package clazz; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.nio.ByteBuffer; import java.nio.channels.FileChannel; public class MyClassLoader extends ClassLoader{ // @Override // public Class> loadClass(String name) throws ClassNotFoundException { // return findClass(name); // } @Override public Class> findClass(String name) throws ClassNotFoundException { String classPath = MyClassLoader.class.getResource("/").getPath(); //得到classpath String fileName = name.replace(".", "/") + ".class" ; File classFile = new File(classPath , fileName); if(!classFile.exists()){ throw new ClassNotFoundException(classFile.getPath() + " 不存在") ; } ByteArrayOutputStream bos = new ByteArrayOutputStream() ; ByteBuffer bf = ByteBuffer.allocate(1024) ; FileInputStream fis = null ; FileChannel fc = null ; try { fis = new FileInputStream(classFile) ; fc = fis.getChannel() ; while(fc.read(bf) > 0){ bf.flip() ; bos.write(bf.array(),0 , bf.limit()) ; bf.clear() ; } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }finally{ try { fis.close() ; fc.close() ; } catch (IOException e) { e.printStackTrace(); } } byte[] bytes = bos.toByteArray(); return defineClass(name, bytes, 0, bytes.length); } }