URLClassLoader加载jar包

//Test类:
package com.classloader.test;
public class Test {
public static void main(String[] args) {
try {
MyClassLoader.test("file:G:/javaBY/TEST/FBY.jar","com.fby.test.Test");
} catch (Exception ex) {
ex.printStackTrace();
}
}
}

//加载器类
package com.classloader.test;

import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

public class MyClassLoader extends URLClassLoader {

public MyClassLoader(URL url) {
super(new URL[] { url });
}

public static void test(String str, String cls) throws Exception {
URL url = new URL(str);
MyClassLoader t = new MyClassLoader(url);
Class<?> claz = t.findClass(cls);
Method[] methods = claz.getDeclaredMethods();
if (methods != null) {
for (int i = 0; i < methods.length; i++) {
if ("main".equals(methods[i].getName())) {
methods[i].invoke(claz, (Object) new String[] {});
break;
}
}
}
}
}