org.ngrinder.infra.spring.ApiExceptionHandlerResolver.java Source code

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Here is the source code for org.ngrinder.infra.spring.ApiExceptionHandlerResolver.java

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/* 
 * 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.ngrinder.infra.spring;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.io.IOUtils;
import org.ngrinder.common.controller.RestAPI;
import org.ngrinder.common.util.ExceptionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.Ordered;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonObject;

/**
 * Api exception handler which emits the exception message in the form of json.
 *
 * @author junoyoon
 * @since 3.2.3
 */
public class ApiExceptionHandlerResolver implements HandlerExceptionResolver, Ordered {
    private static final Logger LOGGER = LoggerFactory.getLogger(ApiExceptionHandlerResolver.class);
    private static final String JSON_SUCCESS = "success";
    private static final String JSON_CAUSE = "message";
    private static final String JSON_STACKTRACE = "stackTrace";
    private int order;

    private static Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().setPrettyPrinting()
            .create();

    /*
     * (non-Javadoc)
     * 
     * @see org.springframework.core.Ordered#getOrder()
     */
    @Override
    public int getOrder() {
        return order;
    }

    /*
     * (non-Javadoc)
     * 
     * @see
     * org.springframework.web.servlet.HandlerExceptionResolver#resolveException
     * (javax.servlet.http.HttpServletRequest,
     * javax.servlet.http.HttpServletResponse, java.lang.Object,
     * java.lang.Exception)
     */
    @Override
    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler,
            Exception ex) {
        if (!(handler instanceof HandlerMethod)) {
            return null;
        }

        RestAPI methodAnnotation = ((HandlerMethod) handler).getMethodAnnotation(RestAPI.class);
        if (methodAnnotation == null) {
            return null;
        }
        JsonObject object = new JsonObject();
        object.addProperty(JSON_SUCCESS, false);
        object.addProperty(JSON_CAUSE, ex.getMessage());
        StringWriter out = new StringWriter();
        //noinspection ThrowableResultOfMethodCallIgnored
        Throwable throwable = ExceptionUtils.sanitize(ex);
        PrintWriter printWriter = new PrintWriter(out);
        throwable.printStackTrace(printWriter);
        object.addProperty(JSON_STACKTRACE, out.toString());
        IOUtils.closeQuietly(printWriter);
        String jsonMessage = gson.toJson(object);
        try {
            response.setStatus(500);
            response.setContentType("application/json; charset=UTF-8");
            response.addHeader("Pragma", "no-cache");
            PrintWriter writer = response.getWriter();
            writer.write(jsonMessage);
            response.flushBuffer();
        } catch (IOException e) {
            LOGGER.error("Exception was occurred while processing api exception.", e);
        }
        return new ModelAndView();
    }

    public void setOrder(int order) {
        this.order = order;
    }

}