WebApplicationContextUtils源码

package org.springframework.web.context.support;

import javax.servlet.ServletContext;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.util.Assert;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.RequestScope;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.context.request.SessionScope;

public abstract class WebApplicationContextUtils
{
  public static WebApplicationContext getRequiredWebApplicationContext(ServletContext sc)
    throws IllegalStateException
  {
    WebApplicationContext wac = getWebApplicationContext(sc);
    if (wac == null) {
      throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener registered?");
    }
    return wac;
  }

  public static WebApplicationContext getWebApplicationContext(ServletContext sc)
  {
    return getWebApplicationContext(sc, WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
  }

  public static WebApplicationContext getWebApplicationContext(ServletContext sc, String attrName)
  {
    Assert.notNull(sc, "ServletContext must not be null");
    Object attr = sc.getAttribute(attrName);
    if (attr == null) {
      return null;
    }
    if ((attr instanceof RuntimeException)) {
      throw ((RuntimeException)attr);
    }
    if ((attr instanceof Error)) {
      throw ((Error)attr);
    }
    if ((attr instanceof Exception)) {
      IllegalStateException ex = new IllegalStateException();
      ex.initCause((Exception)attr);
      throw ex;
    }
    if (!(attr instanceof WebApplicationContext)) {
      throw new IllegalStateException("Context attribute is not of type WebApplicationContext: " + attr);
    }
    return (WebApplicationContext)attr;
  }

  public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory)
  {
    beanFactory.registerScope("request", new RequestScope());
    beanFactory.registerScope("session", new SessionScope(false));
    beanFactory.registerScope("globalSession", new SessionScope(true));

    beanFactory.registerResolvableDependency(ServletRequest.class, new ObjectFactory() {
      public Object getObject() {
        RequestAttributes requestAttr = RequestContextHolder.currentRequestAttributes();
        if (!(requestAttr instanceof ServletRequestAttributes)) {
          throw new IllegalStateException("Current request is not a servlet request");
        }
        return ((ServletRequestAttributes)requestAttr).getRequest();
      }
    });
    beanFactory.registerResolvableDependency(HttpSession.class, new ObjectFactory() {
      public Object getObject() {
        RequestAttributes requestAttr = RequestContextHolder.currentRequestAttributes();
        if (!(requestAttr instanceof ServletRequestAttributes)) {
          throw new IllegalStateException("Current request is not a servlet request");
        }
        return ((ServletRequestAttributes)requestAttr).getRequest().getSession();
      }
    });
  }
}