类似于文件夹的展开和折叠

if ($(img).attr("src").indexOf("minus.gif") > -1)
{
isNeedCollapse=true;
$(img).attr("src","/omsys2/html/style/default/images/plus.gif");
}
else if ($(img).attr("src").indexOf("plus.gif") > -1)
{
isNeedCollapse = false;
$(img).attr("src","/omsys2/html/style/default/images/minus.gif");
}