用JAVA读存图象有关知识

用java读取图片的三种方式

import javax.imageio.*;//for ImageIO.read
import java.awt.*;//for JFrame and JLabel etc
import javax.swing.*;//for JFrame and JLabel etc
import java.net.*;//for URL
import java.io.*;//for catch (IOException e),File,InputStream, BufferedInputStream,and FileInputStream ect
public class HelloJava{
   public static void main (String[] args){
   Image image = null;
    try {
        // Read from a file
        File sourceimage = new File("source.gif");  //source.gif图片要与HelloJava.java同在一目录下
        image = ImageIO.read(sourceimage);
   
        // Read from an input stream
        InputStream is = new BufferedInputStream(
           new FileInputStream("mid.jpg"));  //mid.jpg图片要与HelloJava.java同在一目录下
        image = ImageIO.read(is);
   
        // Read from a URL
        URL url = new URL("http://www.javaworld.com/images/012407-tipsbox.jpg");
        image = ImageIO.read(url);
    } catch (IOException e) {
    }
   
    // Use a label to display the image
    JFrame frame = new JFrame();
    JLabel label = new JLabel(new ImageIcon(image));
    frame.getContentPane().add(label, BorderLayout.CENTER);
    frame.pack();
    frame.setVisible(true);
    //关闭窗口--退出调试
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     }
}

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/Breeze2003/archive/2008/09/22/2962237.aspx


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java读取图片大小属性

经测试下来，一下两种方案针对不同大小的图片所消耗的时间不同

File file = new File("C:/Documents and Settings/All Users/Documents/My Pictures/示例图片", "Sunset.jpg");

1.采用ImageReader -- 不论图片大小，基本恒定时间，在100ms左右

try {
   Iterator readers = ImageIO.getImageReadersByFormatName("jpg");
   ImageReader reader = (ImageReader)readers.next();
   ImageInputStream iis = ImageIO.createImageInputStream(file);
   reader.setInput(iis, true);
   System.out.println("width:"+reader.getWidth(0));
   System.out.println("height:"+reader.getHeight(0));
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }





2.采用BufferedImage  -- 图片越大，消耗的时间越长，针对百K以下的图片速度较快

try {
   BufferedImage Bi = ImageIO.read(file);  
   System.out.println("width:"+Bi.getWidth());
   System.out.println("height:"+Bi.getHeight());
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }



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java读取图片长宽问题

经测试下来，一下两种方案针对不同大小的图片所消耗的时间不同

File file = new File("C:/Documents and Settings/All Users/Documents/My Pictures/示例图片", "Sunset.jpg");

1.采用ImageReader -- 不论图片大小，基本恒定时间，在100ms左右

try {
   Iterator readers = ImageIO.getImageReadersByFormatName("jpg");
   ImageReader reader = (ImageReader)readers.next();
   ImageInputStream iis = ImageIO.createImageInputStream(file);
   reader.setInput(iis, true);
   System.out.println("width:"+reader.getWidth(0));
   System.out.println("height:"+reader.getHeight(0));
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }





2.采用BufferedImage  -- 图片越大，消耗的时间越长，针对百K以下的图片速度较快

try {
   BufferedImage Bi = ImageIO.read(file);  
   System.out.println("width:"+Bi.getWidth());
   System.out.println("height:"+Bi.getHeight());
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }