logincheckcode.java

前期开发时开发的新闻发布系统

package other;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.security.SecureRandom;
import java.util.Random;
import javax.servlet.http.HttpSession;

public class LoginCheckCode 
{
	 private String checkCode;
	
	 private LoginCheckCode() 
	 {
	     checkCode = "";
	     nextCode();
	 }
	
	 public static LoginCheckCode getInstance(HttpSession session) 
	 {
	     LoginCheckCode logincheckcode = null;
	     if(null != session) 
	     {
	         Object obj = null;
	         synchronized(session) 
	         {
	             obj = session.getAttribute("check");
	         }
	         if(null != obj && (obj instanceof LoginCheckCode)) 
	         {
	             logincheckcode = (LoginCheckCode)obj;
	         }
	         else 
	         {
	             logincheckcode = new LoginCheckCode();
	             synchronized(session) 
	             {
	            	 session.setAttribute("check", logincheckcode);
	             }
	         }
	     }
	     return logincheckcode;
	 }
	
	 public synchronized String nextCode() 
	 {
	     String s = "";
	     SecureRandom securerandom = new SecureRandom();
	     for(int i = 0; i < 4; i ++) 
	     {
	         s = (new StringBuilder()).append(s).append(String.valueOf(securerandom.nextInt(10))).toString();
	     }
	     checkCode = s;
	     return checkCode;
	 }
	
	 public synchronized BufferedImage getImage() 
	 {
	     byte byte0 = 60;
	     byte byte1 = 20;
	     BufferedImage bufferedimage = new BufferedImage(byte0, byte1, 1);
	     Graphics g = bufferedimage.getGraphics();
	     Random random = new Random();
	     g.setColor(getRandColor(200, 250));
	     g.fillRect(0, 0, byte0, byte1);
	     g.setFont(new Font("Times New Roman", 0, 18));
	     g.setColor(getRandColor(160, 200));
	     for(int i = 0; i < 155; i ++) 
	     {
	         int k = random.nextInt(byte0);
	         int l = random.nextInt(byte1);
	         int i1 = random.nextInt(12);
	         int j1 = random.nextInt(12);
	         g.drawLine(k, l, k + i1, l + j1);
	     }
	     for(int j = 0; j < checkCode.length(); j ++) 
	     {
	         String s = checkCode.substring(j, j + 1);
	         g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
	         g.drawString(s, 13 * j + 6, 16);
	     }
	     g.dispose();
	     return bufferedimage;
	 }
	
	 private Color getRandColor(int i, int j) 
	 {
	     Random random = new Random();
	     if(i > 255) 
	     {
	         i = 255;
	     }
	     if(j > 255) 
	     {
	         j = 255;
	     }
	     int k = i + random.nextInt(j - i);
	     int l = i + random.nextInt(j - i);
	     int i1 = i + random.nextInt(j - i);
	     return new Color(k, l, i1);
	 }
	
	 public synchronized String getCheckCode() 
	 {
	     return checkCode;
	 }
}