实现 TabLayout 下标与文字等长，选中字体大小改变

android 使用系统TabLayout 实现 下标与文字等长效果

android 使用系统TabLayout 实现改变Tab选中状态样式

void setTabLyout(){
        setTabPadding(tablayout,resetMeasureW(7));
        tablayout.addOnTabSelectedListener(onTabSelectedListener);
}

TabLayout.OnTabSelectedListener onTabSelectedListener = new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            setTabSelect(tab);
        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {
            tab.setCustomView(null);
        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {

        }
    };

void setTabSelect(TabLayout.Tab tab) { //设置选中后显示的布局
        TextView textView = new TextView(getActivity());
        textView.setTextSize(18);
        textView.setGravity(Gravity.CENTER);
        textView.setTextColor(getResources().getColor(R.color.bgf_textred));
        textView.setText(tab.getText());
        TextPaint tp = textView.getPaint();
        tp.setFakeBoldText(true);
        tab.setCustomView(textView);
    }

 /**
     * 动态计算文字宽度设置指示器宽度
     * @param tabLayout
     * @param padding 相邻tab的间距
     */
    public static void setTabPadding(final TabLayout tabLayout, final int padding) {
        tabLayout.post(new Runnable() {
            @Override
            public void run() {
                //拿到tabLayout的mTabStrip属性
                LinearLayout mTabStrip = (LinearLayout) tabLayout.getChildAt(0);
                for (int i = 0; i < mTabStrip.getChildCount(); i++) {
                    View tabView = mTabStrip.getChildAt(i);
                    //拿到tabView的mTextView属性  tab的字数不固定一定用反射取mTextView
                    tabView.setPadding(0, 0, 0, 0);
                    //设置tab左右间距 注意这里不能使用Padding 因为源码中线的宽度是根据 tabView的宽度来设置的
                    LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) tabView.getLayoutParams();
                    params.width = LinearLayout.LayoutParams.WRAP_CONTENT;
                    params.leftMargin = padding;
                    params.rightMargin = padding;
                    tabView.setLayoutParams(params);
                    tabView.invalidate();
                }
            }
        });

    }

  /**
     * 按750设计图 比例 获取实际宽度
     */
    public static int resetMeasureW(int w) {
        int screenWidth = getScreenWidth(getApplication());
        double mW = w * screenWidth / 375.0;

        return (int) mW;
    }
//屏幕分辨率
    public static DisplayMetrics getDisplayMetrics(Context context) {
        return context.getResources().getDisplayMetrics();
    }
  //屏幕宽度
    public static int getScreenWidth(Context context) {
        return getDisplayMetrics(context).widthPixels;
    }