Java 使用反射调用jar包中的类方式

public class Main { 
    public static void main(String[] args) { 
        try {
 
//          两种方式都可以
            URL url = new File("/Users/wuchen/Documents/IntelliJidea/Applet/out/production/Applet/image.jar").toURI().toURL();
//          URL url = new URL("file:/Users/wuchen/Documents/IntelliJIDEA/Applet/out/production/Applet/image.jar"); 
            URL[] urls = new URL[]{ url }; 
            URLClassLoader loader = new URLClassLoader(urls); 
            Class c = loader.loadClass("image.Buddy"); 
            Object o = c.newInstance(); 
            Method m = c.getMethod("sleep"); 
            m.invoke(o);
 
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (MalfORMedURLException e) {
            e.printStackTrace();
        }
    }
}

package loadjarclass;
import java.io.File;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import org.junit.Test;
public class LoadJarClassTest {
 
 @Test
 public void testLoadClass() throws Exception{
  
  File file=new File("D:/test");//类路径(包文件上一层)
  URL url=file.toURI().toURL();
  ClassLoader loader=new URLClassLoader(new URL[]{url});//创建类载入器
  //import com.sun.org.apache.bcel.internal.util.ClassLoader;
  //ClassLoader classLoader = new ClassLoader(new String[]{""});//类路径
  Class<?> cls=loader.loadClass("loadjarclass.TestTest");//载入指定类。注意一定要带上类的包名
  Object obj=cls.newInstance();//初始化一个实例
  Method method=cls.getMethod("printString",String.class,String.class);//方法名和相应的參数类型
  Object o=method.invoke(obj,"chen","leixing");//调用得到的上边的方法method
  System.out.println(String.valueOf(o));//输出"chenleixing"
  
  
  file=new File("D:/test/commons-lang3.jar");//jar包的路径
  url=file.toURI().toURL();
  loader=new URLClassLoader(new URL[]{url});//创建类载入器
  cls=loader.loadClass("org.apache.commons.lang3.StringUtils");//载入指定类，注意一定要带上类的包名
  method=cls.getMethod("center",String.class,int.class,String.class);//方法名和相应的各个參数的类型
  o=method.invoke(null,"chen",Integer.valueOf(10),"0");//调用得到的上边的方法method(静态方法，第一个參数能够为null)
  System.out.println(String.valueOf(o));//输出"000chen000","chen"字符串两边各加3个"0"字符串
 }
}