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Java example source code file (RandomHandler.java)

This example source code file (RandomHandler.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java tags/keywords

abcdefghijklmnopqrstuvwxyz, content-length, content-type, head, httpexception, illegalargumentexception, io, ioexception, length, methodnotsupportedexception, randomentity, randomhandler, range, string, us-ascii, util

The RandomHandler.java example source code

/*
 * ====================================================================
 * 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.localserver;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.Locale;

import org.apache.http.HttpException;
import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.MethodNotSupportedException;
import org.apache.http.entity.AbstractHttpEntity;
import org.apache.http.protocol.HttpContext;
import org.apache.http.protocol.HttpRequestHandler;



/**
 * A handler that generates random data.
 * 
 *
 *
 * <!-- empty lines to avoid 'svn diff' problems -->
 */
public class RandomHandler
    implements HttpRequestHandler {

    // public default constructor

    /**
     * Handles a request by generating random data.
     * The length of the response can be specified in the request URI
     * as a number after the last /. For example /random/whatever/20
     * will generate 20 random bytes in the printable ASCII range.
     * If the request URI ends with /, a random number of random bytes
     * is generated, but at least one.
     *
     * @param request   the request
     * @param response  the response
     * @param context   the context
     *
     * @throws HttpException    in case of a problem
     * @throws IOException      in case of an IO problem
     */
    public void handle(final HttpRequest request, 
                       final HttpResponse response,
                       final HttpContext context)
        throws HttpException, IOException {

        String method = request.getRequestLine().getMethod().toUpperCase(Locale.ENGLISH);
        if (!"GET".equals(method) && !"HEAD".equals(method)) {
            throw new MethodNotSupportedException
                (method + " not supported by " + getClass().getName());
        }

        String uri = request.getRequestLine().getUri();
        int  slash = uri.lastIndexOf('/');
        int length = -1;
        if (slash < uri.length()-1) {
            try {
                // no more than Integer, 2 GB ought to be enough for anybody
                length = Integer.parseInt(uri.substring(slash+1));

                if (length < 0) {
                    response.setStatusCode(HttpStatus.SC_BAD_REQUEST);
                    response.setReasonPhrase("LENGTH " + length);
                }
            } catch (NumberFormatException nfx) {
                response.setStatusCode(HttpStatus.SC_BAD_REQUEST);
                response.setReasonPhrase(nfx.toString());
            }
        } else {
            // random length, but make sure at least something is sent
            length = 1 + (int)(Math.random() * 79.0);
        }

        if (length >= 0) {

            response.setStatusCode(HttpStatus.SC_OK);

            if (!"HEAD".equals(method)) {
                RandomEntity entity = new RandomEntity(length);
                entity.setContentType("text/plain; charset=US-ASCII");
                response.setEntity(entity);
            } else {
                response.setHeader("Content-Type",
                                   "text/plain; charset=US-ASCII");
                response.setHeader("Content-Length",
                                   String.valueOf(length));
            }
        }

    } // handle


    /**
     * An entity that generates random data.
     * This is an outgoing entity, it supports {@link #writeTo writeTo}
     * but not {@link #getContent getContent}.
     */
    public static class RandomEntity extends AbstractHttpEntity {

        /** The range from which to generate random data. */
        private final static byte[] RANGE;
        static {
            byte[] range = null;
            try {
                range = ("abcdefghijklmnopqrstuvwxyz" +
                         "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "0123456789"
                    ).getBytes("US-ASCII");
            } catch (UnsupportedEncodingException uex) {
                // never, US-ASCII is guaranteed
            }
            RANGE = range;
        }


        /** The length of the random data to generate. */
        protected final long length;


        /**
         * Creates a new entity generating the given amount of data.
         *
         * @param len   the number of random bytes to generate,
         *              0 to maxint
         */
        public RandomEntity(long len) {
            if (len < 0L)
                throw new IllegalArgumentException
                    ("Length must not be negative");
            if (len > Integer.MAX_VALUE)
                throw new IllegalArgumentException
                    ("Length must not exceed Integer.MAX_VALUE");

            length = len;
        }

        /**
         * Tells that this entity is not streaming.
         *
         * @return      false
         */
        public final boolean isStreaming() {
            return false;
        }

        /**
         * Tells that this entity is repeatable, in a way.
         * Repetitions will generate different random data,
         * unless perchance the same random data is generated twice.
         *
         * @return      <code>true
         */
        public boolean isRepeatable() {
            return true;
        }

        /**
         * Obtains the size of the random data.
         *
         * @return      the number of random bytes to generate
         */
        public long getContentLength() {
            return length;
        }


        /**
         * Not supported.
         * This method throws an exception.
         *
         * @return      never anything
         */
        public InputStream getContent() {
            throw new UnsupportedOperationException();
        }


        /**
         * Generates the random content.
         *
         * @param out   where to write the content to
         */
        public void writeTo(OutputStream out) throws IOException {

            final int blocksize = 2048;
            int       remaining = (int) length; // range checked in constructor
            byte[]         data = new byte[Math.min(remaining, blocksize)];

            while (remaining > 0) {
                final int end = Math.min(remaining, data.length);

                double value = 0.0;
                for (int i = 0; i < end; i++) {
                    // we get 5 random characters out of one random value
                    if (i%5 == 0) {
                        value = Math.random();
                    }
                    value = value * RANGE.length;
                    int d = (int) value;
                    value = value - d;
                    data[i] = RANGE[d];
                }
                out.write(data, 0, end);
                out.flush();

                remaining = remaining - end;
            }
            out.close();

        } // writeTo

    } // class RandomEntity


} // class RandomHandler

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