Java---编写利用runtime命令实现自动备份数据库

runtime可实现调用系统命令打开网页

package day;

import java.io.IOException;

public class Runt {
    public static void main(String[] args) {
        Runtime run = Runtime.getRuntime();
        System.out.println("jvm最大内存量为"+ run.maxMemory());
        try {
            run.exec("cmd /c start http://www.baidu.com");    //打开百度
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

实现数据库的定时备份（利用多线程）

package day;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;

public class Db implements Runnable {
    private int m = 0;

    public Db(int m) {
        this.m = m;
    }

    public Db() {
        this.m = 5;
    }

    @Override
    public void run() {
        long ftime = 0;
        int num = 0;
        long start = 0;
        while (true) {
            start += 5;
            SimpleDateFormat sd = new SimpleDateFormat("yyyHHddHHmmss");
            Date d = new Date();
            String ff = sd.format(d) + ".sql";
            Runtime run = Runtime.getRuntime();
            try {
                if (start >= (this.m * 60)) {                       //m分钟后开始备份
                    run.exec("cmd /c D:\m8\mysql-8.0.12\bin\mysqldump.exe -uroot -proot zzz zzz > c:\dbtext\" + ff);     //使用runtime实现数据库备份zzz数组库
                    start = 0;
                    num++;
                    while (num > 3) {                               //文件夹中只存放最近三次的备份，多余则删除
                        File[] f = new File("c:/dbtext").listFiles();
                        var arr = new ArrayList<Long>();
                        for (File fl : f) {
                            ftime = fl.lastModified();
                            arr.add(ftime);
                        }
                        long min = Collections.min(arr);
                        for (File fl : f) {
                            if (fl.lastModified() == min) {
                                fl.delete();
                            }
                        }
                        num--;
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

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package day;
public class Dbtext {
    public static void main(String[] args) {
        Db d = new Db(1);
        Thread th = new Thread(d);                                            //开启线程一直执行
        th.start();
    }
}