JAVA中实现图片对象转换成图片文件和字节数组

JAVA中实现图片对象转换成图片文件和字节数组(Byte[ ])的方法讨论
网上关于这方面的讨论其实有很多，但找起来也不太容易，笔者以JMSL4.0画出的chart对象为例阐释这一过程，希望能带来些启发。

import com.imsl.chart.*;
import java.awt.image.BufferedImage;
import java.io.*;

import javax.imageio.stream.FileImageOutputStream;
import javax.imageio.stream.ImageOutputStream;

public class SampleImageIO {
    public byte[] getByteArray() {
        byte[] b = null;
        try{
        Chart chart = createChart();//generate image
        chart.setScreenSize(new java.awt.Dimension(500,500));
        BufferedImage bi = new BufferedImage(500, 500, BufferedImage.TYPE_4BYTE_ABGR_PRE);
        chart.paintChart(bi.createGraphics()); //generate buffered image

//感觉bufferedimage经常和imageIO成对出现作为对图像对象的标准转化形式。
        File file = new File("D:\\workspace\\SampleImageIO1.png");//deploy file
        javax.imageio.ImageIO.write(bi, "PNG", file);//generate file
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        javax.imageio.ImageIO.write(bi, "png", bos);
        b = bos.toByteArray();//generate byte[]


        //check to get the byte[]

//其实byte[]的最大的用途应该是网站的图片动态显示，下面的code只是实验一下，也顺便介绍一下byte[]转换成文件的操作。
        String newFileName = "d:\\temp\\wine1.png";
        FileImageOutputStream imageOutput = new FileImageOutputStream(new File(newFileName));
        imageOutput.write(b, 0, b.length);
        imageOutput.close();
        System.out.println("Please find image in " + newFileName);       
        }
        catch(Exception ex) {
            System.out.println("Exception: " + ex);
            ex.printStackTrace();           
        }
        return b;
    }

//jmsl画图的code，挺快的，好用，但是人家是收费的library～～，抛砖引玉吧

    static Chart createChart() {       
        Chart chart = new Chart();
        AxisXY axis = new AxisXY(chart);     
        int npoints = 20;
        double dx = .5 * Math.PI/(npoints-1);
        double x[] = new double[npoints];       
        double y[] = new double[npoints];     

        // Generate some data      
        for (int i = 0; i < npoints; i++){           
            x[i] = i * dx;           
            y[i] = Math.cos(x[i]);           
        }       
        new Data(axis, x, y);  
        return chart;
    }   
}