JavaWeb: Servlet生成验证码

最新推荐文章于 2019-12-25 12:10:57 发布

王小涛_同學

最新推荐文章于 2019-12-25 12:10:57 发布

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分类专栏： JavaWeb Java 文章标签： Java JavaWeb IT 编程

本文链接：https://blog.youkuaiyun.com/u013511642/article/details/80382610

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本文介绍了一个使用Java实现的验证码生成器，该生成器能够生成包含随机字符的图像验证码，并提供了自定义字体、颜色及干扰线等功能。此外，还提供了一个简单的HTTP Servlet用于展示如何将验证码图片返回给客户端。

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package cn.itcast;
import java.awt.BasicStroke;
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.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;
public class VCode {
    private int w=70;
    private int h=35;
    private Color bgColor = new Color(240,240,240);
    private Random random = new Random();

    private StringBuilder code = new StringBuilder(4);

    //用户调用这个方法获取图片
    public BufferedImage getImage(){
        /*
         * 我们要写字符
         * 写什么字符,-->随机生成字符,范围0-9,a-z,A-Z
         * 字体::字号::是否粗体::-->全都随机
         * 字符颜色-->都随机
         */
        BufferedImage img = createImage();
        Graphics g = img.getGraphics();
        //画东西
        for(int i=0;i<4;i++){
            String ch = this.randomChar();//获取随机字符
            code.append(ch);

            g.setColor(this.randomColor());//随机颜色
            g.setFont(this.randomFont());//随机字体
            g.drawString(ch, w/4*i, h-5); //写字
        }
        this.drawLine(img); //画干扰线
        return img; 
    }
    //这个方法必须在getImage()方法之后调用!
    public String getCode(){
        return code.toString();
    }

    private Color randomColor(){
        int r = random.nextInt(256);
        int g = random.nextInt(256);
        int b = random.nextInt(256);
        return new Color(r,g,b);
    }
    /*
     * 随机生成字符
     */
    private String codes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    private String randomChar(){
            int index = random.nextInt(codes.length());
            return codes.charAt(index)+"";
        }
    /*
     * 字体名  样式  大小
     */
    private String[] fontName = {"宋体","华文楷体","黑体","华文新魏","华文隶书","微软雅黑","楷体"};
    private int[] fontSize = {24,25,26,27,28};//字号范围
    private Font randomFont(){

        int index =random.nextInt(fontName.length);//若数组长度为7,则生成数值为0-6
        String name = fontName[index];

        int style = random.nextInt(4);

        index = random.nextInt(fontSize.length);
        int size= fontSize[index];

        return new Font(name,style,size);
    }   
    private BufferedImage createImage() {
        /*
         * 1.创建图片
         * 2.设置背景色
         */
        BufferedImage img = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        //设置画笔颜色
        img.getGraphics().setColor(bgColor);
        //直充一个与图片大小一样的矩形,即设置背景色
        img.getGraphics().fillRect(0, 0, w, h); 
        return img;
    }
    private void drawLine(BufferedImage img){
        Graphics2D g = (Graphics2D)img.getGraphics();
        g.setColor(Color.BLACK);
        g.setStroke(new BasicStroke(1.5F));
        for(int i=0;i<5;i++){
            int x1=random.nextInt(w);
            int y1=random.nextInt(h);
            int x2=random.nextInt(w);
            int y2=random.nextInt(h);

            g.drawLine(x1, y1, x2, y2);
        }
    }
    public static void saveImage(BufferedImage img,OutputStream out) throws IOException{
        ImageIO.write(img, "jpeg", out);    
    }   
}

package cn.itcast;

import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;

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

public class BServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        VCode vc = new VCode();
        BufferedImage img = vc.getImage();
        System.out.println(vc.getCode());
        VCode.saveImage(img, response.getOutputStream());


    }

}

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">

    <title>My JSP 'index.jsp' starting page</title>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
  </head>

  <body>
    This is my JSP page. <br>
    验证码:<input type="text" name="vcode" size = "3"/> <br/>
    <img id="vc" src="/verifyCodeTest/BServlet" border="2"/>
   <a href='javascript:_change()'>看不清换一张</a>
   <script type="text/javascript">
    function _change(){
        var img =document.getElementById("vc");
        img.src="/verifyCodeTest/BServlet?a="+new Date().getTime();
    }

   </script>


    <br/>
    <input type="submit" value="提交">
  </body>
</html>

效果图