org.ambraproject.rhino.rest.LoggingInterceptor.java Source code

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Here is the source code for org.ambraproject.rhino.rest.LoggingInterceptor.java

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/*
 * Copyright (c) 2017 Public Library of Science
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

package org.ambraproject.rhino.rest;

import com.google.common.base.Joiner;
import com.google.common.collect.Iterators;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Enumeration;
import java.util.Iterator;

/**
 * Logs attributes of incoming HTTP requests.
 */
public class LoggingInterceptor extends HandlerInterceptorAdapter {

    private static final Logger log = LoggerFactory.getLogger(LoggingInterceptor.class);

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        if (log.isDebugEnabled()) {
            log.debug(describe(request));
        }
        return super.preHandle(request, response, handler);
    }

    private static String asStringLiteral(Object input) {
        String text = String.valueOf(input);
        if (input == null) {
            return text;
        }

        /*
         * TODO: Use org.apache.commons.lang.StringEscapeUtils?
         * StringEscapeUtils is a little funny with forward-slashes, which makes these values hard to read. So for now,
         * just handle some simple cases by hand. The returned values are not guaranteed to be parsable in any particular
         * context; this is just for human readability.
         */
        text = text.replace("\\", "\\\\").replace("\"", "\\\"");
        return '"' + text + '"';
    }

    private static final Joiner JOINER = Joiner.on(", ");
    private static final String INDENT = "  ";

    /**
     * Build a message describing a request.
     *
     * @param request the request to describe
     * @return the description
     */
    private static String describe(HttpServletRequest request) {
        StringBuilder message = new StringBuilder();
        message.append(request.getMethod()).append(' ').append(request.getRequestURI());
        String queryString = request.getQueryString();
        if (queryString != null) {
            message.append(" ? ").append(queryString);
        }
        message.append('\n');

        // Append a list of headers
        for (Enumeration headerNames = request.getHeaderNames(); headerNames.hasMoreElements();) {
            String headerName = (String) headerNames.nextElement();
            message.append(INDENT).append(asStringLiteral(headerName)).append(": ");
            Enumeration<?> headers = request.getHeaders(headerName);
            Iterator<String> headerStrings = Iterators.transform(Iterators.forEnumeration(headers),
                    LoggingInterceptor::asStringLiteral);
            JOINER.appendTo(message, headerStrings);
            message.append('\n');
        }

        return message.toString();
    }

}