java获得一张图片的rgb值

import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import java.io.*;
public class Test1
{
    public static void main(String args[])
    {

        int [] rgb = new int [ 3 ];

        File file = new File( "b.jpg" );
        BufferedImage bi= null ;
        try
        {
            bi = ImageIO.read(file);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        int width=bi.getWidth();
        int height=bi.getHeight();
        int minx=bi.getMinX();
        int miny=bi.getMinY();
        System.out.println( "width=" +width+ ",height=" +height+ "." );
        System.out.println( "minx=" +minx+ ",miniy=" +miny+ "." );
        for ( int i=minx;i

        {
            for ( int j=miny;j

            {
                int pixel=bi.getRGB(i,j);
                rgb[ 0 ] = (pixel & 0xff0000 ) >> 16 ;
                rgb[ 1 ] = (pixel & 0xff00 ) >> 8 ;
                rgb[ 2 ] = (pixel & 0xff );
                System.out.println( "i=" +i+ ",j=" +j+ ":(" +rgb[ 0 ]+ "," +rgb[ 1 ]+ "," +rgb[ 2 ]+ ")" );
                            }
        }
    }

}