有时候我们需要针对文件进行备份,每次全量备份不仅浪费服务器硬件资源也对带宽造成极大的不必要的浪费,所以我们需要对文件进行增量备份,下面只针对文件的增量变更操作进行监听。
package com.file;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import org.apache.commons.io.filefilter.FileFilterUtils;
import org.apache.commons.io.monitor.FileAlterationListenerAdaptor;
import org.apache.commons.io.monitor.FileAlterationMonitor;
import org.apache.commons.io.monitor.FileAlterationObserver;
public class _indexMain {
// 标记文件已读行数
private static Map<String, Long> currentMap = new ConcurrentHashMap<String, Long>();
private static String drictoryPath = "C:\\Users\\Administrator\\Desktop";
public static void main(String[] args) {
initListenFile();
startFileListener();
}
/***
* 扫描文件夹下要监听的文件,这里只监听txt文件
*/
private static void initListenFile() {
File filesDrictory = new File(drictoryPath);
if (filesDrictory.exists()) {
File[] files = filesDrictory.listFiles(new FileFilter() {
@Override
public boolean accept(File pathname) {
String fileName = pathname.getName();
return fileName.substring(fileName.lastIndexOf(".") + 1).equals("txt");
}
});
for (File file : files) {
currentMap.put(file.getAbsolutePath(), 0L);
}
}
}
// 启用文件监听
private static void startFileListener() {
// 监控目录
// 轮询间隔 1 秒
long interval = TimeUnit.SECONDS.toMillis(1);
// 创建一个文件观察器用于处理文件的格式,只监听txt文件
FileAlterationObserver observer = new FileAlterationObserver(drictoryPath,
FileFilterUtils.and(FileFilterUtils.fileFileFilter(), FileFilterUtils.suffixFileFilter(".txt")
/** ,FileFilterUtils.prefixFileFilter("111") */), // 过滤文件格式
null);
observer.addListener(new FileListener());
// 创建文件变化监听器
FileAlterationMonitor monitor = new FileAlterationMonitor(interval, observer);
// 开始监控
try {
monitor.start();
Set<String> allList = currentMap.keySet();
for (String string : allList) {
System.out.println(string);
}
System.out.println("已监听已上" + currentMap.size() + "个文件");
} catch (Exception e) {
e.printStackTrace();
}
}
// 文件变更监听适配器
private static class FileListener extends FileAlterationListenerAdaptor {
@Override
public void onFileDelete(File file) {
// TODO Auto-generated method stub
System.out.println("[删除]:" + file.getAbsolutePath());
currentMap.remove(file.getAbsolutePath());
}
@Override
public void onFileCreate(File file) {
// TODO Auto-generated method stub
System.out.println("[创建]:" + file.getAbsolutePath());
currentMap.put(file.getAbsolutePath(), 0L);
}
@Override
public void onFileChange(File file) {
BufferedReader br;
try {
InputStreamReader isr = new InputStreamReader(new FileInputStream(file), "UTF-8");
br = new BufferedReader(isr);
if (br.ready()) {
long lines = currentMap.get(file.getAbsolutePath());
lines += br.lines().skip(lines <= 0L ? 0L : lines).peek(FileListener::msgAll).count();
//更新读取到当前文件的偏移量
currentMap.put(file.getAbsolutePath(), lines);
}
//关闭文件流
br.close();
isr.close();
} catch (Exception e) {
e.printStackTrace();
}
}
private static void msgAll(String msg) {
System.out.println("新增内容:" + msg);
}
}
}