自定义ClassLoader加载class文件

package com.yd.wmsc.util;

public class Test {
public void say(){
            System.out.println("Say Hello");
        }
}

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;


public class DiskClassLoader extends ClassLoader {

private String mLibPath;

public DiskClassLoader(String path) {
// TODO Auto-generated constructor stub
        mLibPath = path;
    }

    @Override
protected Class<?> findClass(String name) throws ClassNotFoundException {
// TODO Auto-generated method stub

        String fileName = getFileName(name);

        File file = new File(mLibPath,fileName);

try {
            FileInputStream is = new FileInputStream(file);

            ByteArrayOutputStream bos = new ByteArrayOutputStream();
int len = 0;
try {
while ((len = is.read()) != -1) {
                    bos.write(len);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

byte[] data = bos.toByteArray();
            is.close();
            bos.close();

return defineClass(name,data,0,data.length);

        } catch (IOException e) {
// TODO Auto-generated catch block
            e.printStackTrace();
        }

return super.findClass(name);
    }

//获取要加载 的class文件名
private String getFileName(String name) {
// TODO Auto-generated method stub
int index = name.lastIndexOf('.');
if(index == -1){ 
return name+".class";
        }else{
return name.substring(index+1)+".class";
        }
    }
}

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class ClassLoaderTest {

public static void main(String[] args) {
// TODO Auto-generated method stub
//创建自定义classloader对象。
        DiskClassLoader diskLoader = new DiskClassLoader("D:\\");
try {
//加载class文件
            Class c = diskLoader.loadClass("com.yd.wmsc.util.Test");
if(c != null){
try {
                    Object obj = c.newInstance();
                    Method method = c.getDeclaredMethod("say",null);
//通过反射调用Test类的say方法
                    method.invoke(obj, null);
                } catch (InstantiationException | IllegalAccessException 
| NoSuchMethodException
| SecurityException | 
                        IllegalArgumentException | 
                        InvocationTargetException e) {
// TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        } catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}