本文實例為大家分享了Java圖片驗證碼代碼，供大家參考，具體內容如下
網頁顯示效果:
index.jsp
使用兩種方式強製圖片更新：
1、設置圖片輸出時不緩存。
2、用js改變請求的地址。
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><html> <head> <title>第一個web項目的主頁</title> <script type="text/javascript"> function changeImg(){ var _img=document.getElementById("_img"); var time=new Date().getTime();//瀏覽器認為相同的動作(被過濾)沒必要應答,所以用時間值改變src值(即請求)(事實上是同一請求) _img.src="confirm?"+time;//用js改變請求的地址} </script> </head> <body> <h2>主頁主頁</h2> <h2>湖南長沙</h2> <h3>發布方式一......</h3> <img src="images/1.jpg"/> <br/> <a href="jsps/a.jsp">去到子頁</a> <hr/> <form > 姓名:<input type="text" name="nmae"/><br/> 密碼:<input type="password" name="pwd"/> <br/> 確認密碼:<input type="text" name=pwd2/> <br/> 驗證碼:<input type="text" /><img id="_img" src="confirm"/> <!-- 不可行<a href="confirm">看不清</a> <br/> --> <a href="javascript:changeImg();">看不清</a> <br/> <input type="submit" value="註冊"/> </form> </body></html>自動生成驗證碼的java代碼
關鍵類(以下類為基礎部分的內容)
BufferedImage
ImageIO
Graphics/Graphics2D
import java.awt.Color;import java.awt.Font;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.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ImageServlet extends HttpServlet{ @Override protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// System.out.println("jinlaile"); resp.setContentType("image/jpeg");//jpeg是圖片格式。設置響應內容的類型為jpeg的圖片int width=64; int height=40; BufferedImage bImg=new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g=bImg.getGraphics(); //背景g.setColor(Color.white); g.fillRect(0, 0, width, height); //字體顏色g.setFont(new Font("aa", Font.BOLD,18)); //用隨機數生成驗證碼:4個0~9以內的整數Random r=new Random(); for(int i=0;i<=4;i++){ int t=r.nextInt(10);//10以內的隨機整數int y=10+r.nextInt(20);//上下位置:10~30 Color c=new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)); g.setColor(c); g.drawString(""+t, i*16, y); } //畫干擾線for(int i=1;i<8;i++){ Color c=new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)); g.setColor(c); g.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width), r.nextInt(height)); } //把圖形刷到bImg對像中g.dispose();//相當於IO中的close()方法帶自動flush(); ImageIO.write(bImg,"JPEG", resp.getOutputStream());//通過resp獲取req的outputStream對象,發向客戶端的socket的封裝,即寫到客戶端}}web.xml
<?xml version="1.0" encoding="UTF-8"?><web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <!-- 訪問安全目錄WEB-INF中的b.jsp文件--> <servlet> <servlet-name>bbbb</servlet-name> <jsp-file>/WEB-INF/b.jsp</jsp-file> </servlet> <!-- 訪問生成驗證碼的java代碼--> <servlet> <servlet-name>img</servlet-name> <servlet-class>cn.hncu.servlet.ImageServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>bbbb</servlet-name> <url-pattern>/bb.asp</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>img</servlet-name> <url-pattern>/confirm</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>