FMDB是平常我们很经常用的数据库框架，它特点是：
1.使用方便；
2.对比苹果自带CoreData框架更轻量级和灵活；
3.提供多线程安全，原来的SQLite并不是线程安全；
4.还可以把多个任务包装成事务，提高效率。
-
(一)多线程安全
FMDB的线程安全主要在于串行，比如下面例子：
FMDatabaseQueue *queue = [FMDatabaseQueue databaseQueueWithPath:self.dbPath];
//多任务并发添加，执行顺序是顺序执行的
dispatch_queue_t queuet = dispatch_queue_create("queuet", DISPATCH_QUEUE_CONCURRENT);
dispatch_async(queuet, ^{
for (int i = 0; i < 100; i ++) {
[queue inDatabase:^(FMDatabase * _Nonnull db) {
if ([db open]) {
BOOL result = [self.db executeUpdate:@"create table if not exists t_database_queue2 (userID integer primary key autoincrement,name text not null,number integer not null);"];
if (result) {
NSString * insertSql1 = [NSString stringWithFormat:@"insert into t_database_queue2 (userID,name,number) values (%d,'%d',%d)",i,i,i];
BOOL res = [self.db executeUpdate:insertSql1];
if (!res) {
NSLog(@"失败%d",i);
}
}
}
}];
}
});
dispatch_async(queuet, ^{
for (int i = 0; i < 100; i ++) {
[queue inDatabase:^(FMDatabase * _Nonnull db) {
if ([db open]) {
BOOL result = [self.db executeUpdate:@"create table if not exists t_database_queue2 (userID integer primary key autoincrement,name text not null,number integer not null);"];
if (result) {
NSString * insertSql1 = [NSString stringWithFormat:@"insert into t_database_queue2 (userID,name,number) values (%d,'%d',%d)",i+50,i,i];
BOOL res = [self.db executeUpdate:insertSql1];
if (!res) {
NSLog(@"失败%d",i);
}
}
}
}];
}
});
- 我们从源码可以看到：
- (void)inDatabase:(__attribute__((noescape)) void (^)(FMDatabase *db))block {
...
//同步串行队列中执行
dispatch_sync(_queue, ^() {
FMDatabase *db = [self database];
block(db);
if ([db hasOpenResultSets]) {
#if defined(DEBUG) && DEBUG
NSSet *openSetCopy = FMDBReturnAutoreleased([[db valueForKey:@"_openResultSets"] copy]);
for (NSValue *rsInWrappedInATastyValueMeal in openSetCopy) {
FMResultSet *rs = (FMResultSet *)[rsInWrappedInATastyValueMeal pointerValue];
}
#endif
}
});
FMDBRelease(self);
}
-
(二)二次封装
每次都手写sql语句和处理对应model很麻烦，所以进行二次封装，直接参考别人的代码：
- 保存数据
- (BOOL)jq_insertTable:(NSString *)tableName dicOrModel:(id)parameters
{
NSArray *columnArr = [self getColumnArr:tableName db:_db];//获取表的字段
return [self insertTable:tableName dicOrModel:parameters columnArr:columnArr];
}
- (BOOL)insertTable:(NSString *)tableName dicOrModel:(id)parameters columnArr:(NSArray *)columnArr
{
BOOL flag;
NSDictionary *dic;
if ([parameters isKindOfClass:[NSDictionary class]]) {
dic = parameters;
}else {
dic = [self getModelPropertyKeyValue:parameters tableName:tableName clomnArr:columnArr];//runtime获取属性字段
}
//拼接 Sql 语句
NSMutableString *finalStr = [[NSMutableString alloc] initWithFormat:@"INSERT INTO %@ (", tableName];//sql
NSMutableString *tempStr = [NSMutableString stringWithCapacity:0];
NSMutableArray *argumentsArr = [NSMutableArray arrayWithCapacity:0];
for (NSString *key in dic) {
if (![columnArr containsObject:key] || [key isEqualToString:@"pkid"]) {
continue;
}
[finalStr appendFormat:@"%@,", key];
[tempStr appendString:@"?,"];
[argumentsArr addObject:dic[key]];//添加value
}
[finalStr deleteCharactersInRange:NSMakeRange(finalStr.length-1, 1)];
if (tempStr.length)
[tempStr deleteCharactersInRange:NSMakeRange(tempStr.length-1, 1)];
[finalStr appendFormat:@") values (%@)", tempStr];
flag = [_db executeUpdate:finalStr withArgumentsInArray:argumentsArr];
return flag; //拼接绑定的操作
}
// 获取model的key和value
- (NSDictionary *)getModelPropertyKeyValue:(id)model tableName:(NSString *)tableName clomnArr:(NSArray *)clomnArr
{
NSMutableDictionary *mDic = [NSMutableDictionary dictionaryWithCapacity:0];
unsigned int outCount;
objc_property_t *properties = class_copyPropertyList([model class], &outCount);//runtime获取属性字段
for (int i = 0; i < outCount; i++) {
NSString *name = [NSString stringWithCString:property_getName(properties[i]) encoding:NSUTF8StringEncoding];
if (![clomnArr containsObject:name]) {
continue;
}
id value = [model valueForKey:name];
if (value) {
[mDic setObject:value forKey:name];
}
}
free(properties);
return mDic;
}
- 读取数据
//数据库数据->model
- (NSArray *)jq_lookupTable:(NSString *)tableName dicOrModel:(id)parameters whereFormat:(NSString *)format, ...
{
va_list args;
va_start(args, format);
NSString *where = format?[[NSString alloc] initWithFormat:format locale:[NSLocale currentLocale] arguments:args]:format;
va_end(args);
NSMutableArray *resultMArr = [NSMutableArray arrayWithCapacity:0];
NSDictionary *dic;
NSMutableString *finalStr = [[NSMutableString alloc] initWithFormat:@"select * from %@ %@", tableName, where?where:@""];
NSArray *clomnArr = [self getColumnArr:tableName db:_db];
FMResultSet *set = [_db executeQuery:finalStr];
//字典
if ([parameters isKindOfClass:[NSDictionary class]]) {
...
}else {
Class CLS;
if ([parameters isKindOfClass:[NSString class]]) {
if (!NSClassFromString(parameters)) {
CLS = nil;
} else {
CLS = NSClassFromString(parameters);
}
} else if ([parameters isKindOfClass:[NSObject class]]) {//model类型
CLS = [parameters class];
} else {
CLS = parameters;
}
if (CLS) {
NSDictionary *propertyType = [self modelToDictionary:CLS excludePropertyName:nil];//runtime获取属性字段
while ([set next]) {
//kvc赋值
id model = CLS.new;
for (NSString *name in clomnArr) {
if ([propertyType[name] isEqualToString:SQL_TEXT]) {
id value = [set stringForColumn:name];
if (value)
[model setValue:value forKey:name];
} else if ([propertyType[name] isEqualToString:SQL_INTEGER]) {
[model setValue:@([set longLongIntForColumn:name]) forKey:name];
} else if ([propertyType[name] isEqualToString:SQL_REAL]) {
[model setValue:[NSNumber numberWithDouble:[set doubleForColumn:name]] forKey:name];
} else if ([propertyType[name] isEqualToString:SQL_BLOB]) {
id value = [set dataForColumn:name];
if (value)
[model setValue:value forKey:name];
}
}
[resultMArr addObject:model];
}
}
}
return resultMArr;
}
- (NSDictionary *)modelToDictionary:(Class)cls excludePropertyName:(NSArray *)nameArr
{
NSMutableDictionary *mDic = [NSMutableDictionary dictionaryWithCapacity:0];
unsigned int outCount;
objc_property_t *properties = class_copyPropertyList(cls, &outCount);//runtime获取属性字段
for (int i = 0; i < outCount; i++) {
NSString *name = [NSString stringWithCString:property_getName(properties[i]) encoding:NSUTF8StringEncoding];
if ([nameArr containsObject:name]) continue;
NSString *type = [NSString stringWithCString:property_getAttributes(properties[i]) encoding:NSUTF8StringEncoding];
id value = [self propertTypeConvert:type];
if (value) {
[mDic setObject:value forKey:name];
}
}
free(properties);
return mDic;
}
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