怎么用Java实时读取日志文件

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编码实现

写日志文件，每秒写200条记录，并且记录写的时间

import java.io.File;import java.io.IOException;import java.io.RandomAccessFile;import java.text.SimpleDateFormat;import java.util.Date;public class LogReader implements Runnable {    private File logFile = null;    private long lastTimeFileSize = 0; // 上次文件大小    private static SimpleDateFormat dateFormat = new SimpleDateFormat(            "yyyy-MM-dd HH:mm:ss");    public LogReader(File logFile) {        this.logFile = logFile;        lastTimeFileSize = logFile.length();    }    /**     * 实时输出日志信息     */    public void run() {        while (true) {            try {                long len = logFile.length();                if (len < lastTimeFileSize) {                    System.out.println("Log file was reset. Restarting logging from start of file.");                    lastTimeFileSize = len;                } else if(len > lastTimeFileSize) {                    RandomAccessFile randomFile = new RandomAccessFile(logFile, "r");                    randomFile.seek(lastTimeFileSize);                    String tmp = null;                    while ((tmp = randomFile.readLine()) != null) {                        System.out.println(dateFormat.format(new Date()) + "\t"                                + tmp);                    }                    lastTimeFileSize = randomFile.length();                    randomFile.close();                }            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }                        try {                Thread.sleep(50);            } catch (InterruptedException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }    }}

实时读取日志文件，每隔1秒读一次

import java.io.File;import java.io.IOException;import java.io.RandomAccessFile;import java.text.SimpleDateFormat;import java.util.Date;public class LogReader implements Runnable {    private File logFile = null;    private long lastTimeFileSize = 0; // 上次文件大小    private static SimpleDateFormat dateFormat = new SimpleDateFormat(            "yyyy-MM-dd HH:mm:ss");    public LogReader(File logFile) {        this.logFile = logFile;        lastTimeFileSize = logFile.length();    }    /**     * 实时输出日志信息     */    public void run() {        while (true) {            try {                RandomAccessFile randomFile = new RandomAccessFile(logFile, "r");                randomFile.seek(lastTimeFileSize);                String tmp = null;                while ((tmp = randomFile.readLine()) != null) {                    System.out.println(dateFormat.format(new Date()) + "\t"                            + tmp);                }                lastTimeFileSize = randomFile.length();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            try {                Thread.sleep(500);            } catch (InterruptedException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }    }}

开启写线程、读线程，将实时信息打印在控制台。

import java.io.File;public class RunRun {    public static void main(String[] args) {        File logFile = new File("mock.log");        Thread wthread = new Thread(new LogWrite(logFile));        wthread.start();        Thread rthread = new Thread(new LogReader(logFile));        rthread.start();    }}

在读写的过程中，我们可以手动将mock.log文件重命名，发现依旧可以实时读。

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