FMDB的使用

曾经终败给现在 2022-08-09 18:49 134阅读 0赞

\#import <Foundation/Foundation.h>  
\#import "Student.h"  
  
@interface StudentManager : NSObject  
  
\+ (instancetype)sharedManager;  
  
\- (BOOL)add:(Student \*)student;  
\- (BOOL)delete:(Student \*)student;  
\- (BOOL)update:(Student \*)student;  
\- (NSMutableArray \*)selectAll;

@end

\#import "StudentManager.h"  
\#import "FMDatabase.h"  
  
@implementation StudentManager  
\{  
    FMDatabase \*\_dataBase; // FMDB对象，这个对象负责数据库操作，它关联了我们的数据库文件  
\}  
  
\+ (instancetype)sharedManager \{  
    static StudentManager \*manager = nil;  
    @synchronized(self) \{  
        if (manager == nil) \{  
            manager = \[\[StudentManager alloc\] init\];  
        \}  
    \}  
    return manager;  
\}  
  
\- (id)init \{  
    if (self = \[super init\]) \{  
        // 配置数据库  
        // 1. 获取沙盒路径，因为数据库文件要存储在沙盒中  
        NSString \*documentPath = \[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0\]; // 找到沙盒下面的Docuemnts文件夹路径，相当于 \[NSHomeDirectory() stringByAppendingPathComponents:@"Document"\]  
          
        // 2. 在沙盒中指定数据库文件路径  
        NSString \*dbPath = \[documentPath stringByAppendingPathComponent:@"DBDemo.db"\];  
          
        // 3. 新建FMDB对象并调用initWithPath关联数据库文件  
        \_dataBase = \[\[FMDatabase alloc\] initWithPath:dbPath\];  
          
        // 4.  打开数据库创建表格  
        // 打开数据库文件，如果这个文件（dbPath）原来是存在的, 则直接打开，不会破坏原来的内容  
        // 如果不存在，则自动创建一个空的数据库文件  
        if (\[\_dataBase open\]) \{  
             NSString \*sql = @"create table if not exists student(id varchar(128), name text, age integer, headImage blob)"; // blob：存放二进制，data  
            if (\[\_dataBase executeUpdate:sql\]) \{  
                NSLog(@"成功创建表格 student");  
            \}  
        \}  
        \[\_dataBase close\];  
    \}  
    return self;  
\}  
  
\- (BOOL)add:(Student \*)student \{  
    if (!\[\_dataBase open\]) \{  
        return NO;  
    \}  
    NSString \*sql = @"insert into student values(?,?,?,?)"; // ?占位，?表示的对象要等下填充，特别注意，在FMDB里面，要用对象填充，所以如果要填充整型，就必湏用包装器NSNumber包装成对象  
      
    // 执行sql语句  
    BOOL success = \[\_dataBase executeUpdate:sql, student.id, student.name, \[NSNumber numberWithInt:student.age\], UIImageJPEGRepresentation(student.headImage, 1.0)\];  
    if (success) \{  
        NSLog(@"成功插入一条数据");  
    \}  
    \[\_dataBase close\];  
    return success;  
\}  
  
\- (BOOL)delete:(Student \*)student \{  
    return \[self deleteById:student.id\];  
\}  
  
\- (BOOL)deleteById:(NSString \*)studentId \{  
    if (\[\_dataBase open\] == NO) \{  
        return NO;  
    \}  
    NSString \*sql = @"delete from student where id=?";  
    BOOL success = \[\_dataBase executeUpdate:sql, studentId\];  
    \[\_dataBase close\];  
    return success;  
\}  
  
\- (BOOL)update:(Student \*)student \{  
    // 根据id更新  
    if (\[\_dataBase open\] == NO) \{  
        return NO;  
    \}  
    NSString \*sql = @"update student set name=?, age=?, headImage=? where id=?";  
    BOOL success = \[\_dataBase executeUpdate:sql, student.name, \[NSNumber numberWithInt:student.age\], UIImageJPEGRepresentation(student.headImage, 1.0), student.id\];  
    \[\_dataBase close\];  
    return success;  
\}  
  
\- (NSMutableArray \*)selectAll \{  
    if (\[\_dataBase open\] == NO) \{  
        return nil;  
    \}  
    NSString \*sql = @"select \* from student";  
    FMResultSet \*set = \[\_dataBase executeQuery:sql\];  
    NSMutableArray \*array = \[NSMutableArray array\];  
    while (\[set next\]) \{  
        Student \*student = \[\[Student alloc\] init\];  
        // \[set stringForColumn:@"xxx"\] 根据域名xxx取相应的数据  
        student.id   = \[set stringForColumn:@"id"\];  
        student.name = \[set stringForColumn:@"name"\];  
        student.age  = \[set intForColumn:@"age"\];  
        // \[set intForColumnIndex:3\];  
        student.headImage = \[UIImage imageWithData:\[set dataForColumn:@"headImage"\]\];  
        \[array addObject:student\];  
    \}  
    \[\_dataBase close\];  
    return array;  
\}  
  
@end