iOS 数据储存--SQLite 操作数据库-FMDB，sqlite数据类型，保存图片，demo

1、SQLite 语句中 数据类型的储存

/* 不区分大小写

char(长度)。字符串

NULL. 空值

INTEGER. 整型

REAL.浮点型

TEXT.文本类型

BLOB. 二进制类型，用来存储文件，比如图片。

2、通过单利 操作数据库保存 ：Id Name UIImage .h+.m

#import <Foundation/Foundation.h>

@interface SaveDateToLocal : NSObject

+(SaveDateToLocal*)SaveDateToLocalShare;

/**
添加数据

@param Id id
@param Image uiimage
@param Name string
*/
-(void)SaveDateAddDateWithId:(NSString*)Id ImageviewImage:(UIImage*)Image nickName:(NSString*)Name;

/**
修改数据

@param Id id
@param Name name
@param Image uiimage
*/
-(void)SaveDatechangeMessageWithId:(NSString*)Id Name:(NSString*)Name  Image:(UIImage *)Image;

/**
查找数据

@param Id id
@return 包含数据的字典
*/
-(NSDictionary*)SaveDatesearchMessageWithId:(NSString*)Id;

/**
删除数据

@param Id id
*/
-(void)SaveDatedeleteMessageWithId:(NSString*)Id;

@end

.m

将图片转化成base64编码格式的字符串，直接以字符串的形式存放入数据库
存取方法不做过多介绍，上篇已经做过介绍，主要展示以下转化过程：

[html] view plain copy
//图片转化为base64字符串
UIImage *originImage = [UIImage imageNamed:@"origin.png"];
NSData *data = UIImageJPEGRepresentation(originImage, 1.0f);
NSString *encodedImageStr =[[NSString alloc] initWithData:data  encoding:NSUTF8StringEncoding];;
NSLog(@"Encoded image:%@", encodedImageStr);

[html] view plain copy
//base64字符串转化为图片
NSData *decodedImageData = [@"testdata" dataUsingEncoding:NSUTF8StringEncoding];
UIImage *decodedImage = [UIImage imageWithData:decodedImageData];
NSLog(@"Decoded image size: %@", NSStringFromCGSize(decodedImage.size));

*/
#import "SaveDateToLocal.h"
#import <FMDatabase.h>

@implementation SaveDateToLocal
static SaveDateToLocal * saveDateToLocal =nil;
static  FMDatabase * dataBase = nil;//静态变量全局使用

+(SaveDateToLocal*)SaveDateToLocalShare{

static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{

saveDateToLocal =[[self alloc]init];

NSString * strpath =[NSHomeDirectory() stringByAppendingPathComponent:@"Documents/userchat.db"];

//创建数据库
dataBase = [FMDatabase databaseWithPath:strpath];
//打开数据库
BOOL ret = [dataBase open];
if (ret == NO) {
NSLog(@"数据库打开失败");
}else{
NSLog(@"数据库打开成功");
}

//1.准备sqlite语句
/* 不区分大小写
char(长度)。字符串
NULL. 空值
INTEGER. 整型
REAL.浮点型
TEXT.文本类型
BLOB. 二进制类型，用来存储文件，比如图片。
*/
//userchat  数据库名字
//(Id char(30), Name char(40), Image blob )   数据名字+类型
NSString *sqlite = @"create table if not exists userchat(Id char(30), Name char(40), Image blob );";
//2.执行sqlite语句

int result = [dataBase executeUpdate:sqlite];
//3.sqlite语句是否执行成功

if (result == YES) {
NSLog(@"创建表成功");
} else {
NSLog(@"创建表失败");
}

});

return saveDateToLocal;

}

//插入数据
-(void)SaveDateAddDateWithId:(NSString*)Id ImageviewImage:(UIImage*)Image nickName:(NSString*)Name{

//插入之前 先查询有没有 有了就替换

NSDictionary * dict =[self SaveDatesearchMessageWithId:Id];

if (dict) {

//有值  替换／更新
[self SaveDatechangeMessageWithId:Id Name:Name Image:Image];

}
else{

NSString *sql = @"insert into userchat(Id , Name, Image) values(?, ?, ?);";

//图片转化为data
NSData *data =UIImageJPEGRepresentation(Image, 1.0);

NSLog(@"Encoded image:%@", data);
//? 在这里 类似OC中的  %@
BOOL ret = [dataBase executeUpdate:sql,Id, Name, data];
if (ret == YES) {
NSLog(@"插入成功");
}else{

NSLog(@"插入失败");
}

}
}

-(void)SaveDatechangeMessageWithId:(NSString*)Id Name:(NSString*)Name  Image:(UIImage *)Image
{

//图片转化为data字符串
NSData *data =UIImageJPEGRepresentation(Image, 1.0);

// 1、创建sql语句
NSString *sql = @"update userchat set Name =? , Image = ? where Id = ?;";
// 2、执行sql语句
BOOL ret = [dataBase executeUpdate:sql, Name,data,Id];
if (ret == YES) {
NSLog(@"修改数据成功");
}
}

-(NSDictionary*)SaveDatesearchMessageWithId:(NSString*)Id
{

NSMutableDictionary * dict =[NSMutableDictionary dictionary];

// 1、写sql语句
NSString *sql = @"select *from userchat where Id = ? ;";
FMResultSet *set = [dataBase executeQuery:sql,Id];
//使用while循环
while ([set next]) {
//FMResultSet是一个集合，保存所有符合条件的数据
//next是一个自动循环的指针,调用next可以遍历整个集合
//当遍历完成以后,next会指向空,循环退出

//将数据从集合中取出
NSString *name = [set stringForColumn:@"Name"];

if (name.length>0) {
NSData * image = [set dataForColumn:@"Image"];

//NSData *decodedImageData = [image dataUsingEncoding:NSUTF8StringEncoding];
UIImage *decodedImage = [UIImage imageWithData:image];

NSDictionary * userchat =@{@"Name":name,@"Image":decodedImage};

[dict setDictionary:userchat];

break ;

}

}

return dict;
}

-(void)SaveDatedeleteMessageWithId:(NSString*)Id
{
NSString *sql = @"delete from userchat where Name = ?;";
BOOL ret = [dataBase executeUpdate:sql,Id];
if (ret == YES) {
NSLog(@"删除成功");
}else{

NSLog(@"删除shibai");
}
}
@end

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