为啥每次点init或destroy按钮都会重新创建session，运行结果如下：

1.进入index.jsp

requestInitialized : name = null

ServletRequest_attributeReplaced: org.apache.catalina.ASYNC_SUPPORTED

sessionCreated

requestDestroyed

2.第一次点击init按钮

requestInitialized : name = null

ServletRequest_attributeReplaced: org.apache.catalina.ASYNC_SUPPORTED

sessionCreated

ServletRequest_attributeAdded: requestName

HttpSession_attributeAdded: sessionName

ServletContext_attributeReplaced: applicationName

requestDestroyed

3.第二次点击init按钮

requestInitialized : name = null

ServletRequest_attributeReplaced: org.apache.catalina.ASYNC_SUPPORTED

sessionCreated

ServletRequest_attributeAdded: requestName

HttpSession_attributeAdded: sessionName

ServletContext_attributeReplaced: applicationName

requestDestroyed

4.点击destroy按钮

requestInitialized : name = null

ServletRequest_attributeReplaced: org.apache.catalina.ASYNC_SUPPORTED

sessionCreated

HttpSession_attributeAdded: sessionName

ServletContext_attributeReplaced: applicationName

requestDestroyed