类加载双亲委派机制问题

Question

protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException { synchronized (getClassLoadingLock(name)) { // First, check if the class has already been loaded /*第一先判断这个类有没有被加载过 如果加载过，返回该类的Class对象
没有加载过返回 null
*/
Class<?> c = findLoadedClass(name);
//如果这个类没有加载过
if (c == null) {
long t0 = System.nanoTime();
try {
//先看父类加载器可不可以加载，parent == null代表着使用根类加载器加载
if (parent != null) {
c = parent.loadClass(name, false);
} else {
c = findBootstrapClassOrNull(name);
}
} catch (ClassNotFoundException e) {
// ClassNotFoundException thrown if class not found
// from the non-null parent class loader
}
//如果父类加载器加载不了，再用本类加载器加载
if (c == null) {
// If still not found, then invoke findClass in order
// to find the class.
long t1 = System.nanoTime();
c = findClass(name);

                // this is the defining class loader; record the stats
                sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0);
                sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
                sun.misc.PerfCounter.getFindClasses().increment();
            }
        }
        //resolve为true进行类加载链接操作，反之不进行
        if (resolve) {
            resolveClass(c);
        }
        return c;
    }
}

有个疑惑，问一下loadClass这个方法可以看出向上委托，是在哪一行代码体现出来了向下查找的？或者说没有缓存，真正加载的动作是在哪一行代码提现的，有谁可以解释一下吗？

Answer 1

向上委托，父类无法加载则抛出异常并子类捕获执行，依次递归，直至找到并加载