iPhone开发进阶（9）--- 用SQLite管理数据库

时间  2019-11-10
标签 iphone 开发 进阶 sqlite 管理 数据库 栏目 iPhone 繁體版
原文   原文链接
  • 博主：易飞扬
  • 原文连接 : http://www.yifeiyang.net/iphone-developer-advanced-9-management-database-using-sqlite/
  • 转载请保留上面文字。

    • iPhone开发进阶（9）--- 用SQLite管理数据库linux

    今天咱们来看看 iPhone 中数据库的使用方法。iPhone 中使用名为 SQLite 的数据库管理系统。它是一款轻型的数据库，是遵照ACID的关联式数据库管理系统，它的设计目标是嵌入式的，并且目前已经在不少嵌入式产品中使用了它，它 占用资源很是的低，在嵌入式设备中，可能只须要几百K的内存就够了。它可以支持Windows/Linux/Unix等等主流的操做系统，同时可以跟不少 程序语言相结合，好比Tcl、PHP、Java等，还有ODBC接口，一样比起Mysql、PostgreSQL这两款开源世界著名的数据库管理系统来 讲，它的处理速度比他们都快。sql

    其使用步骤大体分为如下几步：数据库

    1. 建立DB文件和表格
    2. 添加必须的库文件(FMDB for iPhone, libsqlite3.0.dylib)
    3. 经过 FMDB 的方法使用 SQLite
    建立DB文件和表格 

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    $ sqlite3 sample.db
sqlite> CREATE TABLE TEST(
   ...>  id INTEGER PRIMARY KEY,
   ...>  name VARCHAR(255)
   ...> );

    简单地使用上面的语句生成数据库文件后，用一个图形化SQLite管理工具，好比 Lita 来管理仍是很方便的。app

    而后将文件(sample.db)添加到工程中。iphone

    添加必须的库文件(FMDB for iPhone, libsqlite3.0.dylib)

    首先添加 Apple 提供的 sqlite 操做用程序库 ibsqlite3.0.dylib 到工程中。svn

    位置以下
/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS${VER}.sdk/usr/lib/libsqlite3.0.dylib


    这样一来就能够访问数据库了，可是为了更加方便的操做数据库，这里使用 FMDB for iPhone。函数

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    svn co http://flycode.googlecode.com/svn/trunk/fmdb fmdb

    如上下载该库，并将如下文件添加到工程文件中：工具

    FMDatabase.h
FMDatabase.m
FMDatabaseAdditions.h
FMDatabaseAdditions.m
FMResultSet.h
FMResultSet.m
    经过 FMDB 的方法使用 SQLite

    使用 SQL 操做数据库的代码在程序库的 fmdb.m 文件中大部分都列出了、只是链接数据库文件的时候须要注意 — 执行的时候，参照的数据库路径位于 Document 目录下，以前把刚才的 sample.db 文件拷贝过去就行了。post

    位置以下
/Users/xxxx/Library/Application Support/iPhone Simulator/User/Applications/xxxx/Documents/sample.db

    如下为连接数据库时的代码：测试

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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]);
  }
}// 链接DBFMDatabase* 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.");
}

    接下来再看看用 DAO 的形式来访问数据库的使用方法，代码总体构造以下。


    sqlite

    首先建立以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)
   ...> );
    建立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
    建立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 <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

    下面是访问 TbNote 表格的类。

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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

    为了确认程序正确，咱们添加一个 UITableView。使用 initWithNibName 测试 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

    最后咱们开看看链接DB，和添加 ViewController 的处理。这一一样不使用 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
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