BufferedImage与byte[]互转

转载自：http://www.cnblogs.com/XL-Liang/archive/2011/12/30/2307220.html
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);    //image为BufferedImage类型
}

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(8888);
        Socket s = server.accept();
        DataOutputStream dout = new DataOutputStream(s.getOutputStream());
        BufferedImage image = ImageIO.read(new File("1.gif"));
        ByteArrayOutputStream out = new ByteArrayOutputStream();
boolean flag = ImageIO.write(image, "gif", out);
byte[] b = out.toByteArray();
        dout.write(b);
        s.close();
    }

}

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.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;
    MyPanel panel;
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",8888);
                    PrintWriter out = new PrintWriter(s.getOutputStream());
                    out.print("a");
                    DataInputStream in = new DataInputStream(s.getInputStream());
byte[]b = new byte[1000000];
                    in.read(b);
                    ByteArrayInputStream bin = new ByteArrayInputStream(b);
                    BufferedImage image = ImageIO.read(bin);
                    ImageIO.write(image, "gif", new File("2.gif"));
                    s.close();
                } catch (Exception e) {
                }
            }
        });
        panel = new MyPanel();
        add(panel);

    }
public static void main(String[] args) throws Exception {
        T6Client frame = new T6Client();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

}