博主:易飛揚 原文鏈接 : http://www.yifeiyang.net/iphone-developer-advanced-9-management-database-using-sqlite/ 轉載請保留上面文字。
iPhone開發進階(9)--- 用SQLite管理數據庫
今天我們來看看 iPhone 中數據庫的使用方法。iPhone 中使用名爲 SQLite 的數據庫管理系統。它是一款輕型的數據庫,是遵守ACID的關聯式數據庫管理系統,它的設計目標是嵌入式的,而且目前已經在很多嵌入式產品中使用了它,它佔用資源非常的低,在嵌入式設備中,可能只需要幾百K的內存就夠了。它能夠支持Windows/Linux/Unix等等主流的操作系統,同時能夠跟很多程序語言相結合,比如Tcl、PHP、Java等,還有ODBC接口,同樣比起Mysql、PostgreSQL這兩款開源世界著名的數據庫管理系統來講,它的處理速度比他們都快。
其使用步驟大致分爲以下幾步:
- 創建DB文件和表格
- 添加必須的庫文件(FMDB for iPhone, libsqlite3.0.dylib)
- 通過 FMDB 的方法使用 SQLite
- 創建DB文件和表格
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$ sqlite3 sample.db sqlite> CREATE TABLE TEST( ...> id INTEGER PRIMARY KEY, ...> name VARCHAR(255) ...> ); |
簡單地使用上面的語句生成數據庫文件後,用一個圖形化SQLite管理工具,比如 Lita 來管理還是很方便的。
然後將文件(sample.db)添加到工程中。
- 添加必須的庫文件(FMDB for iPhone, libsqlite3.0.dylib)
首先添加 Apple 提供的 sqlite 操作用程序庫 ibsqlite3.0.dylib 到工程中。
位置如下 /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS${VER}.sdk/usr/lib/libsqlite3.0.dylib
這樣一來就可以訪問數據庫了,但是爲了更加方便的操作數據庫,這裏使用 FMDB for iPhone。
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svn co http://flycode.googlecode.com/svn/trunk/fmdb fmdb |
如上下載該庫,並將以下文件添加到工程文件中:
FMDatabase.h FMDatabase.m FMDatabaseAdditions.h FMDatabaseAdditions.m FMResultSet.h FMResultSet.m
- 通過 FMDB 的方法使用 SQLite
使用 SQL 操作數據庫的代碼在程序庫的 fmdb.m 文件中大部分都列出了、只是連接數據庫文件的時候需要注意 — 執行的時候,參照的數據庫路徑位於 Document 目錄下,之前把剛纔的 sample.db 文件拷貝過去就好了。
位置如下 /Users/xxxx/Library/Application Support/iPhone Simulator/User/Applications/xxxx/Documents/sample.db
以下爲鏈接數據庫時的代碼:
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BOOL success; NSError *error; NSFileManager *fm = [NSFileManager defaultManager]; NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"sample.db"]; success = [fm fileExistsAtPath:writableDBPath]; if(!success){ NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"sample.db"]; success = [fm copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error]; if(!success){ NSLog([error localizedDescription]); } } // 連接DB FMDatabase* db = [FMDatabase databaseWithPath:writableDBPath]; if ([db open]) { [db setShouldCacheStatements:YES]; // INSERT [db beginTransaction]; int i = 0; while (i++ < 20) { [db executeUpdate:@"INSERT INTO TEST (name) values (?)" , [NSString stringWithFormat:@"number %d", i]]; if ([db hadError]) { NSLog(@"Err %d: %@", [db lastErrorCode], [db lastErrorMessage]); } } [db commit]; // SELECT FMResultSet *rs = [db executeQuery:@"SELECT * FROM TEST"]; while ([rs next]) { NSLog(@"%d %@", [rs intForColumn:@"id"], [rs stringForColumn:@"name"]); } [rs close]; [db close]; }else{ NSLog(@"Could not open db."); } |
接下來再看看用 DAO 的形式來訪問數據庫的使用方法,代碼整體構造如下。
首先創建如下格式的數據庫文件:
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$ sqlite3 sample.db sqlite> CREATE TABLE TbNote( ...> id INTEGER PRIMARY KEY, ...> title VARCHAR(255), ...> body VARCHAR(255) ...> ); |
- 創建DTO(Data Transfer Object)
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//TbNote.h #import <Foundation/Foundation.h> @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 |
- 創建DAO(Data Access Objects)
這裏將 FMDB 的函數調用封裝爲 DAO 的方式。
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//BaseDao.h #import <Foundation/Foundation.h> @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 取得打開的數據庫 SqlSampleAppDelegate *appDelegate = (SqlSampleAppDelegate *)[[UIApplication sharedApplication] delegate]; db = [[appDelegate db] retain]; } return self; } // 子類中實現 -(NSString *)setTable:(NSString *)sql{ return NULL; } - (void)dealloc { [db release]; [super dealloc]; } @end |
下面是訪問 TbNote 表格的類。
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//TbNoteDao.h #import <Foundation/Foundation.h> #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 |
爲了確認程序正確,我們添加一個 UITableView。使用 initWithNibName 測試 DAO。
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//NoteController.h #import <UIKit/UIKit.h> @class TbNoteDao; @interface NoteController : UIViewController <UITableViewDataSource, UITableViewDelegate>{ 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 |
最後我們開看看連接DB,和添加 ViewController 的處理。這一同樣不使用 Interface Builder。
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//SqlSampleAppDelegate.h #import <UIKit/UIKit.h> @class FMDatabase; @interface SqlSampleAppDelegate : NSObject <UIApplicationDelegate> { 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 |