上一篇Shiro源码解析-登录篇中提到了在登录验证成功后有对session的处理，但未详细分析，本文对此部分源码详细分析下。
1. 分析切入点：DefaultSecurityManger的login方法
public Subject login(Subject subject, AuthenticationToken token) throws AuthenticationException {
AuthenticationInfo info;
try {
info = authenticate(token);
} catch (AuthenticationException ae) {
try {
onFailedLogin(token, ae, subject);
} catch (Exception e) {
if (log.isInfoEnabled()) {
log.info("onFailedLogin method threw an " +
"exception. Logging and propagating original AuthenticationException.", e);
}
}
throw ae; //propagate
}
Subject loggedIn = createSubject(token, info, subject); // 登录用户验证成功之后进行session处理
onSuccessfulLogin(token, info, loggedIn);
return loggedIn;
}
继续DefaultSecurityManger
protected Subject createSubject(AuthenticationToken token, AuthenticationInfo info, Subject existing) {
SubjectContext context = createSubjectContext();
context.setAuthenticated(true);
context.setAuthenticationToken(token);
context.setAuthenticationInfo(info);
if (existing != null) {
context.setSubject(existing);
}
return createSubject(context); // 此处创建Subject
}
DefaultSecurityManger的createSubject方法
public Subject createSubject(SubjectContext subjectContext) {
//create a copy so we don't modify the argument's backing map:
SubjectContext context = copy(subjectContext);
//ensure that the context has a SecurityManager instance, and if not, add one:
context = ensureSecurityManager(context);
//Resolve an associated Session (usually based on a referenced session ID), and place it in the context before
//sending to the SubjectFactory. The SubjectFactory should not need to know how to acquire sessions as the
//process is often environment specific - better to shield the SF from these details:
context = resolveSession(context);
//Similarly, the SubjectFactory should not require any concept of RememberMe - translate that here first
//if possible before handing off to the SubjectFactory:
context = resolvePrincipals(context);
Subject subject = doCreateSubject(context);
//save this subject for future reference if necessary:
//(this is needed here in case rememberMe principals were resolved and they need to be stored in the
//session, so we don't constantly rehydrate the rememberMe PrincipalCollection on every operation).
//Added in 1.2:
save(subject); // 在这一步存储session
return subject;
}
protected void save(Subject subject) {
this.subjectDAO.save(subject);
}
2. 转移到DefaultSubjectDAO
调用DefaultSubjectDAO.save(subject)方法
public Subject save(Subject subject) {
if (isSessionStorageEnabled(subject)) { // 默认sessionStorage是enabled
saveToSession(subject); // 看这里
} else {
log.trace("Session storage of subject state for Subject [{}] has been disabled: identity and " +
"authentication state are expected to be initialized on every request or invocation.", subject);
}
return subject;
}
调用DefaultSubjectDAO.saveToSession(subject)方法
protected void saveToSession(Subject subject) {
//performs merge logic, only updating the Subject's session if it does not match the current state:
mergePrincipals(subject);
mergeAuthenticationState(subject);
}
调用DefaultSubjectDAO的mergePrincipals方法
protected void mergePrincipals(Subject subject) {
//merge PrincipalCollection state:
PrincipalCollection currentPrincipals = null;
//SHIRO-380: added if/else block - need to retain original (source) principals
//This technique (reflection) is only temporary - a proper long term solution needs to be found,
//but this technique allowed an immediate fix that is API point-version forwards and backwards compatible
//
//A more comprehensive review / cleaning of runAs should be performed for Shiro 1.3 / 2.0 +
if (subject.isRunAs() && subject instanceof DelegatingSubject) {
try {
Field field = DelegatingSubject.class.getDeclaredField("principals");
field.setAccessible(true);
currentPrincipals = (PrincipalCollection)field.get(subject);
} catch (Exception e) {
throw new IllegalStateException("Unable to access DelegatingSubject principals property.", e);
}
}
if (currentPrincipals == null || currentPrincipals.isEmpty()) {
currentPrincipals = subject.getPrincipals();
}
Session session = subject.getSession(false); // 取得session，如果不存在，并不会主动创建session
if (session == null) {
if (!isEmpty(currentPrincipals)) {
session = subject.getSession(); // 第一次用户访问时，会创建session，那么session是如何创建的呢？在缓存还是在DB中，请继续往下看
session.setAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY, currentPrincipals);
}
// otherwise no session and no principals - nothing to save
} else {
PrincipalCollection existingPrincipals =
(PrincipalCollection) session.getAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY);
if (isEmpty(currentPrincipals)) {
if (!isEmpty(existingPrincipals)) {
session.removeAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY);
}
// otherwise both are null or empty - no need to update the session
} else {
if (!currentPrincipals.equals(existingPrincipals)) {
session.setAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY, currentPrincipals);
}
// otherwise they're the same - no need to update the session
}
}
}
3. 转移到DelegatingSubject
调用DelegatingSubject的getSession
public Session getSession() {
return getSession(true); // 参数为true，表示不存在此session时创建
}
public Session getSession(boolean create) {
if (log.isTraceEnabled()) {
log.trace("attempting to get session; create = " + create +
"; session is null = " + (this.session == null) +
"; session has id = " + (this.session != null && session.getId() != null));
}
if (this.session == null && create) {
//added in 1.2:
if (!isSessionCreationEnabled()) {
String msg = "Session creation has been disabled for the current subject. This exception indicates " +
"that there is either a programming error (using a session when it should never be " +
"used) or that Shiro's configuration needs to be adjusted to allow Sessions to be created " +
"for the current Subject. See the " + DisabledSessionException.class.getName() + " JavaDoc " +
"for more.";
throw new DisabledSessionException(msg);
}
log.trace("Starting session for host {}", getHost());
SessionContext sessionContext = createSessionContext();
Session session = this.securityManager.start(sessionContext); // session创建，从这里再往下走（这里的securityMananger是SessionSecurityManager）
this.session = decorate(session);
}
return this.session;
}
4. 转移到SessionSecurityManager
public Session start(SessionContext context) throws AuthorizationException {
return this.sessionManager.start(context); // 如果没有设置sessionManager，则调用默认的ServletContainerSessionManager（内存存储session），demo代码使用如下
}
5. 如果像demo中soure一样，设置了的sessionManager为DefaultWebSessionManager，那么接下来会转移为到它的父类AbstractValidatingSessionManager
protected Session createSession(SessionContext context) throws AuthorizationException {
enableSessionValidationIfNecessary();
return doCreateSession(context);
}
protected Session doCreateSession(SessionContext context) {
Session s = newSessionInstance(context);
if (log.isTraceEnabled()) {
log.trace("Creating session for host {}", s.getHost());
}
create(s); // 在此处创建Session
return s;
}
protected Session newSessionInstance(SessionContext context) {
return getSessionFactory().createSession(context);
}
6. 调用DefaultSessionManager
protected void create(Session session) {
if (log.isDebugEnabled()) {
log.debug("Creating new EIS record for new session instance [" + session + "]");
}
sessionDAO.create(session); // 到这里大家应该看到了，你配置的SessionDAO在什么时候调用，demo中使用EnterpriseCacheSessionDAO
}
7. 先调用的父类CachingSessionDAO的create方法
public Serializable create(Session session) {
Serializable sessionId = super.create(session);// 这里只是生成sessionId，至于生成使用的算法可以在config中设置sessionIdGenerator
cache(session, sessionId); // 生成session并存储到cache，过程在下面
return sessionId;
}
8. 接下来cache方法
protected void cache(Session session, Serializable sessionId) {
if (session == null || sessionId == null) {
return;
}
Cache<Serializable, Session> cache = getActiveSessionsCacheLazy(); // 创建cache，名字默认为shiro-activeSessionCache
if (cache == null) {
return;
}
cache(session, sessionId, cache); // 存储到cache
}
protected void cache(Session session, Serializable sessionId, Cache<Serializable, Session> cache) {
cache.put(sessionId, session); // 这里调用的Ehcache的put方法，最终是存储在cache中（当然，如果你自定义了SessionDAO，那就可以存储在你指定的地方）
}
到这里大家基本都明白了整个过程吧，通过源码分析我们可以明白以下关键点
- SessionManager什么时候调用
- SessionDAO何时调用
- SessionId什么时候生成
- Session什么时候存储到Cache
如有问题，欢迎评论回复！