Shiro学习（22）集成验证码

在做用户登录功能时，很多时候都需要验证码支持，验证码的目的是为了防止机器人模拟真实用户登录而恶意访问，如暴力破解用户密码/恶意评论等。目前也有一些验证码比较简单，通过一些OCR工具就可以解析出来；另外还有一些验证码比较复杂（一般通过如扭曲、加线条/噪点等干扰）防止OCR工具识别；但是在中国就是人多，机器干不了的可以交给人来完成，所以在中国就有很多打码平台，人工识别验证码；因此即使比较复杂的如填字、算数等类型的验证码还是能识别的。所以验证码也不是绝对可靠的，目前比较可靠还是手机验证码，但是对于用户来说相对于验证码还是比较麻烦的。

对于验证码图片的生成，可以自己通过如Java提供的图像API自己去生成，也可以借助如JCaptcha这种开源Java类库生成验证码图片；JCaptcha提供了常见的如扭曲、加噪点等干扰支持。本章代码基于《第十六章综合实例》。

一、添加JCaptcha依赖

Java代码

<dependency>
<groupId>com.octo.captcha</groupId>
<artifactId>jcaptcha</artifactId>
<version>2.0-alpha-1</version>
</dependency>
<dependency>
<groupId>com.octo.captcha</groupId>
<artifactId>jcaptcha-integration-simple-servlet</artifactId>
<version>2.0-alpha-1</version>
<exclusions>
<exclusion>
<artifactId>servlet-api</artifactId>
<groupId>javax.servlet</groupId>
</exclusion>
</exclusions>
</dependency>

com.octo.captcha . jcaptcha 提供了jcaptcha 核心；而jcaptcha-integration-simple-servlet提供了与Servlet集成。

二、GMailEngine

来自https://code.google.com/p/musicvalley/source/browse/trunk/musicvalley/doc/springSecurity/springSecurityIII/src/main/java/com/spring/security/jcaptcha/GMailEngine.java?spec=svn447&r=447（目前无法访问了），仿照JCaptcha2.0编写类似GMail验证码的样式；具体请参考com.github.zhangkaitao.shiro.chapter22.jcaptcha.GMailEngine。

三、MyManageableImageCaptchaService

提供了判断仓库中是否有相应的验证码存在。

Java代码

public class MyManageableImageCaptchaService extends
DefaultManageableImageCaptchaService {
public MyManageableImageCaptchaService(
com.octo.captcha.service.captchastore.CaptchaStore captchaStore,
com.octo.captcha.engine.CaptchaEngine captchaEngine,
int minGuarantedStorageDelayInSeconds,
int maxCaptchaStoreSize,
int captchaStoreLoadBeforeGarbageCollection) {
super(captchaStore, captchaEngine, minGuarantedStorageDelayInSeconds,
maxCaptchaStoreSize, captchaStoreLoadBeforeGarbageCollection);
}
public boolean hasCapcha(String id, String userCaptchaResponse) {
return store.getCaptcha(id).validateResponse(userCaptchaResponse);
}
}

四、JCaptcha工具类

提供相应的API来验证当前请求输入的验证码是否正确。

Java代码

public class JCaptcha {
public static final MyManageableImageCaptchaService captchaService
= new MyManageableImageCaptchaService(new FastHashMapCaptchaStore(),
new GMailEngine(), 180, 100000, 75000);
public static boolean validateResponse(
HttpServletRequest request, String userCaptchaResponse) {
if (request.getSession(false) == null) return false;
boolean validated = false;
try {
String id = request.getSession().getId();
validated =
captchaService.validateResponseForID(id, userCaptchaResponse)
.booleanValue();
} catch (CaptchaServiceException e) {
e.printStackTrace();
}
return validated;
}
public static boolean hasCaptcha(
HttpServletRequest request, String userCaptchaResponse) {
if (request.getSession(false) == null) return false;
boolean validated = false;
try {
String id = request.getSession().getId();
validated = captchaService.hasCapcha(id, userCaptchaResponse);
} catch (CaptchaServiceException e) {
e.printStackTrace();
}
return validated;
}
}

validateResponse()：验证当前请求输入的验证码否正确；并从CaptchaService中删除已经生成的验证码；

hasCaptcha()：验证当前请求输入的验证码是否正确；但不从CaptchaService中删除已经生成的验证码（比如Ajax验证时可以使用，防止多次生成验证码）；

五、JCaptchaFilter

用于生成验证码图片的过滤器。

Java代码

public class JCaptchaFilter extends OncePerRequestFilter {
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
response.setDateHeader("Expires", 0L);
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");
response.setContentType("image/jpeg");
String id = request.getRequestedSessionId();
BufferedImage bi = JCaptcha.captchaService.getImageChallengeForID(id);
ServletOutputStream out = response.getOutputStream();
ImageIO.write(bi, "jpg", out);
try {
out.flush();
} finally {
out.close();
}
}
}

CaptchaService使用当前会话ID当作key获取相应的验证码图片；另外需要设置响应内容不进行浏览器端缓存。

Java代码

<filter>
<filter-name>JCaptchaFilter</filter-name>
<filter-class>
com.github.zhangkaitao.shiro.chapter22.jcaptcha.JCaptchaFilter
</filter-class>
</filter>
<filter-mapping>
<filter-name>JCaptchaFilter</filter-name>
<url-pattern>/jcaptcha.jpg</url-pattern>
</filter-mapping>

这样就可以在页面使用/jcaptcha.jpg地址显示验证码图片。

六、JCaptchaValidateFilter

用于验证码验证的Shiro过滤器。

Java代码

public class JCaptchaValidateFilter extends AccessControlFilter {
private boolean jcaptchaEbabled = true;//是否开启验证码支持
private String jcaptchaParam = "jcaptchaCode";//前台提交的验证码参数名
private String failureKeyAttribute = "shiroLoginFailure"; //验证失败后存储到的属性名
public void setJcaptchaEbabled(boolean jcaptchaEbabled) {
this.jcaptchaEbabled = jcaptchaEbabled;
}
public void setJcaptchaParam(String jcaptchaParam) {
this.jcaptchaParam = jcaptchaParam;
}
public void setFailureKeyAttribute(String failureKeyAttribute) {
this.failureKeyAttribute = failureKeyAttribute;
}
protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {
//1、设置验证码是否开启属性，页面可以根据该属性来决定是否显示验证码
request.setAttribute("jcaptchaEbabled", jcaptchaEbabled);
HttpServletRequest httpServletRequest = WebUtils.toHttp(request);
//2、判断验证码是否禁用或不是表单提交（允许访问）
if (jcaptchaEbabled == false || !"post".equalsIgnoreCase(httpServletRequest.getMethod())) {
return true;
}
//3、此时是表单提交，验证验证码是否正确
return JCaptcha.validateResponse(httpServletRequest, httpServletRequest.getParameter(jcaptchaParam));
}
protected boolean onAccessDenied(ServletRequest request, ServletResponse response) throws Exception {
//如果验证码失败了，存储失败key属性
request.setAttribute(failureKeyAttribute, "jCaptcha.error");
return true;
}
}

七、MyFormAuthenticationFilter

用于验证码验证的Shiro拦截器在用于身份认证的拦截器之前运行；但是如果验证码验证拦截器失败了，就不需要进行身份认证拦截器流程了；所以需要修改下如FormAuthenticationFilter身份认证拦截器，当验证码验证失败时不再走身份认证拦截器。

Java代码

public class MyFormAuthenticationFilter extends FormAuthenticationFilter {
protected boolean onAccessDenied(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {
if(request.getAttribute(getFailureKeyAttribute()) != null) {
return true;
}
return super.onAccessDenied(request, response, mappedValue);
}
}

即如果之前已经错了，那直接跳过即可。

八、spring-config-shiro.xml

Java代码

<bean id="authcFilter"
class="com.github.zhangkaitao.shiro.chapter22.jcaptcha.MyFormAuthenticationFilter">
<property name="usernameParam" value="username"/>
<property name="passwordParam" value="password"/>
<property name="rememberMeParam" value="rememberMe"/>
<property name="failureKeyAttribute" value="shiroLoginFailure"/>
</bean>
<bean id="jCaptchaValidateFilter"
class="com.github.zhangkaitao.shiro.chapter22.jcaptcha.JCaptchaValidateFilter">
<property name="jcaptchaEbabled" value="true"/>
<property name="jcaptchaParam" value="jcaptchaCode"/>
<property name="failureKeyAttribute" value="shiroLoginFailure"/>
</bean>
<bean id="shiroFilter" class="org.apache.shiro.spring.web.ShiroFilterFactoryBean">
<property name="securityManager" ref="securityManager"/>
<property name="loginUrl" value="/login"/>
<property name="filters">
<util:map>
<entry key="authc" value-ref="authcFilter"/>
<entry key="sysUser" value-ref="sysUserFilter"/>
<entry key="jCaptchaValidate" value-ref="jCaptchaValidateFilter"/>
</util:map>
</property>
<property name="filterChainDefinitions">
<value>
/static/** = anon
/jcaptcha* = anon
/login = jCaptchaValidate,authc
/logout = logout
/authenticated = authc
/** = user,sysUser
</value>
</property>
</bean>