Java验证码生成库kaptcha使用简介
## kaptcha
kaptcha 是一个非常实用的验证码生成工具。有了它，你可以生成各种样式的验证码，因为它是可配置的。kaptcha工作的原理是调用 com.google.code.kaptcha.servlet.KaptchaServlet，生成一个图片。同时将生成的验证码字符串放到 HttpSession中。
使用kaptcha可以方便的配置：
验证码的字体
验证码字体的大小
验证码字体的字体颜色
验证码内容的范围(数字，字母，中文汉字！)
验证码图片的大小，边框，边框粗细，边框颜色
验证码的干扰线(可以自己继承com.google.code.kaptcha.NoiseProducer写一个自定义的干扰线)
验证码的样式(鱼眼样式、3D、普通模糊……当然也可以继承com.google.code.kaptcha.GimpyEngine自定义样式)
详细信息请看下面的web.xml文件
下面介绍一下用法:
1.首先去官网下载jar:[http://code.google.com/p/kaptcha/](http://code.google.com/p/kaptcha/)
2.建立一个web项目，导入kaptcha-2.3.jar到环境变量中。
## Servlet方式
配置web.xml文件，之后访问 /kaptcha.jpg
```
<!--Kaptcha 验证码 -->
<servlet>
<servlet-name>kaptcha</servlet-name>
<servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet
</servlet-class>
<init-param>
<param-name>kaptcha.border</param-name>
<param-value>no</param-value>
</init-param>
<init-param>
<param-name>kaptcha.border.color</param-name>
<param-value>105,179,90</param-value>
</init-param>
<init-param>
<param-name>kaptcha.textproducer.font.color</param-name>
<param-value>red</param-value>
</init-param>
<init-param>
<param-name>kaptcha.image.width</param-name>
<param-value>250</param-value>
</init-param>
<init-param>
<param-name>kaptcha.image.height</param-name>
<param-value>90</param-value>
</init-param>
<init-param>
<param-name>kaptcha.textproducer.font.size</param-name>
<param-value>70</param-value>
</init-param>
<init-param>
<param-name>kaptcha.session.key</param-name>
<param-value>code</param-value>
</init-param>
<init-param>
<param-name>kaptcha.textproducer.char.length</param-name>
<param-value>4</param-value>
</init-param>
<init-param>
<param-name>kaptcha.textproducer.font.names</param-name>
<param-value>宋体,楷体,微软雅黑</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>kaptcha</servlet-name>
<url-pattern>/kaptcha.jpg</url-pattern>
</servlet-mapping>
```
## 配置验证码生成器
在applicationContext.xml中配置：
```
<bean id="captchaProducer" class="com.google.code.kaptcha.impl.DefaultKaptcha">
<property name="config">
<bean class="com.google.code.kaptcha.util.Config">
<constructor-arg>
<props>
<prop key="kaptcha.border">no</prop>
<prop key="kaptcha.border.color">105,179,90</prop>
<prop key="kaptcha.textproducer.font.color">red</prop>
<prop key="kaptcha.image.width">250</prop>
<prop key="kaptcha.textproducer.font.size">90</prop>
<prop key="kaptcha.image.height">90</prop>
<prop key="kaptcha.session.key">code</prop>
<prop key="kaptcha.textproducer.char.length">4</prop>
<prop key="kaptcha.textproducer.font.names">宋体,楷体,微软雅黑</prop>
</props>
</constructor-arg>
</bean>
</property>
</bean>
```
## SpringMVC图片生成器
```
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import com.google.code.kaptcha.Constants;
import com.google.code.kaptcha.Producer;
@Controller
@RequestMapping("/")
public class CaptchaImageCreateController {
private Producer captchaProducer = null;
@Autowired
public void setCaptchaProducer(Producer captchaProducer) {
this.captchaProducer = captchaProducer;
}
@RequestMapping("/captcha.jpg")
public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
response.setDateHeader("Expires", 0);
// Set standard HTTP/1.1 no-cache headers.
response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
// Set IE extended HTTP/1.1 no-cache headers (use addHeader).
response.addHeader("Cache-Control", "post-check=0, pre-check=0");
// Set standard HTTP/1.0 no-cache header.
response.setHeader("Pragma", "no-cache");
// return a jpeg
response.setContentType("image/jpeg");
// create the text for the image
String capText = captchaProducer.createText();
// store the text in the session
request.getSession().setAttribute(Constants.KAPTCHA_SESSION_KEY, capText);
// create the image with the text
BufferedImage bi = captchaProducer.createImage(capText);
ServletOutputStream out = response.getOutputStream();
// write the data out
ImageIO.write(bi, "jpg", out);
try {
out.flush();
} finally {
out.close();
}
return null;
}
}
```
## Struts2图片生成器
访问的URL请自行配置，这里的image方法可以向浏览器输出图片流;
```
package com.zhenzhigu.ssh.action;
import java.awt.image.BufferedImage;
import java.io.OutputStream;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.ServletActionContext;
import org.springframework.beans.factory.annotation.Autowired;
import com.google.code.kaptcha.Constants;
import com.google.code.kaptcha.Producer;
import com.opensymphony.xwork2.ActionSupport;
public class ValidateCodeImage extends ActionSupport {
@Autowired
private Producer captchaProducer = null;
public String image() throws Exception {
HttpServletRequest request = ServletActionContext.getRequest();
HttpServletResponse response = ServletActionContext.getResponse();
response.setDateHeader("Expires", 0);
//禁用浏览器缓存
response.setHeader("Cache-Control","no-store, no-cache, must-revalidate");
response.addHeader("Cache-Control", "post-check=0, pre-check=0");
response.setHeader("Pragma", "no-cache");
//设置MIME类型为jpg
response.setContentType("image/jpeg");
//创建一个验证码字符串
String capText = captchaProducer.createText();
//把字符串存到HttpSession中
request.getSession().setAttribute(Constants.KAPTCHA_SESSION_KEY,capText);
//生成验证码图片
BufferedImage bi = captchaProducer.createImage(capText);
OutputStream out = response.getOutputStream();
//通过输出流把图片写到用户的浏览器中
ImageIO.write(bi, "jpg", out);
return null;
}
}
```
## 页面获取验证码图片
图片路径请根据实际情况填写。
```
<img src="/captcha.jpg" width="55" height="20" id="vci"/>
<script type="text/javascript">
$(function(){
//点击刷新
$('#vci').click(function(){
$(this).attr('src', '/captcha.jpg' + Math.random() );
})
});
</script> <br> $(function(){
//点击刷新<br> $('#vci').click(function(){
$(this).attr('src', '/captcha.jpg' + Math.random() );
})<br> });
```
## Java取验证码
```
String code = (String)session.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
```
## 验证码相关设置
### 全部都是数字
```
<init-param>
<param-name>kaptcha.textproducer.char.string</param-name>
<param-value>0123456789</param-value>
</init-param>
```
### 去掉干扰线
```
<init-param>
<param-name>kaptcha.noise.impl</param-name>
<param-value>com.google.code.kaptcha.impl.NoNoise</param-value>
</init-param>
```