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);
}
}