shiro：shiro认证流程源码分析

1、shiro认证流程源码分析

（1）输入用户名和密码进行登录

 UsernamePasswordToken token=new UsernamePasswordToken(username,password);

（2）下一步

 subject.login(token);

（3）查看login源码

 public void login(AuthenticationToken token) throws AuthenticationException {
        this.clearRunAsIdentitiesInternal();
        Subject subject = this.securityManager.login(this, token);//---------------
        String host = null;
        PrincipalCollection principals;
        if (subject instanceof DelegatingSubject) {
            DelegatingSubject delegating = (DelegatingSubject)subject;
            principals = delegating.principals;
            host = delegating.host;
        } else {
            principals = subject.getPrincipals();
        }

        if (principals != null && !principals.isEmpty()) {
            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 = this.decorate(session);
            } else {
                this.session = null;
            }

        } else {
            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);
        }
    }

（4）查看securityManager.login（安全管理器）

  public Subject login(Subject subject, AuthenticationToken token) throws AuthenticationException {
        AuthenticationInfo info;
        try {
            info = this.authenticate(token);
        } catch (AuthenticationException var7) {
            AuthenticationException ae = var7;

            try {
                this.onFailedLogin(token, ae, subject);
            } catch (Exception var6) {
                if (log.isInfoEnabled()) {
                    log.info("onFailedLogin method threw an exception.  Logging and propagating original AuthenticationException.", var6);
                }
            }

            throw var7;
        }

        Subject loggedIn = this.createSubject(token, info, subject);
        this.onSuccessfulLogin(token, info, loggedIn);
        return loggedIn;
    }

（5）查看authenticate（安全管理器）

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

（6）authenticator.authenticate（认证器）

 public final AuthenticationInfo authenticate(AuthenticationToken token) throws AuthenticationException {
        if (token == null) {
            throw new IllegalArgumentException("Method argument (authentication token) cannot be null.");
        } else {
            log.trace("Authentication attempt received for token [{}]", token);

            AuthenticationInfo info;
            try {
                info = this.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 var8) {
                AuthenticationException ae = null;
                if (var8 instanceof AuthenticationException) {
                    ae = (AuthenticationException)var8;
                }

                if (ae == null) {
                    String msg = "Authentication failed for token submission [" + token + "].  Possible unexpected error? (Typical or expected login exceptions should extend from AuthenticationException).";
                    ae = new AuthenticationException(msg, var8);
                    if (log.isWarnEnabled()) {
                        log.warn(msg, var8);
                    }
                }

                try {
                    this.notifyFailure(token, ae);
                } catch (Throwable var7) {
                    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, var7);
                    }
                }

                throw ae;
            }

            log.debug("Authentication successful for token [{}].  Returned account [{}]", token, info);
            this.notifySuccess(token, info);
            return info;
        }
    }

（7）doAuthenticate

在这里完成realm的加载

    protected AuthenticationInfo doAuthenticate(AuthenticationToken authenticationToken) throws AuthenticationException {
        this.assertRealmsConfigured();//确认配置了realm
        Collection<Realm> realms = this.getRealms();//或取到所有的realm
        return realms.size() == 1 ? this.doSingleRealmAuthentication((Realm)realms.iterator().next(), authenticationToken) :
        this.doMultiRealmAuthentication(realms, authenticationToken);//realms就是认证的时候会执行的realm
    }//一个realm就执行单realm认证，否则执行多realm认证