servlet动态生成验证码

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于 2020-12-21 17:43:25 发布

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文章标签： servlet java

本文链接：https://blog.youkuaiyun.com/ningziwen/article/details/111479654

版权

HTML部分：

<b>验证码：</b>
<div class="inptinfo">
    <input name="checkCode" class="inpt" style="width: 50%" placeholder="请输入验证码!" type="text" id="checkCode" title="验证码区分大小写"  size="8"  maxlength="4" />  
	<img src="localhost:8080/test/PictureCheckCode" id="CreateCheckCode" align="top" style="width:80px; height: 2.5rem;">
    <a href="javascript:;" onclick="myReload()"><br>看不清，换一个</a>
</div>

PictureCheckCode类：

import java.awt.*;  
import java.awt.geom.*;  
import java.awt.image.*;  
import java.io.*;  
import java.util.*;  
  
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
import javax.servlet.http.HttpSession;  
import javax.imageio.ImageIO;

public class PictureCheckCode extends HttpServlet{
	private static final long serialVersionUID = 1L; 
	public PictureCheckCode() {  
        super();  
    }  
	  
    public void destroy() {  
        super.destroy();   
    }  
  
    public void init() throws ServletException {  
        super.init();  
    }  
    
    /*该方法主要作用是获得随机生成的颜色*/   
    public Color getRandColor(int s,int e){  
        Random random=new Random ();  
        if(s>255) s=255;  
        if(e>255) e=255;  
        int r,g,b;  
        r=s+random.nextInt(e-s);    //随机生成RGB颜色中的r值  
        g=s+random.nextInt(e-s);    //随机生成RGB颜色中的g值  
        b=s+random.nextInt(e-s);    //随机生成RGB颜色中的b值  
        return new Color(r,g,b);  
    }  
  
    @Override  
    public void service(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
        //设置不缓存图片  
        response.setHeader("Pragma", "No-cache");  
        response.setHeader("Cache-Control", "No-cache");  
        response.setDateHeader("Expires", 0);  
        //指定生成的响应图片,一定不能缺少这句话,否则错误.  
        response.setContentType("image/jpeg");  
        int width=86,height=22;     //指定生成验证码的宽度和高度  
        BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //创建BufferedImage对象,其作用相当于一图片  
        Graphics g=image.getGraphics();     //创建Graphics对象,其作用相当于画笔  
        Graphics2D g2d=(Graphics2D)g;       //创建Grapchics2D对象  
        Random random=new Random();  
        Font mfont=new Font("宋体",Font.BOLD,16); //定义字体样式  
        g.setColor(getRandColor(200,250));  
        g.fillRect(0, 0, width, height);    //绘制背景  
        g.setFont(mfont);                   //设置字体  
        g.setColor(getRandColor(180,200));  
          
        //绘制100条颜色和位置全部为随机产生的线条,该线条为2f  
        for(int i=0;i<100;i++){  
            int x=random.nextInt(width-1);  
            int y=random.nextInt(height-1);  
            int x1=random.nextInt(6)+1;  
            int y1=random.nextInt(12)+1;  
            BasicStroke bs=new BasicStroke(2f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL); //定制线条样式  
            Line2D line=new Line2D.Double(x,y,x+x1,y+y1);  
            g2d.setStroke(bs);  
            g2d.draw(line);     //绘制直线  
        }  
        //输出由英文，数字，和中文随机组成的验证文字，具体的组合方式根据生成随机数确定。  
        String sRand="";  
        String ctmp="";  
        int itmp=0;  
        //制定输出的验证码为四位  
        for(int i=0;i<4;i++){  
            switch(random.nextInt(2)){  
                case 1:     //生成A-Z的字母  
                     itmp=random.nextInt(26)+65;  
                     ctmp=String.valueOf((char)itmp);  
                     break;  
                case 2:     //生成汉字  
                     String[] rBase={"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"};   
                     //生成第一位区码  
                     int r1=random.nextInt(3)+11;  
                     String str_r1=rBase[r1];  
                     //生成第二位区码  
                     int r2;  
                     if(r1==13){  
                         r2=random.nextInt(7);     
                     }else{  
                         r2=random.nextInt(16);  
                     }  
                     String str_r2=rBase[r2];  
                     //生成第一位位码  
                     int r3=random.nextInt(6)+10;  
                     String str_r3=rBase[r3];  
                     //生成第二位位码  
                     int r4;  
                     if(r3==10){  
                         r4=random.nextInt(15)+1;  
                     }else if(r3==15){  
                         r4=random.nextInt(15);  
                     }else{  
                         r4=random.nextInt(16);  
                     }  
                     String str_r4=rBase[r4];  
                     //将生成的机内码转换为汉字  
                     byte[] bytes=new byte[2];  
                     //将生成的区码保存到字节数组的第一个元素中  
                     String str_12=str_r1+str_r2;  
                     int tempLow=Integer.parseInt(str_12, 16);  
                     bytes[0]=(byte) tempLow;  
                     //将生成的位码保存到字节数组的第二个元素中  
                     String str_34=str_r3+str_r4;  
                     int tempHigh=Integer.parseInt(str_34, 16);  
                     bytes[1]=(byte)tempHigh;  
                     ctmp=new String(bytes);  
                     break;  
                default:  
                     itmp=random.nextInt(10)+48;  
                     ctmp=String.valueOf((char)itmp);  
                     break;  
            }  
            sRand+=ctmp;  
            Color color=new Color(20+random.nextInt(110),20+random.nextInt(110),random.nextInt(110));  
            g.setColor(color);  
            //将生成的随机数进行随机缩放并旋转制定角度 PS.建议不要对文字进行缩放与旋转,因为这样图片可能不正常显示  
            /*将文字旋转制定角度*/  
            Graphics2D g2d_word=(Graphics2D)g;  
            AffineTransform trans=new AffineTransform();  
            trans.rotate((45)*3.14/180,15*i+8,7);  
            /*缩放文字*/  
            float scaleSize=random.nextFloat()+0.8f;  
            if(scaleSize>1f) scaleSize=1f;  
            trans.scale(scaleSize, scaleSize);  
            g2d_word.setTransform(trans);  
            g.drawString(ctmp, 15*i+18, 6);  
        }  
        HttpSession session=request.getSession(true);  
        session.setAttribute("randCheckCode", sRand);  
        g.dispose();    //释放g所占用的系统资源  
        ImageIO.write(image,"JPEG",response.getOutputStream()); //输出图片  
    }  
}

java方法验证：

//乱码
this.getResponse().setContentType("text/html; charset=UTF-8 " );
PrintWriter out = this.getResponse().getWriter();
//验证码
System.out.println(getSession().getAttribute("randCheckCode"));
System.out.println("原来的"+checkCode);
if(((checkCode.toUpperCase()).equals(((String)getSession().getAttribute("randCheckCode")).toUpperCase()))) {
    this.getRequest().setAttribute("parafresh", true);
 	this.getRequest().setAttribute("returnMessage", "验证码有误……");
	return "refresh";
}

servlet需要配置web.xml

<!-- 二维码 -->
<servlet>  
    <servlet-name>PictureCheckCode</servlet-name>  
    <servlet-class>PictureCheckCode路径</servlet-class>  
</servlet>
<servlet-mapping>  
    <servlet-name>PictureCheckCode</servlet-name>  
    <url-pattern>/PictureCheckCode</url-pattern>  
</servlet-mapping>

效果展示