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自定义类加载器com.mashibing.jvm.c2_classloader.T011_ClassReloading1 和 T012_ClassReloading2
打破双亲委派机制的方法 1, 重写loadClass()有的结论有问题，当然也跟自定义加载器有关，跟楼上的问题的bug2类似：
T011_ClassReloading1 -> 在只重写findClass方法的基础上，多次调用msbClassLoader.loadClass("com.mashibing.jvm.Hello")方法，因为Hello这个类是被APPClassLoader加载过的，所以不管调用多少次msbClassLoader.loadClass方法，返回的Class都是同一个，而如果调用的是一个全新的、从未被任何加载器加载过的class，结论就不一样了，调用两次msbClassLoader.loadClass方法，如果两次中间不把msbClassLoader重新new，则loadClass返回的class是同一个，如果重新new了，那么两次的load结果返回的Class是不同的；
T012_ClassReloading2 -> 在重写loadClass的基础上，第一次调用m.loadClass("com.mashibing.jvm.Hello")会重新覆盖掉APPClassLoader加载的Hello.class，此时的Hello的加载器会变为m，而m 重新new之后在loadClass，将会再次覆盖，这种情况下，无论被加载的类是否被任何的加载器加载过，只要是新new 的m，调用m.loadClass，都会重新加载一次，重新加载的和之前的class不一样。
总结，在只重写findClass基础上，如果加载的从未加载过的class，同一个加载器加载多少次，返回值都是一个，new的加载器加载的是不同的；在重写loadClass的基础上，同一个加载器加载多少次都是新的，新new的加载器，每次new，每次load都会产生不同的class
自定义类加载器com.mashibing.jvm.c2_classloader.T006_MSBClassLoader
BUG说明:
1.这里读取class文件时,判断条件应该是while ((b = fis.read()) != -1),而不是!=0
2.这里没报错是因为根本没用到自定义的findClass,项目中已经存在的类直接由Launcher$AppClassLoader加载出来了
顺便提两个问题:
1.因为不在项目空间的class才会用到自定义加载器,那么没有类的格式,怎么使用它啊?
2.为啥自定义的类加载器,走自己的findClass或者由AppClassLoader加载时,不会执行被加载类的静态代码块中的打印命令呢?
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