动手实现随机验证码

动手实现随机验证码
首先，来写一个画验证码图片的Java类：


package com.XiongYi.validationCode;




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;


import javax.servlet.ServletException;


import javax.servlet.http.HttpServlet;


import javax.servlet.http.HttpServletRequest;


import javax.servlet.http.HttpServletResponse;






public class ValidationCode extends HttpServlet...{






public static String getValidationCodes(OutputStream os)...{




char codeTable[]=...{


'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',


'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',


'1','2','3','4','5','6','7','8','9'


}; //判断时大小写不区分，另外，没有使用'O'和'0'，也是怕混淆的麻烦




BufferedImage image = new BufferedImage(60, 20,


BufferedImage.TYPE_INT_RGB);


//生成60×20的RGB图片


Graphics graphic = image.getGraphics();


//背景色


graphic.setColor(new Color(0xDCDCDC));


graphic.fillRect(0, 0, 60, 20);




char codes[] = new char[4];


//随机产生验证码




for(int i=0; i<=3; i++) ...{


codes[i] = codeTable[(int)(codeTable.length*Math.random())];


}




//把字画上去


graphic.setColor(Color.BLACK);


graphic.setFont(new Font("Arial", Font.BOLD, 16));




for(int i=0; i<=3; i++)...{


graphic.drawChars(codes, i, 1, 2+15*i, 15+i);


//把codes[i]画到坐标为[10+5*i,15+i]的地方去


}




//15个干扰点


Random rand = new Random();


for (int i=0;i<15;i++)


graphic.drawOval(rand.nextInt(60),rand.nextInt(20),1,1);




//释放此图形的上下文并释放它所使用的所有系统资源


graphic.dispose();






try ...{


ImageIO.write(image, "JPEG", os);




} catch (IOException e) ...{


e.printStackTrace();


}




return new String(codes,0,codes.length);


}




public void doGet(HttpServletRequest request, HttpServletResponse response)




throws ServletException, IOException ...{


doPost(request,response);


}




public void doPost(HttpServletRequest request, HttpServletResponse response)




throws ServletException, IOException ...{


request.getSession().setAttribute("validationCodes", getValidationCodes(response.getOutputStream()));


}




}



然后，写一个Servlet将生成的图片写入页面：


package com.XiongYi.servlet;




import java.io.IOException;


import javax.servlet.ServletException;


import javax.servlet.http.HttpServlet;


import javax.servlet.http.HttpServletRequest;


import javax.servlet.http.HttpServletResponse;




import com.XiongYi.validationCode.ValidationCode;






public class ValidationServlet extends HttpServlet ...{




public void doGet(HttpServletRequest request, HttpServletResponse response)




throws ServletException, IOException ...{


doPost(request,response);


}




public void doPost(HttpServletRequest request, HttpServletResponse response)




throws ServletException, IOException ...{


String str = ValidationCode.getValidationCodes(response.getOutputStream());


request.getSession().setAttribute("validationCodes", str);


}




}



接着，在login.jsp中加入如下表单：




<%...


String path = request.getContextPath();


String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";


%>




<form action="<%=basePath+"servlet/LoginServlet"%>">


<img src="<%=basePath+"servlet/ValidationServlet"%>"/>


<br>


<input type="text" name="codes"/>


<input type="submit"/>


</form>

再写进行后台判断的Servlet：


package com.XiongYi.servlet;




import java.io.IOException;


import javax.servlet.ServletException;


import javax.servlet.http.HttpServlet;


import javax.servlet.http.HttpServletRequest;


import javax.servlet.http.HttpServletResponse;






public class LoginServlet extends HttpServlet ...{


public void doGet(HttpServletRequest request, HttpServletResponse response)




throws ServletException, IOException ...{


doPost(request,response);


}


public void doPost(HttpServletRequest request, HttpServletResponse response)




throws ServletException, IOException ...{




if(request.getSession().getAttribute("validationCodes").toString().toLowerCase()


.equals(request.getParameter("codes").toString().toLowerCase()))


response.getOutputStream().println("Right!");


else


response.getOutputStream().println("Wrong!");




}




}



怎么样，很容易吧，那就快尝试一下吧！o(∩_∩)o...