java验证码

最新推荐文章于 2023-03-04 21:04:57 发布

caoyishuai

最新推荐文章于 2023-03-04 21:04:57 发布

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分类专栏： java 文章标签： java string servlet xmlhttprequest ajax image

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首先是生成的验证码程序

package com.cfcc.cms.verification;

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 ImageServlet extends HttpServlet{


	private static final long serialVersionUID = 1L;
	   public void doGet(HttpServletRequest request, HttpServletResponse response)
       throws ServletException, IOException {

   response.setContentType("image/jpeg");//设置相应类型,告诉浏览器输出的内容为图片
   response.setHeader("Pragma", "No-cache");//设置响应头信息，告诉浏览器不要缓存此内容
   response.setHeader("Cache-Control", "no-cache");
   response.setDateHeader("Expire", 0);
   RandomValidateCode randomValidateCode = new RandomValidateCode();
   try {
       randomValidateCode.getRandcode(request, response);//输出图片方法
   } catch (Exception e) {
       e.printStackTrace();
   }
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
       throws ServletException, IOException {
   doGet(request, response);
}


}

package com.cfcc.cms.verification;

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

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class RandomValidateCode {
	  public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key
	    private Random random = new Random();
	    private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生的字符串
	    
	    private int width = 80;//图片宽
	    private int height = 26;//图片高
	    private int lineSize = 40;//干扰线数量
	    private int stringNum = 4;//随机产生字符数量
	    /*
	     * 获得字体
	     */
	    private Font getFont(){
	        return new Font("Fixedsys",Font.CENTER_BASELINE,18);
	    }
	    /*
	     * 获得颜色
	     */
	    private Color getRandColor(int fc,int bc){
	        if(fc > 255)
	            fc = 255;
	        if(bc > 255)
	            bc = 255;
	        int r = fc + random.nextInt(bc-fc-16);
	        int g = fc + random.nextInt(bc-fc-14);
	        int b = fc + random.nextInt(bc-fc-18);
	        return new Color(r,g,b);
	    }
	    /**
	     * 生成随机图片
	     */
	    public void getRandcode(HttpServletRequest request,
	            HttpServletResponse response) {
	        HttpSession session = request.getSession();
	        //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
	        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
	        Graphics g = image.getGraphics();//产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
	        g.fillRect(0, 0, width, height);
	        g.setFont(new Font("Times New Roman",Font.ROMAN_BASELINE,18));
	        g.setColor(getRandColor(110, 133));
	        //绘制干扰线
	        for(int i=0;i<=lineSize;i++){
	            drowLine(g);
	        }
	        //绘制随机字符
	        String randomString = "";
	        for(int i=1;i<=stringNum;i++){
	            randomString=drowString(g,randomString,i);
	        }
	        session.removeAttribute(RANDOMCODEKEY);
	        session.setAttribute(RANDOMCODEKEY, randomString);
	        System.out.println("图片"+randomString);
	        g.dispose();
	        try {
	            ImageIO.write(image, "JPEG", response.getOutputStream());//将内存中的图片通过流动形式输出到客户端
	        } catch (Exception e) {
	            e.printStackTrace();
	        }
	    }
	    /*
	     * 绘制字符串
	     */
	    private String drowString(Graphics g,String randomString,int i){
	        g.setFont(getFont());
	        g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));
	        String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
	        randomString +=rand;
	        g.translate(random.nextInt(3), random.nextInt(3));
	        g.drawString(rand, 13*i, 16);
	        return randomString;
	    }
	    /*
	     * 绘制干扰线
	     */
	    private void drowLine(Graphics g){
	        int x = random.nextInt(width);
	        int y = random.nextInt(height);
	        int xl = random.nextInt(13);
	        int yl = random.nextInt(15);
	        g.drawLine(x, y, x+xl, y+yl);
	    }
	    /*
	     * 获取随机的字符
	     */
	    public String getRandomString(int num){
	        return String.valueOf(randString.charAt(num));
	    }

}

这里是验证码显示图片的地方

<input type="text" id="randomCode" name="randomCode"/><img title="点击更换" οnclick="javascript:refresh(this);" id = "img" src="../../imageServlet"/><br/>

这里是点击刷新图片

function refresh(obj) {
		        obj.src = "../../imageServlet?"+Math.random();
		    }

这里是servlet中的配置，这样加载页面的时候直接就会加载验证码程序了，要注意上面的src要写相对路径到WEB_INF同级

	<servlet>
	    <servlet-name>ImageServlet</servlet-name>
	    <servlet-class>com.cfcc.cms.verification.ImageServlet</servlet-class>
	 </servlet>

	 <servlet-mapping>
	   <servlet-name>ImageServlet</servlet-name>
	   <url-pattern>/imageServlet</url-pattern>
	 </servlet-mapping>

然后是前台jsp页面的ajax请求部分。

			function isRightCode(){
				//获取请求
				var xmlHttp = null;
				xmlHttp=GetXmlHttpObject();
					
				if (xmlHttp==null){
			    	alert ("您的浏览器不支持AJAX！请使用IE浏览器");
			    	return;
			    }

			//我们需要将这部分改变下，这个就是你的输入框的id，通过jquery获取之后，将它设置为name = c 的形式，以供后台getParameter获取
			    var code = $("#randomCode").attr("value"); 
			    //alert(code);
				//发出post请求
			    xmlHttp.open("POST","../../checkServlet",true);//此处的url需要找到和WEB_INF同级，否则找不到映射的
			    xmlHttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
			    code = "c="+code;
			    code = encodeURI(encodeURI(code));	
			    //请求获取到的结果
			    var result;
			    xmlHttp.onreadystatechange=function(){
			  		if (xmlHttp.readyState == 4 && xmlHttp.status == 200){//发送和接受都成功
			  			result = xmlHttp.responseText;
			  			result = result.replace(/(^\s*)|(\s*$)/g,'');//去掉因为网络传输出现的空格
						
				//这里是业务逻辑的处理，即调用ajax之后返回的结果
						if(result == 1){
							alert("验证码为空");						
							return false;
						}else if(result == 3){
							alert("验证码不正确");
							refresh(document.getElementById("img"));
							document.getElementById("randomCode").value = "";
							return false;
						}else {
							document.form.submit();
						}
						
			  		}else if(xmlHttp.readyState != 4){//正在处理中
			  			//alert("正在处理中请稍后..........");
			  		}else if(xmlHttp.status == 404){//未找到页面
			  			alert("请求页面未找到，请联系维护人员！");
			  			return;
			  		} else {//未知错误
			  			alert("发生未知错误"+ xmlHttp.status +"，请联系管理员！");
			  			return;
			  		}
			  	};
			    xmlHttp.send(code);	
			}
		  //获取ajax请求
			function GetXmlHttpObject(){
		  		var xmlHttp=null;
		 		try{
		    		// Firefox, Opera 8.0+, Safari
		    		xmlHttp=new XMLHttpRequest();
		    	}catch (e){
		    		// Internet Explorer
		    		try{
		     			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		      		}catch (e){
		      			xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
		      		}
		    	}
		  		return xmlHttp;
			}

这个弄好页面的处理之后，写后台的处理

package com.cfcc.cms.verification;

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 CheckServlet extends HttpServlet {    
    private static final long serialVersionUID = 1L;  
  
    public void doGet(HttpServletRequest request, HttpServletResponse response)    
            throws ServletException, IOException {    
    
        doPost(request, response);    
    }    
    public void doPost(HttpServletRequest request, HttpServletResponse response)    
            throws ServletException, IOException {    
    
        //response.setContentType("text/html;charset=utf-8");    
        String validateC = (String) request.getSession().getAttribute("RANDOMVALIDATECODEKEY");    
        String veryCode = request.getParameter("c");    
        //PrintWriter out = response.getWriter();

//下面的就是将输出输出到页面了，即页面里的result就是这里的输出
        if(veryCode==null||"".equalsIgnoreCase(veryCode)){    
        	response.getWriter().write("1");//验证码为空
        }else{    
            if(validateC.equalsIgnoreCase(veryCode)){   
            	response.getWriter().write("2");
            }else{    
            	response.getWriter().write("3"); //验证码不正确
            }    
        }    
   
    }    
    
}

这个类编写好之后，要将web.xml中写上mapping

	  <servlet>
	    <servlet-name>checkServlet</servlet-name>
	    <servlet-class>com.cfcc.cms.verification.CheckServlet</servlet-class>
	  </servlet>
	
	 <servlet-mapping>
	   <servlet-name>checkServlet</servlet-name>
	   <url-pattern>/checkServlet</url-pattern>
	 </servlet-mapping>

这样一来，在页面验证之后，如果验证成功，则直接调用document.form.submit();就可以了。

在写这个demo的时候碰到过一个问题，就是开头我是在java程序中处理了验证码正确与否，然后拼成字符串到页面去做处理了，这样会很麻烦，所以应该返回结果去页面处理就可以了。

不要以为验证码的httpservlet和你自己提交的要写一起，实际是分开的，ajax请求的时候是单独写的一个servlet，并且是单独配置的xml。所以在处理完ajax请求之后才去调用submit方法提交后台了。