隨機生成四位數驗證碼,包括漢字,數字,英文大小寫。
1.Servlet類
package servlet; import java.awt.BasicStroke; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.geom.AffineTransform; import java.awt.geom.Line2D; import java.awt.image.BufferedImage; import java.io.IOException; 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; public class PictureCheckCode extends HttpServlet { private static final long serialVersionUID = 1L; public PictureCheckCode() { super(); } public void destroy() { super.destroy(); } public void init() throws ServletException { super.init(); } /*該方法主要作用是獲得隨機生成的顏色*/ public Color getRandColor(int s,int e){ Random random=new Random (); if(s>255) s=255; if(e>255) e=255; int r,g,b; r=s+random.nextInt(e-s); //隨機生成RGB顏色中的r值 g=s+random.nextInt(e-s); //隨機生成RGB顏色中的g值 b=s+random.nextInt(e-s); //隨機生成RGB顏色中的b值 return new Color(r,g,b); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("this is doGet method"); this.doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //設置不緩存圖片 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "No-cache"); response.setDateHeader("Expires", 0); //指定生成的響應圖片,一定不能缺少這句話,否則錯誤. response.setContentType("image/jpeg"); int width=80,height=35; //指定生成驗證碼的寬度和高度 BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //創建BufferedImage對象,其作用相當於一圖片 Graphics g=image.getGraphics(); //創建Graphics對象,其作用相當於畫筆 Graphics2D g2d=(Graphics2D)g; //創建Grapchics2D對象 Random random=new Random(); Font mfont=new Font("楷體",Font.BOLD,16); //定義字體樣式 g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height); //繪制背景 g.setFont(mfont); //設置字體 g.setColor(getRandColor(180,200)); //繪制100條顏色和位置全部為隨機產生的線條,該線條為2f for(int i=0;i<100;i++){ int x=random.nextInt(width-1); int y=random.nextInt(height-1); int x1=random.nextInt(6)+1; int y1=random.nextInt(12)+1; BasicStroke bs=new BasicStroke(2f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL); //定制線條樣式 Line2D line=new Line2D.Double(x,y,x+x1,y+y1); g2d.setStroke(bs); g2d.draw(line); //繪制直線 } //輸出由英文,數字,和中文隨機組成的驗證文字,具體的組合方式根據生成隨機數確定。 String sRand=""; String ctmp=""; int itmp=0; //制定輸出的驗證碼為四位 for(int i=0;i<4;i++){ switch(random.nextInt(3)){ case 1: //生成A-Z的字母 itmp=random.nextInt(26)+65; ctmp=String.valueOf((char)itmp); break; case 2: //生成漢字 String[] rBase={"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"}; //生成第一位區碼 int r1=random.nextInt(3)+11; String str_r1=rBase[r1]; //生成第二位區碼 int r2; if(r1==13){ r2=random.nextInt(7); }else{ r2=random.nextInt(16); } String str_r2=rBase[r2]; //生成第一位位碼 int r3=random.nextInt(6)+10; String str_r3=rBase[r3]; //生成第二位位碼 int r4; if(r3==10){ r4=random.nextInt(15)+1; }else if(r3==15){ r4=random.nextInt(15); }else{ r4=random.nextInt(16); } String str_r4=rBase[r4]; //將生成的機內碼轉換為漢字 byte[] bytes=new byte[2]; //將生成的區碼保存到字節數組的第一個元素中 String str_12=str_r1+str_r2; int tempLow=Integer.parseInt(str_12, 16); bytes[0]=(byte) tempLow; //將生成的位碼保存到字節數組的第二個元素中 String str_34=str_r3+str_r4; int tempHigh=Integer.parseInt(str_34, 16); bytes[1]=(byte)tempHigh; ctmp=new String(bytes); break; default: itmp=random.nextInt(10)+48; ctmp=String.valueOf((char)itmp); break; } sRand+=ctmp; Color color=new Color(20+random.nextInt(110),20+random.nextInt(110),random.nextInt(110)); g.setColor(color); //將生成的隨機數進行隨機縮放並旋轉制定角度 PS.建議不要對文字進行縮放與旋轉,因為這樣圖片可能不正常顯示 /*將文字旋轉制定角度*/ Graphics2D g2d_word=(Graphics2D)g; AffineTransform trans=new AffineTransform(); trans.rotate((45)*3.14/180,15*i+8,7); /*縮放文字*/ float scaleSize=random.nextFloat()+0.8f; if(scaleSize>1f) scaleSize=1f; trans.scale(scaleSize, scaleSize); g2d_word.setTransform(trans); g.drawString(ctmp, 15*i+18, 14); } HttpSession session=request.getSession(true); session.setAttribute("randCheckCode", sRand); System.out.println(sRand); g.dispose(); //釋放g所占用的系統資源 ImageIO.write(image,"JPEG",response.getOutputStream()); //輸出圖片 } }
2.web.xml配置
<servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>PictureCheckCode</servlet-name> <servlet-class>servlet.PictureCheckCode</servlet-class> </servlet> <servlet-mapping> <servlet-name>PictureCheckCode</servlet-name> <url-pattern>/pictureCheckCode</url-pattern> </servlet-mapping>
3.jsp頁面輸出驗證碼
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>登錄頁面</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <script language="javascript"> function myReload() { document.getElementById("CreateCheckCode").src = document .getElementById("CreateCheckCode").src + "?nocache=" + new Date().getTime(); } </script> </head> <body> <form action="loginServlet" method="get"> <p class="font tdheight"> 驗證碼:<input type="text" name="checkCode" > <img src="pictureCheckCode" id="CreateCheckCode" align="middle" > <br> <a href="" onclick="myReload()" > 看不清,換一個</a> </p> <br><input type="submit" value="提交" class="font" > </form> </body> </html>
4.後台Servlet判斷驗證碼是否與輸入一致
通過request.getParameter(“checkCode”)獲取輸入驗證碼,與session.getAttribute(“randCheckCode”)比較是否一致。
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String code = request.getParameter("checkCode"); HttpSession session = request.getSession(); if (!code.equals(session.getAttribute("randCheckCode"))) { request.setAttribute("errormsg", "驗證碼不正確"); } System.out.println(request.getAttribute("errormsg")); }
運行結果:
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