从Web框架看Cookie名字更改

前言

这两天由登录拦截想起的单点登录，重点看了token跟session-cookie这种机制，发现移动端还是token的好，又看了http8连问，产生许多疑问，此次就记录会话到cookie更改名字
会话，即TCP建立连接后数据通信前的操作,TCP的三次握手就创建了一个会话，TCP关闭连接就是关闭会话,Servlet在会话建立时会创建Session以及一个Cookie，Cookie默认名字是"JSESSIONID",但是我发现其中有一个判断，获取不到值才使用此名，结合浏览器接口查看，确实http名字都是JSESSIONID，此刻我在想此名应当可以被更改，最后页如尝所愿，确实可以更改，接着我往下查看所有操纵几乎都在阿帕奇卡特琳娜这个包下完成，org.apache.catalina。

查看路径

org.apache.catalina.connector.doGetSession(boolean create){
 ...
   if (this.session != null && context.getServletContext().getEffectiveSessionTrackingModes()
                        .contains(SessionTrackingMode.COOKIE)) {
        Cookie cookie = ApplicationSessionCookieConfig.createSessionCookie(context, this.session.getIdInternal(), this.isSecure());
        this.response.addSessionCookieInternal(cookie);
    }
 ...
}

org.apache.catalina.core.ApplicationSessionCookieConfig类里

    public static Cookie createSessionCookie(Context context, String sessionId, boolean secure) {
        SessionCookieConfig scc = context.getServletContext().getSessionCookieConfig();
        Cookie cookie = new Cookie(SessionConfig.getSessionCookieName(context), sessionId);

看一下如何获取CookieName的
org.apache.catalina.util.SessionConfig

    public static String getSessionCookieName(Context context) {
        String result = getConfiguredSessionCookieName(context);
        if (result == null) {
            result = "JSESSIONID";
        }
        return result;
    }

当时第一眼看到此处，心里咯噔一下，此处判空给默认值莫不是可以手动配置，后来查阅完成确实是在groovy脚本中扫描配置能进行更改，此处便是CookieName直接返回的地方，继续往下挖掘看看名字是如何获取的，此方法依旧在SessionConfig类里

    private static String getConfiguredSessionCookieName(Context context) {
        if (context != null) {
            //1.此处的Context应当是StandardContext类，
            String cookieName = context.getSessionCookieName();
            if (cookieName != null && cookieName.length() > 0) {
                return cookieName;
            }
            //2.此处的getServletContext()是org.apache.catalina.core.ApplicationContext implements ServletContext
            SessionCookieConfig scc = context.getServletContext().getSessionCookieConfig();
            cookieName = scc.getName();
            if (cookieName != null && cookieName.length() > 0) {
                return cookieName;
            }
        }

        return null;
    }

如上代码1处Context应为StandardContext类里拥有getSessionCookieName()方法，目前尚不知其在哪里设置的Cookie值
如上2处Context为StandardContext，类中getServletContext()获取的为ApplicationContext,它是StandardContext类中的一个成员变量。
ApplicationContext类中

...
    SessionCookieConfig sessionCookieConfig；
    public ApplicationContext(StandardContext context) {
        this.context = context;
        this.service = ((Engine)context.getParent().getParent()).getService();
        this.sessionCookieConfig = new ApplicationSessionCookieConfig(context);
        this.populateSessionTrackingModes();
    }

可以看出来基本上取的就是ApplicationSessionCookieConfig,此类就是一个实体类

    private static final StringManager sm = StringManager.getManager("org.apache.catalina.core");
    private boolean httpOnly;
    private boolean secure;
    private int maxAge = -1;
    private String comment;
    private String domain;
    private String name;
    private String path;
    private StandardContext context;

点击类中的setName方法经IDE跳转后到达

    void receiver(String name, Class aClass, Closure closure = null) {
        addInfo("About to instantiate receiver of type [" + clazz.name + "]");
        ReceiverBase receiver = aClass.newInstance();
        receiver.context = context;
        if(closure != null) {
            ComponentDelegate componentDelegate = new ComponentDelegate(receiver);
            componentDelegate.context = context;
            closure.delegate = componentDelegate;
            closure.resolveStrategy = Closure.DELEGATE_FIRST
            closure();
        }
        try {
            receiver.start()
        } catch (RuntimeException e) {
            addError("Failed to start receiver of type [" + aClass.getName() + "]", e)
        }
    }

此处是一个脚本委托类，方法被反射调用，往上翻看代码可以发现当前类为groovy脚本类

    void scan(String scanPeriodStr = null) {
        if (scanPeriodStr) {
            ReconfigureOnChangeTask rocTask = new ReconfigureOnChangeTask();
            rocTask.setContext(context);
            context.putObject(CoreConstants.RECONFIGURE_ON_CHANGE_TASK, rocTask);
            try {
                Duration duration = Duration.valueOf(scanPeriodStr);
                ScheduledExecutorService scheduledExecutorService = context.getScheduledExecutorService();

                ScheduledFuture<?> scheduledFuture = scheduledExecutorService.scheduleAtFixedRate(rocTask, duration.getMilliseconds(), duration.getMilliseconds(), TimeUnit.MILLISECONDS);
                context.addScheduledFuture(scheduledFuture);
                addInfo("Setting ReconfigureOnChangeTask scanning period to " + duration);
            } catch (NumberFormatException nfe) {
                addError("Error while converting [" + scanPeriodStr + "] to long", nfe);
            }
        }
    }

通过定时扫描配置文件获取值