1. shiro介紹

Apache Shiro是一個強大易用的Java安全框架，提供了認證、授權、加密和會話管理等功能：?

• 認證 - 用戶身份識別，常被稱為用戶“登錄”；
• 授權 - 訪問控制；
• 密碼加密 - 保護或隱藏數據防止被偷窺；
• 會話管理 - 每用戶相關的時間敏感的狀態。

對于任何一個應用程序，Shiro都可以提供全面的安全管理服務。并且相對于其他安全框架，Shiro要簡單的多。

2. shiro源碼概況

? ? 先要了解shiro的基本框架(見http://www.cnblogs.com/davidwang456/p/4425145.html)。

? ? 然后看一下各個組件之間的關系：

一下內容參考：http://kdboy.iteye.com/blog/1154644

Subject：即“當前操作用戶”。但是，在Shiro中，Subject這一概念并不僅僅指人，也可以是第三方進程、后臺帳戶（Daemon Account）或其他類似事物。它僅僅意味著“當前跟軟件交互的東西”。但考慮到大多數目的和用途，你可以把它認為是Shiro的“用戶”概念。?
Subject代表了當前用戶的安全操作，SecurityManager則管理所有用戶的安全操作。?

SecurityManager：它是Shiro框架的核心，典型的Facade模式，Shiro通過SecurityManager來管理內部組件實例，并通過它來提供安全管理的各種服務。?

Realm： Realm充當了Shiro與應用安全數據間的“橋梁”或者“連接器”。也就是說，當對用戶執行認證（登錄）和授權（訪問控制）驗證時，Shiro會從應用配置的Realm中查找用戶及其權限信息。?
從這個意義上講，Realm實質上是一個安全相關的DAO：它封裝了數據源的連接細節，并在需要時將相關數據提供給Shiro。當配置Shiro時，你必須至少指定一個Realm，用于認證和（或）授權。配置多個Realm是可以的，但是至少需要一個。?
Shiro內置了可以連接大量安全數據源（又名目錄）的Realm，如LDAP、關系數據庫（JDBC）、類似INI的文本配置資源以及屬性文件等。如果缺省的Realm不能滿足需求，你還可以插入代表自定義數據源的自己的Realm實現。

Shiro主要組件還包括：?
Authenticator ：認證就是核實用戶身份的過程。這個過程的常見例子是大家都熟悉的“用戶/密碼”組合。多數用戶在登錄軟件系統時，通常提供自己的用戶名（當事人）和支持他們的密碼（證書）。如果存儲在系統中的密碼（或密碼表示）與用戶提供的匹配，他們就被認為通過認證。?
Authorizer ：授權實質上就是訪問控制 - 控制用戶能夠訪問應用中的哪些內容，比如資源、Web頁面等等。?
SessionManager ：在安全框架領域，Apache Shiro提供了一些獨特的東西：可在任何應用或架構層一致地使用Session API。即，Shiro為任何應用提供了一個會話編程范式 - 從小型后臺獨立應用到大型集群Web應用。這意味著，那些希望使用會話的應用開發者，不必被迫使用Servlet或EJB容器了。或者，如果正在使用這些容器，開發者現在也可以選擇使用在任何層統一一致的會話API，取代Servlet或EJB機制。?
CacheManager :對Shiro的其他組件提供緩存支持。?

3. 做一個demo，跑shiro的源碼，從login開始：

第一步：用戶根據表單信息填寫用戶名和密碼，然后調用登陸按鈕。內部執行如下：

UsernamePasswordToken token = new UsernamePasswordToken(loginForm.getUsername(), loginForm.getPassphrase()); token.setRememberMe(true);Subject currentUser = SecurityUtils.getSubject();currentUser.login(token);

第二步：代理DelegatingSubject繼承Subject執行login

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;}}

第三步：調用DefaultSecurityManager繼承SessionsSecurityManager執行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); onSuccessfulLogin(token, info, loggedIn);return loggedIn;}

第四步：認證管理器AuthenticatingSecurityManager繼承RealmSecurityManager執行authenticate方法：

/*** Delegates to the wrapped {@link org.apache.shiro.authc.Authenticator Authenticator} for authentication.*/public AuthenticationInfo authenticate(AuthenticationToken token) throws AuthenticationException {return this.authenticator.authenticate(token);}

第五步：抽象認證管理器AbstractAuthenticator繼承Authenticator, LogoutAware 執行authenticate方法：

public final AuthenticationInfo authenticate(AuthenticationToken token) throws AuthenticationException {if (token == null) {throw new IllegalArgumentException("Method argumet (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);}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;}

第六步：ModularRealmAuthenticator繼承AbstractAuthenticator執行doAuthenticate方法

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);}}

接著調用：

/*** Performs the authentication attempt by interacting with the single configured realm, which is significantly* simpler than performing multi-realm logic.** @param realm the realm to consult for AuthenticationInfo.* @param token the submitted AuthenticationToken representing the subject's (user's) log-in principals and credentials.* @return the AuthenticationInfo associated with the user account corresponding to the specified {@code token}*/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;}

第七步：AuthenticatingRealm繼承CachingRealm執行getAuthenticationInfo方法

public final AuthenticationInfo getAuthenticationInfo(AuthenticationToken token) throws AuthenticationException {AuthenticationInfo info = getCachedAuthenticationInfo(token); //從緩存中讀取if (info == null) {//otherwise not cached, perform the lookup:info = doGetAuthenticationInfo(token); //緩存中讀不到，則到數據庫或者ldap或者jndi等去讀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;}

1. 從緩存中讀取的方法：

/*** Checks to see if the authenticationCache class attribute is null, and if so, attempts to acquire one from* any configured {@link #getCacheManager() cacheManager}. If one is acquired, it is set as the class attribute.* The class attribute is then returned.** @return an available cache instance to be used for authentication caching or {@code null} if one is not available.* @since 1.2*/private Cache<Object, AuthenticationInfo> getAuthenticationCacheLazy() {if (this.authenticationCache == null) {log.trace("No authenticationCache instance set. Checking for a cacheManager...");CacheManager cacheManager = getCacheManager();if (cacheManager != null) {String cacheName = getAuthenticationCacheName();log.debug("CacheManager [{}] configured. Building authentication cache '{}'", cacheManager, cacheName);this.authenticationCache = cacheManager.getCache(cacheName);}}return this.authenticationCache;}

2. 從數據庫中讀取的方法：

JdbcRealm繼承 AuthorizingRealm執行doGetAuthenticationInfo方法

protected AuthenticationInfo doGetAuthenticationInfo(AuthenticationToken token) throws AuthenticationException {UsernamePasswordToken upToken = (UsernamePasswordToken) token;String username = upToken.getUsername();// Null username is invalidif (username == null) {throw new AccountException("Null usernames are not allowed by this realm.");}Connection conn = null;SimpleAuthenticationInfo info = null;try {conn = dataSource.getConnection();String password = null;String salt = null;switch (saltStyle) {case NO_SALT:password = getPasswordForUser(conn, username)[0];break;case CRYPT:// TODO: separate password and hash from getPasswordForUser[0]throw new ConfigurationException("Not implemented yet");//break;case COLUMN: String[] queryResults = getPasswordForUser(conn, username);password = queryResults[0];salt = queryResults[1];break;case EXTERNAL:password = getPasswordForUser(conn, username)[0];salt = getSaltForUser(username);}if (password == null) {throw new UnknownAccountException("No account found for user [" + username + "]");}info = new SimpleAuthenticationInfo(username, password.toCharArray(), getName());if (salt != null) {info.setCredentialsSalt(ByteSource.Util.bytes(salt));}} catch (SQLException e) {final String message = "There was a SQL error while authenticating user [" + username + "]";if (log.isErrorEnabled()) {log.error(message, e);}// Rethrow any SQL errors as an authentication exceptionthrow new AuthenticationException(message, e);} finally {JdbcUtils.closeConnection(conn);}return info;}

接著調用sql語句：

private String[] getPasswordForUser(Connection conn, String username) throws SQLException {String[] result;boolean returningSeparatedSalt = false;switch (saltStyle) {case NO_SALT:case CRYPT:case EXTERNAL:result = new String[1];break;default:result = new String[2];returningSeparatedSalt = true;}PreparedStatement ps = null;ResultSet rs = null;try {ps = conn.prepareStatement(authenticationQuery);ps.setString(1, username);// Execute queryrs = ps.executeQuery();// Loop over results - although we are only expecting one result, since usernames should be uniqueboolean foundResult = false;while (rs.next()) {// Check to ensure only one row is processedif (foundResult) {throw new AuthenticationException("More than one user row found for user [" + username + "]. Usernames must be unique.");}result[0] = rs.getString(1);if (returningSeparatedSalt) {result[1] = rs.getString(2);}foundResult = true;}} finally {JdbcUtils.closeResultSet(rs);JdbcUtils.closeStatement(ps);}return result;}

其中authenticationQuery定義如下：

protected String authenticationQuery = DEFAULT_AUTHENTICATION_QUERY;protected static final String DEFAULT_AUTHENTICATION_QUERY = "select password from users where username = ?";

4. 小結

Apache Shiro 是功能強大并且容易集成的開源權限框架，它能夠完成認證、授權、加密、會話管理等功能。認證和授權為權限控制的核心，簡單來說，“認證”就是證明你是誰？ Web 應用程序一般做法通過表單提交用戶名及密碼達到認證目的。“授權”即是否允許已認證用戶訪問受保護資源。

參考文獻：

http://kdboy.iteye.com/blog/1154644

http://www.ibm.com/developerworks/cn/java/j-lo-shiro/?

?

轉載于:https://www.cnblogs.com/davidwang456/p/4428421.html

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