Question

Java的imageIO读取图片后，怎么把他显示在panel上呢？

Answer 1

您好：读取bmp文件到BufferedImage中

File file2 = new File("c:\\testimages\\tttt" + ".bmp");
// BufferedImage bi = backstore.getBufferedImage();
try {
output = ImageIO.read(file2);
} catch (IOException e) {
e.printStackTrace();
}

输出bmp文件

File file2 = new File("c:\\testimages\\tttt" + ".bmp");
ImageIO.write(bi, "bmp", file2);

Byte[]输出到文件

byte[] buf =UtilZip.zipObjectToByte(cache);
File file2 = new File("c:\\testimages\\cache.bin");
FileOutputStream fos =new FileOutputStream(file2);
fos.write(buf);
fos.flush();
fos.close();

读文件到Byte[]中

File file2 = new File("c:\\testimages\\cache.bin");
FileInputStream fis = new FileInputStream(file2);
byte[] buf = new byte[(int) file2.length()];
fis.read(buf);
fis.close();

填充颜色到整个画布

BufferedImage bi = backstore.getBufferedImage();
Graphics g2 = bi.getGraphics();
g2.setColor(Color.red);
g2.fillRect(0, 0, Common.width,
Common.height);

图像变灰操作

public finalBufferedImage getGrayPicture(BufferedImage originalPic) {
int imageWidth = originalPic.getWidth();
int imageHeight = originalPic.getHeight();

BufferedImage newPic = new BufferedImage(imageWidth, imageHeight,
BufferedImage.TYPE_3BYTE_BGR);

ColorConvertOp cco = new ColorConvertOp(ColorSpace
.getInstance(ColorSpace.CS_GRAY), null);
cco.filter(originalPic, newPic);
return newPic;
}

ImageIO
javax.imageio.ImageIO lets you save and restore Images to disk in a platform independent format. It works using plug-in modules that handle various formats including "gif", "png" and "jpeg" (all lower case, or all upper case, but not mixed). "jpeg" or "jpg" is acceptable. Use ImageIO. getWriterFormatNames() to find out which types are supported on your platform:

import javax.imageio.ImageIO;

public class Jai
{

public static void main ( String[] args )
{
String[] names = ImageIO.getWriterFormatNames();
for ( String name: names )
{
System.out.println( name );
}
}
}

Loading an Image from raw bytes
Here raw bytes represent the image of a *.gif, *.png or

// raw bytes to BufferedImage
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import javax.imageio.ImageIO;
...
BufferedImage image = ImageIO.read ( new ByteArrayInputStream ( rawImageBytes ) );

Saving an Image to raw bytes
// BufferedImage to raw bytes
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
...

// O P E N
ByteArrayOutputStream baos = new ByteArrayOutputStream( 1000 );

// W R I T E
ImageIO.write( aBufferedImage, "jpeg" ,
baos );

// C L O S E
baos.flush();
byte[] resultImageAsRawBytes = baos.toByteArray();

baos.close();

Loading a BufferedImage from a file
// file to BufferedImage
import java.awt.image. BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
...
BufferedImage image = ImageIO.read( new File( "rabbit.jpg" ) );
Saving a BufferedImage to a file
// BufferedImage to File
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
...
ImageIO.write( aBufferedImage, "jpeg" ,
new File ( "snap.jpg" ) );

ImageWriteParam is a way of controlling exactly how the image in encoded. There is currently no PNG support for it. This is not for injecting meta info.
Loading a BufferedImage from an URL
// url to BufferedImage
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
...
BufferedImage image = null;
try
{
image = ImageIO.read( url );
}
catch ( IOException e )
{
System.out.println( "image missing" );
}

Converting Image to BufferedImage
// Image to BufferedImage
import java.awt.image.BufferedImage;
import java.awt.Image;
...
BufferedImage bufferedImage = new BufferedImage ( imageWidth,
imageHeight,
BufferedImage.TYPE_INT_BGR );
bufferedImage.createGraphics().drawImage( image, 0, 0, this );