java web验证码生成总结(包括servlet、jsp和struts2实现)

一、使用纯Servlet实现验证码

(1)在web.xml配置:
<servlet> <servlet-name>image</servlet-name> <servlet-class>org.test.web.AuthImage</servlet-class> </servlet> <servlet-mapping> <servlet-name>image</servlet-name> <url-pattern>/authImage</url-pattern> </servlet-mapping>

(2)servlet源码

public class AuthImage extends HttpServlet { private static final String CONTENT_TYPE = "text/html; charset=gb2312"; //设置字母的大小,大小 private Font mFont = new Font("Times New Roman", Font.PLAIN, 17); public void init() throws ServletException { super.init(); } 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); } public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0); //表明生成的响应是图片 response.setContentType("image/jpeg"); int width=100, height=18; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); Random random = new Random(); g.setColor(getRandColor(200,250)); g.fillRect(1, 1, width-1, height-1); g.setColor(new Color(102,102,102)); g.drawRect(0, 0, width-1, height-1); g.setFont(mFont); g.setColor(getRandColor(160,200)); //画随机线 for (int i=0;i<155;i++) { int x = random.nextInt(width - 1); int y = random.nextInt(height - 1); int xl = random.nextInt(6) + 1; int yl = random.nextInt(12) + 1; g.drawLine(x,y,x + xl,y + yl); } //从另一方向画随机线 for (int i = 0;i < 70;i++) { int x = random.nextInt(width - 1); int y = random.nextInt(height - 1); int xl = random.nextInt(12) + 1; int yl = random.nextInt(6) + 1; g.drawLine(x,y,x - xl,y - yl); } //生成随机数,并将随机数字转换为字母 String sRand=""; for (int i=0;i<6;i++) { int itmp = random.nextInt(26) + 65; char ctmp = (char)itmp; sRand += String.valueOf(ctmp); g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110))); g.drawString(String.valueOf(ctmp),15*i+10,16); } HttpSession session = request.getSession(true); session.setAttribute("rand",sRand); g.dispose(); ImageIO.write(image, "JPEG", response.getOutputStream()); } public void destroy() { } }

(3)页面显示

<img src="authImage"/>

 

 

 

二、使用纯jsp实现验证码

<%@ page language="java" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" contentType="image/jpeg" pageEncoding="UTF-8"%><% //设置页面不缓存 response.setHeader("Pragma","No-cache"); response.setHeader("Cahce-Control","no-cache"); response.setDateHeader("Expires",0); //在内存中创建图片 int width=60,height=20; BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); //获取图形上下文 Graphics g= image.getGraphics(); //生成随机类 Random random= new Random(); //设置背景颜色 g.setColor(new Color(160,200,100)); g.fillRect(0,0,width,height); //设置字体 g.setFont(new Font("Times New Roman",Font.PLAIN,18)); //随机产生50条干扰线，使图形中的验证码不易被其他的程序探测到 g.setColor(new Color(160,200,200)); for(int i=0;i<50;i++) { int x=random.nextInt(width); int y=random.nextInt(height); int x1=random.nextInt(width); int y1=random.nextInt(height); g.drawLine(x,y,x+x1,y+y1); } //随机产生验证码（6位数字） String sRand=""; for(int i=0;i<6;i++) { String rand=String.valueOf(random.nextInt(10)); sRand+=rand; //将验证码显示到图象 g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110))); g.drawString(rand,13*i+6,16); } session.setAttribute("rand",sRand); //////将产生的验证码存储到sesson中 g.dispose(); ImageIO.write(image,"JPEG",response.getOutputStream()); out.clear(); //*********** out=pageContext.pushBody();//********** %>

 

 

三、使用Struts2来实现验证码

(1)定义一个生成验证码的工具类

package com.cn.hospital.util;import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.util.Random; import javax.imageio.ImageIO; import javax.imageio.stream.ImageOutputStream; public class RandomNumUtil { private ByteArrayInputStream image;//图像 private String str;//验证码 private RandomNumUtil(){ init();//初始化属性 } /* * 取得RandomNumUtil实例 */ public static RandomNumUtil Instance(){ return new RandomNumUtil(); } /* * 取得验证码图片 */ public ByteArrayInputStream getImage(){ return this.image; } /* * 取得图片的验证码 */ public String getString(){ return this.str; } private void init() { // 在内存中创建图象 int width=85, height=20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); // 生成随机类 Random random = new Random(); // 设定背景色 g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height); // 设定字体 g.setFont(new Font("Times New Roman",Font.PLAIN,18)); // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到 g.setColor(getRandColor(160,200)); for (int i=0;i<155;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); } // 取随机产生的认证码(6位数字) String sRand=""; for (int i=0;i<6;i++){ String rand=String.valueOf(random.nextInt(10)); sRand+=rand; // 将认证码显示到图象中 g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+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(rand,13*i+6,16); } //赋值验证码 this.str=sRand; //图象生效 g.dispose(); ByteArrayInputStream input=null; ByteArrayOutputStream output = new ByteArrayOutputStream(); try{ ImageOutputStream imageOut = ImageIO.createImageOutputStream(output); ImageIO.write(image, "JPEG", imageOut); imageOut.close(); input = new ByteArrayInputStream(output.toByteArray()); }catch(Exception e){ System.out.println("验证码图片产生出现错误："+e.toString()); } this.image=input;/* 赋值图像 */ } /* * 给定范围获得随机颜色 */ 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); } }

(2)定义一个验证码输出的action

package com.cn.hospital.action;import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import org.springframework.context.annotation.Scope;import org.springframework.stereotype.Controller;import com.cn.hospital.util.RandomCharUtil;import com.cn.hospital.util.RandomNumUtil;import com.opensymphony.xwork2.ActionContext;import com.opensymphony.xwork2.ActionSupport;@Controller("utilAction")@Scope("prototype")public class UtilAction extends ActionSupport{ private static final long serialVersionUID = -7193209177116825032L; private ByteArrayInputStream inputStream; private int width; private int height; private int fontSize; private int codeLength; private int disturbType; public String validNumGenerate() throws Exception{ RandomNumUtil rdnu=RandomNumUtil.Instance(); this.setInputStream(rdnu.getImage());//取得带有随机字符串的图片 ActionContext.getContext().getSession().put("random", rdnu.getString());//取得随机字符串放入HttpSession return SUCCESS; } public void setInputStream(ByteArrayInputStream inputStream) { this.inputStream = inputStream; } public ByteArrayInputStream getInputStream() { return inputStream; } }

(3)struts.xml配置

<!-- 产生随机验证码 --> <action name="randNum" class="utilAction" method="validNumGenerate"> <result name="success" type="stream"> <param name="contentType">image/jpeg</param> <param name="inputName">inputStream</param> </result> </action>

 

 

四、小结

    对于java的web技术，归根究底还是在服务器端执行的servlet.从上面的三种不同实现中，我们很容易察觉到他们存在一个共同点，那就是返回浏览器端的contentType。

    servlet:使用response.setContentType(" ");方法来实现

    jsp:在<@ page contentType=" ">中来实现

    struts2:通过配置<param name="contentType"> </param>来实现

 

至于验证码的产生其实比较简单，在这里就不深究了。就此一点小感想，与同行共勉。