org.apache.hive.http.ConfServlet.java Source code

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Here is the source code for org.apache.hive.http.ConfServlet.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.hive.http;

import java.io.IOException;
import java.io.Writer;

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

import org.apache.hadoop.conf.Configuration;

/**
 * A servlet to print out the running configuration data.
 */
public class ConfServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    private static final String FORMAT_JSON = "json";
    private static final String FORMAT_XML = "xml";
    private static final String FORMAT_PARAM = "format";

    /**
     * Return the Configuration of the daemon hosting this servlet.
     * This is populated when the HttpServer starts.
     */
    private Configuration getConfFromContext() {
        Configuration conf = (Configuration) getServletContext().getAttribute(HttpServer.CONF_CONTEXT_ATTRIBUTE);
        assert conf != null;
        return conf;
    }

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        if (!HttpServer.isInstrumentationAccessAllowed(getServletContext(), request, response)) {
            return;
        }

        String format = request.getParameter(FORMAT_PARAM);
        if (null == format) {
            format = FORMAT_XML;
        }

        if (FORMAT_XML.equals(format)) {
            response.setContentType("text/xml; charset=utf-8");
        } else if (FORMAT_JSON.equals(format)) {
            response.setContentType("application/json; charset=utf-8");
        }

        Writer out = response.getWriter();
        try {
            writeResponse(getConfFromContext(), out, format);
        } catch (BadFormatException bfe) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, bfe.getMessage());
        }
        out.close();
    }

    /**
     * Guts of the servlet - extracted for easy testing.
     */
    static void writeResponse(Configuration conf, Writer out, String format)
            throws IOException, BadFormatException {
        if (FORMAT_JSON.equals(format)) {
            Configuration.dumpConfiguration(conf, out);
        } else if (FORMAT_XML.equals(format)) {
            conf.writeXml(out);
        } else {
            throw new BadFormatException("Bad format: " + format);
        }
    }

    public static class BadFormatException extends Exception {
        private static final long serialVersionUID = 1L;

        public BadFormatException(String msg) {
            super(msg);
        }
    }
}