动态验证码 关键代码
import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;/** * 动态验证码 关键代码 * @author xiaer * */public class ImageEnsure {public ImageEnsure() {}private char mapTable[]={'A','B','C','D','E','F','G','H','I','J','K','L','M','N','P','Q','R','S','T','U','V','W','X','Y','Z','0','1','2','3','4','5','6','7','8','9'};public String getEnsure(int width, int height, OutputStream os) {if(width<=0)width=60;if(height<=0)height=20;BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); // 设定背景色 g.setColor(new Color(0xFCF000)); g.fillRect(0, 0, width, height); //画边框 g.setColor(Color.black); g.drawRect(0,0,width-1,height-1); // 取随机产生的认证码String strEnsure = "";// 4代表4位验证码for(int i=0; i<4; ++i) { strEnsure += mapTable[(int)(mapTable.length*Math.random())];} // 将认证码显示到图象中 g.setColor(Color.black); g.setFont(new Font("Atlantic Inline",Font.PLAIN,18)); String str = strEnsure.substring(0,1); g.drawString(str,8,17); str = strEnsure.substring(1,2); g.drawString(str,20,15); str = strEnsure.substring(2,3); g.drawString(str,35,18); str = strEnsure.substring(3,4); g.drawString(str,45,15); // 随机产生50个干扰点Random rand = new Random();for (int i=0;i<50;i++) { int x = rand.nextInt(width); int y = rand.nextInt(height); g.drawOval(x,y,1,1); } // 释放图形上下文g.dispose(); try {// 输出图象到页面 ImageIO.write(image, "JPEG", os);} catch (IOException e) {return "";}finally{}return strEnsure;}/*public static void main(String []args) {try{BufferedOutputStream os = new BufferedOutputStream(new FileOutputStream("c:\\test.jpg")); new ImageEnsure().getEnsure(100, 200, os);os.flush();os.close();} catch(Exception e) {}}*/}
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