com.prodyna.devcon.backend.ChuckNorrisFactController.java Source code

Introduction

Here is the source code for com.prodyna.devcon.backend.ChuckNorrisFactController.java

Source

/**
 * Copyright (c) 2001-present PRODYNA AG. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 */
package com.prodyna.devcon.backend;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.Random;
import java.util.logging.Logger;

import javax.annotation.PostConstruct;

import org.apache.commons.io.IOUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * ReST controller for the Chuck Norris facts service.
 * 
 * @author Florian Assmus, PRODYNA AG
 *
 */
@RestController
public class ChuckNorrisFactController {

    private static final Logger log = Logger.getLogger(ChuckNorrisFactController.class.getName());

    /**
     * Name of file containing the Chuck Norris facts relative to the current
     * class loader.
     */
    private static final String CHUCK_NORRIS_FACTS_FILE_NAME = "Chuck_Norris_Facts.txt";

    /**
     * List of Chuck Norris facts.
     */
    private List<String> chuckNorrisFacts;

    /**
     * Generator for random numbers used to look up a Chuck Norris fact.
     */
    private Random randomGenerator = new Random();

    /**
     * Load facts about Chuck Norris from a file into memory.
     * 
     * @throws IOException
     *             is thrown if the Chuck Norris facts could not be loaded.
     */
    @PostConstruct
    public void loadChuckNorrisFacts() throws IOException {
        InputStream in = getClass().getClassLoader().getResource(CHUCK_NORRIS_FACTS_FILE_NAME).openStream();
        chuckNorrisFacts = IOUtils.readLines(in, "UTF-8");
    }

    /**
     * Method for retrieving a fact about Chuck Norris.
     * 
     * @return Fact about Chuck Norris.
     */
    @RequestMapping("/chucknorrisfact")
    public ChuckNorrisFact chuckNorrisFact() throws InterruptedException {

        // Simple way to slow down service for simulation purposes.
        //      try {
        //         Thread.sleep(15000);
        //      } catch (InterruptedException e) {
        //         // Do nothing.
        //      }

        // Get a random fact and return it.
        int factIndex = getRandomInt(0, chuckNorrisFacts.size() - 1);
        String chuckNorrisFact = chuckNorrisFacts.get(factIndex);
        return new ChuckNorrisFact(factIndex, chuckNorrisFact);
    }

    /**
     * Get a random {@link Integer} based on the give range.
     * 
     * @param start
     *            Lowest random number.
     * @param end
     *            Highest random number
     * @return Random number within the given range.
     */
    public int getRandomInt(int start, int end) {
        if (start > end) {
            throw new IllegalArgumentException("Start cannot exceed End.");
        }

        // get the range, casting to long to avoid overflow problems
        long range = (long) end - (long) start + 1;
        // compute a fraction of the range, 0 <= frac < range
        long fraction = (long) (range * randomGenerator.nextDouble());
        int randomNumber = (int) (fraction + start);

        return randomNumber;
    }
}