FMDB For iPhone DAO示例
来源：http://www.yifeiyang.net/iphone-developer-advanced-9-management-database-using-sqlite/
代码整体构造如下：
首先创建如下格式的数据库文件：
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$ sqlite3 sample.db
sqlite> CREATE TABLE TbNote(
...> id INTEGER PRIMARY KEY,
...> title VARCHAR(255),
...> body VARCHAR(255)
...> );
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创建DTO（Data Transfer Object）
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//TbNote.h
#import
@interface TbNote : NSObject {
int index;
NSString *title;
NSString *body;
}
@property (nonatomic, retain) NSString *title;
@property (nonatomic, retain) NSString *body;
- (id)initWithIndex:(int)newIndex Title:(NSString *)newTitle Body:(NSString *)newBody;
- (int)getIndex;
@end
//TbNote.m
#import "TbNote.h"
@implementation TbNote
@synthesize title, body;
- (id)initWithIndex:(int)newIndex Title:(NSString *)newTitle Body:(NSString *)newBody{
if(self = [super init]){
index = newIndex;
self.title = newTitle;
self.body = newBody;
}
return self;
}
- (int)getIndex{
return index;
}
- (void)dealloc {
[title release];
[body release];
[super dealloc];
}
@end
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创建DAO（Data Access Objects）
这里将 FMDB 的函数调用封装为 DAO 的方式。
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//BaseDao.h
#import
@class FMDatabase;
@interface BaseDao : NSObject {
FMDatabase *db;
}
@property (nonatomic, retain) FMDatabase *db;
-(NSString *)setTable:(NSString *)sql;
@end
//BaseDao.m
#import "SqlSampleAppDelegate.h"
#import "FMDatabase.h"
#import "FMDatabaseAdditions.h"
#import "BaseDao.h"
@implementation BaseDao
@synthesize db;
- (id)init{
if(self = [super init]){
// 由 AppDelegate 取得打开的数据库
SqlSampleAppDelegate *appDelegate = (SqlSampleAppDelegate *)[[UIApplication sharedApplication] delegate];
db = [[appDelegate db] retain];
}
return self;
}
// 子类中实现
-(NSString *)setTable:(NSString *)sql{
return NULL;
}
- (void)dealloc {
[db release];
[super dealloc];
}
@end
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下面是访问 TbNote 表格的类。
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//TbNoteDao.h
#import
#import "BaseDao.h"
@interface TbNoteDao : BaseDao {
}
-(NSMutableArray *)select;
-(void)insertWithTitle:(NSString *)title Body:(NSString *)body;
-(BOOL)updateAt:(int)index Title:(NSString *)title Body:(NSString *)body;
-(BOOL)deleteAt:(int)index;
@end
//TbNoteDao.m
#import "FMDatabase.h"
#import "FMDatabaseAdditions.h"
#import "TbNoteDao.h"
#import "TbNote.h"
@implementation TbNoteDao
-(NSString *)setTable:(NSString *)sql{
return [NSString stringWithFormat:sql, @"TbNote"];
}
// SELECT
-(NSMutableArray *)select{
NSMutableArray *result = [[[NSMutableArray alloc] initWithCapacity:0] autorelease];
FMResultSet *rs = [db executeQuery:[self setTable:@"SELECT * FROM %@"]];
while ([rs next]) {
TbNote *tr = [[TbNote alloc]
initWithIndex:[rs intForColumn:@"id"]
Title:[rs stringForColumn:@"title"]
Body:[rs stringForColumn:@"body"]
];
[result addObject:tr];
[tr release];
}
[rs close];
return result;
}
// INSERT
-(void)insertWithTitle:(NSString *)title Body:(NSString *)body{
[db executeUpdate:[self setTable:@"INSERT INTO %@ (title, body) VALUES (?,?)"], title, body];
if ([db hadError]) {
NSLog(@"Err %d: %@", [db lastErrorCode], [db lastErrorMessage]);
}
}
// UPDATE
-(BOOL)updateAt:(int)index Title:(NSString *)title Body:(NSString *)body{
BOOL success = YES;
[db executeUpdate:[self setTable:@"UPDATE %@ SET title=?, body=? WHERE id=?"], title, body, [NSNumber numberWithInt:index]];
if ([db hadError]) {
NSLog(@"Err %d: %@", [db lastErrorCode], [db lastErrorMessage]);
success = NO;
}
return success;
}
// DELETE
- (BOOL)deleteAt:(int)index{
BOOL success = YES;
[db executeUpdate:[self setTable:@"DELETE FROM %@ WHERE id = ?"], [NSNumber numberWithInt:index]];
if ([db hadError]) {
NSLog(@"Err %d: %@", [db lastErrorCode], [db lastErrorMessage]);
success = NO;
}
return success;
}
- (void)dealloc {
[super dealloc];
}
@end
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为了确认程序正确，添加一个 UITableView。使用 initWithNibName 测试 DAO。
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//NoteController.h
#import
@class TbNoteDao;
@interface NoteController : UIViewController
UITableView *myTableView;
TbNoteDao *tbNoteDao;
NSMutableArray *record;
}
@property (nonatomic, retain) UITableView *myTableView;
@property (nonatomic, retain) TbNoteDao *tbNoteDao;
@property (nonatomic, retain) NSMutableArray *record;
@end
//NoteController.m
#import "NoteController.h"
#import "TbNoteDao.h"
#import "TbNote.h"
@implementation NoteController
@synthesize myTableView, tbNoteDao, record;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {
tbNoteDao = [[TbNoteDao alloc] init];
[tbNoteDao insertWithTitle:@"TEST TITLE" Body:@"TEST BODY"];
// [tbNoteDao updateAt:1 Title:@"UPDATE TEST" Body:@"UPDATE BODY"];
// [tbNoteDao deleteAt:1];
record = [[tbNoteDao select] retain];
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
myTableView = [[UITableView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
myTableView.delegate = self;
myTableView.dataSource = self;
self.view = myTableView;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [record count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
}
TbNote *tr = (TbNote *)[record objectAtIndex:indexPath.row];
cell.text = [NSString stringWithFormat:@"%i %@", [tr getIndex], tr.title];
return cell;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (void)dealloc {
[super dealloc];
}
@end
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最后开看看连接DB，和添加 ViewController 的处理。这一同样不使用 Interface Builder。
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//SqlSampleAppDelegate.h
#import
@class FMDatabase;
@interface SqlSampleAppDelegate : NSObject
UIWindow *window;
FMDatabase *db;
}
@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) FMDatabase *db;
- (BOOL)initDatabase;
- (void)closeDatabase;
@end
//SqlSampleAppDelegate.m
#import "SqlSampleAppDelegate.h"
#import "FMDatabase.h"
#import "FMDatabaseAdditions.h"
#import "NoteController.h"
@implementation SqlSampleAppDelegate
@synthesize window;
@synthesize db;
- (void)applicationDidFinishLaunching:(UIApplication *)application {
if (![self initDatabase]){
NSLog(@"Failed to init Database.");
}
NoteController *ctrl = [[NoteController alloc] initWithNibName:nil bundle:nil];
[window addSubview:ctrl.view];
[window makeKeyAndVisible];
}
- (BOOL)initDatabase{
BOOL success;
NSError *error;
NSFileManager *fm = [NSFileManager defaultManager];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"sample.db"];
success = [fm fileExistsAtPath:writableDBPath];
if(!success){
NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"sample.db"];
success = [fm copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error];
if(!success){
NSLog([error localizedDescription]);
}
success = NO;
}
if(success){
db = [[FMDatabase databaseWithPath:writableDBPath] retain];
if ([db open]) {
[db setShouldCacheStatements:YES];
}else{
NSLog(@"Failed to open database.");
success = NO;
}
}
return success;
}
- (void) closeDatabase{
[db close];
}
- (void)dealloc {
[db release];
[window release];
[super dealloc];
}
@end
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