JAVA多线程放号器

做一个放号器, 多个线程同时申请号码不重复,断电后能恢复.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

比如:

线程1 : 1, 4, 5, 6,   8,   9,   14…

线程2 : 2, 3, 7, 10, 11, 12,  13…

 

package org.leno.j2se.lesson3.multiThread;

 

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.RandomAccessFile;

 

/**

 * @author leno

 *    一个简单的放号器, 多个线程同时申请号码不重复,断电后能恢复.

 */

public class SendCode implements Runnable{

       //号码

       int code = 0;

       RandomAccessFile raf = null;

       //初始化块

       {

              try {

                     raf = new RandomAccessFile("sendCode.txt","rw");

                     code = raf.readInt();

                     System.out.println("恢复上次记录："+code);

              } catch (FileNotFoundException e) {

                     System.out.println("文件找不到！");

              }catch (IOException e) {

                     System.out.println("没有合适的整数值");

              }

       }

      

       public void run() {

                     while(true){

                            synchronized (this) {

                                   try {

                                          Thread.sleep(300);

                                   } catch (InterruptedException e) {

                                          // TODO Auto-generated catch block

                                          e.printStackTrace();

                                   }

                                   code++;

                                   try {

                                          raf.seek(0);//从文件开头以字节为单位测量的偏移量位置，在该位置设置文件指针

                                          raf.writeInt(code);//从文件指针的当前位置开始写

                                   } catch (IOException e) {

                                          // TODO Auto-generated catch block

                                          e.printStackTrace();

                                   }

                                   System.out.println(Thread.currentThread().getName()+"申请到号码："+code);

                            }

                     }

       }

 

       public static void main(String[] args) {

              SendCode sc = new SendCode();

              new Thread(sc,"一号线程").start();

              new Thread(sc,"二号线程").start();

              new Thread(sc,"三号线程").start();

              new Thread(sc,"四号线程").start();

       }

}