contextloaderplugin.java

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package com.laoer.bbscs.web.servlet;

import javax.servlet.*;

import org.apache.struts.action.*;
import org.apache.struts.config.*;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.context.ApplicationContextException;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.context.ConfigurableWebApplicationContext;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import org.springframework.web.context.support.XmlWebApplicationContext;
import org.springframework.web.struts.*;

/**
 * <p>Title: 天乙社区</p>
 *
 * <p>Description: BBSCS</p>
 *
 * <p>Copyright: Copyright (c) 2006</p>
 *
 * <p>Company: Laoer.com</p>
 *
 * @author Gong Tianyi
 * @version 7.0
 */
public class ContextLoaderPlugIn
    implements PlugIn {

  /**
   * Suffix for WebApplicationContext namespaces. If a Struts ActionServlet is
   * given the name "action" in a context, the namespace used by this PlugIn will
   * resolve to "action-servlet".
   */
  public static final String DEFAULT_NAMESPACE_SUFFIX = "-servlet";

  /**
   * Default context class for ContextLoaderPlugIn.
   * @see org.springframework.web.context.support.XmlWebApplicationContext
   */
  public static final Class DEFAULT_CONTEXT_CLASS = XmlWebApplicationContext.class;

  /**
   * Prefix for the ServletContext attribute for the WebApplicationContext.
   * The completion is the Struts module name.
   */
  public static final String SERVLET_CONTEXT_PREFIX = WebApplicationContext.
      ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE;

  protected final Log logger = LogFactory.getLog(getClass());

  /** Custom WebApplicationContext class */
  private Class contextClass = DEFAULT_CONTEXT_CLASS;

  /** Namespace for this servlet */
  private String namespace;

  /** Explicit context config location */
  private String contextConfigLocation;

  /** The Struts ActionServlet that this PlugIn is registered with */
  private ActionServlet actionServlet;

  /** The Struts ModuleConfig that this PlugIn is registered with */
  private ModuleConfig moduleConfig;

  /** WebApplicationContext for the ActionServlet */
  private WebApplicationContext webApplicationContext;

  /**
   * Set a custom context class by name. This class must be of type WebApplicationContext,
   * when using the default ContextLoaderPlugIn implementation, the context class
   * must also implement ConfigurableWebApplicationContext.
   * @see #createWebApplicationContext
   */
  public void setContextClassName(String contextClassName) throws ClassNotFoundException {
    this.contextClass = ClassUtils.forName(contextClassName);
  }

  /**
   * Set a custom context class. This class must be of type WebApplicationContext,
   * when using the default ContextLoaderPlugIn implementation, the context class
   * must also implement ConfigurableWebApplicationContext.
   * @see #createWebApplicationContext
   */
  public void setContextClass(Class contextClass) {
    this.contextClass = contextClass;
  }

  /**
   * Return the custom context class.
   */
  public Class getContextClass() {
    return contextClass;
  }

  /**
   * Set a custom namespace for the ActionServlet,
   * to be used for building a default context config location.
   */
  public void setNamespace(String namespace) {
    this.namespace = namespace;
  }

  /**
   * Return the namespace for the ActionServlet, falling back to default scheme if
   * no custom namespace was set: e.g. "test-servlet" for a servlet named "test".
   */
  public String getNamespace() {
    if (this.namespace != null) {
      return this.namespace;
    }
    if (this.actionServlet != null) {
      return this.actionServlet.getServletName() + DEFAULT_NAMESPACE_SUFFIX;
    }
    return null;
  }

  /**
   * Set the context config location explicitly, instead of relying on the default
   * location built from the namespace. This location string can consist of
   * multiple locations separated by any number of commas and spaces.
   */
  public void setContextConfigLocation(String contextConfigLocation) {
    this.contextConfigLocation = contextConfigLocation;
  }

  /**
   * Return the explicit context config location, if any.
   */
  public String getContextConfigLocation() {
    return contextConfigLocation;
  }

  /**
   * Create the ActionServlet's WebApplicationContext.
   */
  public final void init(ActionServlet actionServlet, ModuleConfig moduleConfig) throws
      ServletException {
    long startTime = System.currentTimeMillis();
    if (logger.isInfoEnabled()) {
      logger.info("ContextLoaderPlugIn for Struts ActionServlet '" + actionServlet.getServletName() +
                  ", module '" + moduleConfig.getPrefix() + "': initialization started");
    }

    this.actionServlet = actionServlet;
    this.moduleConfig = moduleConfig;
    try {
      this.webApplicationContext = initWebApplicationContext();
      onInit();
    }
    catch (RuntimeException ex) {
      logger.error("Context initialization failed", ex);
      throw ex;
    }

    if (logger.isInfoEnabled()) {
      long elapsedTime = System.currentTimeMillis() - startTime;
      logger.info("ContextLoaderPlugIn for Struts ActionServlet '" + actionServlet.getServletName() +
                  "', module '" + moduleConfig.getPrefix() + "': initialization completed in " +
                  elapsedTime + " ms");
    }
  }

  /**
   * Return the Struts ActionServlet that this PlugIn is associated with.
   */
  public final ActionServlet getActionServlet() {
    return actionServlet;
  }

  /**
   * Return the name of the ActionServlet that this PlugIn is associated with.
   */
  public final String getServletName() {
    return this.actionServlet.getServletName();
  }

  /**
   * Return the ServletContext that this PlugIn is associated with.
   */
  public final ServletContext getServletContext() {
    return this.actionServlet.getServletContext();
  }

  /**
   * Return the Struts ModuleConfig that this PlugIn is associated with.
   */
  public final ModuleConfig getModuleConfig() {
    return moduleConfig;
  }

  /**
   * Return the prefix of the ModuleConfig that this PlugIn is associated with.
   * @see org.apache.struts.config.ModuleConfig#getPrefix
   */
  public final String getModulePrefix() {
    return this.moduleConfig.getPrefix();
  }

  /**
   * Initialize and publish the WebApplicationContext for the ActionServlet.
   * Delegates to createWebApplicationContext for actual creation.
   * <p>Can be overridden in subclasses. Call <code>getActionServlet</code>
   * and/or <code>getModuleConfig</code> to access the Struts configuration
   * that this PlugIn is associated with.
   * @throws org.springframework.beans.BeansException if the context couldn't be initialized
   * @throws IllegalStateException if there is already a context for the Struts ActionServlet
   * @see #createWebApplicationContext
   * @see #getActionServlet
   * @see #getServletName
   * @see #getServletContext
   * @see #getModuleConfig
   * @see #getModulePrefix
   */
  protected WebApplicationContext initWebApplicationContext() throws BeansException,
      IllegalStateException {
    getServletContext().log("Initializing WebApplicationContext for Struts ActionServlet '" +
                            getServletName() + "', module '" + getModulePrefix() + "'");
    WebApplicationContext parent = WebApplicationContextUtils.getWebApplicationContext(
        getServletContext());

    WebApplicationContext wac = createWebApplicationContext(parent);
    if (logger.isInfoEnabled()) {
      logger.info("Using context class '" + wac.getClass().getName() + "' for servlet '" +
                  getServletName() + "'");
    }

    // Publish the context as a servlet context attribute.
    String attrName = getServletContextAttributeName();
    getServletContext().setAttribute(attrName, wac);
    if (logger.isDebugEnabled()) {
      logger.debug("Published WebApplicationContext of Struts ActionServlet '" + getServletName() +
                   "', module '" + getModulePrefix() + "' as ServletContext attribute with name [" +
                   attrName + "]");
    }

    return wac;
  }

  /**
   * Instantiate the WebApplicationContext for the ActionServlet, either a default
   * XmlWebApplicationContext or a custom context class if set. This implementation
   * expects custom contexts to implement ConfigurableWebApplicationContext.
   * Can be overridden in subclasses.
   * @throws org.springframework.beans.BeansException if the context couldn't be initialized
   * @see #setContextClass
   * @see org.springframework.web.context.support.XmlWebApplicationContext
   */
  protected WebApplicationContext createWebApplicationContext(WebApplicationContext parent) throws
      BeansException {

    if (logger.isDebugEnabled()) {
      logger.debug("ContextLoaderPlugIn for Struts ActionServlet '" + getServletName() +
                   "', module '" + getModulePrefix() +
                   "' will try to create custom WebApplicationContext " +
                   "context of class '" + getContextClass().getName() + "', using parent context [" +
                   parent + "]");
    }
    if (!ConfigurableWebApplicationContext.class.isAssignableFrom(getContextClass())) {
      throw new ApplicationContextException(
          "Fatal initialization error in ContextLoaderPlugIn for Struts ActionServlet '" +
          getServletName() +
          "', module '" + getModulePrefix() + "': custom WebApplicationContext class [" +
          getContextClass().getName() + "] is not of type ConfigurableWebApplicationContext");
    }

    ConfigurableWebApplicationContext wac =
        (ConfigurableWebApplicationContext) BeanUtils.instantiateClass(getContextClass());
    wac.setParent(parent);
    wac.setServletContext(getServletContext());
    wac.setNamespace(getNamespace());
    if (getContextConfigLocation() != null) {
      wac.setConfigLocations(
          StringUtils.tokenizeToStringArray(
              getContextConfigLocation(),
              ConfigurableWebApplicationContext.CONFIG_LOCATION_DELIMITERS));
    }
    wac.addBeanFactoryPostProcessor(
        new BeanFactoryPostProcessor() {
      public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
        beanFactory.addBeanPostProcessor(new ActionServletAwareProcessor(getActionServlet()));
      }
    }
    );
    wac.refresh();
    return wac;
  }

  /**
   * Return the ServletContext attribute name for this PlugIn's WebApplicationContext.
   * Default implementation returns SERVLET_CONTEXT_PREFIX + module prefix.
   * @see #SERVLET_CONTEXT_PREFIX
   * @see #getModulePrefix
   */
  public String getServletContextAttributeName() {
    //return SERVLET_CONTEXT_PREFIX + getModulePrefix();
    return SERVLET_CONTEXT_PREFIX;
  }

  /**
   * Return this PlugIn's WebApplicationContext.
   */
  public final WebApplicationContext getWebApplicationContext() {
    return webApplicationContext;
  }

  /**
   * Callback for custom initialization after the context has been set up.
   * @throws ServletException if initialization failed
   */
  protected void onInit() throws ServletException {
  }

  /**
   * Close the WebApplicationContext of the ActionServlet.
   * @see org.springframework.context.ConfigurableApplicationContext#close
   */
  public void destroy() {
    getServletContext().log("Closing WebApplicationContext of Struts ActionServlet '" +
                            getServletName() + "', module '" + getModulePrefix() + "'");
    if (getWebApplicationContext() instanceof ConfigurableApplicationContext) {
      ( (ConfigurableApplicationContext) getWebApplicationContext()).close();
    }
  }
}