必背代码-Sevlet实现验证码

标签：servlet   验证码   

package cn.lijun;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 生成随机图片，即为验证码的生成(BufferImage(jdkApi内存图片))
 * 为了防止编程实现图片识别验证码，而产生的恶意注册，登陆。
 * 生产的验证码图片需要以下要求：
 * 1.底色
 * 2.随机数
 * 3.干扰线
 * 4.字符旋转
 * @author Administrator
 *
 */
public class ResponseRandomPic extends HttpServlet {

		public static final  int WIDTH = 120;
		public final static int HEIGHT = 25 ;
		

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
			BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
			
			Graphics g = image.getGraphics();
			
			//1.设置背景色
			setBackGround(g);
			
			//2.设置图形边框
			setBorder(g);
			
			//3.画干扰线
			drawRandomLine(g);
			
			//4.给图形生成随机文字
			drawRandomNum(g);
			
			//5.把图形写给浏览器
			response.setContentType("image / jpeg");
			ImageIO.write(image, "jpg", response.getOutputStream());
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request,response);
	}
	
	private void drawRandomNum(Graphics g) {
		
		Graphics2D g2d = (Graphics2D) g;
		
		// 生成随机数
		final char randomStr[] = {'a' ,'b' ,'c','d','e' , 'f' ,'g' , 'h','i','j' , 'k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
		final int len = 6;
		
		g2d.setColor(Color.RED);
		g2d.setFont(new Font("宋体",Font.BOLD , 20));
		
		int x = 10;
		for(int  i = 0 ; i < len ; i ++ ){
			String ranStr = "";
			int y = new Random().nextInt(5)+17;
			System.out.println("y:"+y);
			
			ranStr = randomStr[new Random().nextInt(26)]+"";
			
			//随机旋转(30度以内旋转)
			int degree = new Random().nextInt()%30;//生成-30-30的随机数
			g2d.rotate(degree*Math.PI/180, x, y);
			
			//为了不影响下一个字的旋转，把图片旋转回去(重置旋转)
			g2d.rotate(-degree*Math.PI/180, x, y);
			g2d.drawString(ranStr,x ,y);
			
			x +=17;
		}
	}
	
	private void drawRandomLine(Graphics g) {
		// TODO Auto-generated method stub
		g.setColor(Color.green);
		for(int i = 0 ; i < 5 ; i ++){
			int x1 = new Random().nextInt(WIDTH);
			int y1 = new Random().nextInt(HEIGHT);
			int x2 = new Random().nextInt(WIDTH);
			int y2 = new Random().nextInt(HEIGHT);
			g.drawLine(x1, y1, x2, y2);
		}
	}
	private void setBorder(Graphics g) {
		// TODO Auto-generated method stub
		g.setColor(Color.BLUE);
		g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
	}
	private void setBackGround(Graphics g) {
		// 设置背景色
		g.setColor(Color.WHITE);
		g.fillRect(0, 0, WIDTH,HEIGHT);
	}

}


以下为前台js代码:

<img src="/servletStu/ResponseRandom.action" onclick="this.src = this.src ?new Date().getTime()" style="cusor:hand"/>

必背代码-Sevlet实现验证码

标签：servlet   验证码   

原文地址：http://blog.csdn.net/u010218226/article/details/44306555