我正在尝试将Image对象转换为字节数组,然后返回到Image(这样我就可以将图像存储在Apache Derby数据库的blob对象中)。
我可以将Image转换为字节数组(下面的代码),但我无法将字节转换回图像。作为更复杂的我正在使用J2ME,所以我不能使用javax.image。*。 你能帮我吗?
由于
package six.util;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.ImageObserver;
import java.awt.Component;
import java.awt.MediaTracker;
import java.awt.Graphics;
import java.awt.image.DataBufferByte;
import java.awt.image.WritableRaster;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.image.PixelGrabber;
import java.util.ArrayList;
public class ImageConverter extends Component
{
private MediaTracker mediaTracker;
private Image image;
private ImageConverter(Image image)
{
super();
this.mediaTracker = new MediaTracker(this);
this.mediaTracker.addImage(image, 0);
this.image = image;
}
private BufferedImage convert()
{
/*
* Have to wait for image to load.
*/
try
{
this.mediaTracker.waitForID(0);
}catch(InterruptedException e)
{
}
System.out.println("-1");
GraphicsConfiguration graphicsConfig = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
BufferedImage bimage = graphicsConfig.createCompatibleImage(this.image.getWidth(null),this.image.getHeight(null));
System.out.println("-2");
Graphics g = bimage.getGraphics();
g.drawImage(image, 0, 0, null);
return bimage;
}
private static byte[] convertIntToByteArray(int integer)
{
byte[] bytes = new byte[4];
bytes[0] =(byte)( integer >> 24 );
bytes[1] =(byte)( (integer << 8) >> 24 );
bytes[2] =(byte)( (integer << 16) >> 24 );
bytes[3] =(byte)( (integer << 24) >> 24 );
return bytes;
}
private static int convertByteArrayToInt(byte[] bytes)
{
return (bytes[0] << 32) | (bytes[1] << 24) | (bytes[2] << 16) | (bytes[3] << 8) | bytes[4];
}
private static byte[] convertIntArrayToByteArray(int[] integers)
{
byte[] bytes = new byte[integers.length*4];
for (int index = 0; index < integers.length; index++)
{
byte[] integerBytes = convertIntToByteArray(integers[index]);
bytes[index*4] = integerBytes[0];
bytes[1 + (index*4)] = integerBytes[1];
bytes[2 + (index*4)] = integerBytes[2];
bytes[3 + (index*4)] = integerBytes[3];
}
return bytes;
}
private static int[] convertByteArrayToIntArray(byte[] bytes)
{
ArrayList integers = new ArrayList();
for (int index = 0; index < bytes.length; index += 4)
{
byte[] fourBytes = new byte[4];
fourBytes[0] = bytes[index];
fourBytes[1] = bytes[index+1];
fourBytes[2] = bytes[index+2];
fourBytes[3] = bytes[index+3];
int integer = convertByteArrayToInt(fourBytes);
integers.add(new Integer(integer));
}
int[] ints = new int[bytes.length/4];
for (int index = 0; index < integers.size() ; index++)
{
ints[index] = ((Integer)integers.get(index)).intValue();
}
return ints;
}
public static byte[] convertToBytes(Image image)
{
System.out.println("A");
ImageConverter converter = new ImageConverter(image);
System.out.println("B");
BufferedImage bufferedImage = converter.convert();
System.out.println("C");
PixelGrabber pixelGrabber = new PixelGrabber(image,0,0,bufferedImage.getWidth(),bufferedImage.getHeight(),true);
System.out.println("D");
try
{
if(pixelGrabber.grabPixels())
{
Object pixels = pixelGrabber.getPixels();
if (pixels instanceof byte[])
{
return (byte[])pixels;
}
return convertIntArrayToByteArray((int[])pixels);
}
}catch(InterruptedException e)
{
}
return null;
}
}
答案 0 :(得分:3)
我不知道javame,但这不会起作用吗?
javax.microedition.lcdui.Image.createImage(new ByteArrayInputStream(byte[]))
答案 1 :(得分:1)
要重新创建图像,您可以在Image类(http://java.sun.com/javame/reference/apis/jsr118/)中使用方法createRGBImage,但请注意,图像中的每个像素使用4个字节。宽度为200 x 200像素的图像总共将有40000像素,这将占用移动设备中160KB的内存。
之前我在J2ME中使用过图像,但只是将图像从服务器发送到客户端。在这种情况下,您可以更改服务器上图像的分辨率(您有代码和原始功率),将其编码为JPEG,然后将其发送到客户端。 Image.createImage(...)方法可以创建运行应用程序的J2ME引擎支持的任何编码格式的图像。我相信JPEG将永远被接受。
即使您需要这些图像供将来使用,也可以将服务器返回的byte []缓冲区保存在Record Store中,然后再使用它。