JSP实现验证码

作者：gqk:

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 验证码我们可以用javaSE中的GUI去完成：

核心代码：

封装验证码类:

package com.xkrj.yzm;

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

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.swing.JFrame;

public class DrawYzm  extends JFrame{//继承JFrame窗口
	private int width = 900;//验证码宽度
    private int height = 240;//验证码高度
    private int codeCount = 4;//验证码个数
    private int lineCount = 300;//混淆线个数
    
    //定义验证码内容
    char[] codeSequence = { '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', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
    	//画验证码
    public 	void getCode(HttpServletRequest request,HttpServletResponse response) throws IOException{
    	//定义随机数类
    	Random r = new Random();
    	//创建StringBulider类拼接验证码
    	StringBuilder builderCode = new StringBuilder();
    	//定义画布
        BufferedImage buffImg = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);	
        //创建画笔
       Graphics g =  buffImg.getGraphics();
       //设置颜色和边框
       g.setColor(Color.black);
       //画矩形
       g.drawRect(0,0,width,height);
       //2.设置颜色,填充内部
       g.setColor(Color.white);
       g.fillRect(1,1,width-2,height-2);
     //3.设置干扰线
       g.setColor(Color.red);

       for (int i = 0; i < lineCount; i++) {
           g.drawLine(r.nextInt(width),r.nextInt(width),r.nextInt(width),r.nextInt(width));
       }
       //4.设置验证码
       g.setColor(Color.blue);
       //4.1设置验证码字体
       g.setFont(new Font("微软雅黑",Font.LAYOUT_LEFT_TO_RIGHT,150));
       for (int i = 0; i < codeCount; i++) {
           char c = codeSequence[r.nextInt(codeSequence.length)];
           builderCode.append(c);
           g.drawString(c+"",150*(i+1),175);
       }
       //5.输出到屏幕
       ServletOutputStream sos = response.getOutputStream();
       ImageIO.write(buffImg,"png",sos);
       //6.保存到session中
       HttpSession session = request.getSession();
       session.setAttribute("codeValidate",builderCode.toString());
       //7.禁止图像缓存。
       response.setHeader("Pragma", "no-cache");
       response.setHeader("Cache-Control", "no-cache");
       response.setDateHeader("Expires", 0);
       response.setContentType("image/png");
       //8.关闭sos
       sos.close();
    	
    }

}

　　Servlet中调用：

package com.xkrj.yzm;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/codeServlet")
public class CodeServlet extends HttpServlet {
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// TODO Auto-generated method stub
		this.doPost(req, resp);
	}
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		DrawYzm dy= new DrawYzm();
		dy.getCode(req, resp);
				
	}
}

 

　　

可以用ajax进行验证，验证码已经绑定再Session之中，验证比较简单就不写了！