Spring和ServletContextListener

Question

我在这里读了一些文章和帖子，关于

@Autowired
ServletContext context;

我从ServletContextListener到@Controller的实现。但是当我运行它时，我得到了一个很长的异常：

org.springframework.beans.factory.UnsatisfiedDependencyException:
Error creating bean with name 'trendsoftCtrl':
Unsatisfied dependency expressed through field 'context':
No qualifying bean of type [javax.servlet.ServletContext] found for dependency [javax.servlet.ServletContext]:
expected at least 1 bean which qualifies as autowire candidate for this dependency.
Dependency annotations:
{@org.springframework.beans.factory.annotation.Autowired(required=true)};
nested exception is
org.springframework.beans.factory.NoSuchBeanDefinitionException:
No qualifying bean of type [javax.servlet.ServletContext] found for dependency [javax.servlet.ServletContext]:
expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations:
{@org.springframework.beans.factory.annotation.Autowired(required=true)}

这是我的课程。

@WebListener
public class TRSCListner implements ServletContextListener {

@Override
public void contextInitialized(ServletContextEvent event) {
    ServletContext context = event.getServletContext();
    String beanFileName = context.getInitParameter("springBeans");

    GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
    ctx.load(beanFileName);
    ctx.refresh();
    NewsDao newsDao = ctx.getBean("newsDao", NewsDao.class);

    context.setAttribute("appContext", ctx);
    context.setAttribute("dao", newsDao);
}

@Override
public void contextDestroyed(ServletContextEvent event) {
    ServletContext context = event.getServletContext();
    GenericXmlApplicationContext ctx = (GenericXmlApplicationContext) context.getAttribute("appContext");
    ctx.close();
}

}

还有另一个

@Controller
public class TrendsoftCtrl {

@Autowired
ServletContext context; 

@RequestMapping ("/welcome")
public ModelAndView helloWorld() {
    NewsDao newsDao = (NewsDao) context.getAttribute("dao");
    List<News> news = newsDao.getAll();

    StringBuilder message = new StringBuilder();

    for (News n : news) {
        message.append(n.getCategory().getName() + "<br>");
        message.append(n.getName() + "<br>");
        message.append(n.getData() + "<br><br>");
    }

    return new ModelAndView("welcome", "news", message.toString());
}

public ServletContext getContext() {
    return context;
}

public void setContext(ServletContext context) {
    this.context = context;
}

}

Answer 1

默认情况下，@Autowired将执行依赖项检查，以确保属性已正确连接。当Spring找不到匹配的bean进行连接时，它将抛出异常。要修复此问题，您可以通过将@Autowired的“required”属性设置为false来禁用此检查功能。

@自动连线(required=false)

即使Spring找不到匹配的bean，它也不会设置person属性。