plus.cache.clear实现白名单效果保存localStorage

实现方法很简单，使用前把所有localStorage的key和值存储到两个数组，plus.cache.clear清除完成后利用循环重新写入即可

function plusReady() {  
    var key = []  
    var key_ = []  
    for (let i = 0; i < localStorage.length; i++) {  
        key.push(localStorage.key(i))  //获取所有localStorage的key  
        key_.push(localStorage.getItem(localStorage.key(i)))  //获取所有localStorage的值  
        length = localStorage.length  //获取所有localStorage数量  
        if (i == localStorage.length - 1) {  
            plus.nativeUI.confirm("确定清除缓存数据？", function (e) {  
                if (e.index == 0) {  
                    plus.cache.clear(function () { });//清除缓存  
                    plus.nativeUI.toast('已清除缓存');  
                    for (let a = 0; a < length; a++) {  
                        localStorage.setItem(key[a], key_[a])  //清除完毕后利用重新写入localStorage  
                    }  
                }  
            }, "清除缓存数据", ["确定", "取消"]);  
        }  
    }  
}  
if (window.plus) {  
    plusReady();  
} else {  
    document.addEventListener('plusready', plusReady, false);  
}