Android应用双击返回键退出

@Override
    public void onBackPressed() {
        // TODO 退出提示
        if (System.currentTimeMillis() - mExitTime > 1000) {
            if (mDrawerLayout.isDrawerOpen(GravityCompat.START)) {
                mDrawerLayout.closeDrawer(GravityCompat.START);
            }
            //点击间隔大于2s
            Toast.makeText(this, getResources().getString(R.string.exit_app), Toast.LENGTH_SHORT).show();
            mExitTime = System.currentTimeMillis();
        } else {
            //连续点击2次退出应用
            finish();
        }
        return;
    }