iOS-FMDB本地存储之一种封装思想

1.前提工作

安装cocoapods,并且导入

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

2.创建可视化表

首先创建.bundle文件用来装所有表(便于管理)



然后在.string里面规定自己表定义格式如下图:
表名:user_friends
主键:USER_CODE
字段:数组

3.加载表定义

创建一个manager 来管理表,加载表定义,需要传入你.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.创建表

/**
* 根据定义创建数据库表
*
*/
- (BOOL)createTableWithConfig:(NSDictionary *)tableDefine withDb:(FMDatabase *)db

数据库创建表具体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)

你所需要的是表名,主键,及各种字段名字拼成以上格式,这里不多说可以文章底部github下载demo自己研究这里不多说

5.打开数据库的管理类

在这创建manger,并传入存储路径
保证数据库,操作在同一线程操作,当我们在程序中运用到多线程的时候，那么你必须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，比如你两个线程同时去操作sql，就会造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,再执行其他线程任务
一般说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所以叫重量锁，或者叫对象monitor），而synchronized的锁机制会根据线程竞争情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
参考链接：www.jianshu.com/p/5dbb07c8d…

6.创建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 @"需要子类实现";
}
- (NSString *)getTable {
return @"需要子类实现";
}

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。操作数据库的代码写在block里，如：
FMDatabaseQueue是一个串行队列，它不支持串行任务嵌套执行
以下代码比较简单不予多说自己看

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
//如果主键没值,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,如果在主线程执行,方便查找
[self printSQLLog:insertSQL values:insertValues];

}];
return execute;
}

删

//删
- (BOOL)remove:(SQConditionBean *)condition {
FMDatabaseQueue *dbQueue = [[self getDataSource] dbQueue];
__bloc
4000
k 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,如果在主线程执行,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,如果在主线程执行,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,如果在主线程执行,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.创建条件SQConditionBean 拼接where语句

携带一个字典

@property (nonatomic, strong) NSMutableDictionary *conditionDict;
/**
*  添加条件(操作符是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 (操作符是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:www.jianshu.com/p/5dbb07c8d…
Demo下载地址:github.com/yuhechuan/S…
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版权地址：https://www.jianshu.com/p/9ffafc37a88f
作者：有毒的程序猿
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