iOS-FMDB本地存储之一种封装思想

1.前提工做

安装cocoapods,而且导入

pod 'FMDB/FTS', '2.5'               # sqlite操做
pod 'FCFileManager', '1.0.17'       # sqlite操做
pod 'GCJSONKit', '1.5.0'            # JSON和对象互转

2.建立可视化表

首先建立.bundle文件用来装全部表(便于管理)

而后在.string里面规定本身表定义格式以下图:
表名:user_friends
主键:USER_CODE
字段:数组

3.加载表定义

建立一个manager 来管理表,加载表定义,须要传入你.bundle文件的名字和数据库存储路径.

/**
 * 初始化数据对象
 * @param defineFileName :  数据库定义文件
 * @param  filePath : 数据库文件路径
 */
- (instancetype)initWithDBDefine:(NSString * )bundleName filePath:(NSString *)filePath {
    if (self =[super init]) {
        self.dbFile = filePath;
        [self loadTableDefinition:bundleName];
    }
    return self;
}

4.建立表

/**
 * 根据定义建立数据库表
 *
 */
- (BOOL)createTableWithConfig:(NSDictionary *)tableDefine withDb:(FMDatabase *)db

数据库建立表具体sql语句

CREATE TABLE IF NOT EXISTS user_friends(USER_CODE TEXT primary key not null,USER_NAME TEXT,FRIEND_CODE TEXT,USER_IMG_SRC TEXT,USER_SHORT_NAME TEXT,USER_EN_NAME TEXT,USER_SEX TEXT,DEPT_NAME TEXT,USER_POST TEXT)

你所须要的是表名,主键,及各类字段名字拼成以上格式,这里很少说能够文章底部github下载demo本身研究这里很少说

5.打开数据库的管理类

在这建立manger,并传入存储路径
保证数据库,操做在同一线程操做,当咱们在程序中运用到多线程的时候，那么你必需要考虑的就是各线程抢占资源的问题，不能让同一时间多个线程去抢一个资源，好比你两个线程同时去操做sql，就会形成有脏读数据或者查不到数据，或者查的是脏数据.

#import "SQliteUser.h"

@interface SQliteUser ()

@property (nonatomic, strong) SqliteManager *manager;

@end

@implementation SQliteUser

SINGLETON_FOR_CLASS(SQliteUser);//宏单例

- (SqliteManager *)manager {
    if (_manager) {
        return _manager;
    }
    @synchronized(self) {
        if (!_manager) {
             NSString *dbPath = [NSString stringWithFormat:@"%@%@",NSHomeDirectory(),@"/Documents/yuhechuan.db"];
            _manager = [[SqliteManager alloc] initWithDBDefine:@"user" filePath:dbPath];
        }
    }
    return _manager;
}

@end

synchronized同步锁,保证一个线程执行完成,再执行其余线程任务
通常说synchronized是加锁，或者说是加对象锁，其实对象锁只是synchronized在实现锁机制中的一种锁（重量锁，用这种方式互斥线程开销大因此叫重量锁，或者叫对象monitor），而synchronized的锁机制会根据线程竞争状况在运行会有偏向锁、轻量锁、对象锁，自旋锁（或自适应自旋锁）等
参考连接：http://www.jianshu.com/p/5dbb...

6.建立DAO

@implementation SQBaseDAO

子类继承baseDAO 实现下面两个父类的方法,来告诉manger,表名和主键

-(NSString *)getPK {
    return @"须要子类实现";
}
- (NSString *)getTable {
    return @"须要子类实现";
}

获取Sqlite管理类和其中的FMDatabaseQueue

-(SqliteManager *)getDataSource {
    return [[SQliteUser sharedInstance] manager];
}

7.实现增,删,改,查

首先调用数据库的方法应在FMDB提供的方法里面执行

-(void)inDatabase:(void (^)(FMDatabase *db))block

这个方法提供了一个代码块。操做数据库的代码写在block里，如：
FMDatabaseQueue是一个串行队列，它不支持串行任务嵌套执行
如下代码比较简单不予多说本身看

增

//增
- (BOOL)insert:(NSDictionary *)data {
    //安全线程
    FMDatabaseQueue *dbQueue = [[self getDataSource] dbQueue];
    __block BOOL execute = NO;
    [dbQueue inDatabase:^(FMDatabase *db) {
        NSMutableDictionary *mData = [NSMutableDictionary dictionaryWithDictionary:data];
        NSString *pk = [self getPK];//主键
        NSString * table = [self getTable];//表名
        //若是主键没值,主动生成主键
        if (![mData objectForKey:pk]) {
            [mData setObject:[[NSUUID UUID] UUIDString] forKey:pk];
        }
        NSMutableString *insertKey = [NSMutableString stringWithCapacity:0];
        NSMutableString *insertValuesString = [[NSMutableString alloc] init];
        NSMutableArray *insertValues = [[NSMutableArray alloc] init];
        NSArray *columnArray = [mData allKeys];
        for (int i = 0; i < columnArray.count; i++) {
            NSString *columnName = columnArray[i];
            id value = [mData objectForKey:columnName];
            if (!value) {
                continue;
            }
            if (insertKey.length > 0) {
                [insertKey appendString:@","];
                [insertValuesString appendString:@","];
            }
            
            [insertKey appendString:columnName];
            [insertValuesString appendString:@"?"];
            
            [insertValues addObject:value];
        }
        // 拼接insertSQL 语句  采用 replace 插入
        NSString *insertSQL = [NSString stringWithFormat:@"replace into %@(%@) values(%@)", table, insertKey, insertValuesString];
        execute = [db executeUpdate:insertSQL withArgumentsInArray:insertValues];
        //打印日志,若是在主线程执行,方便查找
        [self printSQLLog:insertSQL values:insertValues];
        
    }];
    return execute;
}

删

//删
- (BOOL)remove:(SQConditionBean *)condition {
    FMDatabaseQueue *dbQueue = [[self getDataSource] dbQueue];
    __block BOOL execute = NO;
    [dbQueue inDatabase:^(FMDatabase *db) {
        NSString *table = [self getTable];
        NSMutableString *deleteSQL = [NSMutableString stringWithFormat:@"delete from %@  ", table];
        // 添加where 语句
        NSMutableArray *valuearray = [NSMutableArray array];
        //获取条件字符串
        NSDictionary *dict = [condition conditionDict];
        NSString *sqlwhere = [self dictionaryToSqlWhere:dict andValues:valuearray];
        if (sqlwhere.length > 0) {
            [deleteSQL appendString:@" where "];
            [deleteSQL appendString:sqlwhere];
        }
        execute = [db executeUpdate:deleteSQL withArgumentsInArray:valuearray];
        //打印日志,若是在主线程执行,方便查找
        [self printSQLLog:deleteSQL values:valuearray];

    }];
    return execute;
}

改

//改
- (BOOL)modify:(NSDictionary *)data {
    FMDatabaseQueue *dbQueue = [[self getDataSource ] dbQueue];
    __block BOOL execute = NO;
    [dbQueue inDatabase:^(FMDatabase *db) {
        NSString *pk = [self getPK];//主键
        NSString * table = [self getTable];//表名
        NSMutableString *updateKey = [NSMutableString string];//更新key集合
        NSMutableArray *updateValues = [[NSMutableArray alloc] init];//更新的value集合
        NSArray *columnArray = data.allKeys;
        for (NSString *key in columnArray) {
            //不是主键字段
            if (![key isEqualToString:pk]) {
                if (updateKey.length > 0) {
                    [updateKey appendString:@","];
                }
                [updateKey appendFormat:@"%@=?", key];
            }
            id value = [data objectForKey:key];
            [updateValues addObject:value];
        }
        NSMutableString *updateSQL = [NSMutableString stringWithFormat:@"update %@ set %@ where %@=?", table, updateKey,[updateValues lastObject]];
        execute = [db executeUpdate:updateSQL withArgumentsInArray:updateValues];
        //打印日志,若是在主线程执行,方便查找
        [self printSQLLog:updateSQL values:updateValues];
    }];
    return execute;
}

查

//查
    - (NSMutableArray *)query:(SQConditionBean *)condition{
        FMDatabaseQueue *dbQueue = [[self getDataSource ] dbQueue];
        __block NSMutableArray *results = [[NSMutableArray alloc] init];
        [dbQueue inDatabase:^(FMDatabase *db) {
            NSString * table = [self getTable];
            NSString *columnsString = @"*";
            
            //build query
            NSMutableString *query = [NSMutableString stringWithFormat:@"select %@ from %@", columnsString, table];
            NSMutableArray *whereValues = [NSMutableArray array];
            
            //build where
            NSString *wherekey = [self dictionaryToSqlWhere:[condition conditionDict] andValues:whereValues];
            if ( wherekey.length > 0) {
                [query appendFormat:@" where %@", wherekey];
            }
            
            //execute
            FMResultSet *set = nil;
            if (whereValues.count == 0) {
                set = [db executeQuery:query];
            } else {
                set = [db executeQuery:query withArgumentsInArray:whereValues];
            }
            //打印日志,若是在主线程执行,方便查找
            [self printSQLLog:query values:whereValues];
            
            
            while ([set next]) {
                NSDictionary *rowData = [self resultToDic:set];
                [results addObject:rowData];
            }
            [set close];
    
        }];
        return results;
    }

8.建立条件SQConditionBean 拼接where语句

携带一个字典

@property (nonatomic, strong) NSMutableDictionary *conditionDict;
/**
 *  添加条件(操做符是AND)
 *
 *  @param value 值
 *  @param key   字段
 */
-(void) set:(id)value forKey:(NSString *)key {
    if (value) {
        [conditionDict setValue:value forKey:key];
    }
}
/**
 *  添加  != 条件 (操做符是AND)
 *
 *  @param value 值
 *  @param key   字段
 */
-(void) andNE:(id)value forKey:(NSString *)key {
    NSString * query =  [NSString stringWithFormat:@"%@ != ", key];
    [conditionDict setValue:value forKey:query];
}

参考资料:http://www.jianshu.com/p/5dbb...
Demo下载地址:https://github.com/yuhechuan/...

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版权地址：https://www.jianshu.com/p/9ff...

做者：有毒的程序猿

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