一直不喜歡說太多東西，直接上程式碼。

    主要是以下幾個步驟：

1、專案加入cas-client-core-3.2.1.jar到lib中

        2、匯入證書（此步驟根據專案判斷是否需要操作）

        3、配置web.xml

        4、編寫客戶端程式碼（filter,servlet,....）

        5、進行驗證

1、專案加入cas-client-core-3.2.1.jar到lib中

      http://download.csdn.net/download/qq741437836/9740128          （不用積分）

2、匯入證書（此步驟根據專案判斷是否需要操作）

      將cacerts檔案匯入JDK目錄（C:\ProgramFiles\Java\jdk1.7.0_67\jre\lib\security）建議直接替換即可。

3、配置web.xml

<filter>
	   <filter-name>CAS Single Sign Out Filter</filter-name>
	   <filter-class>org.jasig.cas.client.session.SingleSignOutFilter</filter-class>
	</filter>
	<filter>
	  <filter-name>CAS Authentication Filter</filter-name>
	  <filter-class>org.jasig.cas.client.authentication.AuthenticationFilter</filter-class>
	  <init-param>
	    <param-name>casServerLoginUrl</param-name>
	    <param-value>服務端地址(https://login.xxxx.cn/cas)
 
</param-value>
	  </init-param>
	  <init-param>
	    <param-name>serverName</param-name>
	    <param-value>http://你的專案地址(http://ip:port)</param-value>
	  </init-param>
	</filter>
	<filter>
	    <filter-name>CAS Validation Filter</filter-name>
	    <filter-class>org.jasig.cas.client.validation.Cas10TicketValidationFilter</filter-class>
	    <init-param>
	        <param-name>casServerUrlPrefix</param-name>
	        <param-value>服務端地址
 
(https://login.xxxx.cn/cas)</param-value>
	    </init-param>
	    <init-param>
	        <param-name>serverName</param-name>
			<param-value>http://你的專案地址(http://ip:port)</param-value>
	    </init-param>
	    <init-param>
	        <param-name>redirectAfterValidation</param-name>
	        <param-value>true</param-value>
	    </init-param>
	</filter>
	<filter>
	  <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>
	  <filter-class>org.jasig.cas.client.util.HttpServletRequestWrapperFilter</filter-class>
	</filter>
	<filter>
	  <filter-name>CAS Assertion Thread Local Filter</filter-name>
	  <filter-class>org.jasig.cas.client.util.AssertionThreadLocalFilter</filter-class>
	</filter>
	
	<filter-mapping>
	   <filter-name>CAS Single Sign Out Filter</filter-name>
	   <url-pattern>/*</url-pattern>
	</filter-mapping>
	<filter-mapping>
	    <filter-name>CAS Authentication Filter</filter-name>
	    <url-pattern>/*</url-pattern>
	</filter-mapping>
	<filter-mapping>
	    <filter-name>CAS Validation Filter</filter-name>
	    <url-pattern>/*</url-pattern>
	</filter-mapping>
	<filter-mapping>
	    <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>
	    <url-pattern>/*</url-pattern>
	</filter-mapping>
	<filter-mapping>
	    <filter-name>CAS Assertion Thread Local Filter</filter-name>
	    <url-pattern>/*</url-pattern>
	</filter-mapping>
	<listener>
	    <listener-class>org.jasig.cas.client.session.SingleSignOutHttpSessionListener</listener-class>
	</listener>

                下面的filter-mapping根據你專案實際情況進行配置。

4、編寫客戶端程式碼

@Override
	public boolean service(Request request, Response response, RequestHandler handler)
			throws IOException {
		//http://ip:port/web/cas
		
		if (request.getPath().equals("/cas")){
			try {
				Cookie[] cookies = httpServletRequest.getCookies();
				String loginCookie = null;
				if (null != cookies) {
					for (Cookie cookie : cookies) {
						if ("k".equals(cookie.getName())) {
							loginCookie = cookie.getValue();
							break;
						}
					}
				}
				if(loginCookie == null){
					Assertion assertion = AssertionHolder.getAssertion();
					String userNo = assertion.getPrincipal().getName();//cas認證登入使用者(郵箱字首)
					if(!StringUtil.isEmpty(userNo)){
						doLogin(userNo);//根據cas返回值進行授權操作
						return true;
					}else{
						response.sendRedirect(request.getContextPath() + "/logout");
						return true;
					}
				}else{
					enter();
					return true;
				}
			} catch (Exception e) {
				e.printStackTrace();
				response.sendRedirect(request.getContextPath() + "/logout");
				return true;
			}
		}else{
			if(request.getPath().equals("/")){
				response.sendRedirect(request.getContextPath() + "/logout");
				return true;
			}else{
				return handler.service(request, response);
			}
		}
	}

private void doLogin(String userNo) throws IOException {
String remoteAddr = httpServletRequest.getHeader("X-Real-IP") == null ? httpServletRequest.getRemoteAddr()
: httpServletRequest.getHeader("X-Real-IP");
LoginResult rm = xxxx.loginByCasSrv(userNo, remoteAddr, "ZHS");
if (rm != null && "success".equals(rm.getResultMsg())) {
Cookie cookie = new Cookie("k", rm.getPermitCode());
cookie.setHttpOnly(true);
cookie.setPath(httpServletRequest.getContextPath() + "/");
cookie.setMaxAge(-1);
cookie.setSecure(httpServletRequest.isSecure());
httpServletResponse.addCookie(cookie);
enter();
} else {
String toast = null;
if ("user_invalidate".equals(rm.getResultMsg())) {
toast = "使用者凍結";
} else if ("tenant_invalidate".equals(rm.getResultMsg())) {
toast = "使用者不存在";
} else if ("uid_duplicate".equals(rm.getResultMsg())) {
toast = "使用者不存在";
}
else {
toast = "密碼錯誤";
}
httpServletResponse.getWriter().append(toast);
}
}

/**
 * 進入系統頁面，根據url引數判斷是進入什麼頁面
 * 
 * @throws IOException
 */
private void enter() throws IOException {
String target = httpServletRequest.getParameter("target");
String id = httpServletRequest.getParameter("id");
if (target != null && !target.isEmpty()) {
String url = null;
if (target.equals("xxxx")) {
url = httpServletRequest.getContextPath() + "/home/xxxx/" + id;
} else if (target.equals("yyyy")) {
url = httpServletRequest.getContextPath() + "/home/yyyy/" + id;
}
httpServletResponse.sendRedirect(url);
} else {
httpServletResponse.sendRedirect(httpServletRequest.getContextPath() + "/home");
}


}

            比較完整，稍作修改就可使用。

5、進行驗證