1. 授权需要继承 AuthorizingRealm 类, 并实现其 doGetAuthorizationInfo 方法
2. AuthorizingRealm 类继承自 AuthenticatingRealm, 但没有实现 AuthenticatingRealm 中的 
doGetAuthenticationInfo, 所以认证和授权只需要继承 AuthorizingRealm 就可以了. 同时实现他的两个抽象方法.

1. 为什么使用 MD5 盐值加密: 
即使两个人的密码一样，加密后的值 也是不一样，更加安全
2. 如何做到:
1). 在 doGetAuthenticationInfo 方法返回值创建 SimpleAuthenticationInfo 对象的时候, 需要使用
SimpleAuthenticationInfo(principal, credentials, credentialsSalt, realmName) 构造器
2). 使用 ByteSource.Util.bytes() 来计算盐值. 
3). 盐值需要唯一: 一般使用随机字符串或 user id
4). 使用 new SimpleHash(hashAlgorithmName, credentials, salt, hashIterations); 来计算盐值加密后的密码的值. 

1. 如何把一个字符串加密为 MD5 
2. 替换当前 Realm 的 credentialsMatcher 属性. 直接使用 HashedCredentialsMatcher 对象, 并设置加密算法即可. 

密码的比对:
通过 AuthenticatingRealm 的 credentialsMatcher 属性来进行的密码的比对!

1. 获取当前的 Subject. 调用 SecurityUtils.getSubject();
2. 测试当前的用户是否已经被认证. 即是否已经登录. 调用 Subject 的 isAuthenticated() 
3. 若没有被认证, 则把用户名和密码封装为 UsernamePasswordToken 对象
1). 创建一个表单页面
2). 把请求提交到 SpringMVC 的 Handler
3). 获取用户名和密码. 
4. 执行登录: 调用 Subject 的 login(AuthenticationToken) 方法. 
5. 自定义 Realm 的方法, 从数据库中获取对应的记录, 返回给 Shiro.
1). 实际上需要继承 org.apache.shiro.realm.AuthenticatingRealm 类
2). 实现 doGetAuthenticationInfo(AuthenticationToken) 方法. 
6. 由 shiro 完成对密码的比对.

package com.mikey.www;

/**
 * @author Mikey
 * @Title:
 * @Description:
 * @date 2018/11/1 21:32
 * @Version 1.0
 */
import org.apache.shiro.SecurityUtils;
import org.apache.shiro.authc.*;
import org.apache.shiro.config.IniSecurityManagerFactory;
import org.apache.shiro.mgt.SecurityManager;
import org.apache.shiro.session.Session;
import org.apache.shiro.subject.Subject;
import org.apache.shiro.util.Factory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * Simple Quickstart application showing how to use Shiro''s API.
 *
 * @since 0.9 RC2
 */
public class Quickstart {

    private static final transient Logger log = LoggerFactory.getLogger(Quickstart.class);


    public static void main(String[] args) {

        // The easiest way to create a Shiro SecurityManager with configured
        // realms, users, roles and permissions is to use the simple INI config.
        // We''ll do that by using a factory that can ingest a .ini file and
        // return a SecurityManager instance:

        // Use the shiro.ini file at the root of the classpath
        // (file: and url: prefixes load from files and urls respectively):
        Factory<SecurityManager> factory = new IniSecurityManagerFactory("classpath:shiro.ini");
        SecurityManager securityManager = factory.getInstance();

        // for this simple example quickstart, make the SecurityManager
        // accessible as a JVM singleton.  Most applications wouldn''t do this
        // and instead rely on their container configuration or web.xml for
        // webapps.  That is outside the scope of this simple quickstart, so
        // we''ll just do the bare minimum so you can continue to get a feel
        // for things.
        SecurityUtils.setSecurityManager(securityManager);

        // Now that a simple Shiro environment is set up, let''s see what you can do:

        // get the currently executing user:
        // 获取当前的 Subject. 调用 SecurityUtils.getSubject();
        Subject currentUser = SecurityUtils.getSubject();

        // Do some stuff with a Session (no need for a web or EJB container!!!)
        // 测试使用 Session
        // 获取 Session: Subject#getSession()
        Session session = currentUser.getSession();
        session.setAttribute("someKey", "aValue");
        String value = (String) session.getAttribute("someKey");
        if (value.equals("aValue")) {
            log.info("---> Retrieved the correct value! [" + value + "]");
        }

        // let''s login the current user so we can check against roles and permissions:
        // 测试当前的用户是否已经被认证. 即是否已经登录.
        // 调动 Subject 的 isAuthenticated()
        if (!currentUser.isAuthenticated()) {
            // 把用户名和密码封装为 UsernamePasswordToken 对象
            UsernamePasswordToken token = new UsernamePasswordToken("lonestarr", "vespa");
            // rememberme
            token.setRememberMe(true);
            try {
                // 执行登录.
                currentUser.login(token);
            }
            // 若没有指定的账户, 则 shiro 将会抛出 UnknownAccountException 异常.
            catch (UnknownAccountException uae) {
                log.info("----> There is no user with username of " + token.getPrincipal());
                return;
            }
            // 若账户存在, 但密码不匹配, 则 shiro 会抛出 IncorrectCredentialsException 异常。
            catch (IncorrectCredentialsException ice) {
                log.info("----> Password for account " + token.getPrincipal() + " was incorrect!");
                return;
            }
            // 用户被锁定的异常 LockedAccountException
            catch (LockedAccountException lae) {
                log.info("The account for username " + token.getPrincipal() + " is locked.  " +
                        "Please contact your administrator to unlock it.");
            }
            // ... catch more exceptions here (maybe custom ones specific to your application?
            // 所有认证时异常的父类.
            catch (AuthenticationException ae) {
                //unexpected condition?  error?
            }
        }

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

        //test a role:
        // 测试是否有某一个角色. 调用 Subject 的 hasRole 方法.
        if (currentUser.hasRole("schwartz")) {
            log.info("----> May the Schwartz be with you!");
        } else {
            log.info("----> Hello, mere mortal.");
            return;
        }

        //test a typed permission (not instance-level)
        // 测试用户是否具备某一个行为. 调用 Subject 的 isPermitted() 方法。
        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.");
        }

        //a (very powerful) Instance Level permission:
        // 测试用户是否具备某一个行为.
        if (currentUser.isPermitted("user:delete:zhangsan")) {
            log.info("----> You are permitted to ''drive'' the winnebago with license plate (id) ''eagle5''.  " +
                    "Here are the keys - have fun!");
        } else {
            log.info("Sorry, you aren''t allowed to drive the ''eagle5'' winnebago!");
        }

        //all done - log out!
        // 执行登出. 调用 Subject 的 Logout() 方法.
        System.out.println("---->" + currentUser.isAuthenticated());

        currentUser.logout();

        System.out.println("---->" + currentUser.isAuthenticated());

        System.exit(0);
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    id="WebApp_ID" version="2.5">
    
    <!-- needed for ContextLoaderListener -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </context-param>

    <!-- Bootstraps the root web application context before servlet initialization -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    
    <!-- The front controller of this Spring Web application, responsible for handling all application requests -->
    <servlet>
        <servlet-name>spring</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- Map all requests to the DispatcherServlet for handling -->
    <servlet-mapping>
        <servlet-name>spring</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
    <!-- Shiro Filter is defined in the spring application context: -->
    <!-- 
    1. 配置  Shiro 的 shiroFilter.  
    2. DelegatingFilterProxy 实际上是 Filter 的一个代理对象. 默认情况下, Spring 会到 IOC 容器中查找和 
    <filter-name> 对应的 filter bean. 也可以通过 targetBeanName 的初始化参数来配置 filter bean 的 id. 
    -->
    <filter>
        <filter-name>shiroFilter</filter-name>
        <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
        <init-param>
            <param-name>targetFilterLifecycle</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>

    <filter-mapping>
        <filter-name>shiroFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    
</web-app>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- =========================================================
         Shiro Core Components - Not Spring Specific
         ========================================================= -->
    <!-- Shiro''s main business-tier object for web-enabled applications
         (use DefaultSecurityManager instead when there is no web environment)-->
    <!--  
    1. 配置 SecurityManager!
    -->     
    <bean id="securityManager" class="org.apache.shiro.web.mgt.DefaultWebSecurityManager">
        <property name="cacheManager" ref="cacheManager"/>
        <property name="authenticator" ref="authenticator"></property>
        
        <property name="realms">
            <list>
                <ref bean="jdbcRealm"/>
                <ref bean="secondRealm"/>
            </list>
        </property>
        
        <property name="rememberMeManager.cookie.maxAge" value="10"></property>
    </bean>

    <!-- Let''s use some enterprise caching support for better performance.  You can replace this with any enterprise
         caching framework implementation that you like (Terracotta+Ehcache, Coherence, GigaSpaces, etc -->
    <!--  
    2. 配置 CacheManager. 
    2.1 需要加入 ehcache 的 jar 包及配置文件. 
    -->     
    <bean id="cacheManager" class="org.apache.shiro.cache.ehcache.EhCacheManager">
        <!-- Set a net.sf.ehcache.CacheManager instance here if you already have one.  If not, a new one
             will be creaed with a default config:
             <property name="cacheManager" ref="ehCacheManager"/> -->
        <!-- If you don''t have a pre-built net.sf.ehcache.CacheManager instance to inject, but you want
             a specific Ehcache configuration to be used, specify that here.  If you don''t, a default
             will be used.: -->
        <property name="cacheManagerConfigFile" value="classpath:ehcache.xml"/> 
    </bean>
    
    <bean id="authenticator" 
        class="org.apache.shiro.authc.pam.ModularRealmAuthenticator">
        <property name="authenticationStrategy">
            <bean class="org.apache.shiro.authc.pam.AtLeastOneSuccessfulStrategy"></bean>
        </property>
    </bean>

    <!-- Used by the SecurityManager to access security data (users, roles, etc).
         Many other realm implementations can be used too (PropertiesRealm,
         LdapRealm, etc. -->
    <!-- 
        3. 配置 Realm 
        3.1 直接配置实现了 org.apache.shiro.realm.Realm 接口的 bean
    -->     
    <bean id="jdbcRealm" class="com.atguigu.shiro.realms.ShiroRealm">
        <property name="credentialsMatcher">
            <bean class="org.apache.shiro.authc.credential.HashedCredentialsMatcher">
                <property name="hashAlgorithmName" value="MD5"></property>
                <property name="hashIterations" value="1024"></property>
            </bean>
        </property>
    </bean>
    
    <bean id="secondRealm" class="com.atguigu.shiro.realms.SecondRealm">
        <property name="credentialsMatcher">
            <bean class="org.apache.shiro.authc.credential.HashedCredentialsMatcher">
                <property name="hashAlgorithmName" value="SHA1"></property>
                <property name="hashIterations" value="1024"></property>
            </bean>
        </property>
    </bean>

    <!-- =========================================================
         Shiro Spring-specific integration
         ========================================================= -->
    <!-- Post processor that automatically invokes init() and destroy() methods
         for Spring-configured Shiro objects so you don''t have to
         1) specify an init-method and destroy-method attributes for every bean
            definition and
         2) even know which Shiro objects require these methods to be
            called. -->
    <!--  
    4. 配置 LifecycleBeanPostProcessor. 可以自定的来调用配置在 Spring IOC 容器中 shiro bean 的生命周期方法. 
    -->       
    <bean id="lifecycleBeanPostProcessor" class="org.apache.shiro.spring.LifecycleBeanPostProcessor"/>

    <!-- Enable Shiro Annotations for Spring-configured beans.  Only run after
         the lifecycleBeanProcessor has run: -->
    <!--  
    5. 启用 IOC 容器中使用 shiro 的注解. 但必须在配置了 LifecycleBeanPostProcessor 之后才可以使用. 
    -->     
    <bean class="org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator"
          depends-on="lifecycleBeanPostProcessor"/>
    <bean class="org.apache.shiro.spring.security.interceptor.AuthorizationAttributeSourceAdvisor">
        <property name="securityManager" ref="securityManager"/>
    </bean>

    <!-- Define the Shiro Filter here (as a FactoryBean) instead of directly in web.xml -
         web.xml uses the DelegatingFilterProxy to access this bean.  This allows us
         to wire things with more control as well utilize nice Spring things such as
         PropertiesPlaceholderConfigurer and abstract beans or anything else we might need: -->
    <!--  
    6. 配置 ShiroFilter. 
    6.1 id 必须和 web.xml 文件中配置的 DelegatingFilterProxy 的 <filter-name> 一致.
                      若不一致, 则会抛出: NoSuchBeanDefinitionException. 因为 Shiro 会来 IOC 容器中查找和 <filter-name> 名字对应的 filter bean.
    -->     
    <bean id="shiroFilter" class="org.apache.shiro.spring.web.ShiroFilterFactoryBean">
        <property name="securityManager" ref="securityManager"/>
        <property name="loginUrl" value="/login.jsp"/>
        <property name="successUrl" value="/list.jsp"/>
        <property name="unauthorizedUrl" value="/unauthorized.jsp"/>
        
        <property name="filterChainDefinitionMap" ref="filterChainDefinitionMap"></property>
        
        <!--  
            配置哪些页面需要受保护. 
            以及访问这些页面需要的权限. 
            1). anon 可以被匿名访问
            2). authc 必须认证(即登录)后才可能访问的页面. 
            3). logout 登出.
            4). roles 角色过滤器
        -->
        <!--  
        <property name="filterChainDefinitions">
            <value>
                /login.jsp = anon
                /shiro/login = anon
                /shiro/logout = logout
                
                /user.jsp = roles[user]
                /admin.jsp = roles[admin]
                
                # everything else requires authentication:
                /** = authc
            </value>
        </property>
        -->
    </bean>
    
    <!-- 配置一个 bean, 该 bean 实际上是一个 Map. 通过实例工厂方法的方式 -->
    <bean id="filterChainDefinitionMap" 
        factory-bean="filterChainDefinitionMapBuilder" factory-method="buildFilterChainDefinitionMap"></bean>
    
    <bean id="filterChainDefinitionMapBuilder"
        class="com.atguigu.shiro.factory.FilterChainDefinitionMapBuilder"></bean>
    
    <bean id="shiroService"
        class="com.atguigu.shiro.services.ShiroService"></bean>

</beans>

<ehcache>

    <!-- Sets the path to the directory where cache .data files are created.

         If the path is a Java System Property it is replaced by
         its value in the running VM.

         The following properties are translated:
         user.home - User''s home directory
         user.dir - User''s current working directory
         java.io.tmpdir - Default temp file path -->
    <diskStore path="java.io.tmpdir"/>
    
    <cache name="authorizationCache"
           eternal="false"
           timeToIdleSeconds="3600"
           timeToLiveSeconds="0"
           overflowToDisk="false"
           statistics="true">
    </cache>

    <cache name="authenticationCache"
           eternal="false"
           timeToIdleSeconds="3600"
           timeToLiveSeconds="0"
           overflowToDisk="false"
           statistics="true">
    </cache>

    <cache name="shiro-activeSessionCache"
           eternal="false"
           timeToIdleSeconds="3600"
           timeToLiveSeconds="0"
           overflowToDisk="false"
           statistics="true">
    </cache>

    <!--Default Cache configuration. These will applied to caches programmatically created through
        the CacheManager.

        The following attributes are required for defaultCache:

        maxInMemory       - Sets the maximum number of objects that will be created in memory
        eternal           - Sets whether elements are eternal. If eternal,  timeouts are ignored and the element
                            is never expired.
        timeToIdleSeconds - Sets the time to idle for an element before it expires. Is only used
                            if the element is not eternal. Idle time is now - last accessed time
        timeToLiveSeconds - Sets the time to live for an element before it expires. Is only used
                            if the element is not eternal. TTL is now - creation time
        overflowToDisk    - Sets whether elements can overflow to disk when the in-memory cache
                            has reached the maxInMemory limit.

        -->
    <defaultCache
        maxElementsInMemory="10000"
        eternal="false"
        timeToIdleSeconds="120"
        timeToLiveSeconds="120"
        overflowToDisk="true"
        />

    <!--Predefined caches.  Add your cache configuration settings here.
        If you do not have a configuration for your cache a WARNING will be issued when the
        CacheManager starts

        The following attributes are required for defaultCache:

        name              - Sets the name of the cache. This is used to identify the cache. It must be unique.
        maxInMemory       - Sets the maximum number of objects that will be created in memory
        eternal           - Sets whether elements are eternal. If eternal,  timeouts are ignored and the element
                            is never expired.
        timeToIdleSeconds - Sets the time to idle for an element before it expires. Is only used
                            if the element is not eternal. Idle time is now - last accessed time
        timeToLiveSeconds - Sets the time to live for an element before it expires. Is only used
                            if the element is not eternal. TTL is now - creation time
        overflowToDisk    - Sets whether elements can overflow to disk when the in-memory cache
                            has reached the maxInMemory limit.

        -->

    <!-- Sample cache named sampleCache1
        This cache contains a maximum in memory of 10000 elements, and will expire
        an element if it is idle for more than 5 minutes and lives for more than
        10 minutes.

        If there are more than 10000 elements it will overflow to the
        disk cache, which in this configuration will go to wherever java.io.tmp is
        defined on your system. On a standard Linux system this will be /tmp"
        -->
    <cache name="sampleCache1"
        maxElementsInMemory="10000"
        eternal="false"
        timeToIdleSeconds="300"
        timeToLiveSeconds="600"
        overflowToDisk="true"
        />

    <!-- Sample cache named sampleCache2
        This cache contains 1000 elements. Elements will always be held in memory.
        They are not expired. -->
    <cache name="sampleCache2"
        maxElementsInMemory="1000"
        eternal="true"
        timeToIdleSeconds="0"
        timeToLiveSeconds="0"
        overflowToDisk="false"
        /> -->

    <!-- Place configuration for your caches following -->

</ehcache>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">
    
    <context:component-scan base-package="com.atguigu.shiro"></context:component-scan>
    
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
    
    <mvc:annotation-driven></mvc:annotation-driven>
    <mvc:default-servlet-handler/>

</beans>

package com.atguigu.shiro.factory;

import java.util.LinkedHashMap;

public class FilterChainDefinitionMapBuilder {

    public LinkedHashMap<String, String> buildFilterChainDefinitionMap(){
        LinkedHashMap<String, String> map = new LinkedHashMap<>();
        
        map.put("/login.jsp", "anon");
        map.put("/shiro/login", "anon");
        map.put("/shiro/logout", "logout");
        map.put("/user.jsp", "authc,roles[user]");
        map.put("/admin.jsp", "authc,roles[admin]");
        map.put("/list.jsp", "user");
        
        map.put("/**", "authc");
        
        return map;
    }
    
}

package com.atguigu.shiro.handlers;

import javax.servlet.http.HttpSession;

import org.apache.shiro.SecurityUtils;
import org.apache.shiro.authc.AuthenticationException;
import org.apache.shiro.authc.UsernamePasswordToken;
import org.apache.shiro.subject.Subject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

import com.atguigu.shiro.services.ShiroService;

@Controller
@RequestMapping("/shiro")
public class ShiroHandler {
    
    @Autowired
    private ShiroService shiroService;
    
    @RequestMapping("/testShiroAnnotation")
    public String testShiroAnnotation(HttpSession session){
        session.setAttribute("key", "value12345");
        shiroService.testMethod();
        return "redirect:/list.jsp";
    }

    @RequestMapping("/login")
    public String login(@RequestParam("username") String username, 
            @RequestParam("password") String password){
        Subject currentUser = SecurityUtils.getSubject();
        
        if (!currentUser.isAuthenticated()) {
            // 把用户名和密码封装为 UsernamePasswordToken 对象
            UsernamePasswordToken token = new UsernamePasswordToken(username, password);
            // rememberme
            token.setRememberMe(true);
            try {
                System.out.println("1. " + token.hashCode());
                // 执行登录. 
                currentUser.login(token);
            } 
            // ... catch more exceptions here (maybe custom ones specific to your application?
            // 所有认证时异常的父类. 
            catch (AuthenticationException ae) {
                //unexpected condition?  error?
                System.out.println("登录失败: " + ae.getMessage());
            }
        }
        
        return "redirect:/list.jsp";
    }
    
}

package com.atguigu.shiro.realms;

import org.apache.shiro.authc.AuthenticationException;
import org.apache.shiro.authc.AuthenticationInfo;
import org.apache.shiro.authc.AuthenticationToken;
import org.apache.shiro.authc.LockedAccountException;
import org.apache.shiro.authc.SimpleAuthenticationInfo;
import org.apache.shiro.authc.UnknownAccountException;
import org.apache.shiro.authc.UsernamePasswordToken;
import org.apache.shiro.crypto.hash.SimpleHash;
import org.apache.shiro.realm.AuthenticatingRealm;
import org.apache.shiro.util.ByteSource;

public class SecondRealm extends AuthenticatingRealm {

    @Override
    protected AuthenticationInfo doGetAuthenticationInfo(
            AuthenticationToken token) throws AuthenticationException {
        System.out.println("[SecondReaml] doGetAuthenticationInfo");
        
        //1. 把 AuthenticationToken 转换为 UsernamePasswordToken 
        UsernamePasswordToken upToken = (UsernamePasswordToken) token;
        
        //2. 从 UsernamePasswordToken 中来获取 username
        String username = upToken.getUsername();
        
        //3. 调用数据库的方法, 从数据库中查询 username 对应的用户记录
        System.out.println("从数据库中获取 username: " + username + " 所对应的用户信息.");
        
        //4. 若用户不存在, 则可以抛出 UnknownAccountException 异常
        if("unknown".equals(username)){
            throw new UnknownAccountException("用户不存在!");
        }
        
        //5. 根据用户信息的情况, 决定是否需要抛出其他的 AuthenticationException 异常. 
        if("monster".equals(username)){
            throw new LockedAccountException("用户被锁定");
        }
        
        //6. 根据用户的情况, 来构建 AuthenticationInfo 对象并返回. 通常使用的实现类为: SimpleAuthenticationInfo
        //以下信息是从数据库中获取的.
        //1). principal: 认证的实体信息. 可以是 username, 也可以是数据表对应的用户的实体类对象. 
        Object principal = username;
        //2). credentials: 密码. 
        Object credentials = null; //"fc1709d0a95a6be30bc5926fdb7f22f4";
        if("admin".equals(username)){
            credentials = "ce2f6417c7e1d32c1d81a797ee0b499f87c5de06";
        }else if("user".equals(username)){
            credentials = "073d4c3ae812935f23cb3f2a71943f49e082a718";
        }
        
        //3). realmName: 当前 realm 对象的 name. 调用父类的 getName() 方法即可
        String realmName = getName();
        //4). 盐值. 
        ByteSource credentialsSalt = ByteSource.Util.bytes(username);
        
        SimpleAuthenticationInfo info = null; //new SimpleAuthenticationInfo(principal, credentials, realmName);
        info = new SimpleAuthenticationInfo("secondRealmName", credentials, credentialsSalt, realmName);
        return info;
    }

    public static void main(String[] args) {
        String hashAlgorithmName = "SHA1";
        Object credentials = "123456";
        Object salt = ByteSource.Util.bytes("admin");;
        int hashIterations = 1024;
        
        Object result = new SimpleHash(hashAlgorithmName, credentials, salt, hashIterations);
        System.out.println(result);
    }
}

package com.atguigu.shiro.realms;

import java.util.HashSet;
import java.util.Set;

import org.apache.shiro.authc.AuthenticationException;
import org.apache.shiro.authc.AuthenticationInfo;
import org.apache.shiro.authc.AuthenticationToken;
import org.apache.shiro.authc.LockedAccountException;
import org.apache.shiro.authc.SimpleAuthenticationInfo;
import org.apache.shiro.authc.UnknownAccountException;
import org.apache.shiro.authc.UsernamePasswordToken;
import org.apache.shiro.authz.AuthorizationInfo;
import org.apache.shiro.authz.SimpleAuthorizationInfo;
import org.apache.shiro.crypto.hash.SimpleHash;
import org.apache.shiro.realm.AuthorizingRealm;
import org.apache.shiro.subject.PrincipalCollection;
import org.apache.shiro.util.ByteSource;

public class ShiroRealm extends AuthorizingRealm {

    @Override
    protected AuthenticationInfo doGetAuthenticationInfo(
            AuthenticationToken token) throws AuthenticationException {
        System.out.println("[FirstRealm] doGetAuthenticationInfo");
        
        //1. 把 AuthenticationToken 转换为 UsernamePasswordToken 
        UsernamePasswordToken upToken = (UsernamePasswordToken) token;
        
        //2. 从 UsernamePasswordToken 中来获取 username
        String username = upToken.getUsername();
        
        //3. 调用数据库的方法, 从数据库中查询 username 对应的用户记录
        System.out.println("从数据库中获取 username: " + username + " 所对应的用户信息.");
        
        //4. 若用户不存在, 则可以抛出 UnknownAccountException 异常
        if("unknown".equals(username)){
            throw new UnknownAccountException("用户不存在!");
        }
        
        //5. 根据用户信息的情况, 决定是否需要抛出其他的 AuthenticationException 异常. 
        if("monster".equals(username)){
            throw new LockedAccountException("用户被锁定");
        }
        
        //6. 根据用户的情况, 来构建 AuthenticationInfo 对象并返回. 通常使用的实现类为: SimpleAuthenticationInfo
        //以下信息是从数据库中获取的.
        //1). principal: 认证的实体信息. 可以是 username, 也可以是数据表对应的用户的实体类对象. 
        Object principal = username;
        //2). credentials: 密码. 
        Object credentials = null; //"fc1709d0a95a6be30bc5926fdb7f22f4";
        if("admin".equals(username)){
            credentials = "038bdaf98f2037b31f1e75b5b4c9b26e";
        }else if("user".equals(username)){
            credentials = "098d2c478e9c11555ce2823231e02ec1";
        }
        
        //3). realmName: 当前 realm 对象的 name. 调用父类的 getName() 方法即可
        String realmName = getName();
        //4). 盐值. 
        ByteSource credentialsSalt = ByteSource.Util.bytes(username);
        
        SimpleAuthenticationInfo info = null; //new SimpleAuthenticationInfo(principal, credentials, realmName);
        info = new SimpleAuthenticationInfo(principal, credentials, credentialsSalt, realmName);
        return info;
    }

    public static void main(String[] args) {
        String hashAlgorithmName = "MD5";
        Object credentials = "123456";
        Object salt = ByteSource.Util.bytes("user");;
        int hashIterations = 1024;
        
        Object result = new SimpleHash(hashAlgorithmName, credentials, salt, hashIterations);
        System.out.println(result);
    }

    //授权会被 shiro 回调的方法
    @Override
    protected AuthorizationInfo doGetAuthorizationInfo(
            PrincipalCollection principals) {
        //1. 从 PrincipalCollection 中来获取登录用户的信息
        Object principal = principals.getPrimaryPrincipal();
        
        //2. 利用登录的用户的信息来用户当前用户的角色或权限(可能需要查询数据库)
        Set<String> roles = new HashSet<>();
        roles.add("user");
        if("admin".equals(principal)){
            roles.add("admin");
        }
        
        //3. 创建 SimpleAuthorizationInfo, 并设置其 reles 属性.
        SimpleAuthorizationInfo info = new SimpleAuthorizationInfo(roles);
        
        //4. 返回 SimpleAuthorizationInfo 对象. 
        return info;
    }
}

package com.atguigu.shiro.realms;

import org.apache.shiro.authc.AuthenticationException;
import org.apache.shiro.authc.AuthenticationInfo;
import org.apache.shiro.authc.AuthenticationToken;
import org.apache.shiro.authz.AuthorizationInfo;
import org.apache.shiro.realm.AuthorizingRealm;
import org.apache.shiro.subject.PrincipalCollection;

public class TestRealm extends AuthorizingRealm {

    //用于授权的方法. 
    @Override
    protected AuthorizationInfo doGetAuthorizationInfo(
            PrincipalCollection principals) {
        // TODO Auto-generated method stub
        return null;
    }

    //用于认证的方法
    @Override
    protected AuthenticationInfo doGetAuthenticationInfo(
            AuthenticationToken token) throws AuthenticationException {
        // TODO Auto-generated method stub
        return null;
    }

}

package com.atguigu.shiro.services;

import java.util.Date;

import org.apache.shiro.SecurityUtils;
import org.apache.shiro.authz.annotation.RequiresRoles;
import org.apache.shiro.session.Session;

public class ShiroService {
    
    @RequiresRoles({"admin"})
    public void testMethod(){
        System.out.println("testMethod, time: " + new Date());
        
        Session session = SecurityUtils.getSubject().getSession();
        Object val = session.getAttribute("key");
        
        System.out.println("Service SessionVal: " + val);
    }
    
}
 

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="shiro" uri="http://shiro.apache.org/tags" %>    
    
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
    
    <h4>List Page</h4>
    
    Welcome: <shiro:principal></shiro:principal>
    
    <shiro:hasRole name="admin">
    <br><br>
    <a href="admin.jsp">Admin Page</a>
    </shiro:hasRole>
    
    <shiro:hasRole name="user">
    <br><br>
    <a href="user.jsp">User Page</a>
    </shiro:hasRole>
    
    <br><br>
    <a href="shiro/testShiroAnnotation">Test ShiroAnnotation</a>
    
    <br><br>
    <a href="shiro/logout">Logout</a>
    
</body>
</html>

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
    
    <h4>Login Page</h4>
    
    <form action="shiro/login" method="POST">
        username: <input type="text" name="username"/>
        <br><br>
        
        password: <input type="password" name="password"/>
        <br><br>
        
        <input type="submit" value="Submit"/>
    </form>
    
</body>
</html>

Connected to server
[2018-11-01 10:26:13,142] Artifact Shiro_Spring_Web:war exploded: Artifact is being deployed, please wait...
十一月 01, 2018 10:26:13 下午 org.apache.catalina.deploy.WebXml setVersion
警告: Unknown version string [4.0]. Default version will be used.
十一月 01, 2018 10:26:13 下午 org.apache.catalina.startup.TldConfig execute
信息: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
十一月 01, 2018 10:26:13 下午 org.apache.catalina.core.StandardContext startInternal
严重: One or more listeners failed to start. Full details will be found in the appropriate container log file
十一月 01, 2018 10:26:13 下午 org.apache.catalina.core.StandardContext startInternal
严重: Context [] startup failed due to previous errors
[2018-11-01 10:26:13,545] Artifact Shiro_Spring_Web:war exploded: Error during artifact deployment. See server log for details.