从数据库检索图像到imageView

Question

There is the table in DB with images. I want, that an Image will show in Image View, but something is wrong and I have SQLException.

 ConnectionHelper ch=new ConnectionHelper();
    ch.Connect();
    String q="SELECT IMG FROM img_ins";

    Statement st=ch.con.createStatement();
    ResultSet rs = st.executeQuery(q);

   InputStream is= rs.getBinaryStream("IMG");
    OutputStream os=new FileOutputStream(new File("img.jpg"));
    byte [] content= new byte[1024];
    int size=0;


        while ((size=is.read(content))!=-1){

            os.write(content, 0, size);
        }

    os.close();
    is.close();

    javafx.scene.image.Image image1=new Image("file:img.jpg", image.getFitWidth(), image.getFitHeight(), true, true);
    image.setImage(image1);
    image.setPreserveRatio(true);
}

Answer 1

From the documentation for ResultSet (my emphasis):

A ResultSet object maintains a cursor pointing to its current row of data. Initially the cursor is positioned before the first row. The next method moves the cursor to the next row

So you need to call next() to point the cursor to each row. Assuming there's at most one row in the table, or that you are only interested in the first row, you could do

ConnectionHelper ch=new ConnectionHelper();
ch.Connect();
String q="SELECT IMG FROM img_ins";

Statement st=ch.con.createStatement();
ResultSet rs = st.executeQuery(q);

if (rs.next()) {
    InputStream is= rs.getBinaryStream("IMG");

    // instead of the next 9 lines, you could just do
    // javafx.scene.image.Image image1 = new Image(is);

    OutputStream os=new FileOutputStream(new File("img.jpg"));
    byte [] content= new byte[1024];
    int size=0;


        while ((size=is.read(content))!=-1){

            os.write(content, 0, size);
        }

    os.close();
    is.close();

    javafx.scene.image.Image image1=new Image("file:img.jpg", image.getFitWidth(), image.getFitHeight(), true, true);
    image.setImage(image1);
    image.setPreserveRatio(true);
}

But note the comments below the OP as well.

Answer 2

Here is an example from a piece of code I wrote. This is an sqlite db

try (Connection conn = DriverManager.getConnection("jdbc:sqlite:contactFX.db");
             Statement stmt = conn.createStatement(); 
             ResultSet rset = stmt.executeQuery(sqlTCNote)) 
        {
            while(rset.next())
            {                
                Company c1 = new Company();  
                c1.setID(Integer.toString(rset.getInt("company_id")));
                c1.setName(rset.getString("company_name"));
                .
                .
                .
                c1.setWebSiteAddress(rset.getString("website_address"));  

                //This part is important to you.
                InputStream input = rset.getBinaryStream("image");
                InputStreamReader inputReader = new InputStreamReader(input);                        
                if(inputReader.ready())
                {
                    File tempFile = new File("tempFile.jpg");

                    FileOutputStream fos = new FileOutputStream(tempFile);
                    byte[] buffer = new byte[1024];
                    while(input.read(buffer) > 0){
                        fos.write(buffer);                        
                    }
                    Image image = new Image(tempFile.toURI().toURL().toString());
                    c1.setImage(image);//right here is where you want to set your imageView with the image.
                }     
                companyData.add(c1);
            }              
        }
        catch(SQLException | IOException ex)
        {
            Logger.getLogger(MainController.class.getName()).log(Level.SEVERE, null, ex);
        }