Java之BufferedImage简谈

1. 创建一个BufferedImage对象:

import java.awt.Frame;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.GraphicsConfiguration;

import java.awt.GraphicsDevice;

import java.awt.GraphicsEnvironment;

import java.awt.Transparency;

import java.awt.image.BufferedImage;

实现代码

 

public class Test extends Frame{

    /**

    * @param args

    */

    public static void main(String[] args) {

       // TODO Auto-generated method stub

       int width = 100;

       int height = 100;

       // 1.创建一个不带透明色的BufferedImage对象

       BufferedImage bimage = new BufferedImage(width, height,

              BufferedImage.TYPE_INT_RGB);

       // 2.创建一个带透明色的BufferedImage对象

       bimage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);

       // 3.创建一个与屏幕相适应的BufferedImage对象

       GraphicsEnvironment ge = GraphicsEnvironment

              .getLocalGraphicsEnvironment();

       GraphicsDevice gs = ge.getDefaultScreenDevice();

       GraphicsConfiguration gc = gs.getDefaultConfiguration();

       // Create an image that does not support transparency

       bimage = gc.createCompatibleImage(width, height, Transparency.OPAQUE);

       // Create an image that supports transparent pixels

       bimage = gc.createCompatibleImage(width, height, Transparency.BITMASK);

       // Create an image that supports arbitrary levels of transparency

       bimage = gc.createCompatibleImage(width, height,

              Transparency.TRANSLUCENT);

    }

    // 4.当然我们也可以在图形上下文来创建一个BufferedImage对象

    public void paint(Graphics g) {

       Graphics2D g2d = (Graphics2D) g;

       int width = 100;

       int height = 100;

       // Create an image that does not support transparency

       BufferedImage bimage = g2d.getDeviceConfiguration()

              .createCompatibleImage(width, height, Transparency.OPAQUE);

       // Create an image that supports transparent pixels

       bimage = g2d.getDeviceConfiguration().createCompatibleImage(width,

              height, Transparency.BITMASK);

       // Create an image that supports arbitrary levels of transparency

       bimage = g2d.getDeviceConfiguration().createCompatibleImage(width,

              height, Transparency.TRANSLUCENT);

    }

}

2.使用BufferedImage的图像剪裁:

public static void main(String[] args) {
  try {
   //从特定文件载入
   BufferedImage bi = ImageIO.read(new File("c:\\test.jpg"));
   bi.getSubimage(0, 0, 10, 10);
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
注意ImageIO.read进行读图操作与以往的InputStream读取比较方便!
3.BufferedImage类型与Byte[]流之间相互转化,以及BufferedImage的显示与传输

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);
}

}

4. BufferedImage与Image之间的相互转换

<一>

BufferedImage input = ImageIO.read(file1);
Image big = input.getScaledInstance(256, 256,Image.SCALE_DEFAULT); //放缩图片
BufferedImage inputbig = new BufferedImage(256, 256,BufferedImage.TYPE_INT_BGR);
inputbig.getGraphics().drawImage(input, 0, 0, 256, 256, null); //画图

 

<二>

public BufferedImage toBufferedImage(Image image) {
if (image instanceof BufferedImage) {
return (BufferedImage) image;
}
image = new ImageIcon(image).getImage();  

//ImageIcon与Image之间的转化: ImageIcon icon = new ImageIcon(image); image = icon.getImage();
boolean hasAlpha = false;
BufferedImage bimage = null;
GraphicsEnvironment ge = GraphicsEnvironment
.getLocalGraphicsEnvironment();
try {
int transparency = Transparency.OPAQUE;
if (hasAlpha) {
transparency = Transparency.BITMASK;
}
GraphicsDevice gs = ge.getDefaultScreenDevice();
GraphicsConfiguration gc = gs.getDefaultConfiguration();
bimage = gc.createCompatibleImage(image.getWidth(null),
image.getHeight(null), transparency);
} catch (HeadlessException e) {
}
if (bimage == null) {
int type = BufferedImage.TYPE_INT_RGB;
if (hasAlpha) {
type = BufferedImage.TYPE_INT_ARGB;
}
bimage = new BufferedImage(image.getWidth(null),
image.getHeight(null), type);
}
Graphics g = bimage.createGraphics();
g.drawImage(image, 0, 0, null);
g.dispose();
return bimage;
}

 

发表评论

电子邮件地址不会被公开。 必填项已用*标注