Java method to determine whether a file has been updated over a period of time
- 2020-04-01 03:38:23
- OfStack
This article illustrates a Java method for determining whether a file is updated over a period of time. Share with you for your reference. The specific implementation method is as follows:
Timer 1.
private Timer timer;
/**
* Simple timer
* @param delay How long before the implementation. ms
* @param period Time between executions. ms
*/
public void test(long delay, long period) {
timer = new Timer();
timer.schedule(new TimerTask() {
public void run() {
//How you do it & NBSP; < br / >
System.out.println(System.currentTimeMillis());
}
}, delay, period);
}
2. Deepen the version
package classloader;
/**
* @author vma
*/
//Customize a classloader & NBSP; < br / >
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;
//Load the class, if the class file has been loaded, if not, return the current & NBSP; < br / >
public Class loadClass(String name) throws ClassNotFoundException, IOException{
if (isClassModified(name)){
dc = new DynamicClassLoader();
return c = dc.findClass(getBytes(name));
}
return c;
}
//Whether the judgment has been modified & NBSP; < br / >
private boolean isClassModified(String filename) {
boolean returnValue = false;
File file = new File(filename);
if (file.lastModified() > lastModified) {
returnValue = true;
}
return returnValue;
}
//Reading the file locally & NBSP; < br / >
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. The method of the thread
class Thread1 extends Thread{
public void run(){
//Invoke the business method (to see if the file has changed)
Thread.currentThread().sleep("100000");
}
I hope this article has been helpful to your Java programming.