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                        /后端開發
                        
                            /Java
                        
                        /Java實現驗證碼制作

驗證碼出不來

<%@?page?language="java"?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>checkCode</title>
	<script?type="text/javascript">
		function?reloadCode(){
			var?time?=?new?Date().getTime();
			document.getElementById("imagecode").src="<%request.getContextPath();%>/yanzheng/ImageServlet?d="+time;
		}
	</script>
</head>
<body>
	驗證碼：<input?type="text"?name="checkcode"/>
		<img?alt="驗證碼"?id="imagecode"?src="<%request.getContextPath();%>/yanzheng/ImageServlet"?/>
		<a?href="javascript:reloadCode();">看不清楚</a><br>

</body>
</html>




package?com.imooc.yanzheng;

import?java.awt.Color;
import?java.awt.Graphics;
import?java.awt.image.BufferedImage;
import?java.io.IOException;
import?java.util.Random;

import?javax.imageio.ImageIO;
import?javax.servlet.ServletException;
import?javax.servlet.annotation.WebServlet;
import?javax.servlet.http.HttpServlet;
import?javax.servlet.http.HttpServletRequest;
import?javax.servlet.http.HttpServletResponse;

/**
?*?Servlet?implementation?class?ImageServlet
?*/
@WebServlet(name="ImageServlet",urlPatterns={"/yanzheng/ImageServlet"})
public?class?ImageServlet?extends?HttpServlet?{
	private?static?final?long?serialVersionUID?=?1L;
???????
????/**
?????*?@see?HttpServlet#HttpServlet()
?????*/
????public?ImageServlet()?{
????????super();
????????//?TODO?Auto-generated?constructor?stub
????}

	/**
	?*?@see?HttpServlet#doGet(HttpServletRequest?request,?HttpServletResponse?response)
	?*/
	public?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)??{

		BufferedImage?bi?=?new?BufferedImage(66,22,BufferedImage.TYPE_INT_RGB);
		Graphics?g?=?bi.getGraphics();
		Color?c?=?new?Color(200,150,255);
		g.setColor(c);
		g.fillRect(0,?0,?68,?22);
		
		char[]?ch?=?"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456798".toCharArray();
		Random?r?=?new?Random();
		int?len?=?ch.length,index;
		StringBuffer?sb?=?new?StringBuffer();
		for(int?i=0;i<4;i++){
			index=r.nextInt(len);
			g.setColor(new?Color(r.nextInt(88),r.nextInt(188),r.nextInt(255)));
			g.drawString(ch[index]+"",?(i*15)+3,?18);
			sb.append(ch[index]);
		}
		request.getSession().setAttribute("piccode",?sb.toString());
		try?{
			ImageIO.write(bi,?"JPG",?response.getOutputStream());
		}?catch?(IOException?e)?{
			//?TODO?Auto-generated?catch?block
			e.printStackTrace();
		}
	
	
	}

	/**
	?*?@see?HttpServlet#doPost(HttpServletRequest?request,?HttpServletResponse?response)
	?*/
	public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)?throws?ServletException,?IOException?{
		//?TODO?Auto-generated?method?stub
		doGet(request,?response);
	}

}