首先，cas 服务端的执行流程是WEB-INF/login-webflow.xml定义的，可以大概看看。
我用的代码是cas-server-3.5.2-release.zip和cas-client-3.2.1-release.zip。
（1）直接访问server端login页面
请求：
GET /cas/login HTTP/1.1
...省略..
响应：
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Pragma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Cache-Control: no-cache
Cache-Control: no-store
Set-Cookie: JSESSIONID=2DA712066025406394C7C644AF16FD18; Path=/cas
Content-Type: text/html;charset=UTF-8
Content-Length: 1993
Date: Wed, 30 Oct 2013 01:53:49 GMT
内容就是登陆表单，省略
对于Server端流程来说，走的是
<decision-state id="ticketGrantingTicketExistsCheck">
<if test="flowScope.ticketGrantingTicketId != null" then="hasServiceCheck" else="gatewayRequestCheck" />
</decision-state>
TGT不存在，走gatewayRequestCheck
<decision-state id="gatewayRequestCheck">
<if test="requestParameters.gateway != '' and requestParameters.gateway != null and flowScope.service != null" then="gatewayServicesManagementCheck" else="serviceAuthorizationCheck" />
</decision-state>
走serviceAuthorizationCheck
<action-state id="serviceAuthorizationCheck"> <evaluate expression="serviceAuthorizationCheck"/> <transition to="generateLoginTicket"/> </action-state>
执行认证check，然后转到generateLoginTicket
<action-state id="generateLoginTicket"> <evaluate expression="generateLoginTicketAction.generate(flowRequestContext)" /> <transition on="generated" to="viewLoginForm" /> </action-state>
生成登录小票，转到login表单
<view-state id="viewLoginForm" view="casLoginView" model="credentials">
<binder>
<binding property="username" />
<binding property="password" />
</binder>
<on-entry>
<set name="viewScope.commandName" value="'credentials'" />
</on-entry>
<transition on="submit" bind="true" validate="true" to="realSubmit">
<evaluate expression="authenticationViaFormAction.doBind(flowRequestContext, flowScope.credentials)" />
</transition>
</view-state>
对应的jsp页面是WEB-INF\view\jsp\default\ui\casLoginView.jsp
--------------------------------------------------------------------------
（2）输入用户名、密码，登录
请求：
POST /cas/login;jsessionid=2DA712066025406394C7C644AF16FD18 HTTP/1.1
Content-Type: application/x-www-form-urlencoded
...部分省略...
Cookie: JSESSIONID=2DA712066025406394C7C644AF16FD18
username=admin&password=1&warn=true<=LT-3-Ahdqm03UKMR9vwuy7A5ZSCMa9zJkNi&execution=e1s1&_eventId=submit&x=53&y=55
其中的LT-3-Ahdqm03UKMR9vwuy7A5ZSCMa9zJkNi就是登录小票，
后台会比较“提交的值”和“后台保存的是否一致”。这个类似于验证码，没啥说的。
响应：
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Pragma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Cache-Control: no-cache
Cache-Control: no-store
Set-Cookie: CASPRIVACY=true; Path=/cas/; Secure
Set-Cookie: CASTGC=TGT-2-DmMvVs9Wy01ScbnMtgtLzgcyX5X14TGcM1f5iGuWIBrlDwTg4Q-cas01.example.org; Path=/cas/
Content-Type: text/html;charset=UTF-8
Content-Length: 1602
Date: Wed, 30 Oct 2013 01:54:03 GMT
后台设置了两个cookie，一个是CASPRIVACY=true，不知道干嘛用的
一个是CASTGC，这个就是TicketGrantingTicket Cookie，就是说，你想买通票，你还得先买门票进去的意思，tgc就是门票。
这样，客户端浏览器就拥有了TGC门票。下次再访问cas server时就会带着这个门票来了。
后台执行流程：
由上面viewLoginForm的定义，表单提交后，会执行authenticationViaFormAction.doBind方法，然后跳到realSubmit
<action-state id="realSubmit"> <evaluate expression="authenticationViaFormAction.submit(flowRequestContext, flowScope.credentials, messageContext)" /> <transition on="warn" to="warn" /> <transition on="success" to="sendTicketGrantingTicket" /> <transition on="error" to="generateLoginTicket" /> <transition on="accountDisabled" to="casAccountDisabledView" /> <transition on="mustChangePassword" to="casMustChangePassView" /> <transition on="accountLocked" to="casAccountLockedView" /> <transition on="badHours" to="casBadHoursView" /> <transition on="badWorkstation" to="casBadWorkstationView" /> <transition on="passwordExpired" to="casExpiredPassView" /> </action-state>
执行authenticationViaFormAction.submit方法，
看一下代码：
public final String submit(final RequestContext context, final Credentials credentials, final MessageContext messageContext) throws Exception {
// Validate login ticket
final String authoritativeLoginTicket = WebUtils.getLoginTicketFromFlowScope(context);
final String providedLoginTicket = WebUtils.getLoginTicketFromRequest(context);
if (!authoritativeLoginTicket.equals(providedLoginTicket)) {
this.logger.warn("Invalid login ticket " + providedLoginTicket);
final String code = "INVALID_TICKET";
messageContext.addMessage(
new MessageBuilder().error().code(code).arg(providedLoginTicket).defaultText(code).build());
return "error";
}
final String ticketGrantingTicketId = WebUtils.getTicketGrantingTicketId(context);
final Service service = WebUtils.getService(context);
if (StringUtils.hasText(context.getRequestParameters().get("renew")) && ticketGrantingTicketId != null && service != null) {
try {
final String serviceTicketId = this.centralAuthenticationService.grantServiceTicket(ticketGrantingTicketId, service, credentials);
WebUtils.putServiceTicketInRequestScope(context, serviceTicketId);
putWarnCookieIfRequestParameterPresent(context);
return "warn";
} catch (final TicketException e) {
if (isCauseAuthenticationException(e)) {
populateErrorsInstance(e, messageContext);
return getAuthenticationExceptionEventId(e);
}
this.centralAuthenticationService.destroyTicketGrantingTicket(ticketGrantingTicketId);
if (logger.isDebugEnabled()) {
logger.debug("Attempted to generate a ServiceTicket using renew=true with different credentials", e);
}
}
}
try {
WebUtils.putTicketGrantingTicketInRequestScope(context, this.centralAuthenticationService.createTicketGrantingTicket(credentials));
putWarnCookieIfRequestParameterPresent(context);
return "success";
} catch (final TicketException e) {
populateErrorsInstance(e, messageContext);
if (isCauseAuthenticationException(e))
return getAuthenticationExceptionEventId(e);
return "error";
}
}
service就是指子系统的URL，由于直接访问的server端login，所以URL中没有service参数，所以grantServiceTicket不会执行。
最后，会createTicketGrantingTicket，然后放到request中。
返回success，跳转到sendTicketGrantingTicket
<action-state id="sendTicketGrantingTicket"> <evaluate expression="sendTicketGrantingTicketAction" /> <transition to="serviceCheck" /> </action-state>
这里是把TicketGrantingTicket写到Cookie。
然后跳到serviceCheck
<!-- <decision-state id="serviceCheck"> <if test="flowScope.service != null" then="generateServiceTicket" else="getSubSystemUrl" /> </decision-state> --> <decision-state id="serviceCheck"> <if test="flowScope.service != null" then="getSubSystemUrl" else="getSubSystemUrl" /> </decision-state> <action-state id="generateServiceTicket"> <evaluate expression="generateServiceTicketAction" /> <transition on="success" to ="warn" /> <transition on="error" to="generateLoginTicket" /> <transition on="gateway" to="gatewayServicesManagementCheck" /> </action-state> <action-state id="getSubSystemUrl"> <evaluate expression="getSubSystemUrlAction.get(flowRequestContext, flowScope.credentials)" /> <transition to ="viewGenericLoginSuccess" /> </action-state>
这段被我改过，原来是：有service到generateServiceTicket，没有直接到viewGenericLoginSuccess
我改成了，都跳到getSubSystemUrl。这个action是我自己加的，目的是去数据库取得子系统URL，并取得用户对每个子系统的权限。
然后跳转到viewGenericLoginSuccess
<end-state id="viewGenericLoginSuccess" view="casLoginGenericSuccessView" />
viewGenericLoginSuccess，也就是登录成功页面，就是服务端WEB-INF\view\jsp\default\ui\casGenericSuccess.jsp这个页面。
我在这里显示了几个子系统的链接。
这里的view写的都是id，实际对应的文件在WEB-INF\classes\default_views.properties中定义。
--------------------------------------------------------------------------
（3）然后点击页面上的链接，访问子系统
请求：
GET /UserManage/ HTTP/1.1
响应：
HTTP/1.1 302 Moved Temporarily
Server: Apache-Coyote/1.1
Location: http://10.0.103.137:8080/cas/login?service=http%3A%2F%2F10.0.103.137%3A8080%2FUserManage%2F
Content-Length: 0
Date: Wed, 30 Oct 2013 01:54:22 GMT
由于子系统增加了CAS client的Filter。
<filter> <filter-name>CAS Authentication Filter</filter-name> <filter-class>org.jasig.cas.client.authentication.AuthenticationFilter</filter-class> <!-- CAS login 服务地址--> <init-param> <param-name>casServerLoginUrl</param-name> <param-value>http://10.0.103.137:8080/cas/login</param-value> </init-param> <!-- 客户端应用服务地址--> <init-param> <param-name>serverName</param-name> <param-value>http://10.0.103.137:8080</param-value> </init-param> <init-param> <param-name>renew</param-name> <param-value>false</param-value> </init-param> <init-param> <param-name>gateway</param-name> <param-value>false</param-value> </init-param> </filter>
看一下AuthenticationFilter的代码：
public final void doFilter(final ServletRequest servletRequest, final ServletResponse servletResponse, final FilterChain filterChain) throws IOException, ServletException {
final HttpServletRequest request = (HttpServletRequest) servletRequest;
final HttpServletResponse response = (HttpServletResponse) servletResponse;
final HttpSession session = request.getSession(false);
final Assertion assertion = session != null ? (Assertion) session.getAttribute(CONST_CAS_ASSERTION) : null;
if (assertion != null) {
filterChain.doFilter(request, response);
return;
}
final String serviceUrl = constructServiceUrl(request, response);
final String ticket = CommonUtils.safeGetParameter(request,getArtifactParameterName());
final boolean wasGatewayed = this.gatewayStorage.hasGatewayedAlready(request, serviceUrl);
if (CommonUtils.isNotBlank(ticket) || wasGatewayed) {
filterChain.doFilter(request, response);
return;
}
final String modifiedServiceUrl;
log.debug("no ticket and no assertion found");
if (this.gateway) {
log.debug("setting gateway attribute in session");
modifiedServiceUrl = this.gatewayStorage.storeGatewayInformation(request, serviceUrl);
} else {
modifiedServiceUrl = serviceUrl;
}
if (log.isDebugEnabled()) {
log.debug("Constructed service url: " + modifiedServiceUrl);
}
final String urlToRedirectTo = CommonUtils.constructRedirectUrl(this.casServerLoginUrl, getServiceParameterName(), modifiedServiceUrl, this.renew, this.gateway);
if (log.isDebugEnabled()) {
log.debug("redirecting to \"" + urlToRedirectTo + "\"");
}
response.sendRedirect(urlToRedirectTo);
}
从Session取assertion，就是登录信息，如果有，就继续执行其他Filter。
然后看有没有ticket，也就是通票。有的话，继续执行其他Filter。
else就拼接URL，跳转。
http://10.0.103.137:8080/cas/login?service=http%3A%2F%2F10.0.103.137%3A8080%2FUserManage%2F
（4）跳转到server端了
请求：
GET /cas/login?service=http%3A%2F%2F10.0.103.137%3A8080%2FUserManage%2F HTTP/1.1
Cookie: CASTGC=TGT-2-DmMvVs9Wy01ScbnMtgtLzgcyX5X14TGcM1f5iGuWIBrlDwTg4Q-cas01.example.org; JSESSIONID=2DA712066025406394C7C644AF16FD18
可以看到,浏览器自动把CASTGC带过来了。
响应：
HTTP/1.1 302 Moved Temporarily
Server: Apache-Coyote/1.1
Pragma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Cache-Control: no-cache
Cache-Control: no-store
Location: http://10.0.103.137:8080/UserManage/?ticket=ST-1-0dnlMstfctMYVcat5wfy-cas01.example.org
Content-Length: 0
Date: Wed, 30 Oct 2013 01:54:22 GMT
又跳回了子系统，但是带着ticket过来的
后台流程：
<decision-state id="ticketGrantingTicketExistsCheck">
<if test="flowScope.ticketGrantingTicketId != null" then="hasServiceCheck" else="gatewayRequestCheck" />
</decision-state>
CASTGC有了，所以走hasServiceCheck
<decision-state id="hasServiceCheck">
<if test="flowScope.service != null" then="renewRequestCheck" else="getSubSystemUrl" />
</decision-state>
service参数也有了，所以走renewRequestCheck
<decision-state id="renewRequestCheck">
<if test="requestParameters.renew != '' and requestParameters.renew != null" then="serviceAuthorizationCheck" else="generateServiceTicket" />
</decision-state>
renew客户端配置的是false，所以请求里无此参数。走generateServiceTicket
<action-state id="generateServiceTicket"> <evaluate expression="generateServiceTicketAction" /> <transition on="success" to ="warn" /> <transition on="error" to="generateLoginTicket" /> <transition on="gateway" to="gatewayServicesManagementCheck" /> </action-state>
看下代码：
protected Event doExecute(final RequestContext context) {
final Service service = WebUtils.getService(context);
final String ticketGrantingTicket = WebUtils.getTicketGrantingTicketId(context);
try {
final String serviceTicketId = this.centralAuthenticationService
.grantServiceTicket(ticketGrantingTicket,
service);
WebUtils.putServiceTicketInRequestScope(context,
serviceTicketId);
return success();
} catch (final TicketException e) {
if (isGatewayPresent(context)) {
return result("gateway");
}
}
return error();
}
根据ticketGrantingTicket和service，生成通票，并放到request中。成功跳到warn
<decision-state id="warn">
<if test="flowScope.warnCookieValue" then="showWarningView" else="redirect" />
</decision-state>
跳转时，不显示提醒页面，所以直接走redirect.
<action-state id="redirect"> <evaluate expression="flowScope.service.getResponse(requestScope.serviceTicketId)" result-type="org.jasig.cas.authentication.principal.Response" result="requestScope.response" /> <transition to="postRedirectDecision" /> </action-state> <decision-state id="postRedirectDecision"> <if test="requestScope.response.responseType.name() == 'POST'" then="postView" else="redirectView" /> </decision-state>
这个看不太懂，反正最后执行redirectView了。
<end-state id="redirectView" view="externalRedirect:${requestScope.response.url}" />
执行跳转，哦了
（5）又回到客户端了
请求：
GET /UserManage/?ticket=ST-1-0dnlMstfctMYVcat5wfy-cas01.example.org HTTP/1.1
响应：
HTTP/1.1 302 Moved Temporarily
Server: Apache-Coyote/1.1
Set-Cookie: JSESSIONID=3A8260292C0430806E231B0E76907137; Path=/UserManage
Location: http://10.0.103.137:8080/UserManage/;jsessionid=3A8260292C0430806E231B0E76907137
Content-Length: 0
Date: Wed, 30 Oct 2013 01:54:24 GMT
这个有点莫名其妙，又跳转了。
这时，是客户端的CAS Validation Filter在作怪。
<filter> <filter-name>CAS Validation Filter</filter-name> <filter-class>org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilter</filter-class> <init-param> <param-name>casServerUrlPrefix</param-name> <param-value>http://10.0.103.137:8080/cas/</param-value> </init-param> <!-- 客户端应用服务地址--> <init-param> <param-name>serverName</param-name> <param-value>http://10.0.103.137:8080</param-value> </init-param> </filter>
它发现URL中有ticket了，马上就拿它去服务端check一下，看是否有效，是否过期什么的。
这里用的是Cas20ProxyReceivingTicketValidationFilter，它继承了AbstractTicketValidationFilter
看看它的doFilter代码：
public final void doFilter(final ServletRequest servletRequest, final ServletResponse servletResponse, final FilterChain filterChain) throws IOException, ServletException {
if (!preFilter(servletRequest, servletResponse, filterChain)) {
return;
}
final HttpServletRequest request = (HttpServletRequest) servletRequest;
final HttpServletResponse response = (HttpServletResponse) servletResponse;
final String ticket = CommonUtils.safeGetParameter(request, getArtifactParameterName());
if (CommonUtils.isNotBlank(ticket)) {
if (log.isDebugEnabled()) {
log.debug("Attempting to validate ticket: " + ticket);
}
try {
final Assertion assertion = this.ticketValidator.validate(ticket, constructServiceUrl(request, response));
if (log.isDebugEnabled()) {
log.debug("Successfully authenticated user: " + assertion.getPrincipal().getName());
}
request.setAttribute(CONST_CAS_ASSERTION, assertion);
if (this.useSession) {
request.getSession().setAttribute(CONST_CAS_ASSERTION, assertion);
}
onSuccessfulValidation(request, response, assertion);
if (this.redirectAfterValidation) {
log. debug("Redirecting after successful ticket validation.");
response.sendRedirect(constructServiceUrl(request, response));
return;
}
} catch (final TicketValidationException e) {
response.setStatus(HttpServletResponse.SC_FORBIDDEN);
log.warn(e, e);
onFailedValidation(request, response);
if (this.exceptionOnValidationFailure) {
throw new ServletException(e);
}
return;
}
}
filterChain.doFilter(request, response);
}
取ticket，然后
final Assertion assertion = this.ticketValidator.validate(ticket, constructServiceUrl(request, response))
看看，直接就返回了assertion，这就是登录者信息，包括用户名什么的。
然后放到request和session里了。
validate方法，实际是调用的AbstractUrlBasedTicketValidator的validate方法，看看
final String validationUrl = constructValidationUrl(ticket, service);
if (log.isDebugEnabled()) {
log.debug("Constructing validation url: " + validationUrl);
}
try {
log.debug("Retrieving response from server.");
final String serverResponse = retrieveResponseFromServer(new URL(validationUrl), ticket);
if (serverResponse == null) {
throw new TicketValidationException("The CAS server returned no response.");
}
if (log.isDebugEnabled()) {
log.debug("Server response: " + serverResponse);
}
return parseResponseFromServer(serverResponse);
} catch (final MalformedURLException e) {
throw new TicketValidationException(e);
}
构建一个URL，然后读取响应。实际调用的AbstractCasProtocolUrlBasedTicketValidator的retrieveResponseFromServer方法
protected final String retrieveResponseFromServer(final URL validationUrl, final String ticket) {
if (this.hostnameVerifier != null) {
return CommonUtils.getResponseFromServer(validationUrl, this.hostnameVerifier, getEncoding());
} else {
return CommonUtils.getResponseFromServer(validationUrl, getEncoding());
}
}
不知道走的那个，但都是getResponseFromServer方法，看看先。
public static String getResponseFromServer(final URL constructedUrl, final HostnameVerifier hostnameVerifier, final String encoding) {
URLConnection conn = null;
try {
conn = constructedUrl.openConnection();
if (conn instanceof HttpsURLConnection) {
((HttpsURLConnection)conn).setHostnameVerifier(hostnameVerifier);
}
final BufferedReader in;
if (CommonUtils.isEmpty(encoding)) {
in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
} else {
in = new BufferedReader(new InputStreamReader(conn.getInputStream(), encoding));
}
String line;
final StringBuilder stringBuffer = new StringBuilder(255);
while ((line = in.readLine()) != null) {
stringBuffer.append(line);
stringBuffer.append("\n");
}
return stringBuffer.toString();
} catch (final Exception e) {
LOG.error(e.getMessage(), e);
throw new RuntimeException(e);
} finally {
if (conn != null && conn instanceof HttpURLConnection) {
((HttpURLConnection)conn).disconnect();
}
}
}
就是直接访问URL，读取数据。
-------------------------
代码看完，看抓包数据吧。
实际上，上面带着ticket跳回客户端后，Filter发起了一个访问
请求：
GET /cas/serviceValidate?ticket=ST-1-0dnlMstfctMYVcat5wfy-cas01.example.org&service=http%3A%2F%2F10.0.103.137%3A8080%2FUserManage%2F%3Bjsessionid%3D3A8260292C0430806E231B0E76907137 HTTP/1.1
User-Agent: Java/1.6.0_26
看，User-Agent是Java哦~~
响应：
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Content-Type: text/html;charset=UTF-8
Content-Language: zh-CN
Content-Length: 177
Date: Wed, 30 Oct 2013 01:54:24 GMT
<cas:serviceResponse xmlns:cas='http://www.yale.edu/tp/cas'>
<cas:authenticationSuccess>
<cas:user>admin</cas:user>
</cas:authenticationSuccess>
</cas:serviceResponse>
可以看到，服务端给返回的xml数据，只有用户名。
实际上，想返回更多信息也是可以的，需要修改服务端配置，具体方法请搜索，大概是：cas 登录 返回更多信息
服务端/serviceValidate这个请求是
<servlet>
<servlet-name>cas</servlet-name>
<servlet-class>
org.jasig.cas.web.init.SafeDispatcherServlet
</servlet-class>
</servlet>
这个Servlet响应的，但没看太明白，反正最后调到了ServiceValidateController的handleRequestInternal方法里
里面有一句：
final Assertion assertion = this.centralAuthenticationService.validateServiceTicket(serviceTicketId, service);
实际是调用CentralAuthenticationServiceImpl的validateServiceTicket方法
这个类有
@NotNull
private TicketRegistry ticketRegistry;
/** New Ticket Registry for storing and retrieving services tickets. Can point to the same one as the ticketRegistry variable. */
@NotNull
private TicketRegistry serviceTicketRegistry;
实际上，ticket信息就是保存在这两个变量里的。
里面有这样的代码：
final ServiceTicket serviceTicket = (ServiceTicket) this.serviceTicketRegistry.getTicket(serviceTicketId, ServiceTicket.class); final List<Authentication> chainedAuthenticationsList = serviceTicket.getGrantingTicket().getChainedAuthentications(); final Authentication authentication = chainedAuthenticationsList.get(chainedAuthenticationsList.size() - 1); final Principal principal = authentication.getPrincipal();
所以，能拿到Ticket或grant ticket的话，就可以拿到当前用户信息。
后面看不动了，大概就是把用户信息写到响应里吧。
（6）跳转到之前访问的子系统URL
请求：
GET /UserManage/;jsessionid=3A8260292C0430806E231B0E76907137 HTTP/1.1
Cookie: JSESSIONID=3A8260292C0430806E231B0E76907137
实际上，到前一步，用户信息已经去到，认证过程已经完毕了，单点登录已经实现。
后面就是正常访问子系统了。
但，每次请求，AuthenticationFilter仍然会检查一下。
看一下AuthenticationFilter的代码：
public final void doFilter(final ServletRequest servletRequest, final ServletResponse servletResponse, final FilterChain filterChain) throws IOException, ServletException {
final HttpServletRequest request = (HttpServletRequest) servletRequest;
final HttpServletResponse response = (HttpServletResponse) servletResponse;
final HttpSession session = request.getSession(false);
final Assertion assertion = session != null ? (Assertion) session.getAttribute(CONST_CAS_ASSERTION) : null;
if (assertion != null) {
filterChain.doFilter(request, response);
return;
}
.....
由于已经登录，assertion不为空，所以直接跳过了。对性能影响不大。
（7）执行logout时，实际是访问server端的logout
请求：
GET /cas/logout HTTP/1.1
Cookie: CASTGC=TGT-2-DmMvVs9Wy01ScbnMtgtLzgcyX5X14TGcM1f5iGuWIBrlDwTg4Q-cas01.example.org; JSESSIONID=0F5355FE89E099FF14E149CF9C55644C
响应：
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Pragma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Cache-Control: no-cache
Cache-Control: no-store
Set-Cookie: CASTGC=""; Expires=Thu, 01-Jan-1970 00:00:10 GMT; Path=/cas/
Set-Cookie: CASPRIVACY=""; Expires=Thu, 01-Jan-1970 00:00:10 GMT; Path=/cas/
Set-Cookie: JSESSIONID=6DA0ACAEBA3A801CB897E98CE5E92AFC; Path=/cas
Content-Type: text/html;charset=UTF-8
Content-Language: zh-CN
Content-Length: 728
Date: Wed, 30 Oct 2013 03:31:39 GMT
设置Cookie过期。Session总是新起一个。
然后内容里有：
<script>window.location="/cas/login";</script>
同时，会通知所有已登录的子系统，进行退出操作
请求：
POST /UserManage/ HTTP/1.1
Content-Type: application/x-www-form-urlencoded
Cache-Control: no-cache
Pragma: no-cache
User-Agent: Java/1.6.0_26
Host: 10.0.103.137:8080
Accept: text/html, p_w_picpath/gif, p_w_picpath/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive
Content-Length: 484
logoutRequest=%3Csamlp%3ALogoutRequest+xmlns%3Asamlp%3D%22urn%3Aoasis%3Anames%3Atc%3ASAML%3A2.0%3Aprotocol%22+ID%3D%22LR-2-0EQR24uNI0TlMr52CzUYMuf1fOAsQg1O447%22+Version%3D%222.0%22+IssueInstant%3D%222013-10-30T11%3A31%3A39Z%22%3E%3Csaml%3ANameID+xmlns%3Asaml%3D%22urn%3Aoasis%3Anames%3Atc%3ASAML%3A2.0%3Aassertion%22%3E%40NOT_USED%40%3C%2Fsaml%3ANameID%3E%3Csamlp%3ASessionIndex%3EST-2-nfx6OgRedoAMqowQayXr-cas01.example.org%3C%2Fsamlp%3ASessionIndex%3E%3C%2Fsamlp%3ALogoutRequest%3E
响应：
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Content-Length: 0
Date: Wed, 30 Oct 2013 03:31:39 GMT
响应是由客户端的SingleSignOutFilter做出的。
public void doFilter(final ServletRequest servletRequest, final ServletResponse servletResponse, final FilterChain filterChain) throws IOException, ServletException {
final HttpServletRequest request = (HttpServletRequest) servletRequest;
if (handler.isTokenRequest(request)) {
handler.recordSession(request);
} else if (handler.isLogoutRequest(request)) {
handler.destroySession(request);
// Do not continue up filter chain
return;
} else {
log.trace("Ignoring URI " + request.getRequestURI());
}
filterChain.doFilter(servletRequest, servletResponse);
}
（8）奇怪的一点，退出后，在登录页面，马上进行登录，
提交后，服务端还会执行一次跳转。
HTTP/1.1 302 Moved Temporarily
Server: Apache-Coyote/1.1
Pragma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Cache-Control: no-cache
Cache-Control: no-store
Set-Cookie: JSESSIONID=3911117B64346B50E24F36632C2419D7; Path=/cas
Location: http://10.0.103.137:8080/cas/login
Content-Length: 0
Date: Wed, 30 Oct 2013 03:37:07 GMT
非得重新生成一个session才干~~导致登录页面又刷了一下，这时再登录就OK了。
奇怪，奇怪~~
原因不明，调查中~~
----------------
我靠：
登录成功后，马上点退出，就有此问题
等几秒，再点退出，就无此问题。
原因是，登录成功后，会马上咔嚓掉session，默认是2秒后挂掉。
马上点退出，Session还没挂，所以不会重建Session，
所以，登录页面提交时，是带着这个Session的ID去的，而此时Session挂掉了，故引起页面刷新。
而等几秒再退出，会创建新session，故后面无问题。
更多信息请看
http://www.mytju.com/classcode/news_readNews.asp?newsID=504 | 
