private int iOld = -1; 
        private void listView1_ItemSelectionChanged(object sender, ListViewItemSelectionChangedEventArgs e)
        {
            if (listView1.SelectedIndices.Count > 0) //若有选中项 
            {
                if (iOld == -1)
                {
                    listView1.Items[listView1.SelectedIndices[0]].BackColor = Color.FromArgb(49, 106, 197); //设置选中项的背景颜色 
                    iOld = listView1.SelectedIndices[0]; //设置当前选中项索引 
                }
                else
                {
                    if (listView1.SelectedIndices[0] != iOld)
                    {
                        listView1.Items[listView1.SelectedIndices[0]].BackColor = Color.FromArgb(49, 106, 197); //设置选中项的背景颜色 
                        listView1.Items[iOld].BackColor = Color.FromArgb(239, 248, 250); //恢复默认背景色 
                        iOld = listView1.SelectedIndices[0]; //设置当前选中项索引 
                    }
                }
            }
            else //若无选中项 
            {
                listView1.Items[iOld].BackColor = Color.FromArgb(239, 248, 250); //恢复默认背景色 
                iOld = -1; //设置当前处于无选中项状态 
            } 
        }