android设置tablayout下划线长度代码

设置tablayout下划线长度的方法（android.support.design.widget.TabLayout）

public static void setIndicator(Context context, TabLayout tabs, int leftDip, int rightDip) {
    Class<?> tabLayout = tabs.getClass();
    Field tabStrip = null;
    try {
        tabStrip = tabLayout.getDeclaredField("mTabStrip");
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    }
    tabStrip.setAccessible(true);
    LinearLayout ll_tab = null;
    try {
        ll_tab = (LinearLayout) tabStrip.get(tabs);
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }
    int left = (int) (getDisplayMetrics(context).density * leftDip);
    int right = (int) (getDisplayMetrics(context).density * rightDip);
    for (int i = 0; i < ll_tab.getChildCount(); i++) {
        View child = ll_tab.getChildAt(i);
        child.setPadding(0, 0, 0, 0);
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(0, LinearLayout.LayoutParams.MATCH_PARENT, 1);
        params.leftMargin = left;
        params.rightMargin = right;
        child.setLayoutParams(params);
        child.invalidate();
    }
}
public static DisplayMetrics getDisplayMetrics(Context context) {
    DisplayMetrics metric = new DisplayMetrics();
    ((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(metric);
    return metric;
}
public static float getPXfromDP(float value, Context context) {
    return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, value,
            context.getResources().getDisplayMetrics());
}
调用方式，在你的activity里面

tab_title = (TabLayout) findViewById(R.id.tab_fragment_title);
tab_title.post(new Runnable() {
    @Override
    public void run() {
       setIndicator(PigTallyActivity.this,tab_title,50,50);
    }
});