适配器模式.cpp

#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <memory>
using namespace std;// 解决两个类之间的兼容性问题
// 转换接口调用
// 3种角色
// Target（目标抽象类），定义需要暴露的接口
// Adaptee（适配者类），被适配角色，多个老接口
// Adapter（适配器类），包装类，转换器角色// 既有东西增减内容就成为了一个适配器
// 容器适配器，双端队列deque减少东西就能实现stack和queue
// 算法适配器，std::bind(绑定器)
// 迭代器适配器，reverse_iterator(反向迭代器)，对迭代器iterator的简单封装namespace ns1
{class LogToFile // 日志文件操作相关类{public:void initfile() {}                        // 做日志文件初始化工作，比如打开文件等等void writetofile(const char *pcontent) {} // 将日志内容写入文件void readfromfile() {}                    // 从日志中读取一些信息void closefile() {}                       // 关闭日志文件};
}namespace ns2
{class LogToDatabase // 日志操作相关类（数据库版本）{public:void initdb() {}                        // 连接数据库，做一些基本的数据库连接设置等void writetodb(const char *pcontent) {} // 将日志内容写入数据库void readfromdb() {}                    // 从数据库中读取一些日志信息void closedb() {}                       // 关闭到数据库的连接};
}namespace ns3
{class LogToFile // 日志文件操作相关类{public:void initfile() {}                        // 做日志文件初始化工作，比如打开文件等等void writetofile(const char *pcontent) {} // 将日志内容写入文件void readfromfile() {}                    // 从日志中读取一些信息void closefile() {}                       // 关闭日志文件};class LogToDatabase{public:virtual ~LogToDatabase() {}virtual void initdb() = 0; // 不一定非是纯虚函数virtual void writetodb(const char *pcontent) = 0;virtual void readfromdb() = 0;virtual void closedb() = 0;};class LogAdapter : public LogToDatabase // 对象适配器，通过组合，委托实现{shared_ptr<LogToFile> m_pfile;public:LogAdapter(const shared_ptr<LogToFile> &pfile = make_shared<LogToFile>()) : m_pfile(pfile) {} // 形参是老接口所属类void initdb() override{cout << "LogAdapter::initdb() Adapter LogToFile::initfile()" << endl;m_pfile->initfile();}void writetodb(const char *pcontent) override{cout << "LogAdapter::writetodb() Adapter LogToFile::writetofile()" << endl;m_pfile->writetofile(pcontent);}void readfromdb() override{cout << "LogAdapter::readfromdb() Adapter LogToFile::readfromdb()" << endl;m_pfile->readfromfile();}void closedb() override{cout << "LogAdapter::closedb() Adapter LogToFile::closedb()" << endl;m_pfile->closefile();}};
}namespace ns4
{class LogToFile // 日志文件操作相关类{public:void initfile() {}                        // 做日志文件初始化工作，比如打开文件等等void writetofile(const char *pcontent) {} // 将日志内容写入文件void readfromfile() {}                    // 从日志中读取一些信息void closefile() {}                       // 关闭日志文件};class LogToDatabase{public:virtual ~LogToDatabase() {}virtual void initdb() = 0; // 不一定非是纯虚函数virtual void writetodb(const char *pcontent) = 0;virtual void readfromdb() = 0;virtual void closedb() = 0;};class LogAdapter : public LogToDatabase, private LogToFile // 类适配器，通过继承实现接口的适配{public:void initdb() override{cout << "LogAdapter::initdb() Adapter LogToFile::initfile()" << endl;initfile();}void writetodb(const char *pcontent) override{cout << "LogAdapter::writetodb() Adapter LogToFile::writetofile()" << endl;writetofile(pcontent);}void readfromdb() override{cout << "LogAdapter::readfromdb() Adapter LogToFile::readfromdb()" << endl;readfromfile();}void closedb() override{cout << "LogAdapter::closedb() Adapter LogToFile::closedb()" << endl;closefile();}};
}int main()
{
#if 0using namespace ns1;shared_ptr<LogToFile> plog(new LogToFile());plog->initfile();plog->writetofile("Write a log to the log file"); // 写一条日志到日志文件中plog->readfromfile();plog->closefile();
#endif#if 0using namespace ns2;shared_ptr<LogToDatabase> plogdb(new LogToDatabase());plogdb->initdb();plogdb->writetodb("Write a log to the database"); // 写一条日志到数据库中plogdb->closedb();plogdb->readfromdb();
#endif#if 0using namespace ns3;//shared_ptr<LogToFile> plog2(new LogToFile());//shared_ptr<LogToDatabase> plogdb2(new LogAdapter(plog2));shared_ptr<LogToDatabase> plogdb2(new LogAdapter());plogdb2->initdb();plogdb2->writetodb("Writing a log to the database is actually writing a log to the log file");plogdb2->readfromdb();plogdb2->closedb();
#endif#if 1using namespace ns4;shared_ptr<LogToDatabase> plogdb3(new LogAdapter());plogdb3->initdb();plogdb3->writetodb("Writing a log to the database is actually writing a log to the log file");plogdb3->readfromdb();plogdb3->closedb();
#endifcout << "Over!\n";return 0;
}