Java PageContext.getAttribute方法代碼示例

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 * Locate and return the specified bean, from an optionally specified
 * scope, in the specified page context.  If no such bean is found,
 * return <code>null</code> instead.  If an exception is thrown, it will
 * have already been saved via a call to <code>saveException()</code>.
 *
 * @param pageContext Page context to be searched
 * @param name Name of the bean to be retrieved
 * @param scopeName Scope to be searched (page, request, session, application)
 *  or <code>null</code> to use <code>findAttribute()</code> instead
 * @return JavaBean in the specified page context
 * @exception JspException if an invalid scope name
 *  is requested
 */
public Object lookup(PageContext pageContext, String name, String scopeName)
        throws JspException {

    if (scopeName == null) {
        return pageContext.findAttribute(name);
    }

    try {
        return pageContext.getAttribute(name, instance.getScope(scopeName));

    } catch (JspException e) {
        saveException(pageContext, e);
        throw e;
    }

}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
public static ScopeManager get(PageContext page) {
    ScopeManager mngr = (ScopeManager) page.getAttribute(MNGR_KEY);
    if (mngr == null) {
        mngr = new ScopeManager(page);
        page.setAttribute(MNGR_KEY, mngr);
    }
    return mngr;
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 * Returns true if the custom tags are in XHTML mode.
 */
public boolean isXhtml(PageContext pageContext) {
    String xhtml =
            (String) pageContext.getAttribute(
                    Globals.XHTML_KEY,
                    PageContext.PAGE_SCOPE);

    return "true".equalsIgnoreCase(xhtml);
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 * <p>Returns true if the custom tags are in XHTML mode.</p>
 *
 * @since Struts 1.1
 * @deprecated Use {@link org.apache.struts.taglib.TagUtils#isXhtml(PageContext)} instead.
 * This will be removed after Struts 1.2.
 */
public static boolean isXhtml(PageContext pageContext) {
    // :TODO: Remove after Struts 1.2

    String xhtml =
            (String) pageContext.getAttribute(
                    Globals.XHTML_KEY,
                    PageContext.PAGE_SCOPE);

    return "true".equalsIgnoreCase(xhtml);

}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 * Get object from requested context.
 * Context can be 'component'.
 * @param beanName Name of the bean to find.
 * @param scope Search scope (see {@link PageContext}).
 * @param pageContext Page context.
 * @return requested bean or <code>null</code> if not found.
 */
public Object getAttribute(
    String beanName,
    int scope,
    PageContext pageContext) {
        
    if (scope == ComponentConstants.COMPONENT_SCOPE){
        return getAttribute(beanName);
    }
    
    return pageContext.getAttribute(beanName, scope);
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 *
 * Finds the ImplicitObjects associated with the PageContext,
 * creating it if it doesn't yet exist.
 **/
public static ImplicitObjects getImplicitObjects (PageContext pContext)
{
  ImplicitObjects objs = 
    (ImplicitObjects)
    pContext.getAttribute (sAttributeName,
                           PageContext.PAGE_SCOPE);
  if (objs == null) {
    objs = new ImplicitObjects (pContext);
    pContext.setAttribute (sAttributeName,
                           objs,
                           PageContext.PAGE_SCOPE);
  }
  return objs;
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 *
 * Creates the Map that "wraps" page-scoped attributes
 **/
public static Map<String, Object> createPageScopeMap(PageContext pContext)
{
  final PageContext context = pContext;
  return new EnumeratedMap<String, Object> ()
    {
      public Enumeration<String> enumerateKeys () 
      {
        return context.getAttributeNamesInScope
          (PageContext.PAGE_SCOPE);
      }

      public Object getValue (Object pKey) 
      {
         if (pKey instanceof String) {
           return context.getAttribute
             ((String) pKey,
              PageContext.PAGE_SCOPE);
         }
         else {
           return null;
         }
      }

      public boolean isMutable ()
      {
        return true;
      }
    };
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 *
 * Creates the Map that "wraps" request-scoped attributes
 **/
public static Map<String, Object> createRequestScopeMap (PageContext pContext)
{
  final PageContext context = pContext;
  return new EnumeratedMap<String, Object> ()
    {
      public Enumeration<String> enumerateKeys () 
      {
        return context.getAttributeNamesInScope
          (PageContext.REQUEST_SCOPE);
      }

      public Object getValue (Object pKey) 
      {
        if (pKey instanceof String) {
          return context.getAttribute
            ((String) pKey, 
             PageContext.REQUEST_SCOPE);
        }
        else {
          return null;
        }
      }

      public boolean isMutable ()
      {
        return true;
      }
    };
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 *
 * Creates the Map that "wraps" application-scoped attributes
 **/
public static Map<String, Object> createApplicationScopeMap (PageContext pContext)
{
  final PageContext context = pContext;
  return new EnumeratedMap<String, Object> ()
    {
      public Enumeration<String> enumerateKeys () 
      {
        return context.getAttributeNamesInScope
          (PageContext.APPLICATION_SCOPE);
      }

      public Object getValue (Object pKey) 
      {
        if (pKey instanceof String) {
          return context.getAttribute
            ((String) pKey, 
             PageContext.APPLICATION_SCOPE);
        }
        else {
          return null;
        }
      }

      public boolean isMutable ()
      {
        return true;
      }
    };
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
public static ScopeManager get(PageContext page) {
	ScopeManager mngr = (ScopeManager) page.getAttribute(MNGR_KEY);
	if (mngr == null) {
		mngr = new ScopeManager(page);
		page.setAttribute(MNGR_KEY, mngr);
	}
	return mngr;
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 * Return the form action converted into a server-relative URL.
 */
public String getActionMappingURL(String action, String module, PageContext pageContext, boolean contextRelative) {

    HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();

    String contextPath = request.getContextPath();
    StringBuffer value = new StringBuffer();
    // Avoid setting two slashes at the beginning of an action:
    //  the length of contextPath should be more than 1
    //  in case of non-root context, otherwise length==1 (the slash)
    if (contextPath.length() > 1) value.append(contextPath);

    ModuleConfig moduleConfig = ModuleUtils.getInstance().getModuleConfig(module, request, pageContext.getServletContext());

    if ((moduleConfig != null) && (!contextRelative)) {
        value.append(moduleConfig.getPrefix());
    }

    // Use our servlet mapping, if one is specified
    String servletMapping =
            (String) pageContext.getAttribute(
                    Globals.SERVLET_KEY,
                    PageContext.APPLICATION_SCOPE);

    if (servletMapping != null) {

        String queryString = null;
        int question = action.indexOf("?");
        if (question >= 0) {
            queryString = action.substring(question);
        }

        String actionMapping = getActionMappingName(action);
        if (servletMapping.startsWith("*.")) {
            value.append(actionMapping);
            value.append(servletMapping.substring(1));

        } else if (servletMapping.endsWith("/*")) {
            value.append(
                    servletMapping.substring(0, servletMapping.length() - 2));
            value.append(actionMapping);

        } else if (servletMapping.equals("/")) {
            value.append(actionMapping);
        }
        if (queryString != null) {
            value.append(queryString);
        }
    }

    // Otherwise, assume extension mapping is in use and extension is
    // already included in the action property
    else {
        if (!action.startsWith("/")) {
            value.append("/");
        }
        value.append(action);
    }

    return value.toString();
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 *
 * Creates the Map that "wraps" session-scoped attributes
 **/
public static Map<String, Object> createSessionScopeMap (PageContext pContext)
{
  final PageContext context = pContext;
  return new EnumeratedMap<String, Object> ()
    {
      public Enumeration<String> enumerateKeys () 
      {
        return context.getAttributeNamesInScope
          (PageContext.SESSION_SCOPE);
      }

      public Object getValue (Object pKey) 
      {
        if (pKey instanceof String) {
          return context.getAttribute
            ((String) pKey, 
             PageContext.SESSION_SCOPE);
        }
        else {
          return null;
        }
      }

      public boolean isMutable ()
      {
        return true;
      }
    };
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 * Get object from requested context. Return <code>null</code> if not found.
 * Context can be "component" or normal JSP contexts.
 * @param beanName Name of bean to retrieve.
 * @param scope Scope from which bean must be retrieved.
 * @param pageContext Current pageContext.
 * @return Requested bean or <code>null</code> if not found.
 */
public static Object getAttribute(String beanName, int scope, PageContext pageContext) {
    if (scope == ComponentConstants.COMPONENT_SCOPE) {
        ComponentContext compContext = ComponentContext.getContext(pageContext.getRequest());
        return compContext.getAttribute(beanName);
    }
    return pageContext.getAttribute(beanName, scope);
}
 

import javax.servlet.jsp.PageContext; //導入方法依賴的package包/類
/**
 * If the base object is <code>null</code>, sets an existing scoped
 * attribute to the new value, or creates a new scoped attribute if one
 * does not exist by this name.
 *
 * <p>If the provided attribute name matches the key of an attribute 
 * in page scope, request scope, session scope, or application scope, the 
 * corresponding attribute value will be replaced by the provided value.
 * Otherwise, a new page scope attribute will be created with the
 * given name and value.</p>
 *
 * <p>The <code>propertyResolved</code> property of the 
 * <code>ELContext</code> object must be set to <code>true</code> by 
 * this resolver before returning if base is <code>null</code>. If 
 * this property is not <code>true</code> after this method is called,
 * the caller should ignore the return value.</p>
 *
 * @param context The context of this evaluation.
 * @param base Only <code>null</code> is handled by this resolver.
 *     Other values will result in an immediate return.
 * @param property The name of the scoped attribute to set.
 * @param val The value for the scoped attribute.
 * @throws NullPointerException if context is <code>null</code>.
 * @throws ELException if an exception was thrown while performing
 *     the property or variable resolution. The thrown exception
 *     must be included as the cause property of this exception, if
 *     available.
 */
public void  setValue(ELContext context,
                      Object base,
                      Object property,
                      Object val) {
    if (context == null) {
        throw new NullPointerException();
    }

    if (base == null) {
        context.setPropertyResolved(true);
        if (property instanceof String) {
            PageContext ctxt = (PageContext)
                                   context.getContext(JspContext.class);
            String attr = (String) property;
            if (ctxt.getAttribute(attr, PageContext.REQUEST_SCOPE) != null)
                ctxt.setAttribute(attr, val, PageContext.REQUEST_SCOPE);
            else if (ctxt.getAttribute(attr, PageContext.SESSION_SCOPE) != null)
                ctxt.setAttribute(attr, val, PageContext.SESSION_SCOPE);
            else if (ctxt.getAttribute(attr, PageContext.APPLICATION_SCOPE) != null)
                ctxt.setAttribute(attr, val, PageContext.APPLICATION_SCOPE);
            else {
                ctxt.setAttribute(attr, val, PageContext.PAGE_SCOPE);
            }
        }
    }
}