Shiro的subject实质上是当前执行用户的特定视图。

通过org.apache.shiro.SecurityUtils可以查询当前执行用户：

Subject currentUser = SecurityUtils.getSubject();

获取当前执行用户的session：

（在非web、非EJB的情况下，Shiro自动使用自带session；如果是web或者EJB应用，则Shiro自动使用HttpSession，不需要人为改变。）

Session session = currentUser.getSession();
session.setAttribute( "someKey", "aValue" );

案例一：

验证用户是否为认证用户：

if ( !currentUser.isAuthenticated() ) {//collect user principals and credentials in a gui specific manner//such as username/password html form, X509 certificate, OpenID, etc.//We'll use the username/password example here since it is the most common.//(do you know what movie this is from? ;) UsernamePasswordToken token = new UsernamePasswordToken("lonestarr", "vespa"); //this is all you have to do to support 'remember me' (no config - built in!): token.setRememberMe(true); currentUser.login(token); }

验证失败，提示信息：

ry {currentUser.login( token );//if no exception, that's it, we're done!
} catch ( UnknownAccountException uae ) {//username wasn't in the system, show them an error message? } catch ( IncorrectCredentialsException ice ) { //password didn't match, try again? } catch ( LockedAccountException lae ) { //account for that username is locked - can't login. Show them a message? } ... more types exceptions to check if you want ... } catch ( AuthenticationException ae ) { //unexpected condition - error? }

案例二（展示当前用户信息）：

//print their identifying principal (in this case, a username):
log.info( "User [" + currentUser.getPrincipal() + "] logged in successfully." );

案例三（判断当前用户角色）：

if ( currentUser.hasRole( "schwartz" ) ) {log.info("May the Schwartz be with you!" );
} else {log.info( "Hello, mere mortal." ); }

案例四（验证当前用户权限）：

if ( currentUser.isPermitted( "lightsaber:weild" ) ) {log.info("You may use a lightsaber ring.  Use it wisely.");
} else {log.info("Sorry, lightsaber rings are for schwartz masters only."); }

案例五（退出登录）：

currentUser.logout(); //removes all identifying information and invalidates their session too.

Shiro支持创建subject的实例，但不推荐。因为我们平常可以直接通过getSubject来获取当前执行用户。个别情况需要创建subject：

1.当前没有用户可以与系统进行交互，但是为保持系统的运行，需要假设一个用户，此时可以创建一个subject，比如admin用户。

2.集成测试时，需要创建一个临时的subject用以进入下一步的测试。

3.应用的后台进程运行的时候，需要一个subject。

（如果已经拥有了一个subject，但是需要和其他线程共享的话，需要调用Subject.associateWith*方法。）

subject的创建

案例六（Subject.Builder，创建subject，而无需知道其中细节，会访问到SecurityManager的SecurityUtils.getSecurityManager()方法。）：

Subject subject = new Subject.Builder().buildSubject()

案例七（自建securityManager）：

SecurityManager securityManager = //acquired from somewhere
Subject subject = new Subject.Builder(securityManager).buildSubject();

案例八（利用session创建新的subject）：

Serializable sessionId = //acquired from somewhere
Subject subject = new Subject.Builder().sessionId(sessionId).buildSubject();

案例九（创建subject，并将其属性映射到验证属性中）：

Object userIdentity = //a long ID or String username, or whatever the "myRealm" requires String realmName = "myRealm"; PrincipalCollection principals = new SimplePrincipalCollection(userIdentity, realmName); Subject subject = new Subject.Builder().principals(principals).buildSubject();

将自建的subject与线程进行绑定：

1.系统的自动绑定，Subject.execute*方法的调用。

2.手动的绑定。

3.利用已绑定的线程来绑定到新的线程，Subject.associateWith*方法的调用。

（subject与线程绑定，则可以在线程执行过程中取到信息；subject与线程取消绑定，则线程可以被回收。）

案例十（调用execute方法，参数为runable实例，实现subject的自动绑定与拆除）：

Subject subject = //build or acquire subject
subject.execute( new Runnable() {public void run() {//subject is 'bound' to the current thread now //any SecurityUtils.getSubject() calls in any //code called from here will work } }); //At this point, the Subject is no longer associated //with the current thread and everything is as it was before

案例十一（调用execute方法，参数为callable实例，实现subject的自动绑定与拆除）：

Subject subject = //build or acquire subject
MyResult result = subject.execute( new Callable<MyResult>() {public MyResult call() throws Exception {//subject is 'bound' to the current thread now //any SecurityUtils.getSubject() calls in any //code called from here will work ... //finish logic as this Subject ... return myResult; } }); //At this point, the Subject is no longer associated //with the current thread and everything is as it was before

案例十二（spring远程调用subject）：

Subject.Builder builder = new Subject.Builder();
//populate the builder's attributes based on the incoming RemoteInvocation
...
Subject subject = builder.buildSubject();return subject.execute(new Callable() {public Object call() throws Exception { return invoke(invocation, targetObject); } });

线程池的清理：

Subject subject = new Subject.Builder()...
ThreadState threadState = new SubjectThreadState(subject);
threadState.bind();
try {//execute work as the built Subject
} finally { //ensure any state is cleaned so the thread won't be //corrupt in a reusable or pooled thread environment threadState.clear(); }

案例十三（callable）：

Subject subject = new Subject.Builder()...
Callable work = //build/acquire a Callable instance.
//associate the work with the built subject so SecurityUtils.getSubject() calls works properly:
work = subject.associateWith(work);
ExecutorService executorService = new java.util.concurrent.Executors.newCachedThreadPool();
//execute the work on a different thread as the built Subject: executor.execute(work);

案例十四（runable）：

Subject subject = new Subject.Builder()...
Runnable work = //build/acquire a Runnable instance.
//associate the work with the built subject so SecurityUtils.getSubject() calls works properly: work = subject.associateWith(work); Executor executor = new java.util.concurrent.Executors.newCachedThreadPool(); //execute the work on a different thread as the built Subject: executor.execute(work);