总结servlet和jsp的对象及问题

 对象如下

  servlet                             jsp

servletcontext                application
servletconfig                  config
httpservletrequest        request
httpservletresponse    response
httpsession                   session
                                         page
                                         pageContext
printwriter                       out(jspWriter)

 

注意

servletcontext是全局对象,一个 servlet只能有一个servletcontext,可以取到所有的servlet的名字

servletconfig 仅对当前的servlet有效,可以取得当前servlet的名字和初始化参数,及配置web.xml是,在jsp页面里不能通过config取到当前jsp页面的名字.

<servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>abcd</servlet-name>
    <servlet-class>aaa.abcd</servlet-class>
    <init-param>
    <param-name>a</param-name>   servletconfig.getInitParameter();
    <param-value>1</param-value>
    </init-param>
  </servlet>

  <servlet-mapping>
    <servlet-name>abcd</servlet-name>
    <url-pattern>/abcd</url-pattern>
  </servlet-mapping>

 

pageContext.setAttribute("str","abcd",pageContext.REQUEST_SCOPE)的设置不能用servlet中的request.getAttribute(str)取到,session范围的可以.所以pageContext和ServletContext是不同的.