Shiro源码分析-初始化-SecurityManager

た入场券 2023-10-16 22:47 43阅读 0赞

源码分析的第一篇以SecurityManager的初始化为题。   
根据ini配置文件初始化shiro的代码主要为两段：

//解析ini文件为Ini对象
    Factory<SecurityManager> factory = new IniSecurityManagerFactory(
            "classpath:shiro-config.ini");
    //根据Ini对象初始化SecurityManager对象
    SecurityManager securityManager = factory.getInstance();

ini文件格式说明请参考：    
[http://zh.wikipedia.org/wiki/INI%E6%AA%94%E6%A1%88][http_zh.wikipedia.org_wiki_INI_E6_AA_94_E6_A1_88]   
java解析ini的方式也比较多，有兴趣可以参考：   
[http://my.oschina.net/tinyframework/blog/214309][http_my.oschina.net_tinyframework_blog_214309]   
**一、Shiro解析ini的步骤如下：**   
1、org.apache.shiro.config.IniSecurityManagerFactory类构造方法：

public IniSecurityManagerFactory(String iniResourcePath) {
            this(Ini.fromResourcePath(iniResourcePath));
        }

将ini文件解析交给Ini的静态方法fromResourcePath完成。并把解析后的Ini对象设置由自身持有

public IniSecurityManagerFactory(Ini config) {
            setIni(config);
        }

2、org.apache.shiro.config.Ini类解析逻辑：

public static Ini fromResourcePath(String resourcePath) throws ConfigurationException {
        if (!StringUtils.hasLength(resourcePath)) {
          throw new IllegalArgumentException("Resource Path argument cannot be null or empty.");
        }
        //此处新建Ini对象
        Ini ini = new Ini();
        ini.loadFromPath(resourcePath);
        return ini;
      }
    
      //根据资源路径获取输入流，交给load方法进行处理
      public void loadFromPath(String resourcePath) throws ConfigurationException {
        InputStream is;
        try {
          is = ResourceUtils.getInputStreamForPath(resourcePath);
        } catch (IOException e) {
          throw new ConfigurationException(e);
        }
        load(is);
      }

ResourceUtils.getInputStreamForPath(resourcePath);这里支持三种获取资源的方式：

3、对获取的资源输入流最终交给文本扫描器Scaner，执行过程代码片段：

public void load(Scanner scanner) {
    
        String sectionName = DEFAULT_SECTION_NAME;
        StringBuilder sectionContent = new StringBuilder();
    
        while (scanner.hasNextLine()) {
    
          String rawLine = scanner.nextLine();
          String line = StringUtils.clean(rawLine);
          //此处跳过ini文件格式的注释及空值
          if (line == null || line.startsWith(COMMENT_POUND) || line.startsWith(COMMENT_SEMICOLON)) {
            //skip empty lines and comments:
            continue;
          }
          //此处主要获取section部分，根据[]规则
          String newSectionName = getSectionName(line);
          if (newSectionName != null) {
            //此处代码主要用于构造Section对象，并放进sections集合中
            addSection(sectionName, sectionContent);
    
            //reset the buffer for the new section:
            sectionContent = new StringBuilder();
    
            sectionName = newSectionName;
    
            if (log.isDebugEnabled()) {
              log.debug("Parsing " + SECTION_PREFIX + sectionName + SECTION_SUFFIX);
            }
          } else {
            //normal line - add it to the existing content buffer:
            sectionContent.append(rawLine).append("\n");
          }
        }
    
        //finish any remaining buffered content:
        addSection(sectionName, sectionContent);
      }

上段代码主要是组装ini文件中的section。细心的同学会发现Section、Ini都是实现了Map接口。Section持有的LinkedHashMap容器实际上是当前section中的所有键值对，而Ini持有的LinkedHashMap容器实际上是所有section名称与section对象的键值对。   
至此，ini文件的解析已经完成，其ini中的内容已全部以map的形式存放在Ini实例中。   
至于保存的结果是什么样的呢？以下面的一段配置为例：

[main]
    #authenticator
    authenticator=org.apache.shiro.authc.pam.ModularRealmAuthenticator
    authenticationStrategy=org.apache.shiro.authc.pam.AtLeastOneSuccessfulStrategy
    authenticator.authenticationStrategy=$authenticationStrategy
    securityManager.authenticator=$authenticator

Ini的sections属性\[key=main，value=Section对象\]，此Section对象内部的props保存了所有main部分key-value映射。目前都是String类型，实例化在下一步完成的。   
**二、由Ini实例构造SecurityManager对象**

SecurityManager securityManager = factory.getInstance();

IniSecurityManagerFactory的继承关系为：   
IniSecurityManagerFactory->IniFactorySupport->AbstractFactory->Factory   
这里的getInstance方法由最上级的抽象类：org.apache.shiro.util.AbstractFactory提供，源码如下：

//该方法只是用于判断是否单例（默认为单例）
      public T getInstance() {
        T instance;
        if (isSingleton()) {
          if (this.singletonInstance == null) {
            this.singletonInstance = createInstance();
          }
          instance = this.singletonInstance;
        } else {
          instance = createInstance();
        }
        if (instance == null) {
          String msg = "Factory 'createInstance' implementation returned a null object.";
          throw new IllegalStateException(msg);
        }
        return instance;
      }
      //由子类IniFactorySupport创建实例
      protected abstract T createInstance();

IniFactorySupport的createInstance实现如下（省略了无关紧要的日志、判断代码）：

public T createInstance() {
        //此处获取解析ini文件产生的Ini对象
        Ini ini = resolveIni();
        T instance;
        if (CollectionUtils.isEmpty(ini)) {
          //如果ini为空，则创建默认实例
          instance = createDefaultInstance();
        } else {
          //根据ini对象创建实例
          instance = createInstance(ini);
        }
        return instance;
      }
      protected abstract T createInstance(Ini ini);
    
      protected abstract T createDefaultInstance();

上面两个抽象方法，则交给实现类IniSecurityManagerFactory完成了。   
先阅读createDefaultInstance方法源码

protected SecurityManager createDefaultInstance() {
            return new DefaultSecurityManager();
        }

终于在这个不起眼的地方，看到了初始化最核心的接口SecurityManager了。稍微暂停一下，发个SecurityManager的类图：

![Center][]

由此图可以看出来，SecurityManager继承了三个接口（认证、授权、session管理），认证授权是安全框架最核心的功能，而shiro提供了自身的session管理机制（这也是shiro的一大亮点）。图中除了DefaultSecurityManager，其它所有类都是抽象类，由此可看出，DefaultSecurityManager是作为默认的安全管理器。   
再来看new DefaultSecurityManager();做的事情

public DefaultSecurityManager() {
            super();
            this.subjectFactory = new DefaultSubjectFactory();
            this.subjectDAO = new DefaultSubjectDAO();
        }

这里暂时不深究每个构造器所做的具体事情。有兴趣的同学，可一直观察DefaultSecurityManager的所有父类构造器的处理逻辑。

<table style="max-width:100%; border-spacing:0px; width:605px; margin-bottom:1.5em; border-width:1px 1px 1px 0px; border-top-style:solid; border-right-style:solid; border-bottom-style:solid; border-top-color:rgb(221,221,221); border-right-color:rgb(221,221,221); border-bottom-color:rgb(221,221,221); font-size:14px; line-height:1.3em; color:rgb(51,51,51); font-family:'Helvetica Neue',Helvetica,Tahoma,Arial,STXihei,'Microsoft YaHei',微软雅黑,sans-serif; background-color:rgb(254,254,254)"> 
 <tbody> 
  <tr style="line-height:1.3em"> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:0px; border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> 类名称</td> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:0px; border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> 构造方法创建的默认对象</td> 
  </tr> 
  <tr style="line-height:1.3em"> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> DefaultSecurityManager</td> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> DefaultSubjectFactory,DefaultSubjectDAO</td> 
  </tr> 
  <tr style="line-height:1.3em"> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> SessionsSecurityManager</td> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> DefaultSessionManager</td> 
  </tr> 
  <tr style="line-height:1.3em"> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> AuthorizingSecurityManager</td> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> ModularRealmAuthorizer</td> 
  </tr> 
  <tr style="line-height:1.3em"> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> AuthenticatingSecurityManager</td> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> ModularRealmAuthenticator</td> 
  </tr> 
  <tr style="line-height:1.3em"> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> RealmSecurityManager</td> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> 无</td> 
  </tr> 
  <tr style="line-height:1.3em"> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> CachingSecurityManager</td> 
   <td style="padding:8px; line-height:1.3em; vertical-align:top; border-top-width:1px; border-top-style:solid; border-top-color:rgb(221,221,221); border-left-width:1px; border-left-style:solid; border-left-color:rgb(221,221,221); font-size:14px"> 无</td> 
  </tr> 
 </tbody> 
</table>

在上面的表格中已经清晰的描述了各个类所设置的默认对象，至于用途后面再讲解。

[http_zh.wikipedia.org_wiki_INI_E6_AA_94_E6_A1_88]: http://zh.wikipedia.org/wiki/INI%E6%AA%94%E6%A1%88
[http_my.oschina.net_tinyframework_blog_214309]: http://my.oschina.net/tinyframework/blog/214309
[Center]: https://img-blog.csdn.net/20151228095505728?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center