SQLite3单例模式（C++）

注意：这代码只能在linux底下运行。

.h 文件 (我的文件是MySql.h)

#ifndef MYSQL_H #define MYSQL_H#include <sqlite3.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <iostream> using namespace std;class MySql { public:static MySql *Instance() //获取唯一单例对象{if(!m_sql)m_sql = new MySql();return m_sql;}void Init(const char* fileName); //初始化void InsertData(); //插入数据void SelectData(int id); //通过id查询数据 private:MySql(); //私有 防止外部调用~MySql();static MySql* m_sql; //静态指针保存单例对象static sqlite3 * db; //数据库类指针char *Sql_statement; //存放执行语句sqlite3_stmt *stmt; //标记数据库的执行信息int rc; //执行返回结果 };#endif // MYSQL_H

.cpp文件 (我的文件是MySql.cpp)

#include "MySql.h"sqlite3 *MySql::db; MySql *MySql::m_sql = NULL;MySql::MySql() {Sql_statement = new char[1024];memset(Sql_statement,0,1024);this->Init("data.db"); }MySql::~MySql() {delete []this->Sql_statement; } //初始化，打开数据库、创建表 void MySql::Init(const char* fileName) {this->rc = sqlite3_open(fileName,&db);if(this->rc == SQLITE_OK){strcpy(this->Sql_statement,"create table student(id int primary key,name text,age int)");this->rc = sqlite3_exec(db,Sql_statement,NULL,NULL,&errMes);if(rc == SQLITE_OK){printf("Success to create table!\n");}memset(Sql_statement,0,1024);} } //向表中插入数据 void MySql::InsertData() {strcpy(this->Sql_statement,"insert into student values(1,'zhangsan',20)");sqlite3_exec(db,this->Sql_statement,NULL,NULL,&errMes);strcpy(this->Sql_statement,"insert into student values(2,'lisi',19)");sqlite3_exec(db,this->Sql_statement,NULL,NULL,&errMes);if(rc == SQLITE_OK){printf("Success to insert data!\n");}memset(Sql_statement,0,1024); } //通过id查询数据 void MySql::SelectData(int id) {const unsigned char *name;int nid = 0;int age = 0;sprintf(this->Sql_statement,"select * from student where id = %d",id);sqlite3_prepare(db,this->Sql_statement,-1,&this->stmt,NULL);while(sqlite3_step(this->stmt) == SQLITE_ROW){nid = sqlite3_column_int(this->stmt, 0);name = sqlite3_column_text(this->stmt, 1);age = sqlite3_column_int(this->stmt, 2);printf("name:%s ,id:%d ,age:%d\n",name,nid,age);} }

main.cpp文件

#include "MySql.h" #include <iostream> using namespace std;int main() {MySql::Instance()->InsertData();MySql::Instance()->SelectData(1);return 0; }

最后把这三个文件放在linux的同一目录底下，然后通过makefile工具进行编译。

MakeFile文件

ELF=main CC=g++ src=$(wildcard *.cpp) objects=$(src:.cpp=.o) $(ELF):$(objects)$(CC) $^ -o $@ -lsqlite3 #注意这里记得加-lsqlite3 $(objects): clean:rm -f $(objects) $(ELF)

（不会Makefile的可以看我博客：MakeFile工具使用）

编译结果：

总结

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