Demo.java

 

package com.java;import java.io.BufferedWriter;import java.io.File;import java.io.FileWriter;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Random;/** * 随机生成从2000到2018每天一个随机四位数，用于MapReduce计算每年最大值测试 *  * @author Logan * @createDate 2019-03-18 * @version 1.0.0 * */public class Demo {    /**     * 生成文件存放在D盘1.txt     */    private static final String PATH = "D:\\1.txt";    private static final SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd");    public static void main(String[] args) {        File file = new File(PATH);        try (                FileWriter writer = new FileWriter(file);                BufferedWriter bufWriter = new BufferedWriter(writer);        ) {            if (!file.exists()) {                file.createNewFile();            }            Calendar start = Calendar.getInstance();            Calendar end = Calendar.getInstance();            start.set(2000, 0, 1);            end.set(2018, 0, 1);            StringBuffer line = null;            while (start.before(end)) {                line = new StringBuffer();                line.append(format.format(start.getTime()));                line.append(getRandom()).append("\n");                bufWriter.write(line.toString());                start.add(Calendar.DATE, 1);            }        } catch (Exception e) {            e.printStackTrace();        }    }    /**     * 随机生成一个四位整数     *      * @return     */    private static int getRandom() {        Random r = new Random();        return r.nextInt(9000) + 1000;    }}

 

 

计算程序参见：

 

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