BufferedImage与byte 互转

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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); }}


           

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