shiro学习笔记-Subject#login(token)实现过程

Love The Way You Lie 2022-11-26 07:59 107阅读 0赞

本博文所有的代码均为shiro官网（http://shiro.apache.org/）中shiro 1.3.2版本中的源码。

追踪Subject的login(AuthenticationToken token)方法，其调用的为DelegatingSubject类的login方法，DelegatingSubject实现了Subject接口，DelegatingSubject\#login如下：

public void login(AuthenticationToken token) throws AuthenticationException {
        clearRunAsIdentitiesInternal();
        Subject subject = securityManager.login(this, token);
    
        PrincipalCollection principals;
    
        String host = null;
    
        if (subject instanceof DelegatingSubject) {
            DelegatingSubject delegating = (DelegatingSubject) subject;
            //we have to do this in case there are assumed identities - we don't want to lose the 'real' principals:
            principals = delegating.principals;
            host = delegating.host;
        } else {
            principals = subject.getPrincipals();
        }
    
        if (principals == null || principals.isEmpty()) {
            String msg = "Principals returned from securityManager.login( token ) returned a null or " +
                    "empty value.  This value must be non null and populated with one or more elements.";
            throw new IllegalStateException(msg);
        }
        this.principals = principals;
        this.authenticated = true;
        if (token instanceof HostAuthenticationToken) {
            host = ((HostAuthenticationToken) token).getHost();
        }
        if (host != null) {
            this.host = host;
        }
        Session session = subject.getSession(false);
        if (session != null) {
            this.session = decorate(session);
        } else {
            this.session = null;
        }
    }

在上面代码的第三行：Subject subject = securityManager.login(this, token); 注意到其调用了SecurityManager的login方法，SecurityManager为接口，实际上调用的其实现类DefaultSecurityManager的login方法，方法如下：

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;
    }

在上面代码第四行：info = authenticate(token); 继续跟踪，发现authenticate(AuthenticationToken token);方法为DefaultSecurityManager的父类AuthenticatingSecurityManager的方法，AuthenticatingSecurityManager\#authenticate方法如下：

1 public AuthenticationInfo authenticate(AuthenticationToken token) throws AuthenticationException {
    2     return this.authenticator.authenticate(token);
    3 }

authenticator为Authenticator接口，继续跟踪，AbstractAuthenticator抽象类实现了Authenticator接口，接下来继续查看AbstractAuthenticator\#authenticate(token);方法：

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;
    }

上面代码第11行：info = doAuthenticate(token); 这个方法为ModularRealmAuthticator类中的方法，因为ModularRealmAuthticator继承了AbstractAuthenticator抽象类。另外，要注意第12行-第16行，如果info==null，就会抛出异常。ModularRealmAuthticator的doAuthenticate(token);方法如下：

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，我们关注上面第五行代码：doSingleRealmAuthentication(realms.iterator().next(), authenticationToken); else语句中的doMultiRealmAuthentication(realms, authenticationToken);类似。跟踪到doSingleRealmAuthentication方法如下：

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;
    }

上面代码第八行：AuthenticationInfo info = realm.getAuthenticationInfo(token); realm为Realm接口，实际上调用的是其实现类AuthenticatingRealm中的getAuthenticationInfo方法，方法如下：

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;
    }

上面代码第三行：AuthenticationInfo info = getCachedAuthenticationInfo(token);从缓存中获取认证信息，如果未获取到，则调用第六行的doGetAuthenticationInfo(token); 方法获取认证信息。继续跟踪，发现有几个类实现了该方法，如下图所示：

![format_png][]

最后，附上SecurityManager和Realm等的类关系图：

**Realm：**

![format_png 1][]

**SecurityManager:**

![format_png 2][]

**Authenticator:**

![format_png 3][]

[format_png]: /images/20221124/ec1ba7e4d09d4e48806cf8bd76c9a2e4.png
[format_png 1]: /images/20221124/5b2be08a723b4b21b7e16926e4c432ea.png
[format_png 2]: /images/20221124/5b5c6d6de00b4aa2b7287a2b35753dfb.png
[format_png 3]: /images/20221124/27f7fc91717c41cdbdebc66be93b46f7.png