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JSP中图片验证的实现

图片验证在有关注册和发表留言经常用到.我在此用jsp写了个.供大家参考. 其中 com.sun.image 不是java的标准包.需要另外下载.相关地址为:


http://java.sun.com/products/java-media/jai/

1. random.jsp (产生四位的随机字符,由0-9,a-z,A-Z构成.并把最终字符串放到session中保存以让后续页面验证真伪) 代码如下:

<%@ page autoFlush="false" import="java.util.*,java.awt.*,java.awt.image.*,
com.sun.image.codec.jpeg.*,java.util.*"%>

<%@ page import="" contentType="text/html; charset=gb2312"%> <% String chose="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; char display[]={'0',' ','0',' ','0',' ','0'},ran[]={'0','0','0','0'},temp; Random rand=new Random(); for(int i=0;i<4;i++){ temp=chose.charAt(rand.nextInt(chose.length())); display[i*2]=temp; ran[i]=temp; }String random=String.valueOf(display); session.setAttribute("random",String.valueOf(ran)); %> <% out.clear(); response.setContentType("image/jpeg"); response.addHeader("pragma","NO-cache"); response.addHeader("Cache-Control","no-cache"); response.addDateHeader("Expries",0); int width=47, height=15; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); //以下填充背景颜色 g.setColor(Color.GREEN); g.fillRect(0, 0, width, height); //设置字体颜色 g.setColor(Color.RED); g.drawString(random,3,10); g.dispose(); ServletOutputStream outStream = response.getOutputStream(); JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(outStream); encoder.encode(image); outStream.close(); %> 2. img.jsp (显示验证图片.由于本程序简单让验证程序也一并放在了一起) 代码如下: <%@ page contentType="text/html; charset=gb2312" language="java"%>

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