MapReduce run custom map and reduce class not found

In the Eclipse development environment, when distributing mapreduce jobs to a cluster, there are often situations where the map and the reduce classes that you define are not available. This time you can make the project into a jar package and then add the jar package to the project. This approach is cumbersome, and it is only necessary to upload your own map and reduce classes to the cluster before configuring the job. The code looks like this:

Method Addurl = URLClassLoader.class.getDeclaredMethod ("Addurl", new class[] {url.class});
Addurl.setaccessible (TRUE);
URLClassLoader ClassLoader = (urlclassloader) classloader.getsystemclassloader ();
String url = "File:///home/bi/Desktop/Job.jar"; Package path Location
URL classurl = new URL (URL);
Addurl.invoke (ClassLoader, new object[] {classurl});