iOS Sqlite3 数据库的升级
在含有数据库的应用中，随着应用版本的迭代更新，以前设计的数据库表很可能不能满足现在的业务需求，所以我们的应用就需要考虑数据库版本更新，以应对当前的业务。在数据库升级的情况中，有需要给老版本的数据库表增加字段或者添加索引的情况，也有增加新表的情况，还有对旧表中的数据进行升级的情况等。下面使用Sqlite3对这些情况给出一种解决方案。
1、整体逻辑概述
1）初始数据库在应用程序中包含一份，然后在程序第一次运行的时候，拷贝到Document一份。
2）对数据库的版本作检查，如果当前数据库的版本没有应用程序的版本大，那么就考虑对数据库做版本升级操作。
3）在数据库升级的时候，让数据库配置表（一个存放数据库表信息的plist文件）和初始化数据库表中的信息做对比，初始化数据库表中没有的字段，在初始化数据库表中新增进去，对于新增的表也一样，需要在初始化数据库表中新建。之后，对数据库中的内容做检查，通过配置文件中的内容和当前版本信息，决定是否对其中的内容做升级和变迁操作。
2、具体实现
1）先看一下一些文件的配置和作用
这里做一些简要说明。
Database.db是一个初始数据库。这里有建立好的数据库文件。在程序第一次运行的时候，会将其从程序中拷贝到沙盒文件中。
tables.plist文件是数据库文件的配置表。具体内容如上图的右半部分。这是一个字典，第一级为数据库的表名，第二级为数据库表中字段。其中字段类型为Number类型，且值为1代表是该表的主键。
DatabaseForUpdate.plist文件是数据升级配置表文件，这个文件中配置了一些信息，该信息用来决定哪个版本一下的应用需要执行该数据库升级的文件，此数据库升级的文件是updateDatabase.sql.
updateDatabase.sql文件是数据库升级的文件。
2）下面给出一些具体的代码
YCHanddleDatabase.m文件
#import "YCHanddleDatabase.h"
#import "YCSystemConfigTool.h"
#import "NSString+Extension.h"
#import "YCSqlite.h"
#define MRDatabaseUpgradeFileName @"DatabaseForUpdate.plist"
#define BelowVersionNeedDatabaseUpgradeKey @"BelowVersionNeedDatabaseUpgrade"
#define DatabaseUpgradeSqlFileNameKey @"DatabaseUpgradeFileNameKey"
#define DatabaseUpgradeSpecificVersionKey @"DatabaseUpgradeSpecificVersion"
@implementation YCHanddleDatabase
- (instancetype)initWithDatabasePath:(NSString *)databasePath {
if (self = [super init]) {
NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSString *databasePath = [documentPath stringByAppendingPathComponent:@"Database.db"];
NSFileManager *fileManager = [NSFileManager defaultManager];
if (![fileManager fileExistsAtPath:databasePath]) {
NSString *localDatabasePath = [[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:@"Database.db"];
[fileManager copyItemAtPath:localDatabasePath toPath:databasePath error:nil];
NSURL *fileUrl = [NSURL fileURLWithPath:databasePath];
[fileUrl setResourceValue:[NSNumber numberWithBool:YES] forKey:NSURLIsExcludedFromBackupKey error:nil];
[self checkoutDatabaseUpgrade];
[YCSystemConfigTool setDatabaseConfigVersion:[[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleShortVersionString"]];
} else {
if (![[YCSystemConfigTool getDatabaseConfigVersioin] isEqualToString:[[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleShortVersionString"]]) {
[self checkoutDatabaseUpgrade];
[YCSystemConfigTool setDatabaseConfigVersion:[[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleShortVersionString"]];
}
}
}
return self;
}
- (void)checkoutDatabaseUpgrade {
NSString *documentPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSString *databasePath = [documentPath stringByAppendingPathComponent:@"Database.db"];
_database = [[YCSqlite alloc] initSqliteWithDbFilePath:databasePath];
[self databaseUpgradeForTables];
[self databaseUpgradeForMrigation];
}
- (void)databaseUpgradeForTables {
NSString *tablesPath = [[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:@"tables.plist"];
NSDictionary *tablesDic = [NSDictionary dictionaryWithContentsOfFile:tablesPath];
NSArray *tableNames = tablesDic.allKeys;
for (NSString *tableName in tableNames) {
BOOL isExists = NO;
NSString *sqlString = @"SELECT [sql] FROM [sqlite_master] WHERE [type]='table' AND [name]=:name";
NSDictionary *params = @{@"name" : tableName};
YCSqliteResultSet *resultSet = [_database qeuryWithSql:sqlString params:params];
if ([resultSet hasNext]) {
[self alterTableWithTablesDictionary:tablesDic tableName:tableName resultSet:resultSet];
isExists = YES;
}
[resultSet close];
if (!isExists) {
NSMutableString *createTableSqlMutableString = [self createTableSqlWithTablesDictionary:tablesDic tableName:tableName];
if (![_database executeSql:createTableSqlMutableString params:nil]) {
NSLog(@"-----Database:%@-----", [_database errmsg]);
}
}
}
}
- (void)alterTableWithTablesDictionary:(NSDictionary *)tablesDic tableName:(NSString *)tableName resultSet:(YCSqliteResultSet *)resultSet {
NSString *createTableSqlString = [[resultSet stringValueAtIndex:0] lowercaseString];
NSDictionary *clonumNameDictionary = [tablesDic valueForKey:tableName];
for (NSString *columnKey in clonumNameDictionary.allKeys) {
NSString *columnName = [columnKey lowercaseString];
if ([createTableSqlString rangeOfString:columnName].location == NSNotFound) {
NSString * columnType = @"VarChar";
NSObject * columnObj = [clonumNameDictionary valueForKey:columnKey];
if ([columnObj isKindOfClass:[NSString class]]) {
columnType = @"text";
} else if ([columnObj isKindOfClass:[NSNumber class]]) {
columnType = @"integer";
}
BOOL isPrimaryKey = [[clonumNameDictionary valueForKey:columnKey] intValue] == 1;
[_database executeSql:[NSString stringWithFormat:@"ALTER TABLE [%@] ADD COLUMN %@ %@;",tableName,columnName,columnType] params:nil];
if (isPrimaryKey) {
[_database executeSql:[NSString stringWithFormat:@"ALTER TABLE [%@] ADD PRIMARY KEY(%@);",tableName, columnName] params:nil];
}
}
}
}
- (NSMutableString *)createTableSqlWithTablesDictionary:(NSDictionary *)tablesDic tableName:(NSString *)tableName {
NSMutableString *createTableSqlMutableString = [NSMutableString stringWithCapacity:1024];
[createTableSqlMutableString appendFormat:@"CREATE TABLE IF NOT EXISTS '%@' ",tableName];
NSDictionary * columnDic = [tablesDic valueForKey:tableName];
NSMutableString *primaryKeyString = [NSMutableString string];
NSInteger i = 0;
for (NSString *columnName in columnDic.allKeys) {
NSString * columnType = @"text";
NSObject * columnObj = [columnDic valueForKey:columnName];
if ([columnObj isKindOfClass:[NSString class]]) {
columnType = @"text";
} else if ([columnObj isKindOfClass: [NSNumber class]]) {
columnType = @"integer";
}
if (i == 0) {
[createTableSqlMutableString appendFormat:@"('%@' %@",columnName,columnType];
} else {
[createTableSqlMutableString appendFormat:@",'%@' %@",columnName,columnType];
}
BOOL isPrimaryKey = [[columnDic valueForKey:columnName] intValue] == 1;
if (isPrimaryKey) {
if (primaryKeyString.length==0) {
[primaryKeyString appendFormat:@"'%@'",columnName];
} else {
[primaryKeyString appendFormat:@",'%@'",columnName];
}
}
i++;
}//end for
if (primaryKeyString.length > 0) {
[createTableSqlMutableString appendFormat:@",PRIMARY KEY(%@)", primaryKeyString];
}
[createTableSqlMutableString appendString:@");"];
return createTableSqlMutableString;
}
- (void)databaseUpgradeForMrigation {
NSMutableArray *databaseUpgradeConfigArray = [NSMutableArray arrayWithContentsOfFile:[[[NSBundle mainBundle] bundlePath] stringByAppendingPathComponent:MRDatabaseUpgradeFileName]];
NSString *oldVersionString;
if ([YCSystemConfigTool getDatabaseConfigVersioin] == nil) {
oldVersionString = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleShortVersionString"];
} else {
oldVersionString = [YCSystemConfigTool getDatabaseConfigVersioin];
}
for (NSDictionary *dict in databaseUpgradeConfigArray) {
if (dict[BelowVersionNeedDatabaseUpgradeKey] != nil) {
NSString *version = dict[BelowVersionNeedDatabaseUpgradeKey];
if (version.integerValue < 0 || [version isGreatThanVersionNumber:oldVersionString]) {
[self databaseCaseFolderUpgradeForDataMigrationWithSqlFileName:dict[DatabaseUpgradeSqlFileNameKey]];
}
}
}
}
- (void)databaseCaseFolderUpgradeForDataMigrationWithSqlFileName:(NSString *)sqlFileName
{
NSString *localPath = [[NSBundle mainBundle] bundlePath];
NSString *sqlStrings = [NSString stringWithContentsOfFile:[localPath stringByAppendingPathComponent:sqlFileName] encoding:NSUTF8StringEncoding error:nil];
NSArray *sqls = [sqlStrings componentsSeparatedByString:@";"];
for (NSString *sql in sqls) {
if ([sql isEqualToString:@""]) {
continue;
}
BOOL flag = [_database executeSql:sql params:nil];
if (!flag) {
NSLog(@"%@^^^^^^sqlite operation occur error", sql);
}
}
}
- (NSString *)getVersionWithDict:(NSDictionary *)dict
{
NSString *version = nil;
if (dict[BelowVersionNeedDatabaseUpgradeKey] != nil) {
version = dict[BelowVersionNeedDatabaseUpgradeKey];
} else if (dict[DatabaseUpgradeSpecificVersionKey]) {
version = dict[DatabaseUpgradeSpecificVersionKey];
} else {
version = @"1.0.0";
}
return version;
}
@end
YCHanddleDatabase.h文件
#import YCHanddleDatabase文件中主要是一些数据库升级的逻辑。主要是两部分，第一部分是数据库完整表的建立，第二部分是数据升级的操作。分别集中在databaseUpgradeForTables和databaseUpgradeForMrigation 方法中。
下面再给出YCHanddleDatabase中涉及到的一些其他文件
YCSqlite.h文件
#import YCSqlite.m文件
#import "YCSqlite.h"
#include YCSqliteResultSet.h文件
#import YCSqliteResultSet.m文件
#import "YCSqliteResultSet.h"
@interface YCSqliteResultSet()
@property (nonnull, assign) sqlite3 *sqlite;
@property (nonnull, assign) sqlite3_stmt *stmt;
@property(nonatomic,readonly,getter = isClosed) BOOL closed;
@end
@implementation YCSqliteResultSet
- (instancetype)initWithStmt:(sqlite3_stmt *)stmt sqlite:(sqlite3 *)sqlite {
if (stmt == NULL || sqlite == NULL) {
return nil;
}
if (self = [super init]) {
_sqlite = sqlite;
_stmt = stmt;
}
return self;
}
- (BOOL)hasNext {
if (_stmt == NULL || _sqlite == NULL) {
return NO;
}
if(_stmt){
return sqlite3_step(_stmt) == SQLITE_ROW;
}
return NO;
}
- (NSString *)stringValueAtIndex:(int)index {
if(_stmt){
const char *cString = (const char *)sqlite3_column_text(_stmt, index);
return cString ? [NSString stringWithCString:cString encoding:NSUTF8StringEncoding] : nil;
}
return nil;
}
- (void)close {
if(!_closed){
if(_stmt){
sqlite3_finalize(_stmt);
_stmt = NULL;
}
_closed = YES;
}
}
@end
YCSystemConfigTool.h文件
#import YCSystemConfigTool.m文件
#import "YCSystemConfigTool.h"
#define DatabaseVersionKey @"DatabaseVersion"
@implementation YCSystemConfigTool
+ (void)saveValue:(id)value forKey:(NSString *)key {
if (!key) {
return;
}
if (!value) {
value = @"";
}
NSMutableDictionary *configDictionary = [NSMutableDictionary dictionaryWithContentsOfFile:SystemConfigPath];
if (!configDictionary) {
configDictionary = [NSMutableDictionary dictionary];
}
[configDictionary setValue:value forKey:key];
[configDictionary writeToFile:SystemConfigPath atomically:YES];
}
+ (id)getValueByKey:(NSString *)key {
if ([[NSFileManager defaultManager] fileExistsAtPath:SystemConfigPath]) {
NSMutableDictionary *configDictionary = [NSMutableDictionary dictionaryWithContentsOfFile:SystemConfigPath];
if (configDictionary) {
return configDictionary[key];
}
}
return nil;
}
+ (void)setDatabaseConfigVersion:(NSString *)version {
[self saveValue:version forKey:DatabaseVersionKey];
}
+ (NSString *)getDatabaseConfigVersioin {
return [self getValueByKey:DatabaseVersionKey];
}
@end
到此基本上给出了所有的文件。感兴趣的读者可以主要看YCHanddleDatabase.m文件中的逻辑。理解该逻辑实现数据库升级的功能就不难了。