转载自 BufferedImage与byte[]互转
一、需要用到的类
java.awt.image.BufferedImage;
javax.imageio.ImageIO;
java.io.*;
二、为什么要将BufferedImage转为byte数组
在传输中，图片是不能直接传的，因此需要把图片变为字节数组，然后传输比较方便；只需要一般输出流的write方法即可；
而字节数组变成BufferedImage能够还原图像；
三、如何取得BufferedImage
BufferedImage image = ImageIO.read(new File("1.gif"));
四、BufferedImage ---->byte[]
ImageIO.write(BufferedImage image,String format,OutputStream out);方法可以很好的解决问题；
参数image表示获得的BufferedImage；
参数format表示图片的格式，比如“gif”等；
参数out表示输出流，如果要转成Byte数组，则输出流为ByteArrayOutputStream即可；
执行完后，只需要toByteArray()就能得到byte[];
五、byte[] ------>BufferedImage
ByteArrayInputStream in = new ByteArrayInputStream(byte[]b); //将b作为输入流；
BufferedImage image = ImageIO.read(InputStream in); //将in作为输入流，读取图片存入image中，而这里in可以为ByteArrayInputStream();
六、显示BufferedImage
public void paint(Graphics g){
super.paint(g);
g.drawImage(image,x,y,width,height,null); //image为BufferedImage类型
}
如果要自动调用paint方法，则需要调用repaint()方法；
七、实例
要求：编写一个网络程序，通过Socket将图片从服务器端传到客户端，并存入文件系统；
Server端：
package org.exam3; import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.net.ServerSocket;
import java.net.Socket; import javax.imageio.ImageIO; public class T6Server { public static void main(String[] args) throws Exception { ServerSocket server = new ServerSocket(8889); System.out.println("服务器开启连接...端口为8889"); Socket s = server.accept(); while(true){ System.out.println("一客户端连接服务器，服务器传输图片..."); DataOutputStream dout = new DataOutputStream(s.getOutputStream()); BufferedImage image = ImageIO.read(new File("1.gif")); //读取1.gif并传输 ByteArrayOutputStream out = new ByteArrayOutputStream(); boolean flag = ImageIO.write(image, "gif", out); byte[] b = out.toByteArray(); dout.write(b); s.close(); System.out.println("图片传送完毕,服务器开启连接...端口为8889"); s = server.accept(); } }
} Client端：
package org.exam3; import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.PrintWriter;
import java.net.Socket; import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel; public class T6Client extends JFrame { JButton button; JPanel panel; int count = 0; BufferedImage image ; public T6Client() { setSize(300, 400); button = new JButton("获取图像"); add(button,BorderLayout.NORTH); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { try { Socket s = new Socket("localhost",8889); PrintWriter out = new PrintWriter(s.getOutputStream()); out.print("a"); DataInputStream in = new DataInputStream(s.getInputStream()); byte[]b = new byte[1024]; ByteArrayOutputStream bout = new ByteArrayOutputStream(); int length = 0; while((length=in.read(b))!=-1){ bout.write(b, 0, length); } ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray()); image = ImageIO.read(bin); repaint(); ImageIO.write(image, "gif", new File("output-"+count+".gif")); count++; s.close(); } catch (Exception e) { } } }); panel = new JPanel(); add(panel); } @Override public void paint(Graphics g){ super.paint(g); g.drawImage(image, 20, 20, 300, 150, null);//image为BufferedImage类型 } public static void main(String[] args) throws Exception { T6Client frame = new T6Client(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } } 
详解)
