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序言
在開(kāi)發(fā)的過(guò)程中，我們會(huì)遇到這樣的一些需求：
- 用戶注冊(cè)完賬號(hào)(如：UserAccount)，在下次登錄的時(shí)候，能夠默認(rèn)顯示該登錄的賬戶
- 用戶設(shè)置了禁止音效、禁止背景音樂(lè)等內(nèi)容，在下次登錄的時(shí)候，希望能夠保持設(shè)置
于是，在開(kāi)發(fā)的過(guò)程中，我們將這一類(lèi)需求，抽象成：
本地?cái)?shù)據(jù)存儲(chǔ)功能
Cocos2dx+Lua引擎中的UserDefault類(lèi)，就為我們實(shí)現(xiàn)了其中一類(lèi)數(shù)據(jù)的存儲(chǔ)。
UserDefault 類(lèi)詳解
下面，將圍繞2點(diǎn)進(jìn)行展開(kāi)：
- UserDefault類(lèi)的功能；
- UserDefault類(lèi)的定義與實(shí)現(xiàn)；
功能
-
UserDefault 類(lèi)在本地（指手機(jī)writable path下）創(chuàng)建一個(gè)
UserDefault.xml文件，來(lái)作為存儲(chǔ)的數(shù)據(jù)庫(kù)。 -
UserDefault.xml可以存儲(chǔ)以下的數(shù)據(jù)類(lèi)型：布爾類(lèi)型、整型、單精度浮點(diǎn)型、雙精度浮點(diǎn)型、字符串類(lèi)型、Data類(lèi)型。 - UserDefault 提供了字符串為關(guān)鍵字的寫(xiě)入和讀取的API接口。
類(lèi)定義與實(shí)現(xiàn)
類(lèi)的定義
頭文件UserDefault.h如下:
#ifndef __SUPPORT_CCUSERDEFAULT_H__
#define __SUPPORT_CCUSERDEFAULT_H__
#include "platform/CCPlatformMacros.h"
#include <string>
#include "base/CCData.h"
/**
* @addtogroup base
* @{
*/
NS_CC_BEGIN
/**
* UserDefault acts as a tiny database. You can save and get base type values by it.
* For example, setBoolForKey("played", true) will add a bool value true into the database.
* Its key is "played". You can get the value of the key by getBoolForKey("played").
*
* It supports the following base types:
* bool, int, float, double, string
*/
class CC_DLL UserDefault
{
public:
// get value methods
/**
* Get bool value by key, if the key doesn't exist, will return false.
* You can set the default value, or it is false.
* @param key The key to get value.
* @return Bool value by `key`.
* @js NA
*/
bool getBoolForKey(const char* key);
/**
* Get bool value by key, if the key doesn't exist, will return passed default value.
* @param key The key to get value.
* @param defaultValue The default value to return if the key doesn't exist.
* @js NA
*/
virtual bool getBoolForKey(const char* key, bool defaultValue);
/**
* Get integer value by key, if the key doesn't exist, will return 0.
* You can set the default value, or it is 0.
* @param key The key to get value.
* @return Integer value of the key.
* @js NA
*/
int getIntegerForKey(const char* key);
/**
* Get bool value by key, if the key doesn't exist, will return passed default value.
* @param key The key to get value.
* @param defaultValue The default value to return if the key doesn't exist.
* @return Integer value of the key.
* @js NA
*/
virtual int getIntegerForKey(const char* key, int defaultValue);
/**
* Get float value by key, if the key doesn't exist, will return 0.0.
* @param key The key to get value.
* @return Float value of the key.
* @js NA
*/
float getFloatForKey(const char* key);
/**
* Get float value by key, if the key doesn't exist, will return passed default value.
* @param key The key to get value.
* @param defaultValue The default value to return if the key doesn't exist.
* @return Float value of the key.
* @js NA
*/
virtual float getFloatForKey(const char* key, float defaultValue);
/**
* Get double value by key, if the key doesn't exist, will return 0.0.
* @param key The key to get value.
* @return Double value of the key.
* @js NA
*/
double getDoubleForKey(const char* key);
/**
* Get double value by key, if the key doesn't exist, will return passed default value.
* @param key The key to get value.
* @param defaultValue The default value to return if the key doesn't exist.
* @return Double value of the key.
* @js NA
*/
virtual double getDoubleForKey(const char* key, double defaultValue);
/**
* Get string value by key, if the key doesn't exist, will return an empty string.
* @param key The key to get value.
* @return String value of the key.
* @js NA
*/
std::string getStringForKey(const char* key);
/**
* Get string value by key, if the key doesn't exist, will return passed default value.
* @param key The key to get value.
* @param defaultValue The default value to return if the key doesn't exist.
* @return String value of the key.
* @js NA
*/
virtual std::string getStringForKey(const char* key, const std::string & defaultValue);
/**
* Get Data value by key, if the key doesn't exist, will return an empty Data.
* @param key The key to get value.
* @return Data value of the key.
* @js NA
*/
Data getDataForKey(const char* key);
/**
* Get Data value by key, if the key doesn't exist, will return an empty Data.
* @param key The key to get value.
* @param defaultValue The default value to return if the key doesn't exist.
* @return Data value of the key.
* @js NA
*/
virtual Data getDataForKey(const char* key, const Data& defaultValue);
// set value methods
/**
* Set bool value by key.
* @param key The key to set.
* @param value A bool value to set to the key.
* @js NA
*/
virtual void setBoolForKey(const char* key, bool value);
/**
* Set integer value by key.
* @param key The key to set.
* @param value A integer value to set to the key.
* @js NA
*/
virtual void setIntegerForKey(const char* key, int value);
/**
* Set float value by key.
* @param key The key to set.
* @param value A float value to set to the key.
* @js NA
*/
virtual void setFloatForKey(const char* key, float value);
/**
* Set double value by key.
* @param key The key to set.
* @param value A double value to set to the key.
* @js NA
*/
virtual void setDoubleForKey(const char* key, double value);
/**
* Set string value by key.
* @param key The key to set.
* @param value A string value to set to the key.
* @js NA
*/
virtual void setStringForKey(const char* key, const std::string & value);
/**
* Set Data value by key.
* @param key The key to set.
* @param value A Data value to set to the key.
* @js NA
*/
virtual void setDataForKey(const char* key, const Data& value);
/**
* You should invoke this function to save values set by setXXXForKey().
* @js NA
*/
virtual void flush();
/**
* delete any value by key,
* @param key The key to delete value.
* @js NA
*/
virtual void deleteValueForKey(const char* key);
/** Returns the singleton.
* @js NA
* @lua NA
*/
static UserDefault* getInstance();
/**
* @js NA
*/
static void destroyInstance();
/**
* You can inherit from platform dependent implementation of UserDefault, such as UserDefaultAndroid,
* and use this function to set delegate, then UserDefault will invoke delegate's implementation.
* For example, your store native data base or other format store.
*
* If you don't want to system default implementation after setting delegate, you can just pass nullptr
* to this function.
*
* @warning It will delete previous delegate
*/
static void setDelegate(UserDefault *delegate);
/** @deprecated Use getInstace() instead.
* @js NA
* @lua NA
*/
CC_DEPRECATED_ATTRIBUTE static UserDefault* sharedUserDefault();
/**@deprecated Use destroyInstance() instead.
* @js NA
*/
CC_DEPRECATED_ATTRIBUTE static void purgeSharedUserDefault();
/** All supported platforms other iOS & Android use xml file to save values. This function is return the file path of the xml path.
* @js NA
*/
static const std::string& getXMLFilePath();
/** All supported platforms other iOS & Android and CC_PLATFORM_WINRT use xml file to save values. This function checks whether the xml file exists or not.
* @return True if the xml file exists, false if not.
* @js NA
*/
static bool isXMLFileExist();
protected:
UserDefault();
virtual ~UserDefault();
private:
static bool createXMLFile();
static void initXMLFilePath();
static UserDefault* _userDefault;
static std::string _filePath;
static bool _isFilePathInitialized;
};
NS_CC_END
// end of base group
/** @} */
#endif // __SUPPORT_CCUSERDEFAULT_H__
為了方便起見(jiàn)，我們可以查看類(lèi)視圖。
UserDefault.png
其中，方法名左側(cè)有一個(gè)圖標(biāo)，它有三種不同的樣式:
Public樣式（圖標(biāo)右下角為空）
Public
Protected樣式（圖標(biāo)右下角為星號(hào)）
Protected
Private樣式（圖標(biāo)右下角為鎖）
Private
字段的左側(cè)圖標(biāo)，同理。
類(lèi)的字段
類(lèi)的Static字段初始化
UserDefault* UserDefault::_userDefault = nullptr;
string UserDefault::_filePath = string("");
bool UserDefault::_isFilePathInitialized = false;
- _userDefault : UserDefault是一個(gè)單例，類(lèi)的實(shí)例存儲(chǔ)在_userDefault字段中
-
_filePath ： 記錄
UserDefault.xml文件所在路徑(此處初始化為可讀寫(xiě)路徑/UserDefault.xml) - _isFilePathInitialized：標(biāo)記_filePath是否被初始化
類(lèi)的方法
類(lèi)的方法，其作用，在UserDefault中說(shuō)的非常明白，這里不做重復(fù)的闡述。
只做一些補(bǔ)充：
- 構(gòu)造函數(shù)和析構(gòu)函數(shù)放空，沒(méi)有業(yè)務(wù)邏輯，被聲明為Protected，可以被子類(lèi)繼承，進(jìn)行功能擴(kuò)展。
類(lèi)的實(shí)現(xiàn)：
- 類(lèi)的實(shí)現(xiàn)過(guò)程中，構(gòu)建了特定結(jié)構(gòu)的xml表：
<?xml version="1.0" encoding="UTF-8"?>
<userDefaultRoot>
<Key1>Value1</Key1>
<Key2>Value2</Key1>
<Key3>Value3</Key1>
</userDefaultRoot>
- 類(lèi)中提供了6類(lèi)數(shù)據(jù)結(jié)構(gòu)的讀取和寫(xiě)入接口，其實(shí)現(xiàn)，都是利用了tinyxml2類(lèi)來(lái)操作規(guī)定了存儲(chǔ)結(jié)構(gòu)的xml文件，對(duì)返回的數(shù)據(jù)做類(lèi)型轉(zhuǎn)換。
tolua
在lua_cocos2dx_auto.cpp文件中，注冊(cè)了lua端調(diào)用此類(lèi)的接口
int lua_register_cocos2dx_UserDefault(lua_State* tolua_S)
{
tolua_usertype(tolua_S,"cc.UserDefault");
tolua_cclass(tolua_S,"UserDefault","cc.UserDefault","",nullptr);
tolua_beginmodule(tolua_S,"UserDefault");
tolua_function(tolua_S,"setIntegerForKey",lua_cocos2dx_UserDefault_setIntegerForKey);
tolua_function(tolua_S,"deleteValueForKey",lua_cocos2dx_UserDefault_deleteValueForKey);
tolua_function(tolua_S,"getFloatForKey",lua_cocos2dx_UserDefault_getFloatForKey);
tolua_function(tolua_S,"getBoolForKey",lua_cocos2dx_UserDefault_getBoolForKey);
tolua_function(tolua_S,"setDoubleForKey",lua_cocos2dx_UserDefault_setDoubleForKey);
tolua_function(tolua_S,"setFloatForKey",lua_cocos2dx_UserDefault_setFloatForKey);
tolua_function(tolua_S,"getStringForKey",lua_cocos2dx_UserDefault_getStringForKey);
tolua_function(tolua_S,"setStringForKey",lua_cocos2dx_UserDefault_setStringForKey);
tolua_function(tolua_S,"flush",lua_cocos2dx_UserDefault_flush);
tolua_function(tolua_S,"getIntegerForKey",lua_cocos2dx_UserDefault_getIntegerForKey);
tolua_function(tolua_S,"getDoubleForKey",lua_cocos2dx_UserDefault_getDoubleForKey);
tolua_function(tolua_S,"setBoolForKey",lua_cocos2dx_UserDefault_setBoolForKey);
tolua_function(tolua_S,"destroyInstance", lua_cocos2dx_UserDefault_destroyInstance);
tolua_function(tolua_S,"getXMLFilePath", lua_cocos2dx_UserDefault_getXMLFilePath);
tolua_function(tolua_S,"isXMLFileExist", lua_cocos2dx_UserDefault_isXMLFileExist);
tolua_endmodule(tolua_S);
std::string typeName = typeid(cocos2d::UserDefault).name();
g_luaType[typeName] = "cc.UserDefault";
g_typeCast["UserDefault"] = "cc.UserDefault";
return 1;
}
總結(jié)
在通讀這個(gè)類(lèi)后，我們完成了UserDefault類(lèi)的源代碼閱讀。
