【发布时间】：2011-08-16 09:25:29
【问题描述】：
首先，我知道我不应该使用 SQLite 数据库来存储图像，但我只存储非常小的网站的 favicon。
我的问题是我尝试将这些 favicon 插入数据库（似乎有效），我使用 -tiffrepresentation 的 -tiffrepresentation 方法将 favicon 转换为 NSData NSimage，然后将其插入我的数据库到 blob专栏：
NSImage *favico = [webview mainFrameIcon];
[appDelegate insertBookmark:[titleField stringValue] url:[urlfield stringValue] data:[favico TIFFRepresentation]]
SQLite 方法如下所示：
-(void)insertBookmark:(NSString *)title url:(NSString *)url data:(NSData *)data
{
NSData *imagedata = [[NSData alloc]initWithData:data];
sqlite3 *database;
if(sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) {
NSString *query = [NSString stringWithFormat:@"INSERT INTO Bookmarks (title, url, image) VALUES ('%@', '%@', '%@')",title, url, data];
const char *querychar = [query UTF8String];
sqlite3_stmt *statement;
if (sqlite3_prepare_v2(database, querychar, -1, &statement, NULL) == SQLITE_OK)
{
int row = 3;
sqlite3_bind_blob(statement, row, [imagedata bytes], [imagedata length], NULL);
sqlite3_step(statement);
sqlite3_finalize(statement);
}
else
{
NSLog(@"Error");
}
[databasePath retain];
[databaseName retain];
}
sqlite3_close(database);
[imagedata release];
}
当我查看数据库时，图像列中有 <data> 之间的值（正常？）
现在，当我从数据库中提取 blob 并尝试将其放入我的对象中时，我在 NSimage 中得到了 null：
-(void) readDatabase {
// Setup the database object
sqlite3 *database;
bookmarks = [[NSMutableArray alloc] init];
// Open the database from the users filessytem
if(sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) {
// Setup the SQL Statement and compile it for faster access
const char *sqlStatement = "SELECT * FROM Bookmarks ORDER BY title ASC";
sqlite3_stmt *compiledStatement;
if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) {
// Loop through the results and add them to the feeds array
while(sqlite3_step(compiledStatement) == SQLITE_ROW) {
// Read the data from the result row
NSString *aTitle = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 1)];
NSString *aUrl = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 2)];
NSData *data = [[NSData alloc] initWithBytes:sqlite3_column_blob(compiledStatement, 3) length:sqlite3_column_bytes(compiledStatement, 3)];
NSImage *image = [[NSImage alloc]initWithData:data];
bookmarkObject *bookmark = [[bookmarkObject alloc] initWithName:aTitle url:aUrl favico:image];
[bookmarks addObject:bookmark];
[bookmark release];
[data release];
[image release];
}
}
// Release the compiled statement from memory
sqlite3_finalize(compiledStatement);
sqlite3_close(database);
[databasePath retain];
[databaseName retain];
}
}
提前致谢
【问题讨论】：
标签： objective-c cocoa sqlite blob nsimage