java 验证码，java,见过好几种类型的验证码，

java 验证码，java,见过好几种类型的验证码，

见过好几种类型的验证码，一开始觉得验证码的生成很神奇，后来发现验证码也是可以用Java轻松实现的。今天就来做一做这件事情。

首先，来写一个画验证码图片的Java类：

package com.xxx.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.xxx.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.xxx.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.xxx.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!");    }}

来自：《四火的唠叨》