嵌入式Linux之我行，主要讲述和总结了本人在学习嵌入式linux中的每个步骤。一为总结经验，二希望能给想入门嵌入式Linux的朋友提供方便。如有错误之处，谢请指正。
一、开发环境
- 主 机：Fedora 9
- 编译器：arm-linux-gcc-3.4.1
- 编辑器： Eclipse
- 开发板：Mini2440
- 数据库：sqlite-3.6.16.tar.gz
二、示例代码
本示例代码是嵌入式CGI WEB应用程序中的一部分，主要实现了用户的登录和用户的验证功能。代码结构分为三层，分别是数据库操作层、数据访问层、业务逻辑层。
- 数据库操作层
sqlitedb.h
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/*
============================================================================
Name : sqlitedb.h
Author : Huang Gang
Version : 1.0.0
Date : 21/07/2009
Copyright : (C) 2009 XXXXXXXX LTD
Description :
Revision History :
============================================================================
*/
#ifndef SQLITEDB_H_
#define SQLITEDB_H_
#include <sqlite3.h> //这个是移植sqlite数据库时编译生成的头文件，在移植篇里提到过
#include <stdio.h>
#include <string>
using namespace std;
/*
*数据集类
*/
class Result
{
public:
Result();
~Result();
int getRowNum(); //获取数据集行数
int getColNum(); //获取数据集列数
int getResultNum(); //获取数据集记录行数
char *getAt(int r, int c); //获取数据集一条记录
friend class SQLiteDB;
private:
int row;
int col;
char **result;
};
class SQLiteDB
{
public:
SQLiteDB();
~SQLiteDB();
bool openDB(const char *db_name); //打开数据库
bool execute(const char *sql); //执行SQL语句，无返回记录的
Result* executeSelect(const char *sql); //执行SQL语句，有返回记录的
bool closeDB(); //关闭数据库
private:
sqlite3 *pDB;
char *pErrMsg;
};
#endif /*SQLITEDB_H_*/
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sqlitedb.cpp
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/*
============================================================================
Name : sqlitedb.cpp
Author : Huang Gang
Version : 1.0.0
Date : 21/07/2009
Copyright : (C) 2009 XXXXXXXX LTD
Description :
Revision History :
============================================================================
*/
#include "sqlitedb.h"
Result::Result()
{
row = 0;
col = 0;
result = NULL;
}
Result::~Result()
{
sqlite3_free_table(result);
}
int Result::getRowNum()
{
return row + 1;
}
int Result::getColNum()
{
return col;
}
int Result::getResultNum()
{
return row;
}
char *Result::getAt(int r, int c)
{
if(r <= row + 1 && c <= col)
{
return result[r * col + c];
}
else
{
return NULL;
}
}
SQLiteDB::SQLiteDB()
{
pDB = NULL;
pErrMsg = NULL;
}
SQLiteDB::~SQLiteDB()
{
if(pDB != NULL)
{
this->closeDB();
}
}
bool SQLiteDB::openDB(const char *db_name)
{
int res = 0;
res = sqlite3_open(db_name, &pDB);
if(res != SQLITE_OK)
{
return false;
}
return true;
}
bool SQLiteDB::execute(const char *sql)
{
if(pDB == NULL)
{
return false;
}
sqlite3_exec(pDB, sql, 0, 0, &pErrMsg);
if(pErrMsg != NULL)
{
pErrMsg = NULL;
return false;
}
return true;
}
Result* SQLiteDB::executeSelect(const char *sql)
{
if(pDB == NULL)
{
return NULL;
}
Result *rs = new Result();
sqlite3_get_table(pDB, sql, &rs->result, &rs->row, &rs->col, &pErrMsg);
if(pErrMsg != NULL)
{
pErrMsg = NULL;
return NULL;
}
return rs;
}
bool SQLiteDB::closeDB()
{
int res = 0;
if(pDB != NULL)
{
res = sqlite3_close(pDB);
if(res == SQLITE_BUSY)
{
return false;
}
}
return true;
}
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2. 数据访问层
user_DAL.h
|
/*
============================================================================
Name : user_DAL.h
Author : Huang Gang
Version : 1.0.0
Date : 29/07/2009
Copyright : (C) 2009 XXXXXXXX LTD
Description :
Revision History :
============================================================================
*/
#ifndef USER_DAL_H_
#define USER_DAL_H_
#include <sstream>
#include <string.h>
#include "sqlitedb.h"
#include "system_DAL.h"
using namespace std;
#define SQLITE_DATABASE_PATH "/usr/bin/ems_service.db" //数据库路径
class User_DAL
{
public:
User_DAL();
~User_DAL();
bool user_Login(char *name, char *pass, const char *sid); //用户登录
int user_Validate(char *sid); //验证用户
string get_CurrentTime(); //获取系统时间
private:
typedef enum
{
LOG_OFF = 0,
LOG_ON = 1
} USER_STATE; //用户登录状态
SQLiteDB sqliteDB;
};
#endif /*USER_DAL_H_*/
|
user_DAL.cpp
|
/*
============================================================================
Name : user_DAL.cpp
Author : Huang Gang
Version : 1.0.0
Date : 29/07/2009
Copyright : (C) 2009 XXXXXXXX LTD
Description :
Revision History :
============================================================================
*/
#include "user_DAL.h"
User_DAL::User_DAL(){}
User_DAL::~User_DAL(){}
bool User_DAL::user_Login(char *name, char *pass, const char *sid)
{
bool ret = false;
Result *result = NULL;
ostringstream sql;
sql << "SELECT id FROM SystemUsers WHERE name = '" << name << "' AND pass = '" << pass << "';";
if(!sqliteDB.openDB(SQLITE_DATABASE_PATH))
{
return false;
}
result = sqliteDB.executeSelect((sql.str()).c_str());
if(result->getResultNum() > 0)
{
sql << "UPDATE SystemUsers SET state = " << LOG_ON << ", time = '" << get_CurrentTime() << "', sid = '" << sid << "' WHERE name = '" << name << "';";
ret = sqliteDB.execute((sql.str()).c_str());
}
sqliteDB.closeDB();
return ret;
}
int User_DAL::user_Validate(char *sid)
{
int ret = 0;
Result *result = NULL;
ostringstream sql;
sql << "SELECT time FROM SystemUsers WHERE sid = '" << sid << "' AND state = " << LOG_ON << ";";
if(!sqliteDB.openDB(SQLITE_DATABASE_PATH))
{
return 0;
}
result = sqliteDB.executeSelect((sql.str()).c_str());
if(result->getResultNum() > 0)
{
System_DAL system_DAL;
int session_timeout = system_DAL.get_SessionTimeout();
if(session_timeout > 0)
{
char *login_time = result->getAt(1, 0);
string curr_time = get_CurrentTime();
struct tm* tmp_time = (struct tm*)malloc(sizeof(struct tm));
strptime(login_time, "%Y-%m-%d %H:%M:%S", tmp_time);
time_t login_t = mktime(tmp_time);
strptime(curr_time.c_str(), "%Y-%m-%d %H:%M:%S", tmp_time);
time_t curr_t = mktime(tmp_time);
int dif_t = static_cast<int> (difftime(curr_t, login_t) / 60);
if(session_timeout > dif_t)
{
sql << "UPDATE SystemUsers SET time = '" << get_CurrentTime() << "' WHERE sid = '" << sid << "' AND state = " << LOG_ON << ";";
sqliteDB.execute((sql.str()).c_str());
ret = 1;
}
else
{
sql << "UPDATE SystemUsers SET state = " << LOG_OFF << " WHERE sid = '" << sid << "' AND state = " << LOG_ON << ";";
sqliteDB.execute((sql.str()).c_str());
ret = -1;
}
}
else
{
ret = 1;
}
}
sqliteDB.closeDB();
return ret;
}
string User_DAL::get_CurrentTime()
{
char s[32];
time_t t = time(0);
strftime(s, sizeof(s), "%Y-%m-%d %H:%M:%S", localtime(&t));
return s;
}
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3. 业务逻辑层
user_manage.h
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/*
============================================================================
Name : user_manage.h
Author : Huang Gang
Version : 1.0.0
Date : 29/07/2009
Copyright : (C) 2009 XXXXXXXX LTD
Description :
Revision History :
============================================================================
*/
#ifndef USER_MANAGE_H_
#define USER_MANAGE_H_
#include "md5.h"
#include "parse.h"
#include "user_DAL.h"
class User_Manage
{
public:
User_Manage();
~User_Manage();
void user_login(Parse list);
bool user_validate(Parse list);
private:
User_DAL user_DAL;
};
extern User_Manage user_manage;
#endif /*USER_MANAGE_H_*/
|
user_manage.cpp
|
/*
============================================================================
Name : user_manage.cpp
Author : Huang Gang
Version : 1.0.0
Date : 29/07/2009
Copyright : (C) 2009 XXXXXXXX LTD
Description :
Revision History :
============================================================================
*/
#include "user_manage.h"
User_Manage user_manage;
User_Manage::User_Manage(){}
User_Manage::~User_Manage(){}
/*
* 功能：系统用户登录
* 参数: 客户端传来的查询字符串
* 返回：无
*/
void User_Manage::user_login(Parse list)
{
char *name = list.get_item_n("name");
char *pass = list.get_item_n("pass");
string sid = MD5Encode((string(name) + string(user_DAL.get_CurrentTime())).c_str());
bool login = user_DAL.user_Login(name, pass, sid.c_str());
if(login)
{
//用户登录成功，跳转到主页并返回Session ID
printf("window.location.href='index.html?sid=%s';", sid.c_str());
}
else
{
//用户登录失败
printf("用户名或密码错误！");
}
}
/*
* 功能：验证系统登录用户
* 参数: 客户端传来的查询字符串
* 返回：是否通过
*/
bool User_Manage::user_validate(Parse list)
{
char *sid = list.get_item_n("sid");
int state = user_DAL.user_Validate(sid);
if(state == 0)
{
//用户没有登录，跳转到登录页
printf("parent.window.location.href='login.html';");
return false;
}
else if(state == -1)
{
//用户登录后长时间没操作Session超时
printf("parent.window.location.href='error.html';");
return false;
}
else
{
//用户验证通过
return true;
}
}
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三、结束语
从示例代码看，sqlite数据库在嵌入式中的应用是非常的简单，跟在Windows下开发Windows应用程序没两样。这里值得一提的是三层结构思想即这里的数据库操作层、数据访问层、业务逻辑层，这使得应用程序的条理和效率更高。通过本篇，相信你已对sqlite数据库的应用有了一定的了解。
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