自定义类加载器一 -优快云博客

本文介绍了一种自定义ClassLoader的实现方式，通过继承ClassLoader并覆盖findClass方法来动态加载类。该实现还包含了获取包名的功能及类数据的抽象加载过程。

package com.yuan.common.asm;

public abstract class AbstractClassLoader extends ClassLoader {

    public AbstractClassLoader(ClassLoader parent){
        super(parent);
    }

    protected String getPackageName(String className){
        String packageName = "";
        int index = className.lastIndexOf(".");
        if(index != -1){
            packageName = className.substring(0, index);
        }
        return packageName;
    }

    protected Class<?> findClass(String name)throws ClassNotFoundException{
        String packageName = getPackageName(name);
        if(super.getPackage(packageName) == null){
            super.definePackage(packageName, packageName, "1.0", "hx", packageName, "1.0", "hx", null);
        }
        try {
            return this.getParent().loadClass(name);
        } catch (Exception e) {
            byte[] b = loadClassData(name);
            return defineClass(name, b, 0, b.length);
        }

    }

    protected abstract byte[] loadClassData(String name) throws ClassNotFoundException;

}