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>) {
            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