C++单例模式

2024-11-20 技术教程

/
单例模式：
C1 getInstance 和m_instance必是static变量，
C2 m_instance必被明确的初始化。
C3 构造函数与拷贝构造函数，析构函数全是private，可以只声明。
C4 需要有明确的Destory函数
C5 需要在线程安全。
/

//Singleton.h#include <iostream>#include <string.h>#include <stdio.h>#include <pthread.h>using namespace std;class Singleton{private: ~Singleton(){Destory();}; Singleton(){}; //copy-construct: Singleton(Singleton& s); string m_name; int m_id; //A1 int m_score;public: int show_info_no_const(void) { cout <<"no const function: name "<< m_name << ", id " << m_id<<endl; return 0; } int show_info(void) const { cout <<"name "<< m_name << ", id " << m_id<<endl; return 0; } void set_name(char* new_name); static Singleton* getInstance(); //C2 void Destory(); static Singleton* m_instance; //C1 static pthread_mutex_t m_mutex;};

//Singleton.cpp#include <iostream>#include <string.h>#include <stdio.h>#include <stdlib.h>#include <pthread.h>#include "Singleton.h"using namespace std;/* 单例模式：C1 getInstance 和m_instance必是static变量，C2 m_instance必被明确的初始化。C3 构造函数与拷贝构造函数，析构函数全是private，可以只声明。C4 需要有明确的Destory函数C5 需要在线程安全。*/Singleton* Singleton::getInstance(){ if(m_instance == NULL) //如果真的空的话，再会加锁，再去完成原子的操作。 { pthread_mutex_lock(&m_mutex); //互斥锁 if(m_instance == NULL) { m_instance = new Singleton; } pthread_mutex_unlock(&m_mutex); //互斥锁 } return m_instance;}void Singleton::Destory(){ delete this;}void Singleton::set_name(char* new_name){ m_name=new_name; //m_id=9;//A1 m_id是不可以再被修改的。}Singleton* Singleton::m_instance = NULL; //C1 C2pthread_mutex_t Singleton::m_mutex = PTHREAD_MUTEX_INITIALIZER;

//main.cpp#include <iostream>#include <string.h>#include <stdio.h>#include <stdlib.h>#include "Singleton.h"int main(){ Singleton::getInstance()->set_name("abc"); Singleton::getInstance()->show_info(); return 0;}