classloaderdemo.java

有关java学习技巧的课件

import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;

public class ClassLoaderDemo {
    public static void main(String[] args) {
        try {
            // 测试路径
            String classPath = args[0];
            // 测试类
            String className = args[1];

            URL url1 = new URL(classPath);
            // 建立ClassLoader
            ClassLoader loader1 = 
                      new URLClassLoader(new URL[] {url1});
            // 加载指定类
            Class c1 = loader1.loadClass(className);
            // 显示类描述
            System.out.println(c1);
        
            URL url2 = new URL(classPath);
            ClassLoader loader2 = 
                      new URLClassLoader(new URL[] {url2});
            Class c2 = loader2.loadClass(className);
        
            System.out.println(c2);
        
            System.out.println("c1 与 c1 为同一实例？" 
                                     + (c1 == c2));
        }
        catch(ArrayIndexOutOfBoundsException e) {
            System.out.println("没有指定类加载路径与名称");
        }
        catch(MalformedURLException e) {
            System.out.println("加载路径错误");
        }
        catch(ClassNotFoundException e) {
            System.out.println("找不到指定的类");
        }
    }
}