*以下仅是部分关键代码
- 应用程序根据用户的身份和凭证（principals和credentials）来构造出AuthenticationToken实例，并调用Subject.login的方法进行登录，其会自动委托给SecurityManager。
try {
Subject subject = SecurityUtils.getSubject();
// 已登陆则 跳到首页
if (subject.isAuthenticated()) {
return "redirect:/personal/zone";
}
// 身份验证
String username = request.getParameter("login_username");
String password = request.getParameter("login_password");
subject.login(new UsernamePasswordToken(username, password));
} catch (AuthenticationException e) {
}
- Subject实例通常上都是DelegatingSubject(或子类)，在验证开始的时候，Subject实例会将验证委托给应用程序配置的SecurityManager，并调用securityManager.login(token)方法进行身份认证。
public class DelegatingSubject implements Subject {
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;
}
}
}
- SecurityManager得到token信息后，通过调用authenticator.authenticate(token)方法，把身份验证委托给内置的Authenticator的实例进行验证。authenticator通常是ModularRealmAuthenticator实例，支持对一个或多个Realm实例进行适配。ModularRealmAuthenticator提供了一种可插拔的认证风格，你可以在此处插入自定义Realm实现。
public class DefaultSecurityManager extends SessionsSecurityManager {
private Authenticator authenticator;
public AuthenticatingSecurityManager() {
super();
this.authenticator = new ModularRealmAuthenticator();
}
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;
}
}
public AuthenticationInfo authenticate(AuthenticationToken token) throws AuthenticationException {
return this.authenticator.authenticate(token);
}
- 如果配置了多个Realm，ModularRealmAuthenticator会根据配置的AuthenticationStrategy（身份验证策略）进行多Realm认证过程。
注：如果应用程序中仅配置了一个Realm，Realm将被直接调用而无需再配置认证策略。
//ModularRealmAuthenticator 继承了 AbstractAuthenticator （authenticate 调用了doAuthenticate）
public class ModularRealmAuthenticator extends AbstractAuthenticator {
private Collection<Realm> realms;
public void setRealms(Collection<Realm> realms) {
this.realms = realms;
}
protected Collection<Realm> getRealms() {
return this.realms;
}
public ModularRealmAuthenticator() {
this.authenticationStrategy = new AtLeastOneSuccessfulStrategy();
}
protected AuthenticationInfo doAuthenticate(AuthenticationToken authenticationToken) throws AuthenticationException {
assertRealmsConfigured();
Collection<Realm> realms = getRealms();
if (realms.size() == 1) {
//仅配置了一个realm
return doSingleRealmAuthentication(realms.iterator().next(), authenticationToken);
} else {
//配置了多个realm
return doMultiRealmAuthentication(realms, authenticationToken);
}
}
public abstract class AbstractAuthenticator implements Authenticator, LogoutAware {
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;
}
protected abstract AuthenticationInfo doAuthenticate(AuthenticationToken token) throws AuthenticationException;```
5.判断每个Realm是否支持提交的token，如果支持Realm就会调用getAuthenticationInfo（token）方法进行认证处理。
protected AuthenticationInfo doSingleRealmAuthentication(Realm realm, AuthenticationToken token) {
//判断realm 是否支持 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;
}
我们自定义realm时一般会继承 AuthorizingRealm，AuthorizingRealm又继承
AuthenticatingRealm
public abstract class AuthenticatingRealm extends CachingRealm implements Initializable {
public final AuthenticationInfo getAuthenticationInfo(AuthenticationToken token) throws AuthenticationException {
AuthenticationInfo info = getCachedAuthenticationInfo(token);
if (info == null) {
//otherwise not cached, perform the lookup:
//调用我们继承时覆盖的方法
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) {
//判断密码是否匹配，如果不匹配将抛出密码错误异常IncorrectCredentialsException；
//另外如果密码重试此处太多将抛出超出重试次数异常ExcessiveAttemptsException；
//在组装SimpleAuthenticationInfo信息时，需要传入：身份信息（用户名）、凭据（密文密码）、盐（username+salt），
//CredentialsMatcher使用盐加密传入的明文密码和此处的密文密码进行匹配。
assertCredentialsMatch(token, info);
} else {
log.debug("No AuthenticationInfo found for submitted AuthenticationToken [{}]. Returning null.", token);
}
return info;
}
protected abstract AuthenticationInfo doGetAuthenticationInfo(AuthenticationToken token) throws AuthenticationException;
}
参考 http://blog.csdn.net/lishehe/article/details/45219023