iOS下FMDB的多线程操作（二）

上一篇记录不使用FMDatabaseQueue来使用多线程，这一篇记录一下使用FMDatabaseQueue的方式。

需要注意的时queue操作中不能嵌套queue操作，否则会各种错误。

当使用FMDatabaseQueue，因为整个项目用同一个queue，所以最好写一个单例。我是这么写的，不知道是否合理，先记录吧。

下面是头文件。

@interface JKDataBase : NSObject

@property (nonatomic, retain, readonly) FMDatabaseQueue *dbQueue;

+ (JKDataBase *)shareInstance;

.m文件就贴一下关键代码。

static JKDataBase *_instance = nil;

+ (instancetype)shareInstance
{
    static dispatch_once_t onceToken ;
    dispatch_once(&onceToken, ^{
        _instance = [[super allocWithZone:NULL] init] ;
    }) ;
    
    return _instance;
}

- (FMDatabaseQueue *)dbQueue
{
    if (_dbQueue == nil) {
        NSString* docsdir = [NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
        NSFileManager *filemanage = [NSFileManager defaultManager];
        docsdir = [docsdir stringByAppendingPathComponent:@"FMDBDemo"];
        BOOL isDir;
        BOOL exit =[filemanage fileExistsAtPath:docsdir isDirectory:&isDir];
        if (!exit || !isDir) {
            [filemanage createDirectoryAtPath:docsdir withIntermediateDirectories:YES attributes:nil error:nil];
        }
        NSString* dbpath = [docsdir stringByAppendingPathComponent:@"myDB.sqlite"];
        _dbQueue = [[FMDatabaseQueue alloc] initWithPath:dbpath];
    }
    return _dbQueue;
}

然后就是User类中的数据库操作。同样也是创建表、插入、删除、更新、查询五类操作。

1、创建数据库表

/** 创建表 */
+ (BOOL)createUserTable
{
    __block BOOL res = NO;
    JKDataBase *jkDB = [JKDataBase shareInstance];
    [jkDB.dbQueue inDatabase:^(FMDatabase *db) {
        NSString *sql = @"CREATE TABLE IF NOT EXISTS User(ID INTEGER PRIMARY KEY, name TEXT, age INTEGER, ID_No TEXT);";
        res = [db executeUpdate:sql];
    }];
    return res;
}

2、插入数据

- (BOOL)save
{
    JKDataBase *jkDB = [JKDataBase shareInstance];
    __block BOOL res = NO;
    [jkDB.dbQueue inDatabase:^(FMDatabase *db) {
        NSString *sql = [NSString stringWithFormat:@"INSERT INTO User(name, age, ID_No) VALUES ('%@', '%d', '%@');", self.name, self.age, self.ID_no];
        res = [db executeUpdate:sql];
    }];
    return res;
}

/** 批量保存用户对象 */
+ (BOOL)saveObjects:(NSArray *)array
{
    __block BOOL res = YES;
    JKDataBase *jkDB = [JKDataBase shareInstance];
    // 如果要支持事务
    [jkDB.dbQueue inTransaction:^(FMDatabase *db, BOOL *rollback) {
        for (User *user in array) {
            NSString *sql = [NSString stringWithFormat:@"INSERT INTO User(name, age, ID_No) VALUES ('%@', '%d', '%@');", user.name, user.age, user.ID_no];
            if (![db executeUpdate:sql]) {
                res = NO;
                *rollback = YES;
                return;
            }
        }
    }];
    return res;
}

3、更新数据

- (BOOL)update
{
    JKDataBase *jkDB = [JKDataBase shareInstance];
    __block BOOL res = NO;
    [jkDB.dbQueue inDatabase:^(FMDatabase *db) {
        NSString *sql = [NSString stringWithFormat:@"UPDATE User SET name = '%@',age = '%d',ID_no = '%@' WHERE ID = '%d';", self.name, self.age, self.ID_no, self.ID];
        res = [db executeUpdate:sql];
    }];
    return res;
}

/** 批量更新用户对象*/
+ (BOOL)updateObjects:(NSArray *)array
{
    __block BOOL res = YES;
    JKDataBase *jkDB = [JKDataBase shareInstance];
    // 如果要支持事务
    [jkDB.dbQueue inTransaction:^(FMDatabase *db, BOOL *rollback) {
        for (User *user in array) {
            NSString *sql = [NSString stringWithFormat:@"UPDATE User SET name = '%@',age = '%d',ID_no = '%@' WHERE ID = '%d';", user.name, user.age, user.ID_no, user.ID];
            BOOL flag = [db executeUpdate:sql];
            if (!flag) {
                res = NO;
                *rollback = YES;
                return;
            }
        }
    }];
    return res;
}

4、删除数据

- (BOOL)deleteObject
{
    JKDataBase *jkDB = [JKDataBase shareInstance];
    __block BOOL res = NO;
    [jkDB.dbQueue inDatabase:^(FMDatabase *db) {
        NSString *sql = [NSString stringWithFormat:@"DELETE FROM User WHERE ID = '%d'",self.ID];
        res = [db executeUpdate:sql];
    }];
    return res;
}

/** 批量删除用户对象 */
+ (BOOL)deleteObjects:(NSArray *)array
{
    __block BOOL res = YES;
    JKDataBase *jkDB = [JKDataBase shareInstance];
    // 如果要支持事务
    [jkDB.dbQueue inTransaction:^(FMDatabase *db, BOOL *rollback) {
        for (User *user in array) {
            NSString *sql = [NSString stringWithFormat:@"DELETE FROM User WHERE ID = '%d'",user.ID];
            BOOL flag = [db executeUpdate:sql];
            if (!flag) {
                res = NO;
                *rollback = YES;
                return;
            }
        }
    }];
    return res;
}

5、查询数据

+ (NSArray *)findAll
{
    JKDataBase *jkDB = [JKDataBase shareInstance];
    NSMutableArray *users = [[NSMutableArray alloc] init];
    [jkDB.dbQueue inDatabase:^(FMDatabase *db) {
        NSString *sql = @"SELECT * FROM User";
        FMResultSet *resultSet = [db executeQuery:sql];
        while ([resultSet next]) {
            User *user = [[User alloc] init];
            user.ID = [resultSet intForColumn:@"ID"];
            user.name = [resultSet stringForColumn:@"name"];
            user.age = [resultSet intForColumn:@"age"];
            user.ID_no = [resultSet stringForColumn:@"ID_no"];
            [users addObject:user];
            [user release];
        }
    }];

    return [users autorelease];
}

/** 查找某个用户 */
+ (instancetype)findFirstBySql:(NSString *)sql
{
    User *user = nil;
    NSArray *users = [self findBySql:sql];
    if (users.count > 0) {
        user = [users firstObject];
    }
    return user;
}

/** 查找用户 */
+ (NSArray *)findBySql:(NSString *)sql
{
    JKDataBase *jkDB = [JKDataBase shareInstance];
    NSMutableArray *users = [[NSMutableArray alloc] init];
    [jkDB.dbQueue inDatabase:^(FMDatabase *db) {
        NSString *select = @"SELECT * FROM User ";
        if (sql) {
            select = [select stringByAppendingString:sql];
        }
        FMResultSet *resultSet = [db executeQuery:select];
        while ([resultSet next]) {
            User *user = [[User alloc] init];
            user.ID = [resultSet intForColumn:@"ID"];
            user.name = [resultSet stringForColumn:@"name"];
            user.age = [resultSet intForColumn:@"age"];
            user.ID_no = [resultSet stringForColumn:@"ID_no"];
            [users addObject:user];
            [user release];
        }
    }];
    
    return [users autorelease];
}

先记录这么多吧，希望能对别人有所帮助。

demo传送门：http://download.csdn.net/detail/u011619283/8838965