org.tec.webapp.web.ErrorServlet.java Source code

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Here is the source code for org.tec.webapp.web.ErrorServlet.java

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/*******************************************************************************
 * Copyright 2014 org.tec
 *
 * 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.tec.webapp.web;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.MimeTypeUtils;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

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

/**
 * servlet to trap errors
 */
@WebServlet("/error")
public class ErrorServlet extends HttpServlet {
    /** serial guid */
    private static final long serialVersionUID = 1L;

    /** the logger */
    protected static final Log LOGGER = LogFactory.getLog(ErrorServlet.class);

    /**
     * hand get request
     * @param request the request instance
     * @param response the response instance
     * @throws ServletException if processing fails
     * @throws IOException if processing fails
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processError(request, response);
    }

    /**
     * hand get request
     * @param request the request instance
     * @param response the response instance
     * @throws ServletException if processing fails
     * @throws IOException if processing fails
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processError(request, response);
    }

    /**
     * process the error
     * @param request the request instance
     * @param response the response instance
     * @throws IOException if processing fails
     */
    protected void processError(HttpServletRequest request, HttpServletResponse response) throws IOException {
        Throwable throwable = (Throwable) request.getAttribute(RequestDispatcher.ERROR_EXCEPTION);
        Integer statusCode = (Integer) request.getAttribute(RequestDispatcher.ERROR_STATUS_CODE);
        String requestUri = (String) request.getAttribute(RequestDispatcher.ERROR_REQUEST_URI);

        LOGGER.error("failed to process " + requestUri + " error code: " + statusCode);

        WebError we;
        if (throwable != null) {
            LOGGER.error("error", throwable);
            we = new WebError(throwable.getMessage(), ErrorCodes.UNRESOLVEABLE_ERROR);
        } else {
            we = new WebError("error", ErrorCodes.UNRESOLVEABLE_ERROR);
        }

        PrintWriter pw = null;
        try {
            response.setStatus(statusCode != null ? statusCode : HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            response.setContentType(MimeTypeUtils.APPLICATION_JSON_VALUE);
            pw = response.getWriter();
            pw.write(we.toJSON());
            pw.flush();
        } finally {
            if (pw != null) {
                pw.close();
            }
        }
    }
}