JAVA產生字母和隨機數字並組建檔案，java產生字母

JAVA產生字母和隨機數字並組建檔案，java產生字母

package com.ishow.control.code;import java.io.*;import java.text.SimpleDateFormat;import java.util.Random;/** * @author Lee * @version 建立時間：Oct 9, 2015 4:12:25 PM */        public class CreateCodeController{    /**     * 產生兌換碼     * @return     * @throws IOException      */    public static void main(String[] args){                Long start = System.currentTimeMillis();                String prefix = "LF";    //首碼         int num = 10;//數字位元         int count = 10000;//產生數量         SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH時mm分");                //組建檔案地址         File f = new File("C:\\Documents and Settings\\Administrator\\案頭\\產生碼" + formatter.format(System.currentTimeMillis()) + ".txt");                OutputStreamWriter writer = null;        BufferedWriter bw = null;                Random random = new Random();        try {            OutputStream os = new FileOutputStream(f);            writer = new OutputStreamWriter(os);            bw = new BufferedWriter(writer);            int i=0;            while(i<count){                String str = "";                for (int j = 0; j < num; j++) {                    int number = random.nextInt(10);                          str+=number+"";                }                str = prefix+str;                try {                    bw.write(str+"\r\n");                } catch (Exception e) {                    i--;                }              i++;            }            bw.flush();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        } finally {            try {                bw.close();            } catch (IOException e) {                e.printStackTrace();            }        }        Long end = System.currentTimeMillis();        System.out.println("bufferedWrite And FileWriterTest's time---------" + (start - end)/1000d);    }}