一、使用纯Servlet实现验证码
(1)在web.xml配置:
[java] view plaincopy
<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
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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
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<img src="authImage"/>
二、使用纯jsp实现验证码
[java] view plaincopy
<%@ 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
[java] view plaincopy
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
[java] view plaincopy
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
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<!-- 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。
java web验证码生成总结(包括servlet、jsp和struts2实现)(转),布布扣,bubuko.com
java web验证码生成总结(包括servlet、jsp和struts2实现)(转)
原文：http://my.oschina.net/u/270597/blog/289226