在java中将java.awt.Image保存到磁盘

Question

I have read clob from oracle procedure and convert them into java.awt.Image object by the following code .

InputStream stream = clob.getAsciiStream();
                ByteArrayOutputStream output = new ByteArrayOutputStream();
                int a1 = stream.read();
                while (a1 >= 0) {
                  output.write((char) a1);
                  a1 = stream.read();
                }
                Image myImage = Toolkit.getDefaultToolkit().createImage(output.toByteArray());
                output.close();

Now, I want to save myImage to hard disk. So, What must I do to save these java.awt.Image to file ?

My try :

I have cast the myImage to BufferedImage and then write this to ImageIo by the following code :

BufferedImage bi = (BufferedImage)myImage;
               ImageIO.write(bi, "jpg",new File("E:\\out.jpg"));

But I am getting the following exception :

Got Exception as : sun.awt.image.ToolkitImage cannot be cast to java.awt.image.BufferedImage
java.lang.ClassCastException: sun.awt.image.ToolkitImage cannot be cast to java.awt.image.BufferedImage
    at com.connect.home.Home.getHomeParameter(Home.java:103)
    at com.connect.home.Home.main(Home.java:141)

How can I remove this error ? Any advice is of great help .

Answer 1

First

Oracle JDBC drivers support the manipulation of data streams in either direction between server and client. The drivers support all stream conversions: binary, ASCII, and Unicode. Following is a brief description of each type of stream:

Binary. Used for RAW bytes of data, and corresponds to the getBinaryStream method

ASCII. Used for ASCII bytes in ISO-Latin-1 encoding, and corresponds to the getAsciiStream method

Unicode. Used for Unicode bytes with the UTF-16 encoding, and corresponds to the getUnicodeStream method

So probably you will need to use clob.getBinaryStream to retrieve your stream.

Second. You can not save ToolKitImage whith ImageIO::write because it expect a RenderedImage instance.And ToolkitImage not implements this interface.

So you have two options.

Read the stream with ImageIO

    RenderedImage image = ImageIO.read(clob.getBinaryStream());
    ImageIO.write(image, "JPG",new File("E:\\out.jpg"));

Or draw the ToolkitImage on a RenderedImage

    BufferedImage bi = new BufferedImage(myImage.getWidth(null), myImage.getHeight(null), BufferedImage.TYPE_INT_RGB);
    bi.getGraphics().drawImage(myImage,0,0, null);
    ImageIO.write(bi, "JPG", new File("E:\\out.jpg"));