目录

1.用户登录认证流程

1.1 生成认证Token

1.2 用户登录认证

1.2.1  SecurityManager login流程解析

1.2.1.1 authenticate方法进行登录认证

1.2.1.1.1 单Realm认证

1.2.1.2 认证通过后创建登录用户对象

1.2.1.2.1 复制SubjectContext

1.2.1.2.2 对subjectContext设置securityManager

1.2.1.2.3 对subjectContext设置session

1.2.1.2.4 对subjectContext设置Principals

1.2.1.2.5 根据subjectContext创建Subject

1.2.1.2.6 保存Subject 

---

Shiro作为一款比较流行的登录认证、访问控制安全框架，被广泛应用在程序员社区；Shiro登录验证、访问控制、Session管理等流程内部都是委托给SecurityManager安全管理器来完成的，SecurityManager安全管理器上篇文章已经进行了详细解析，详见：Shiro框架：Shiro SecurityManager安全管理器解析-CSDN博客，在此基础上，本篇文章继续对Shiro关联链路处理流程之一---登录认证流程 进行解析；

想要深入了解Shiro框架整体原理，可移步：

Shiro框架：ShiroFilterFactoryBean过滤器源码解析-CSDN博客、

Shiro框架：Shiro内置过滤器源码解析-CSDN博客

1.用户登录认证流程

在Shiro框架：Shiro内置过滤器源码解析-CSDN博客内置过滤器分析中，我们知道用户执行登录的认证操作是在过滤器FormAuthenticationFilter中执行的，如下：

    protected boolean onAccessDenied(ServletRequest request, ServletResponse response) throws Exception {if (isLoginRequest(request, response)) {if (isLoginSubmission(request, response)) {if (log.isTraceEnabled()) {log.trace("Login submission detected.  Attempting to execute login.");}return executeLogin(request, response);} else {if (log.isTraceEnabled()) {log.trace("Login page view.");}//allow them to see the login page ;)return true;}} else {if (log.isTraceEnabled()) {log.trace("Attempting to access a path which requires authentication.  Forwarding to the " +"Authentication url [" + getLoginUrl() + "]");}saveRequestAndRedirectToLogin(request, response);return false;}}

登录认证操作是在executeLogin方法中完成的：

    protected boolean executeLogin(ServletRequest request, ServletResponse response) throws Exception {AuthenticationToken token = createToken(request, response);if (token == null) {String msg = "createToken method implementation returned null. A valid non-null AuthenticationToken " +"must be created in order to execute a login attempt.";throw new IllegalStateException(msg);}try {Subject subject = getSubject(request, response);subject.login(token);return onLoginSuccess(token, subject, request, response);} catch (AuthenticationException e) {return onLoginFailure(token, e, request, response);}}

上述源码的执行过程表示为时序图会更直观，时序图如下：

该认证过程主要包含以下几个部分：

1. 根据用户名密码等生成认证Token
2. 获取当前登录用户Subject
3. 调用Subject的login方法进行登录认证
4. 其它的登录成功、或登录失败的拦截方法

下面主要对生成认证Token和用户登录认证实现进行详细说明；

1.1 生成认证Token

createToken的实现在FormAuthenticationFilter内，如下：

这里用户名和密码是通过request请求对象获取的：

    protected AuthenticationToken createToken(ServletRequest request, ServletResponse response) {String username = getUsername(request);String password = getPassword(request);return createToken(username, password, request, response);}

在父类AuthenticatingFilter中进一步实现如下，这里构造了UsernamePasswordToken类，表示采用用户名密码的认证方式；

    protected AuthenticationToken createToken(String username, String password,ServletRequest request, ServletResponse response) {boolean rememberMe = isRememberMe(request);String host = getHost(request);return createToken(username, password, rememberMe, host);}protected AuthenticationToken createToken(String username, String password,boolean rememberMe, String host) {return new UsernamePasswordToken(username, password, rememberMe, host);}

图示UsernamePasswordToken的继承结构：

1.2 用户登录认证

在Subject的login的具体实现如下：

• 实际的login是委托给SecurityManager完成的
• 登录成功后设置当前登录对象为认证成功

下面主要对SecurityManager的login方法进行具体分析； 

1.2.1  SecurityManager login流程解析

login方法具体实现如下：

    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);onSuccessfulLogin(token, info, loggedIn);return loggedIn;}

上述登录流程主要包含2部分内容： 

1. 通过authenticate方法进行登录认证
2. 认证通过后创建登录用户对象

下面分别进行展开分析；

1.2.1.1 authenticate方法进行登录认证

具体的authenticate实现内部又委托给了认证器Authenticator来实现，具体的认证器为ModularRealmAuthenticator，其继承结构如下：

authenticate方法具体实现是在父类AbstractAuthenticator中，如下：

public final AuthenticationInfo authenticate(AuthenticationToken token) throws AuthenticationException {if (token == null) {throw new IllegalArgumentException("Method argument (authentication token) cannot be null.");}log.trace("Authentication attempt received for token [{}]", token);AuthenticationInfo info;try {info = doAuthenticate(token);if (info == null) {String msg = "No account information found for authentication token [" + token + "] by this " +"Authenticator instance.  Please check that it is configured correctly.";throw new AuthenticationException(msg);}} catch (Throwable t) {AuthenticationException ae = null;if (t instanceof AuthenticationException) {ae = (AuthenticationException) t;}if (ae == null) {//Exception thrown was not an expected AuthenticationException.  Therefore it is probably a little more//severe or unexpected.  So, wrap in an AuthenticationException, log to warn, and propagate:String msg = "Authentication failed for token submission [" + token + "].  Possible unexpected " +"error? (Typical or expected login exceptions should extend from AuthenticationException).";ae = new AuthenticationException(msg, t);if (log.isWarnEnabled())log.warn(msg, t);}try {notifyFailure(token, ae);} catch (Throwable t2) {if (log.isWarnEnabled()) {String msg = "Unable to send notification for failed authentication attempt - listener error?.  " +"Please check your AuthenticationListener implementation(s).  Logging sending exception " +"and propagating original AuthenticationException instead...";log.warn(msg, t2);}}throw ae;}log.debug("Authentication successful for token [{}].  Returned account [{}]", token, info);notifySuccess(token, info);return info;}

通过方法doAuthenticate对认证Token进行认证，通过notifySuccess、notifyFailure监听认证通过或失败的事件并调用注册的监听器；

方法doAuthenticate的具体实现是在子类完成的，如下：

    protected AuthenticationInfo doAuthenticate(AuthenticationToken authenticationToken) throws AuthenticationException {assertRealmsConfigured();Collection<Realm> realms = getRealms();if (realms.size() == 1) {return doSingleRealmAuthentication(realms.iterator().next(), authenticationToken);} else {return doMultiRealmAuthentication(realms, authenticationToken);}}

这里首先获取已注册的安全组件Realm，其注册过程是在RealmSecurityManager初始化的过程中完成的（对SecurityManager安全管理器的处理过程感兴趣可以参见：Shiro框架：Shiro SecurityManager安全管理器解析-CSDN博客）

然后根据Realm的个数分别执行单Realm认证或多Realm认证，这里已单Realm认证为例进行说明，多Realm认证类似；

1.2.1.1.1 单Realm认证

通过doSingleRealmAuthentication方法完成单Realm认证，实现如下：

    protected AuthenticationInfo doSingleRealmAuthentication(Realm realm, AuthenticationToken token) {if (!realm.supports(token)) {String msg = "Realm [" + realm + "] does not support authentication token [" +token + "].  Please ensure that the appropriate Realm implementation is " +"configured correctly or that the realm accepts AuthenticationTokens of this type.";throw new UnsupportedTokenException(msg);}AuthenticationInfo info = realm.getAuthenticationInfo(token);if (info == null) {String msg = "Realm [" + realm + "] was unable to find account data for the " +"submitted AuthenticationToken [" + token + "].";throw new UnknownAccountException(msg);}return info;}

这里Reaml接口包含一整套的继承层次实现，如下，这里不过多展开解析；

getAuthenticationInfo是在AuthenticatingRealm中完成的，如下：

    public final AuthenticationInfo getAuthenticationInfo(AuthenticationToken token) throws AuthenticationException {AuthenticationInfo info = getCachedAuthenticationInfo(token);if (info == null) {//otherwise not cached, perform the lookup:info = doGetAuthenticationInfo(token);log.debug("Looked up AuthenticationInfo [{}] from doGetAuthenticationInfo", info);if (token != null && info != null) {cacheAuthenticationInfoIfPossible(token, info);}} else {log.debug("Using cached authentication info [{}] to perform credentials matching.", info);}if (info != null) {assertCredentialsMatch(token, info);} else {log.debug("No AuthenticationInfo found for submitted AuthenticationToken [{}].  Returning null.", token);}return info;}

 这里首先获取AuthenticationInfo对象，要么从缓存中获取，要么通过引入的抽象方法doGetAuthenticationInfo获取（交由应用层子类具体实现）；

获取到AuthenticationInfo后，将其余用户录入的登录Token进行比对，这部分具体是方法assertCredentialsMatch完成的，具体如下：

    protected void assertCredentialsMatch(AuthenticationToken token, AuthenticationInfo info) throws AuthenticationException {CredentialsMatcher cm = getCredentialsMatcher();if (cm != null) {if (!cm.doCredentialsMatch(token, info)) {//not successful - throw an exception to indicate this:String msg = "Submitted credentials for token [" + token + "] did not match the expected credentials.";throw new IncorrectCredentialsException(msg);}} else {throw new AuthenticationException("A CredentialsMatcher must be configured in order to verify " +"credentials during authentication.  If you do not wish for credentials to be examined, you " +"can configure an " + AllowAllCredentialsMatcher.class.getName() + " instance.");}}

这里获取了默认的匹配器SimpleCredentialsMatcher，并调用doCredentialsMatch方法进行匹配，匹配实现如下：

    public boolean doCredentialsMatch(AuthenticationToken token, AuthenticationInfo info) {Object tokenCredentials = getCredentials(token);Object accountCredentials = getCredentials(info);return equals(tokenCredentials, accountCredentials);}

首先获取Credentials，也即用户密码，然后调用equals方法进行匹配，如下通过字节流的方式进行比对（主要是为了安全考虑，系统处理时采用非明文形式）。

    protected boolean equals(Object tokenCredentials, Object accountCredentials) {if (log.isDebugEnabled()) {log.debug("Performing credentials equality check for tokenCredentials of type [" +tokenCredentials.getClass().getName() + " and accountCredentials of type [" +accountCredentials.getClass().getName() + "]");}if (isByteSource(tokenCredentials) && isByteSource(accountCredentials)) {if (log.isDebugEnabled()) {log.debug("Both credentials arguments can be easily converted to byte arrays.  Performing " +"array equals comparison");}byte[] tokenBytes = toBytes(tokenCredentials);byte[] accountBytes = toBytes(accountCredentials);return MessageDigest.isEqual(tokenBytes, accountBytes);} else {return accountCredentials.equals(tokenCredentials);}}

 至此，用户账号密码匹配完成，匹配完成后，会重新创建用户登录对象，并更新用户状态等，下面具体分析；

1.2.1.2 认证通过后创建登录用户对象

认证通过后创建Subject的实现如下：

    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);}@Overrideprotected SubjectContext createSubjectContext() {return new DefaultWebSubjectContext();}

这里创建了DefaultWebSubjectContext，用户Subject创建，其中设置了认证状态、认证Token、已认证信息，然后调用createSubject方法继续进行构造，如下：

    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);return subject;}

如上创建过程包含了以下几部分，分别进行分析;

1.2.1.2.1 复制SubjectContext

对subjectContext调用复制构造方法进行复制，subjectContext底层通过backingMap保存上下文信息：

    public MapContext(Map<String, Object> map) {this();if (!CollectionUtils.isEmpty(map)) {this.backingMap.putAll(map);}}

1.2.1.2.2 对subjectContext设置securityManager

获取securityManager的顺序如下：

1. 首先从subjectContext中获取
2. 若无，则从当前线程上下文中获取
3. 否则将当前securityManager设置到subjectContext中

    protected SubjectContext ensureSecurityManager(SubjectContext context) {if (context.resolveSecurityManager() != null) {log.trace("Context already contains a SecurityManager instance.  Returning.");return context;}log.trace("No SecurityManager found in context.  Adding self reference.");context.setSecurityManager(this);return context;}

    public SecurityManager resolveSecurityManager() {SecurityManager securityManager = getSecurityManager();if (securityManager == null) {if (log.isDebugEnabled()) {log.debug("No SecurityManager available in subject context map.  " +"Falling back to SecurityUtils.getSecurityManager() lookup.");}try {securityManager = SecurityUtils.getSecurityManager();} catch (UnavailableSecurityManagerException e) {if (log.isDebugEnabled()) {log.debug("No SecurityManager available via SecurityUtils.  Heuristics exhausted.", e);}}}return securityManager;}

1.2.1.2.3 对subjectContext设置session

解析session方法如下，其中session的解析顺序为：

1. 首先从subjectContext获取session，判断是否已设置session（见源码2）
2. 否则，通过subjectContext中保存的Subject对象获取关联的session（见源码2）
3. 其次，通过sessionManager Session管理器获取（见源码3）
4. Web服务中，具体的Session管理器为ServletContainerSessionManager，尝试从request请求中获取Servlet管理的Session；（见源码4）

源码1： 

    protected SubjectContext resolveSession(SubjectContext context) {if (context.resolveSession() != null) {log.debug("Context already contains a session.  Returning.");return context;}try {//Context couldn't resolve it directly, let's see if we can since we have direct access to //the session manager:Session session = resolveContextSession(context);if (session != null) {context.setSession(session);}} catch (InvalidSessionException e) {log.debug("Resolved SubjectContext context session is invalid.  Ignoring and creating an anonymous " +"(session-less) Subject instance.", e);}return context;}

源码2： 

    public Session resolveSession() {Session session = getSession();if (session == null) {//try the Subject if it exists:Subject existingSubject = getSubject();if (existingSubject != null) {session = existingSubject.getSession(false);}}return session;}

源码3： 

    protected Session resolveContextSession(SubjectContext context) throws InvalidSessionException {SessionKey key = getSessionKey(context);if (key != null) {return getSession(key);}return null;}public Session getSession(SessionKey key) throws SessionException {return this.sessionManager.getSession(key);}

源码4： ServletContainerSessionManager获取Session

    public Session getSession(SessionKey key) throws SessionException {if (!WebUtils.isHttp(key)) {String msg = "SessionKey must be an HTTP compatible implementation.";throw new IllegalArgumentException(msg);}HttpServletRequest request = WebUtils.getHttpRequest(key);Session session = null;HttpSession httpSession = request.getSession(false);if (httpSession != null) {session = createSession(httpSession, request.getRemoteHost());}return session;}

1.2.1.2.4 对subjectContext设置Principals

resolvePrincipals方法实现如下，这里获取Principals的顺序为：

1. 先从SubjectContext中直接获取Principals（见源码2）
2. 否则，通过SubjectContext中已认证的AuthenticationInfo获取（见源码2）
3. 其次，通过SubjectContext中的Subject获取（见源码2）
4. 再次，通过SubjectContext中的Session获取（见源码2）
5. 最后，通过RememberMeManager中的Cookie中获取

源码1：

    protected SubjectContext resolvePrincipals(SubjectContext context) {PrincipalCollection principals = context.resolvePrincipals();if (isEmpty(principals)) {log.trace("No identity (PrincipalCollection) found in the context.  Looking for a remembered identity.");principals = getRememberedIdentity(context);if (!isEmpty(principals)) {log.debug("Found remembered PrincipalCollection.  Adding to the context to be used " +"for subject construction by the SubjectFactory.");context.setPrincipals(principals);} else {log.trace("No remembered identity found.  Returning original context.");}}return context;}

源码2：从SubjectContext获取Principals

    public PrincipalCollection resolvePrincipals() {PrincipalCollection principals = getPrincipals();if (isEmpty(principals)) {//check to see if they were just authenticated:AuthenticationInfo info = getAuthenticationInfo();if (info != null) {principals = info.getPrincipals();}}if (isEmpty(principals)) {Subject subject = getSubject();if (subject != null) {principals = subject.getPrincipals();}}if (isEmpty(principals)) {//try the session:Session session = resolveSession();if (session != null) {principals = (PrincipalCollection) session.getAttribute(PRINCIPALS_SESSION_KEY);}}return principals;}

1.2.1.2.5 根据subjectContext创建Subject

如下，通过createSubject创建了WebDelegatingSubject对象；

    public Subject createSubject(SubjectContext context) {if (!(context instanceof WebSubjectContext)) {return super.createSubject(context);}WebSubjectContext wsc = (WebSubjectContext) context;SecurityManager securityManager = wsc.resolveSecurityManager();Session session = wsc.resolveSession();boolean sessionEnabled = wsc.isSessionCreationEnabled();PrincipalCollection principals = wsc.resolvePrincipals();boolean authenticated = wsc.resolveAuthenticated();String host = wsc.resolveHost();ServletRequest request = wsc.resolveServletRequest();ServletResponse response = wsc.resolveServletResponse();return new WebDelegatingSubject(principals, authenticated, host, session, sessionEnabled,request, response, securityManager);}

1.2.1.2.6 保存Subject 

 Subject保存是通过DefaultSubjectDAO完成的，

如下，通过saveToSession方法保存Principals和认证状态到Session中；

    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);}

这里在保存Principals的过程中，如果Principals不为空，且非Servlet Session的条件下，这里会调用subject.getSession()方法创建shiro管理的native Session对象：

subject.getSession()方法实现如下：

    public Session getSession() {return getSession(true);}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);this.session = decorate(session);}return this.session;}

如上，通过securityManager的start方法创建Session对象，start具体实现为 ：

    public Session start(SessionContext context) throws AuthorizationException {return this.sessionManager.start(context);}

这里又委托给了Session管理器完成session创建，这里的Session管理器实现为AbstractNativeSessionManager，start方法实现如下：

    public Session start(SessionContext context) {Session session = createSession(context);applyGlobalSessionTimeout(session);onStart(session, context);notifyStart(session);//Don't expose the EIS-tier Session object to the client-tier:return createExposedSession(session, context);}

上述主要完成了以下几部分功能：

1. 通过createSession方法创建SimpleSession对象，其中包括了Session创建、Session保存到            sessionDAO中（比如保存到内存中的子类MemorySessionDAO，或者保存在数据库中的子类        EnterpriseCacheSessionDAO等），SessionId生成等操作；

    图示sessionDAO的整体继承结构：

    

2. Session全局超时时间配置（默认超时时间为30min）

3. onStart将SessionId存储到Cookie中，如下：    

    private void storeSessionId(Serializable currentId, HttpServletRequest request, HttpServletResponse response) {if (currentId == null) {String msg = "sessionId cannot be null when persisting for subsequent requests.";throw new IllegalArgumentException(msg);}Cookie template = getSessionIdCookie();Cookie cookie = new SimpleCookie(template);String idString = currentId.toString();cookie.setValue(idString);cookie.saveTo(request, response);log.trace("Set session ID cookie for session with id {}", idString);}

至此，用户登录认证过程完成了生成认证Token、通过Realm从应用中获取用户认证信息、用户认证Token匹配，以及认证成功后创建用户Subject对象、保存Subject到Session、SessionId保存到Cookie等操作。