jsp+Servlet验证码实现

最新推荐文章于 2025-08-11 01:12:22 发布

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#jsp #验证码 #测试 #servlet

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本文介绍了一个简单的验证码生成系统及后台验证方法。通过Java Servlet技术，实现了动态生成包含随机字符的图片验证码，并通过比较用户输入与Session中存储的验证码来判断输入的正确性。

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两个类，一个用于验证码实现，一个为后台Servlet验证输入是否正确：

CodeUtil.java--------验证码具体实现：

package util;

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.io.PrintWriter;
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;
import javax.servlet.http.HttpSession;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.BodyContent;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageDecoder;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class CodeUtil extends HttpServlet {
	public void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		//System.out.println("哈哈哈");
		response.setContentType("image/jpeg");
		//设置页面不缓存 
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");   
	    response.setDateHeader("Expires", 0);
	    //在内存中创建图像
	    int width = 90;
	    int height = 35;
	    BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
	    //获取图形上下文
	    Graphics g = image.getGraphics();
	    //随机类
	    Random random = new Random();
	    //设定背景
	    g.setColor(getRandColor(200, 250));
	    g.fillRect(0, 0, width, height);
	    //设定字体
	    g.setFont(new Font("Times New Roman",Font.PLAIN,30));
	   //随机产生干扰线
	   g.setColor(getRandColor(160, 200));   
	   for (int i = 0; i < 100; i++) {   
	        int x = random.nextInt(width);   
	        int y = random.nextInt(height);   
	        int xl = random.nextInt(12);   
	        int yl = random.nextInt(12);   
	        g.drawLine(x, y, x + xl, y + yl);   
	   } 
	   //随机产生4位验证码
	   String[] codes = {"0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","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","o","p","q","r","s","t","u","v","w","x","y","z"};
	   String code = "";
	   for(int i=0;i<4;i++){
		   String str = codes[random.nextInt(codes.length)];
		   code += str;
		   // 将认证码显示到图象中
		   g.setColor(new Color(50 + random.nextInt(110), 20 + random.nextInt(110), 30 + random.nextInt(110)));
	       //调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成   
		   g.drawString(str, 18 * i +13, 27);  //文字间距*i+距离左边距，上边距 
	   }
	   HttpSession session=request.getSession();
		// 将认证码存入SESSION   
	   session.setAttribute("code", code);
	   // 图象生效   
	   g.dispose();   
	   // 输出图象到页面   
	   ImageIO.write(image, "JPEG", response.getOutputStream());
	   //加上下面代码,运行时才不会出现java.lang.IllegalStateException: getOutputStream() has already been called ..........等异常
	   response.getOutputStream().flush();  
	   response.getOutputStream().close();  
	   response.flushBuffer();  
	}
	//获取随机颜色
	private Color getRandColor(int fc,int bc){
		Random random = new Random();
		if(fc>255) fc=255;
		if(bc>255) bc=255;
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r,g,b);
		}

}

CheckCodeUtil.java-----------用户输入验证功能

package util;

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;
import javax.servlet.http.HttpSession;

public class CheckCodeUtil extends HttpServlet {
	public void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();
		//从session获取验证码
		HttpSession session=request.getSession();
		String code=session.getAttribute("code").toString();
		System.out.println(code);
		//获取用户输入验证码
		String input=request.getParameter("code");
		System.out.println(input);
		if(code.equalsIgnoreCase(input)){
			//转发数据
			request.setAttribute("result", "true");
			request.getRequestDispatcher("test/regist.jsp").forward(request, response);
//			response.sendRedirect(request.getContextPath()+"/regist/regist.jsp");
		}else{
			request.setAttribute("result", "false");
			request.getRequestDispatcher("test/regist.jsp").forward(request, response);
		}
	}

}

测试页面效果：

测试页面代码：

<%@ page session="true" pageEncoding="utf-8" contentType="text/html; charset=utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<head>
		<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
		<title>Insert title here</title>
		<script>
		  function showResult1(){
		  	alert('输入正确');
		  }
		  function showResult2(){
		  	alert('输入错误');
		  }
		</script>
	</head>
	<% 
		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("utf-8");
		String path=request.getContextPath();
		if(request.getAttribute("result")!=null){
		String result=request.getAttribute("result").toString();
		out.print(result);
		if(result.equals("true")){
			
			out.print("true");
			out.print("<script>showResult1();<script>");
		}else{
			out.print("<script>showResult2();<script>");
		}
		}
	%>
		<body> 
		<br>验证码演示 
		<form action="<%=path %>/checkCodeUtil" method="post">
		<input type="text" size="10" name="code"/>
		<img src="<%=path %>/codeUtil" id="img"/>
		<a href="javascript:;" onclick="document.
			getElementById('img').src='<%=path %>/codeUtil?'+new Date().getTime();">看不清，换一个</a>
		<input type="submit" value="提交">
		</form>
	</body>
</html>