ClassUtils.forName()学习知识点

spring源码解读时，在createWebApplicationContext时，需要对获取的contextClassName进行ClassUtils.forName(String name, ClassLoader classLoander)进行了分析

ClassUtils.forName

    public static Class<?> forName(String name, ClassLoader classLoader) throws ClassNotFoundException, LinkageError {
        Assert.notNull(name, "Name must not be null");

        Class<?> clazz = resolvePrimitiveClassName(name);
        if (clazz == null) {
            clazz = commonClassCache.get(name);
        }
        if (clazz != null) {
            return clazz;
        }

        // "java.lang.String[]" style arrays
        if (name.endsWith(ARRAY_SUFFIX)) {
            String elementClassName = name.substring(0, name.length() - ARRAY_SUFFIX.length());
            Class<?> elementClass = forName(elementClassName, classLoader);
            return Array.newInstance(elementClass, 0).getClass();
        }

        // "[Ljava.lang.String;" style arrays
        if (name.startsWith(NON_PRIMITIVE_ARRAY_PREFIX) && name.endsWith(";")) {
            String elementName = name.substring(NON_PRIMITIVE_ARRAY_PREFIX.length(), name.length() - 1);
            Class<?> elementClass = forName(elementName, classLoader);
            return Array.newInstance(elementClass, 0).getClass();
        }

        // "[[I" or "[[Ljava.lang.String;" style arrays
        if (name.startsWith(INTERNAL_ARRAY_PREFIX)) {
            String elementName = name.substring(INTERNAL_ARRAY_PREFIX.length());
            Class<?> elementClass = forName(elementName, classLoader);
            return Array.newInstance(elementClass, 0).getClass();
        }

        ClassLoader clToUse = classLoader;
        if (clToUse == null) {
            clToUse = getDefaultClassLoader();
        }
        try {
            return (clToUse != null ? clToUse.loadClass(name) : Class.forName(name));
        }
        catch (ClassNotFoundException ex) {
            int lastDotIndex = name.lastIndexOf(PACKAGE_SEPARATOR);
            if (lastDotIndex != -1) {
                String innerClassName =
                        name.substring(0, lastDotIndex) + INNER_CLASS_SEPARATOR + name.substring(lastDotIndex + 1);
                try {
                    return (clToUse != null ? clToUse.loadClass(innerClassName) : Class.forName(innerClassName));
                }
                catch (ClassNotFoundException ex2) {
                    // Swallow - let original exception get through
                }
            }
            throw ex;
        }
    }

是时候就会有一个ClassLoader 类加载器，类加载器详解请看链接

他充ClassLoader 加载，