private Timer timer;  
  
/** 
* 簡易定時器 
* @param delay  多久后開始執行。毫秒 
* @param period 執行的間隔時間。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);  
}

package classloader;  
/** 
 * @author vma 
 */  
// 自定義一個類加載器  
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;  
    //加載類， 如果類文件修改過加載，如果沒有修改，返回當前的  
    public Class loadClass(String name) throws ClassNotFoundException, IOException{  
     if (isClassModified(name)){  
        dc =  new DynamicClassLoader();  
      return c = dc.findClass(getBytes(name));  
     }  
     return c;  
    }  
    //判斷是否被修改過  
    private boolean isClassModified(String filename) {  
        boolean returnValue = false;  
        File file = new File(filename);  
        if (file.lastModified() > lastModified) {  
            returnValue = true;  
        }  
        return returnValue;  
    }  
       // 從本地讀取文件  
       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;
    }
}

class Thread1 extends Thread{
  public void run(){
//調用業務方法（查看文件是否改變）
Thread.currentThread().sleep("100000");
}