SQLite3 基本使用方法（二）

工程目录：

Singleton.h

//.h

#define single_interface(class) + (class *)shared##class;

//.m
// \ 代表下一行也属于宏
// ##是分隔符
#define single_implementation(class) static class *_instance; + (class *)shared##class {     if (_instance == nil) {         _instance = [[self alloc] init];     }     return _instance; }  + (id)allocWithZone:(NSZone *)zone {     static dispatch_once_t onceToken;     dispatch_once(&onceToken, ^{         _instance = [super allocWithZone:zone];     });     return _instance; }

MSUserManager.h

#import <Foundation/Foundation.h>
#import "MSUser.h"
#import <sqlite3.h>
#import "Singleton.h"

@interface MSUserManager : NSObject
{
     sqlite3 * m_pDb;
}

single_interface(MSUserManager)

//增
-(void) addUser:(MSUser *)user;

//删
-(void) deleteUser:(NSInteger)UserId;

//改
- (void)updateUser:(MSUser *)user;

//查
-(NSMutableArray *)allUser;

@end

MSUserManager.m

#import "MSUserManager.h"
#import <sqlite3.h>

@implementation MSUserManager   //单例
single_implementation(MSUserManager)

//在初始化方法中完成数据库链接工作
- (id)init
{
    self = [super init];

    if (self) {

        //1. 创建数据库
        [self openDB];
        //2. 创建数据库表
        [self createTable];

    }

    return self;
}

//打开数据库，如不存在，则创建。
- (void) openDB
{
    //生成存放在沙盒中的数据库完整路径
    NSString * strDocDir = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
    NSString * strDbName = [strDocDir stringByAppendingPathComponent: @"mySqlite3DB.db"];

    //sqlite3 数据库的链接，基于该链接可以进行数据库操作
    if (SQLITE_OK == sqlite3_open(strDbName.UTF8String, &m_pDb))
    {
        NSLog(@"创建/打开数据库成功！");
    }
    else
    {
        NSLog(@"创建/打开数据库失败！");
    }
}

//创建数据库表
//使用DBMANAGE创建，把生成的代码赋值过来就OK了。
//表名：tbl_User
//IF NOT EXISTS

//IOS 把id设为自增，在添加数据的时候，也要用null站位，不能不写。
- (void) createTable
{
    NSString * strSql = @"CREATE TABLE IF NOT EXISTS tbl_User (Id integer NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,UserName text,UserPass text)";

    char * pErrorMsg;
    if (SQLITE_OK ==  sqlite3_exec(m_pDb, strSql.UTF8String, NULL, NULL, &pErrorMsg)) {
        NSLog(@"创建数据表成功!");
    }
    else
    {
        NSLog(@"创建数据表失败!");
    }

}

- (void) execSql:(NSString *)sql msg:(NSString*)msg
{
    char * pErrorMsg;
    if (SQLITE_OK ==  sqlite3_exec(m_pDb, sql.UTF8String, NULL, NULL, &pErrorMsg))
    {
        NSLog(@"%@成功!", msg);
    }
    else
    {
        NSLog(@"%@失败 - %s!", msg, pErrorMsg);
    }
}

#pragma mark - 成员方法

//增
-(void) addUser:(MSUser *)user
{
    NSString * strSql = [NSString stringWithFormat: @"INSERT INTO tbl_User VALUES (null, ‘%@‘, ‘%@‘)",
                         user.UserName   , user.UserPass];

    [self execSql:strSql msg:@"添加"];

}

//删
-(void) deleteUser:(NSInteger)UserId
{
    //和增同理
}

//改
- (void)updateUser:(MSUser *)user
{
    //和增同理
}

//查
-(NSMutableArray *)allUser
{
    NSString * strSql = @"SELECT * FROM tbl_User";

    NSMutableArray * arrReturn = nil;

    //1. 评估准备SQL语法是否正确
    sqlite3_stmt * pStmt = NULL;
    if (SQLITE_OK == sqlite3_prepare_v2(m_pDb, strSql.UTF8String, -1, &pStmt, NULL))
    {
        arrReturn = [NSMutableArray array];

        //2. 如果能正常查询，调用单步执行方法， 依次取得查询结果
        //如果得到一行记录
        while (SQLITE_ROW == sqlite3_step(pStmt))
        {
            //3.获取/显示查询结果
            int nId = sqlite3_column_int(pStmt, 0);
            const unsigned char * pUserName = sqlite3_column_text(pStmt, 1);
            NSString * pUserNameUTF8 = [NSString stringWithUTF8String:(const char *)pUserName];
            const unsigned char * pUserPass = sqlite3_column_text(pStmt, 2);
            NSString * pUserPassUTF8 = [NSString stringWithUTF8String:(const char *)pUserPass];

            MSUser * pUser = [MSUser UserWithId:nId name:pUserNameUTF8 pass:pUserPassUTF8];

            [arrReturn addObject:pUser];
        }
    }
    else
    {
        NSLog(@"sql语法错误!");
    }
    //4. 释放句柄
    sqlite3_finalize(pStmt);

    return arrReturn;
}

@end

MSUser.h

#import <Foundation/Foundation.h>

@interface MSUser : NSObject

//工厂方法

//return User信息
+(id) UserWithId:(NSInteger)nId name:(NSString *)strUserName pass:(NSString *)strUserPass;

@property (assign , nonatomic) NSInteger Id;
@property (strong , nonatomic) NSString * UserName;
@property (strong , nonatomic) NSString * UserPass;

@end

MSUser.m

#import "MSUser.h"

@implementation MSUser

+(id) UserWithId:(NSInteger)nId name:(NSString *)strUserName pass:(NSString *)strUserPass
{
    MSUser * pUser = [[MSUser alloc] init];
    pUser.Id = nId;
    pUser.UserName = strUserName;
    pUser.UserPass = strUserPass;
    return pUser;
}

//
- (NSString *)description
{
    return [NSString stringWithFormat:@"< MSUser:%p  Id:%i  UserName:(%@)  UserPass:(%@) >",
           self, _Id, _UserName, _UserPass];
}

@end

MSViewController.m

#import "MSViewController.h"
#import "MSUserManager.h"
#import "MSUser.h"

@interface MSViewController ()

@end

@implementation MSViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    m_arrUser = [[MSUserManager sharedMSUserManager] allUser];
    NSLog(@"%@", m_arrUser);

}

@end

总结:

　　1. 分层结构比较清晰， Model(User) -- Service(UserManager) -- Controller 。 有木有 像三层架构 呢。。。

　　2. 单例类，需要理解！ 有什么好处？特点？

SQLite3 基本使用方法（二）