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：

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1. package org.exam3;  
2.   
3. import java.awt.image.BufferedImage;  
4. import java.io.ByteArrayOutputStream;  
5. import java.io.DataOutputStream;  
6. import java.io.File;  
7. import java.net.ServerSocket;  
8. import java.net.Socket;  
9.   
10. import javax.imageio.ImageIO;  
11.   
12. public class T6Server {  
13.   
14.     public static void main(String[] args) throws Exception {  
15.         ServerSocket server = new ServerSocket(8888);  
16.         Socket s = server.accept();  
17.         DataOutputStream dout = new DataOutputStream(s.getOutputStream());  
18.         BufferedImage image = ImageIO.read(new File("1.gif"));  
19.         ByteArrayOutputStream out = new ByteArrayOutputStream();  
20.         boolean flag = ImageIO.write(image, "gif", out);  
21.         byte[] b = out.toByteArray();  
22.         dout.write(b);  
23.         s.close();  
24.     }  
25.   
26. }  

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：

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1. package org.exam3;  
2.   
3. import java.awt.BorderLayout;  
4. import java.awt.Graphics;  
5. import java.awt.event.ActionEvent;  
6. import java.awt.event.ActionListener;  
7. import java.awt.image.BufferedImage;  
8. import java.io.ByteArrayInputStream;  
9. import java.io.DataInputStream;  
10. import java.io.File;  
11. import java.io.PrintWriter;  
12. import java.net.Socket;  
13.   
14. import javax.imageio.ImageIO;  
15. import javax.swing.JButton;  
16. import javax.swing.JFrame;  
17. import javax.swing.JPanel;  
18.   
19. public class T6Client extends JFrame {  
20.     JButton button;  
21.     MyPanel panel;  
22.     public T6Client() {  
23.         setSize(300, 400);  
24.         button = new JButton("获取图像");  
25.         add(button,BorderLayout.NORTH);  
26.         button.addActionListener(new ActionListener() {  
27.             public void actionPerformed(ActionEvent event) {  
28.                 try {  
29.                     Socket s = new Socket("localhost",8888);  
30.                     PrintWriter out = new PrintWriter(s.getOutputStream());  
31.                     out.print("a");  
32.                     DataInputStream in = new DataInputStream(s.getInputStream());  
33.                     byte[]b = new byte[1000000];  
34.                     in.read(b);  
35.                     ByteArrayInputStream bin = new ByteArrayInputStream(b);  
36.                     BufferedImage image = ImageIO.read(bin);  
37.                     ImageIO.write(image, "gif", new File("2.gif"));  
38.                     s.close();  
39.                 } catch (Exception e) {  
40.                 }  
41.             }  
42.         });  
43.         panel = new MyPanel();  
44.         add(panel);  
45.   
46.     }  
47.     public static void main(String[] args) throws Exception {  
48.         T6Client frame = new T6Client();  
49.         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
50.         frame.setVisible(true);  
51.     }  
52.   
53. }  

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);}}