TextView在xml文件中加入onClick属性后，clickable值依旧是false的原因。

                case com.android.internal.R.styleable.View_clickable:
                    if (a.getBoolean(attr, false)) {
                        viewFlagValues |= CLICKABLE;
                        viewFlagMasks |= CLICKABLE;
                    }
                    break;

                case R.styleable.View_onClick:
                    if (context.isRestricted()) {
                        throw new IllegalStateException("The android:onClick attribute cannot "
                                + "be used within a restricted context");
                    }

                    final String handlerName = a.getString(attr);
                    if (handlerName != null) {
                        setOnClickListener(new OnClickListener() {
                            private Method mHandler;

                            public void onClick(View v) {
                                if (mHandler == null) {
                                    try {
                                        mHandler = getContext().getClass().getMethod(handlerName,
                                                View.class);
                                    } catch (NoSuchMethodException e) {
                                        int id = getId();
                                        String idText = id == NO_ID ? "" : " with id ‘"
                                                + getContext().getResources().getResourceEntryName(
                                                    id) + "‘";
                                        throw new IllegalStateException("Could not find a method " +
                                                handlerName + "(View) in the activity "
                                                + getContext().getClass() + " for onClick handler"
                                                + " on view " + View.this.getClass() + idText, e);
                                    }
                                }

                                try {
                                    mHandler.invoke(getContext(), View.this);
                                } catch (IllegalAccessException e) {
                                    throw new IllegalStateException("Could not execute non "
                                            + "public method of the activity", e);
                                } catch (InvocationTargetException e) {
                                    throw new IllegalStateException("Could not execute "
                                            + "method of the activity", e);
                                }
                            }
                        });
                    }
                    break;

    /**
     * Register a callback to be invoked when this view is clicked. If this view is not
     * clickable, it becomes clickable.
     *
     * @param l The callback that will run
     *
     * @see #setClickable(boolean)
     */
    public void setOnClickListener(OnClickListener l) {
        if (!isClickable()) {
            setClickable(true);
        }
        getListenerInfo().mOnClickListener = l;
    }

        boolean focusable = mMovement != null || getKeyListener() != null;
        boolean clickable = focusable;
        boolean lOngClickable= focusable;

        n = a.getIndexCount();
        for (int i = 0; i ) {
            int attr = a.getIndex(i);

            switch (attr) {
            case com.android.internal.R.styleable.View_focusable:
                focusable = a.getBoolean(attr, focusable);
                break;

            case com.android.internal.R.styleable.View_clickable:
                clickable = a.getBoolean(attr, clickable);
                break;

            case com.android.internal.R.styleable.View_longClickable:
                longClickable = a.getBoolean(attr, longClickable);
                break;
            }
        }