简单的单身模式(Singleton)

单身模式是比较常用的一种设计模式，比较简单的实现：

static HttpConnect * g_HttpConnect = 0;

HttpConnect * HttpConnect::getHttpSingler()
{
    if (g_HttpConnect == 0)
        g_HttpConnect = new HttpConnect();
    return g_HttpConnect;
}

在头文件的类中定义静态函数：

static HttpConnect * getHttpSingler();

外部调用：

HttpConnect::getHttpSingler()->setServerUrl("http://127.0.0.1:5000");

第二种方式：用模版

#ifndef SINGLETON_H
#define SINGLETON_H

#include <assert.h>

template <class T>
class Singleton
{
public:
    static T* Instance()
    {
        if(!m_Instance) m_Instance = new T;
        assert(m_Instance != NULL);
        return m_Instance;
    }
protected:
    Singleton();
    ~Singleton();
private:
    Singleton(Singleton const&);
    Singleton& operator=(Singleton const&);
    static T* m_Instance;
};

template <class T> T* Singleton<T>::m_Instance=NULL;

#endif // SINGLETON_H

在HttpConnect 类头文件中申明：

typedef Singleton<HttpConnect> HttpSingle;

外部调用：

HttpSingle::Instance()->.....

简单的单身模式(Singleton)

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