java.lang.class学习2--获取构造方法的过程,

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    private Constructor<T> getConstructor0(Class[] parameterTypes,                                        int which) throws NoSuchMethodException    {        Constructor[] constructors = privateGetDeclaredConstructors((which == Member.PUBLIC)); //获取public的构造方法        for (int i = 0; i < constructors.length; i++) {            if (arrayContentsEq(parameterTypes,                                constructors[i].getParameterTypes())) {                return getReflectionFactory().copyConstructor(constructors[i]); //返回构造方法的对象            }        }        throw new NoSuchMethodException(getName() + ".<init>" + argumentTypesToString(parameterTypes));    }    //    // Other helpers and base implementation    //    private static boolean arrayContentsEq(Object[] a1, Object[] a2) {        if (a1 == null) {//比较构造方法的参数            return a2 == null || a2.length == 0;        }        if (a2 == null) {            return a1.length == 0;        }        if (a1.length != a2.length) {            return false;        }        for (int i = 0; i < a1.length; i++) {            if (a1[i] != a2[i]) {                return false;            }        }        return true;    } //    //    // java.lang.reflect.Constructor handling    //    //    // Returns an array of "root" constructors. These Constructor    // objects must NOT be propagated to the outside world, but must    // instead be copied via ReflectionFactory.copyConstructor.    private Constructor[] privateGetDeclaredConstructors(boolean publicOnly) {        checkInitted();        Constructor[] res = null;        if (useCaches) {            clearCachesOnClassRedefinition();            if (publicOnly) {                if (publicConstructors != null) {                    res = (Constructor[]) publicConstructors.get();                }            } else {                if (declaredConstructors != null) {                    res = (Constructor[]) declaredConstructors.get();                }            }            if (res != null) return res;        }        // No cached value available; request value from VM        if (isInterface()) {            res = new Constructor[0];        } else {            res = getDeclaredConstructors0(publicOnly); //本地方法，获取声明的构造方法        }        if (useCaches) {            if (publicOnly) {                publicConstructors = new SoftReference(res);            } else {                declaredConstructors = new SoftReference(res);            }        }        return res;    }