cocos2dx UserDefault 和 LocalStorage 比较

[zhishu520]

cocos 有两种本地存储方式， 一种是UserDefault 另一种是 LocalStorage。 其中UserDefault是基于xml， 而LocalStorage 是基于的sqlite。 至于为什么要搞出两套方案，应该是jsb没办法去使用UserDefault，只能用LocalStorage。

对于使用层面上来说，两者其实拿到的都是字符串类型，然后需要根据自己的需要去进行转换成想要的数据类型，UserDefault封装了几种常用的类型，而LocalStorage是没有封装的.

最后欣赏一下代码

UserDefault 的 字符串 数据的存储读取

string UserDefault::getStringForKey(const char* pKey, const std::string & defaultValue)
{
    const char* value = nullptr;
    tinyxml2::XMLElement* rootNode;
    tinyxml2::XMLDocument* doc;
    tinyxml2::XMLElement* node;
    node =  getXMLNodeForKey(pKey, &rootNode, &doc);
    // find the node
    if (node && node->FirstChild())
    {
        value = (const char*)(node->FirstChild()->Value());
    }

    string ret = defaultValue;

    if (value)
    {
        ret = string(value);
    }

    if (doc) delete doc;

    return ret;
}

static void setValueForKey(const char* pKey, const char* pValue)
{
     tinyxml2::XMLElement* rootNode;
    tinyxml2::XMLDocument* doc;
    tinyxml2::XMLElement* node;
    // check the params
    if (! pKey || ! pValue)
    {
        return;
    }
    // find the node
    node = getXMLNodeForKey(pKey, &rootNode, &doc);
    // if node exist, change the content
    if (node)
    {
        if (node->FirstChild())
        {
            node->FirstChild()->SetValue(pValue);
        }
        else
        {
            tinyxml2::XMLText* content = doc->NewText(pValue);
            node->LinkEndChild(content);
        }
    }
    else
    {
        if (rootNode)
        {
            tinyxml2::XMLElement* tmpNode = doc->NewElement(pKey);//new tinyxml2::XMLElement(pKey);
            rootNode->LinkEndChild(tmpNode);
            tinyxml2::XMLText* content = doc->NewText(pValue);//new tinyxml2::XMLText(pValue);
            tmpNode->LinkEndChild(content);
        }    
    }

    // save file and free doc
    if (doc)
    {
        doc->SaveFile(FileUtils::getInstance()->getSuitableFOpen(UserDefault::getInstance()->getXMLFilePath()).c_str());
        delete doc;
    }
}

LocalStorage 的存储与读取

/** sets an item in the LS */
void localStorageSetItem( const std::string& key, const std::string& value)
{
    assert( _initialized );

    int ok = sqlite3_bind_text(_stmt_update, 1, key.c_str(), -1, SQLITE_TRANSIENT);
    ok |= sqlite3_bind_text(_stmt_update, 2, value.c_str(), -1, SQLITE_TRANSIENT);

    ok |= sqlite3_step(_stmt_update);

    ok |= sqlite3_reset(_stmt_update);

    if (ok != SQLITE_OK && ok != SQLITE_DONE)
        printf("Error in localStorage.setItem()\n");
}

/** gets an item from the LS */
bool localStorageGetItem( const std::string& key, std::string *outItem )
{
    assert( _initialized );

    int ok = sqlite3_reset(_stmt_select);

    ok |= sqlite3_bind_text(_stmt_select, 1, key.c_str(), -1, SQLITE_TRANSIENT);
    ok |= sqlite3_step(_stmt_select);
    const unsigned char *text = sqlite3_column_text(_stmt_select, 0);

    if (ok != SQLITE_OK && ok != SQLITE_DONE && ok != SQLITE_ROW)
    {
        printf("Error in localStorage.getItem()\n");
        return false;
    }
    else if (!text)
    {
        return false;
    }
    else
    {
        outItem->assign((const char*)text);
        return true;
    }
}