判断时间段内文件是否更新

1.定时器

private Timer timer;

    /**
     * 简易定时器
     * @param delay  多久后开始执行。毫秒
     * @param period 执行的间隔时间。毫秒
     */
    public void test(long delay, long period) {
        timer = new Timer();
        timer.schedule(new TimerTask() {
            public void run() {
                //你 的 操作方法
                System.out.println(System.currentTimeMillis());
            }
        }, delay, period);
    }

2.深化版

package classloader;

/**
 * @author vma
 */
// 自定义一个类加载器
public class DynamicClassLoader extends ClassLoader {


    public Class<?> findClass(byte[] b) throws ClassNotFoundException {

        return defineClass(null, b, 0, b.length);
    }

package classloader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
/**
 * @author vma
 */
public class ManageClassLoader {
    DynamicClassLoader dc =null;

    Long lastModified = 0l;
    Class c = null;
    //加载类， 如果类文件修改过加载，如果没有修改，返回当前的
    public Class loadClass(String name) throws ClassNotFoundException, IOException{
     if (isClassModified(name)){
        dc =  new DynamicClassLoader();
      return c = dc.findClass(getBytes(name));
     }
     return c;
    }
    //判断是否被修改过
    private boolean isClassModified(String filename) {
        boolean returnValue = false;
        File file = new File(filename);
        if (file.lastModified() > lastModified) {
            returnValue = true;
        }
        return returnValue;
    }
       // 从本地读取文件
       private byte[] getBytes(String filename) throws IOException {
        File file = new File(filename);
        long len = file.length();
        lastModified = file.lastModified();
        byte raw[] = new byte[(int) len];
        FileInputStream fin = new FileInputStream(file);
        int r = fin.read(raw);
        if (r != len) {
            throw new IOException("Can't read all, " + r + " != " + len);
        }
        fin.close();
        return raw;
    }
}

3.thread

class Thread1 extends Thread{
  public void run(){
//调用业务方法（查看文件是否改变）
Thread.currentThread().sleep("100000");
}