Java实时监控日志文件并输出的方法详解 |
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Java实时监控日志文件并输出的方法详解
想在前台显示数据同步过程中产生的日志文件，在网上找到解决方案，做了代码测试好用。这里做个记录 java.io.RandomAccessFile可以解决同时向文件读和写.为了模拟这个问题,编写LogSvr和 LogView类,LogSvr不断向mock.log日志文件写数据,而 LogView则实时输出日志变化部分的数据. 代码1:日志产生类 package com.fbkj.genelog; import java.io.File; import java.io.FileWriter; import java.io.IOException; import java.io.Writer; import java.text.SimpleDateFormat; import java.util.Date; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class LogSvr { private SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); /** * 将信息记录到日志文件 * @param logFile 日志文件 * @param mesInfo 信息 * @throws IOException */ public void logMsg(File logFile,String mesInfo) throws IOException{ if(logFile == null) { throw new IllegalStateException("logFile can not be null!"); } Writer txtWriter = new FileWriter(logFile,true); txtWriter.write(dateFormat.format(new Date()) +"\t"+mesInfo+"\n"); txtWriter.flush(); } public static void main(String[] args) throws Exception{ final LogSvr logSvr = new LogSvr(); String userdir = System.getProperty("user.dir"); final File tmpLogFile = new File(userdir+"/mock.log"); if(!tmpLogFile.exists()) { tmpLogFile.createNewFile(); } //启动一个线程每5秒钟向日志文件写一次数据 ScheduledExecutorService exec = Executors.newScheduledThreadPool(1); exec.scheduleWithFixedDelay(new Runnable(){ public void run() { try { logSvr.logMsg(tmpLogFile, " 99bill test !"); } catch (IOException e) { throw new RuntimeException(e); } } }, 0, 5, TimeUnit.SECONDS); } } 代码2:显示日志的类 package com.fbkj.genelog; import java.io.File; import java.io.IOException; import java.io.RandomAccessFile; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class LogView { private long lastTimeFileSize = 0; //上次文件大小 /** * 实时输出日志信息 * @param logFile 日志文件 * @throws IOException */ public void realtimeShowLog(File logFile) throws IOException{ //指定文件可读可写 final RandomAccessFile randomFile = new RandomAccessFile(logFile,"rw"); //启动一个线程每10秒钟读取新增的日志信息 ScheduledExecutorService exec = Executors.newScheduledThreadPool(1); exec.scheduleWithFixedDelay(new Runnable(){ public void run() { try { //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"))); } lastTimeFileSize = randomFile.length(); } catch (IOException e) { throw new RuntimeException(e); } } }, 0, 1, TimeUnit.SECONDS); } public static void main(String[] args) throws Exception { String userdir = System.getProperty("user.dir"); LogView view = new LogView(); final File tmpLogFile = new File(userdir+"/mock.log"); view.realtimeShowLog(tmpLogFile); } }先执行LogSvr类,LogSvr类会启动一个线程,每5秒钟向mock.log日志文件写一次数据, 然后再执行LogView类,LogView每隔1秒钟读一次,如果数据有变化则输出变化的部分. 参考 https://www.qedev.com/dev/245197.html |
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