检测日志的

package com.email.service.impl;

import java.io.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

/**
 * 实时显示日志
 */
public class LogView {
    private long lastTimeFileSize = 0; //上次文件大小
    private long count = 0;//记录是否第一次启动
    /**
     * 实时输出日志信息
     *
     * @param logFile 日志文件
     * @throws IOException
     */
    public void realtimeShowLog(File logFile) throws IOException {
        //给文件增加读写权限
        final RandomAccessFile randomFile = new RandomAccessFile(logFile, "rw");
        //启动一个线程每5秒钟读取新增的日志信息
        ScheduledExecutorService exec = Executors.newScheduledThreadPool(2);
        exec.scheduleWithFixedDelay(new Runnable() {
            public void run() {
                try {
                    //不是第一次启动则报警
                    if (count!=0){
                        //获得变化部分的
                        randomFile.seek(lastTimeFileSize);
                        String tmp = "";
                        while ((tmp = randomFile.readLine()) != null) {
                            System.out.println(new String(tmp.getBytes("ISO8859-1")));
                        }
                    }else {
                        count=1;
                    }
                    //记录第一次启动程序时读取的文件长度
                    lastTimeFileSize = randomFile.length();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
        }, 0, 5, TimeUnit.SECONDS);

        //启动线程自动写入文件(模拟系统日志报错)
        exec.scheduleWithFixedDelay(new Runnable() {
            @Override
            public void run() {
                try {
                    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                    randomFile.seek(lastTimeFileSize);
                    String msg=format.format(new Date())+"-----------------系统报错---------------";
                    //最后一行追加文件
                    randomFile.write(msg.getBytes());
                    //换行
                    randomFile.write("\r\n".getBytes());
                }catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
        },1,10,TimeUnit.SECONDS);
    }

    //入口
    public static void main(String[] args) throws Exception {
        LogView view = new LogView();
        final File tmpLogFile = new File("D:\\file111.txt");
        view.realtimeShowLog(tmpLogFile);
    }
}