Servlet not loading on startup

问题

TL;DR: <load-on-startup> does not seem to be causing my Jersey web services to load on startup

I’m trying to set up a simple RESTful web service that will act as a registry for the other RESTful services in the container. To do this I had planned on registering each other web service with the registry service in a static initialize block. Everything was going well until I remembered that servlets aren’t loaded until their first access. A quick web search turned up the <load-on-startup> tag that can be added to the servlet definition in web.xml. Unfortunately, this was already set in my configuration and adding some logging to the static blocks verified that the classes were indeed not being loaded until the first access of each service.

I’m developing these servlets using Jersey annotations and deploying them to Apache Tomcat (both 7.0.22 embedded in netbeans and 6.0.33 deployed remotely fail in the same way). Besides this perceived misbehavior, the servlets have been performing correctly.

Any ideas on what I could be doing wrong?

My web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml</param-value>
    </context-param>
    <filter>
        <filter-name>CORSFilter</filter-name>
        <filter-class>com.foo.bar.CORSFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>CORSFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>2</load-on-startup>
    </servlet>
    <servlet>
        <servlet-name>ServletAdaptor</servlet-name>
        <servlet-class>com.sun.jersey.spi.spring.container.servlet.SpringServlet</servlet-class>
        <init-param>
            <description>Multiple packages, separated by semicolon(;), can be specified in param-value</description>
            <param-name>com.sun.jersey.config.property.packages</param-name>
            <param-value>com.foo.bar.webservices</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>*.htm</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>ServletAdaptor</servlet-name>
        <url-pattern>/resources/*</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>redirect.jsp</welcome-file>
    </welcome-file-list>
</web-app>

回答1:

It was a couple years ago and a couple years of Java Web Stack knowledge later.

I believe this was a case of mistaken identity. I had a non container managed resource that I was trying to get to load on startup. The jersey servlet container was most assuredly loading on start up as the web.xml was specifying. The classes that I wanted to preload were not being referenced by the container itself so were not being loaded with the container.

来源：https://stackoverflow.com/questions/9787332/servlet-not-loading-on-startup

标签

java

servlets

jersey