//设置字符串类型的本地缓存
function setStorage(objName, objValue){
    var sto = window.localStorage;
    if (sto) 
        sto.setItem(objName, objValue);
}
 //读取字符串类型的本地缓存
function getStorage(objName){
    var ret = '';
    var sto = window.localStorage;
    if (sto) 
        ret = sto.getItem(objName);
    return ret;
}

//清除本地缓存，如没指定名称则为清空所有缓存
function clearStorage(objName){ 
    var sto = window.localStorage;
    if (sto) {
        if (objName) 
            sto.removeItem(objName);
        else 
            sto.clear();
    }
}
//设置Json类型的本地缓存
function setStorJson(objName, json){ 
    if (json) 
        setStorage(objName, JSON.stringify(json));
}
//读取Json类型的本地缓存
function getStorJson(objName){ 
    var ret = null;
    var str = getStorage(objName);
    if (str) 
        ret = JSON.parse(str);
    return ret;
}