從iOS的SQLite數據庫中存儲和檢索圖像

Question

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    [self createDB]; 
} 

-(void)createDB { 
    NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *docdir = [path objectAtIndex:0]; //path[0]; 
    dbpath = [docdir stringByAppendingPathComponent:@"arun.sqlite"]; 
    NSLog(@"database path : %@",dbpath); 

    NSFileManager *filemgr = [NSFileManager defaultManager]; 
    if ([filemgr fileExistsAtPath:dbpath] == NO) { 
     //OPEN AND CREATE DATABASE 
     if (sqlite3_open([dbpath UTF8String], &myDB) == SQLITE_OK) { 
      //CREATE TABLE 
      NSString *createSQL = @"CREATE TABLE IF NOT EXISTS STUDENT (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT, ADDRESS TEXT, ROLLNO INTEGER,IMAGE BLOB)"; 

      char *error = nil; 
      if (sqlite3_exec(myDB, [createSQL UTF8String] , NULL, NULL, &error) == SQLITE_OK) { 
       NSLog(@"Database and tables created."); 
      } else { 
        NSLog(@"Error %s",error); 
      } 

      sqlite3_close(myDB); 
     } 
    } 
} 

- (void)saveImage { 
    sqlite3_stmt *compiledStmt; 
    sqlite3 *db; 
    if(sqlite3_open([dbpath UTF8String], &db)==SQLITE_OK) { 
     NSString *insertSQL = [NSString stringWithFormat:@"INSERT INTO STUDENT (ROLLNO,IMAGE) VALUES(\"%@\", \"%@\")", rollnoTxt.text, selectImgvw.image]; 
     if(sqlite3_prepare_v2(db,[insertSQL cStringUsingEncoding:NSUTF8StringEncoding], -1, &compiledStmt, NULL) == SQLITE_OK){ 
      UIImage *image = selectImgvw.image; 
      NSData *imgdata = UIImagePNGRepresentation(image); 

      sqlite3_bind_blob(compiledStmt, 1, [imgdata bytes], (int)[imgdata length], SQLITE_TRANSIENT); 

      if(sqlite3_step(compiledStmt) != SQLITE_DONE) { 
       NSLog(@"Error: %s", sqlite3_errmsg(db)); 
      } else { 
       NSLog(@"Insert into row id = %lld", (sqlite3_last_insert_rowid(db))); 
      } 

      sqlite3_finalize(compiledStmt); 
     } 
    } 
    sqlite3_close(db); 
} 


- (void)showImage { 
    sqlite3_stmt *compiledStmt; 
    sqlite3 *db; 
    if(sqlite3_open([dbpath UTF8String], &db)==SQLITE_OK){ 
     NSString *insertSQL = [NSString stringWithFormat:@"SELECT IMAGE FROM STUDENT WHERE ROLLNO = %@",rollnoTxt.text]; 
     if(sqlite3_prepare_v2(db,[insertSQL cStringUsingEncoding:NSUTF8StringEncoding], -1, &compiledStmt, NULL) == SQLITE_OK) { 
      while(sqlite3_step(compiledStmt) == SQLITE_ROW) { 
       int length = sqlite3_column_bytes(compiledStmt, 0); 
       NSData *imgdata = [NSData dataWithBytes:sqlite3_column_blob(compiledStmt, 0) length:length]; 

       NSLog(@"Length : %ld", [imgdata length]); 

       if(imgdata == nil) 
        NSLog(@"No image found."); 
       else { 
        UIImage *img = [UIImage imageWithData:imgdata]; 
        displayImgvw.image = img; 
       } 
      } 
     } 
     sqlite3_finalize(compiledStmt); 
    } 
    sqlite3_close(db); 
} 

以上是我的代碼片段。 圖像被保存到SQLiteDataBase但問題是，當獲取圖像時，我沒有得到任何價值時飼料圖像視圖。 我一直在做一段時間。有更多的研究，但無法解決它。 如果有人能解決這個問題，請給我建議。

Answer 1

您嘗試在數據庫中存儲完整圖像。

但是，如果您將圖像存儲在文檔目錄路徑。

並將此路徑存儲到數據庫。

然後很容易存儲和檢索圖像。

下面是我的代碼。

對於文件目錄路徑保存圖像

NSString *pathsToReources = [[NSBundle mainBundle] resourcePath]; 
NSString *yourOriginalDatabasePath = [pathsToReources stringByAppendingPathComponent:@"Demo.sqlite"]; 
NSArray *pathsToDocuments =NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
NSString *documentsDirectory = [pathsToDocuments objectAtIndex: 0]; 

NSString *dbPath = [documentsDirectory stringByAppendingPathComponent:@"Demo.sqlite"]; 
if (![[NSFileManager defaultManager] isReadableFileAtPath: dbPath]) { 
    if ([[NSFileManager defaultManager] copyItemAtPath: yourOriginalDatabasePath toPath: dbPath error: NULL] != YES) 
     NSAssert2(0, @"Fail to copy database from %@ to %@", yourOriginalDatabasePath, dbPath); 
} 

databasePath = [[NSString alloc]initWithString: [NSString stringWithFormat:@"%@",dbPath]]; 

const char *dbpath = [databasePath UTF8String]; 
sqlite3_stmt *statement; 
NSString * timestamp = [NSString stringWithFormat:@"%f.png",[[NSDate date] timeIntervalSince1970] * 1000]; 
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES); 
NSString *documentsPath = [paths objectAtIndex:0]; 
NSString *smallpath=[NSString stringWithFormat:@"%@/%@",documentsPath,timestamp]; 

if(sqlite3_open(dbpath, &contactDB)==SQLITE_OK) 
{ 

    NSString *insertSQL = [NSString stringWithFormat:@"insert into Test values('%@','%@')",txtname.text,smallpath]; 
    //img 
    UIImage *img11=img1.image; 
    NSData *data = (UIImageJPEGRepresentation(img11,1.0)); 
    [data writeToFile:smallpath atomically:YES]; 
    const char *inser_stmt=[insertSQL UTF8String]; 
    sqlite3_prepare_v2(contactDB, inser_stmt, -1, &statement, NULL); 
    if (sqlite3_step(statement) == SQLITE_DONE) 
    { 
     NSLog(@"Company Detail insert succesfully"); 

    } 
    else 
    { 
     //self.status.text = @"Failed to add contact"; 
    } 
    sqlite3_finalize(statement); 
    sqlite3_close(contactDB); 
} 

else 
{ 
} 

和檢索圖像

NSString *pathsToReources = [[NSBundle mainBundle] resourcePath]; 
NSString *yourOriginalDatabasePath = [pathsToReources stringByAppendingPathComponent:@"Demo.sqlite"]; 
NSArray *pathsToDocuments = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
NSString *documentsDirectory = [pathsToDocuments objectAtIndex: 0]; 

NSString *dbPath = [documentsDirectory stringByAppendingPathComponent:@"Demo.sqlite"]; 
if (![[NSFileManager defaultManager] isReadableFileAtPath: dbPath]) { 
    if ([[NSFileManager defaultManager] copyItemAtPath: yourOriginalDatabasePath toPath: dbPath error: NULL] != YES) 
     NSAssert2(0, @"Fail to copy database from %@ to %@", yourOriginalDatabasePath, dbPath); 
} 

databasePath = [[NSString alloc]initWithString: [NSString stringWithFormat:@"%@",dbPath]]; 

const char *dbpath = [databasePath UTF8String]; 
sqlite3_stmt *statement; 

if (sqlite3_open(dbpath, &_database) == SQLITE_OK) 
{ 
    NSString *querySQL = [NSString stringWithFormat: @"SELECT Name,image FROM Test"]; 
    const char *query_stmt = [querySQL UTF8String]; 

    if (sqlite3_prepare_v2(_database, query_stmt, -1, &statement, NULL) == SQLITE_OK) 
    { 
     arrimage = [[NSMutableArray alloc] init]; 
     arrname = [[NSMutableArray alloc] init]; 

     while (sqlite3_step(statement) == SQLITE_ROW) 
     { 

      [arrname addObject:[NSString stringWithUTF8String:(char *)sqlite3_column_text(statement,0)]]; 
      [arrimage addObject:[NSString stringWithUTF8String:(char *)sqlite3_column_text(statement,1)]]; 

     } 
     sqlite3_finalize(statement); 
    } 
    sqlite3_close(_database); 
    [tblobj reloadData]; 
}