使用 SQLiteManager 操作 sqlite3 数据库
SQLiteManager
https://github.com/misato/SQLiteManager4iOS
本人以前从事过嵌入式开发,后来转职为iOS开发,即使如此,也绝不想去碰C语言级别的面向过程的 sqlite3 来操作数据库,做高级语言开发还去折腾面向过程的东西,一个小小的nil没判断好就导致程序崩溃, 这就是 sqlite3 APIs 给你带来的问题,只有封装成面向对象的接口才有可能会去用.有一个封装得挺好的 FMDB 是不二的选择,但这个 SQLiteManager 属于轻量级封装,满足了最最基本的需求,但是,他是在开了ARC的情形下使用的,也就是说,没开ARC后会各种泄露......
上面的链接可以下载源码,我修改了源码,适用于我自己,提供如下:
SQLiteManager.h
#import <Foundation/Foundation.h> #import "sqlite3.h" enum errorCodes { kDBNotExists, kDBFailAtOpen, kDBFailAtCreate, kDBErrorQuery, kDBFailAtClose }; @interface SQLiteManager : NSObject { sqlite3 *db; // The SQLite db reference NSString *databaseName; // The database name } - (id)initWithDatabaseNamed:(NSString *)name; // SQLite Operations - (NSError *) openDatabase; - (NSError *) doQuery:(NSString *)sql; - (NSError *)doUpdateQuery:(NSString *)sql withParams:(NSArray *)params; - (NSArray *) getRowsForQuery:(NSString *)sql; - (NSError *) closeDatabase; - (NSInteger)getLastInsertRowID; - (NSString *)getDatabaseDump; @end
SQLiteManager.m
#import "SQLiteManager.h" #define FOLDER_PATH @"/Library/Caches/YOU_FOLDER_NAME" // Private methods @interface SQLiteManager (Private) - (NSString *)getDatabasePath; - (NSError *)createDBErrorWithDescription:(NSString*)description andCode:(int)code; @end @implementation SQLiteManager #pragma mark Init & Dealloc /** * Init method. * Use this method to initialise the object, instead of just "init". * * @param name the name of the database to manage. * * @return the SQLiteManager object initialised. */ - (id)initWithDatabaseNamed:(NSString *)name; { self = [super init]; if (self != nil) { databaseName = [[NSString alloc] initWithString:name]; db = nil; } return self; } #pragma mark SQLite Operations /** * Open or create a SQLite3 database. * * If the db exists, then is opened and ready to use. If not exists then is created and opened. * * @return nil if everything was ok, an NSError in other case. * */ - (NSError *) openDatabase { NSError *error = nil; NSString *databasePath = [self getDatabasePath]; NSLog(@"%@", databasePath); const char *dbpath = [databasePath UTF8String]; int result = sqlite3_open(dbpath, &db); if (result != SQLITE_OK) { const char *errorMsg = sqlite3_errmsg(db); NSString *errorStr = [NSString stringWithFormat:@"The database could not be opened: %@",[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding]]; error = [self createDBErrorWithDescription:errorStr andCode:kDBFailAtOpen]; } return error; } /** * Does an SQL query. * * You should use this method for everything but SELECT statements. * * @param sql the sql statement. * * @return nil if everything was ok, NSError in other case. */ - (NSError *)doQuery:(NSString *)sql { NSError *openError = nil; NSError *errorQuery = nil; //Check if database is open and ready. if (db == nil) { openError = [self openDatabase]; } if (openError == nil) { sqlite3_stmt *statement; const char *query = [sql UTF8String]; sqlite3_prepare_v2(db, query, -1, &statement, NULL); if (sqlite3_step(statement) == SQLITE_ERROR) { const char *errorMsg = sqlite3_errmsg(db); errorQuery = [self createDBErrorWithDescription:[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding] andCode:kDBErrorQuery]; } sqlite3_finalize(statement); errorQuery = [self closeDatabase]; } else { errorQuery = openError; } return errorQuery; } /** * Does an SQL parameterized query. * * You should use this method for parameterized INSERT or UPDATE statements. * * @param sql the sql statement using ? for params. * * @param params NSArray of params type (id), in CORRECT order please. * * @return nil if everything was ok, NSError in other case. */ - (NSError *)doUpdateQuery:(NSString *)sql withParams:(NSArray *)params { NSError *openError = nil; NSError *errorQuery = nil; //Check if database is open and ready. if (db == nil) { openError = [self openDatabase]; } if (openError == nil) { sqlite3_stmt *statement; const char *query = [sql UTF8String]; sqlite3_prepare_v2(db, query, -1, &statement, NULL); //BIND the params! int count =0; for (id param in params ) { count++; if ([param isKindOfClass:[NSString class]] ) sqlite3_bind_text(statement, count, [param UTF8String], -1, SQLITE_TRANSIENT); if ([param isKindOfClass:[NSNumber class]] ) { if (!strcmp([param objCType], @encode(float))) sqlite3_bind_double(statement, count, [param doubleValue]); else if (!strcmp([param objCType], @encode(int))) sqlite3_bind_int(statement, count, [param intValue]); else if (!strcmp([param objCType], @encode(BOOL))) sqlite3_bind_int(statement, count, [param intValue]); else NSLog(@"unknown NSNumber"); } if ([param isKindOfClass:[NSDate class]]) { sqlite3_bind_double(statement, count, [param timeIntervalSince1970]); } if ([param isKindOfClass:[NSData class]] ) { sqlite3_bind_blob(statement, count, [param bytes], [param length], SQLITE_STATIC); } } if (sqlite3_step(statement) == SQLITE_ERROR) { const char *errorMsg = sqlite3_errmsg(db); errorQuery = [self createDBErrorWithDescription:[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding] andCode:kDBErrorQuery]; } sqlite3_finalize(statement); errorQuery = [self closeDatabase]; } else { errorQuery = openError; } return errorQuery; } - (NSInteger)getLastInsertRowID { NSError *openError = nil; sqlite3_int64 rowid = 0; //Check if database is open and ready. if (db == nil) { openError = [self openDatabase]; } if (openError == nil) { rowid = sqlite3_last_insert_rowid(db); } return (NSInteger)rowid; } /** * Does a SELECT query and gets the info from the db. * * The return array contains an NSDictionary for row, made as: key=columName value= columnValue. * * For example, if we have a table named "users" containing: * name | pass * ------------- * admin| 1234 * pepe | 5678 * * it will return an array with 2 objects: * resultingArray[0] = name=admin, pass=1234; * resultingArray[1] = name=pepe, pass=5678; * * So to get the admin password: * [[resultingArray objectAtIndex:0] objectForKey:@"pass"]; * * @param sql the sql query (remember to use only a SELECT statement!). * * @return an array containing the rows fetched. */ - (NSArray *)getRowsForQuery:(NSString *)sql { NSMutableArray *resultsArray = [[NSMutableArray alloc] initWithCapacity:1]; if (db == nil) { [self openDatabase]; } sqlite3_stmt *statement; const char *query = [sql UTF8String]; int returnCode = sqlite3_prepare_v2(db, query, -1, &statement, NULL); if (returnCode == SQLITE_ERROR) { const char *errorMsg = sqlite3_errmsg(db); NSError *errorQuery = [self createDBErrorWithDescription:[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding] andCode:kDBErrorQuery]; NSLog(@"%@", errorQuery); } while (sqlite3_step(statement) == SQLITE_ROW) { int columns = sqlite3_column_count(statement); NSMutableDictionary *result = [[NSMutableDictionary alloc] initWithCapacity:columns]; for (int i = 0; i<columns; i++) { const char *name = sqlite3_column_name(statement, i); NSString *columnName = [NSString stringWithCString:name encoding:NSUTF8StringEncoding]; int type = sqlite3_column_type(statement, i); switch (type) { case SQLITE_INTEGER: { int value = sqlite3_column_int(statement, i); [result setObject:[NSNumber numberWithInt:value] forKey:columnName]; break; } case SQLITE_FLOAT: { float value = sqlite3_column_double(statement, i); [result setObject:[NSNumber numberWithFloat:value] forKey:columnName]; break; } case SQLITE_TEXT: { const char *value = (const char*)sqlite3_column_text(statement, i); [result setObject:[NSString stringWithCString:value encoding:NSUTF8StringEncoding] forKey:columnName]; break; } case SQLITE_BLOB: { int bytes = sqlite3_column_bytes(statement, i); if (bytes > 0) { const void *blob = sqlite3_column_blob(statement, i); if (blob != NULL) { [result setObject:[NSData dataWithBytes:blob length:bytes] forKey:columnName]; } } break; } case SQLITE_NULL: [result setObject:[NSNull null] forKey:columnName]; break; default: { const char *value = (const char *)sqlite3_column_text(statement, i); [result setObject:[NSString stringWithCString:value encoding:NSUTF8StringEncoding] forKey:columnName]; break; } } //end switch } //end for [resultsArray addObject:result]; } //end while sqlite3_finalize(statement); [self closeDatabase]; return resultsArray; } /** * Closes the database. * * @return nil if everything was ok, NSError in other case. */ - (NSError *) closeDatabase { NSError *error = nil; if (db != nil) { if (sqlite3_close(db) != SQLITE_OK){ const char *errorMsg = sqlite3_errmsg(db); NSString *errorStr = [NSString stringWithFormat:@"The database could not be closed: %@",[NSString stringWithCString:errorMsg encoding:NSUTF8StringEncoding]]; error = [self createDBErrorWithDescription:errorStr andCode:kDBFailAtClose]; } db = nil; } return error; } /** * Creates an SQL dump of the database. * * This method could get a csv format dump with a few changes. * But i prefer working with sql dumps ;) * * @return an NSString containing the dump. */ - (NSString *)getDatabaseDump { NSMutableString *dump = [[NSMutableString alloc] initWithCapacity:256]; // info string ;) please do not remove it [dump appendString:@";\n; Dump generated with SQLiteManager4iOS \n;\n; By Misato (2011)\n"]; [dump appendString:[NSString stringWithFormat:@"; database %@;\n", [databaseName lastPathComponent]]]; // first get all table information NSArray *rows = [self getRowsForQuery:@"SELECT * FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%';"]; // last sql query returns something like: // { // name = users; // rootpage = 2; // sql = "CREATE TABLE users (id integer primary key autoincrement, user text, password text)"; // "tbl_name" = users; // type = table; // } //loop through all tables for (int i = 0; i<[rows count]; i++) { NSDictionary *obj = [rows objectAtIndex:i]; //get sql "create table" sentence NSString *sql = [obj objectForKey:@"sql"]; [dump appendString:[NSString stringWithFormat:@"%@;\n",sql]]; //get table name NSString *tableName = [obj objectForKey:@"name"]; //get all table content NSArray *tableContent = [self getRowsForQuery:[NSString stringWithFormat:@"SELECT * FROM %@",tableName]]; for (int j = 0; j<[tableContent count]; j++) { NSDictionary *item = [tableContent objectAtIndex:j]; //keys are column names NSArray *keys = [item allKeys]; //values are column values NSArray *values = [item allValues]; //start constructing insert statement for this item [dump appendString:[NSString stringWithFormat:@"insert into %@ (",tableName]]; //loop through all keys (aka column names) NSEnumerator *enumerator = [keys objectEnumerator]; id obj; while (obj = [enumerator nextObject]) { [dump appendString:[NSString stringWithFormat:@"%@,",obj]]; } //delete last comma NSRange range; range.length = 1; range.location = [dump length]-1; [dump deleteCharactersInRange:range]; [dump appendString:@") values ("]; // loop through all values // value types could be: // NSNumber for integer and floats, NSNull for null or NSString for text. enumerator = [values objectEnumerator]; while (obj = [enumerator nextObject]) { //if it's a number (integer or float) if ([obj isKindOfClass:[NSNumber class]]){ [dump appendString:[NSString stringWithFormat:@"%@,",[obj stringValue]]]; } //if it's a null else if ([obj isKindOfClass:[NSNull class]]){ [dump appendString:@"null,"]; } //else is a string ;) else{ [dump appendString:[NSString stringWithFormat:@"'%@',",obj]]; } } //delete last comma again range.length = 1; range.location = [dump length]-1; [dump deleteCharactersInRange:range]; //finish our insert statement [dump appendString:@");\n"]; } } return dump; } @end #pragma mark - @implementation SQLiteManager (Private) /** * Gets the database file path (in NSDocumentDirectory). * * @return the path to the db file. */ - (NSString *)getDatabasePath{ if([[NSFileManager defaultManager] fileExistsAtPath:databaseName]){ // Already Full Path return databaseName; } else { // 判断文件夹是否存在,不存在则创建文件夹 NSString *docsDir = [NSHomeDirectory() stringByAppendingString:FOLDER_PATH]; if (SQLiteManager_fileOrFolderExistFromSandbox(docsDir) == NO) { SQLiteManager_createFolderForSandbox(docsDir); } return [docsDir stringByAppendingPathComponent:databaseName]; } } #pragma mark 沙盒中创建文件夹 BOOL SQLiteManager_createFolderForSandbox(NSString *filePath) { return [[NSFileManager defaultManager] createDirectoryAtPath:filePath withIntermediateDirectories:YES attributes:nil error:nil]; } #pragma mark 文件或者文件夹是否存在 BOOL SQLiteManager_fileOrFolderExistFromSandbox(NSString *filePath) { return [[NSFileManager defaultManager] fileExistsAtPath:filePath isDirectory:NO]; } /** * Creates an NSError. * * @param description the description wich can be queried with [error localizedDescription]; * @param code the error code (code erors are defined as enum in the header file). * * @return the NSError just created. * */ - (NSError *)createDBErrorWithDescription:(NSString*)description andCode:(int)code { NSDictionary *userInfo = [[NSDictionary alloc] initWithObjectsAndKeys:description, NSLocalizedDescriptionKey, nil]; NSError *error = [NSError errorWithDomain:@"SQLite Error" code:code userInfo:userInfo]; return error; } @end
以下是增删改查以及常规操作:
打开数据库
//打开数据库 SQLiteManager *dbManager = [[SQLiteManager alloc] initWithDatabaseNamed:@"Y.X.db"];
创建表
NSError *error = nil; //创建表 /* id int 主键 user text password text */ error = [dbManager doQuery:@"CREATE TABLE IF NOT EXISTS users (id integer primary key autoincrement, user text, password text);"]; if (error != nil) { NSLog(@"Error: %@",[error localizedDescription]); }
插入
//在表中插入一条记录 error = [dbManager doQuery:@"insert into users (user, password) values ('YouXian','19871220');"]; if (error != nil) { NSLog(@"Error: %@",[error localizedDescription]); }
查询
//查询记录 [[dbManager getRowsForQuery:@"SELECT * FROM users"] enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) { NSLog(@"%@", obj); }];
修改
//修改一条记录 error = [dbManager doQuery:@"update users set user = 'YX',password = '1' where id = 1;"]; if (error != nil) { NSLog(@"Error: %@",[error localizedDescription]); }
删除
//删除一条记录 error = [dbManager doQuery:@"delete from users where id = 1;"]; if (error != nil) { NSLog(@"Error: %@",[error localizedDescription]); }
心得:
如果觉得自己想去捣鼓 C 语言级别的 API 不怕崩溃,可以去试试,对于我而言,不是我对其不感兴趣不愿意研究他,只是,在对性能没有要求的前提下花精力去造车轮子完全没有必要,真心话.
