我们反射通常使用第一种方式,首先来看看Class.forName(clssName):
注意：传入的className必须是类的全路径,否则会报错java.lang.ClassNotFoundException。
public static Class<?> forName(String className)
throws ClassNotFoundException {
return forName0(className, true, ClassLoader.getCallerClassLoader());
}
通过调用forName0方法，使用ClassLoader.getCallerClassLoader()来加载ClassLoader
// Returns the invoker's class loader, or null if none.
// NOTE: This must always be invoked when there is exactly one intervening
// frame from the core libraries on the stack between this method's
// invocation and the desired invoker.
static ClassLoader getCallerClassLoader() {
// NOTE use of more generic Reflection.getCallerClass()
Class caller = Reflection.getCallerClass(3);
// This can be null if the VM is requesting it
if (caller == null) {
return null;
}
// Circumvent security check since this is package-private
return caller.getClassLoader0();
}
在获取ClassLoader调用claser.getClassLoader0() 这是一个私有包，可以避免安全检查。
// Package-private to allow ClassLoader access
native ClassLoader getClassLoader0();
