java类重载，可以用于热更新

package test; import java.io.ByteArrayOutputStream; import java.io.InputStream; import java.net.URL; import java.net.URLConnection; public class MyClassLoader extends ClassLoader{ public MyClassLoader(ClassLoader parent) { super(parent); } public Class loadClass(String name) throws ClassNotFoundException { if(!"test.MyObject".equals(name)) return super.loadClass(name); try { String url = "file:C:\\Users\\Admin\\Desktop\\javaCode\\reloadTest\\bin\\test\\MyObject.class"; URL myUrl = new URL(url); URLConnection connection = myUrl.openConnection(); InputStream input = connection.getInputStream(); ByteArrayOutputStream buffer = new ByteArrayOutputStream(); int data = input.read(); while(data != -1){ buffer.write(data); data = input.read(); } input.close(); byte[] classData = buffer.toByteArray(); return defineClass("test.MyObject", classData, 0, classData.length); } catch (Exception e) { e.printStackTrace(); } return null; } public static void main(String[] args) throws Exception { ClassLoader parentClassLoader = MyClassLoader.class.getClassLoader(); MyClassLoader classLoader = new MyClassLoader(parentClassLoader); Class myObjectClass = classLoader.loadClass("test.MyObject"); Object object1 = myObjectClass.newInstance(); classLoader = new MyClassLoader(parentClassLoader); myObjectClass = classLoader.loadClass("test.MyObject"); object1 = myObjectClass.newInstance(); } }