExceptionMapper implements ExceptionMapper<HttpException> {
    private static final Logger LOGGER = LoggerFactory.getLogger(HttpExceptionMapper.class);

    private static final transient ObjectMapper MAPPER = ObjectMapperFactory.getDefaultMapper();

    @Override
    public Response toResponse(final HttpException exception) {
        ResponseBuilder builder = Response.status(exception.getStatus()).entity(statusToJSON(exception))
                .type(MediaType.APPLICATION_JSON);

        if (exception.getRetryAfter().isPresent()) {
            builder.header("Retry-After", exception.getRetryAfter().get());
        }

        return builder.build();
    }

    private String statusToJSON(final HttpException exception) {
        WealdError err = exception;
        Throwable t = exception.getCause();
        while (t != null) {
            if (t instanceof WealdError) {
                err = (WealdError) t;
            }
            t = t.getCause();
        }
        ErrorInfo errorInfo = new ErrorInfo(null, err.getUserMessage(), err.getMessage(), err.getUrl());

        try {
            return MAPPER.writeValueAsString(errorInfo);
        } catch (JsonProcessingException e) {
            LOGGER.error("Failed to generate JSON for status \"{}\"", errorInfo);
            return "{\"message\":\"An error occurred\"}";
        }
    }
}