Java Code Examples for javax.servlet.jsp.PageContext#findAttribute()

@Override
public Object getValue(ELContext context, Object base, Object property)
        throws NullPointerException, PropertyNotFoundException, ELException {
    if (context == null) {
        throw new NullPointerException();
    }

    if (base == null) {
        context.setPropertyResolved(true);
        if (property != null) {
            String key = property.toString();
            PageContext page = (PageContext) context
                    .getContext(JspContext.class);
            return page.findAttribute(key);
        }
    }

    return null;
}
 

@Override
public Object getValue(ELContext context, Object base, Object property)
        throws NullPointerException, PropertyNotFoundException, ELException {
    if (context == null) {
        throw new NullPointerException();
    }

    if (base == null) {
        context.setPropertyResolved(true);
        if (property != null) {
            String key = property.toString();
            PageContext page = (PageContext) context
                    .getContext(JspContext.class);
            return page.findAttribute(key);
        }
    }

    return null;
}
 

@Override
public Object get(Object key) {
    PageContext pc = getPageContext();
    if (pc == null) {
        Map request = (Map) context.get("request");
        Map session = (Map) context.get("session");
        Map application = (Map) context.get("application");
        if ((request != null) && (request.get(key) != null)) {
            return request.get(key);
        } else if ((session != null) && (session.get(key) != null)) {
            return session.get(key);
        } else if ((application != null) && (application.get(key) != null)) {
            return application.get(key);
        }
    } else {
        try {
            return pc.findAttribute(key.toString());
        } catch (NullPointerException npe) {
            return null;
        }
    }
    return null;
}
 

/**
 * Breaks name up into tokens separated by '.' characters,
 * looks up the first token (in other JSTL scopes) to get a variable.
 * Uses the next token (if there) to get a bean property from the variable.
 * Uses additional tokens to lookup bean properties of bean properties.
 * If the variable or any of those bean properties is a Map
 * then gets the object with the given token as key.
 * @param name The name to lookup.
 * @param pageContext Used to look up attributes.
 */
public static Object getValue(String name, PageContext pageContext) {
  log.debug("Looking up name: " + name + " in PageContext.");
  StringTokenizer tok = new StringTokenizer(name);
  if (tok.hasMoreTokens()) {
    String currentName = tok.nextToken(".");
    log.debug("firstName " + currentName);
    Object retVal = pageContext.findAttribute(currentName);
    
    while (tok.hasMoreTokens()) {
      currentName = tok.nextToken(".");
      log.debug("currentName " + currentName);
      retVal = getBeanProperty(retVal, currentName);
      log.debug("current object: " + retVal);
    }
    return retVal;
  }
  
  return null;
}
 

private PutType getPutType(PageContext pageContext) {
    PutType putType = (PutType) pageContext.findAttribute(getBlockTypeAttributeName(name));
    if (putType == null) {
        return DEFAULT_PUT_TYPE;
    }
    return putType;
}
 

private String getPutContents(PageContext pageContext) {
    String putContents = (String) pageContext.findAttribute(getBlockContentsAttributeName(name));
    if (putContents == null) {
        return "";
    }
    return putContents;
}
 

@Override
public Object getValue(ELContext context, Object base, Object property) {
    Objects.requireNonNull(context);

    Object result = null;

    if (base == null) {
        context.setPropertyResolved(base, property);
        if (property != null) {
            String key = property.toString();
            PageContext page = (PageContext) context.getContext(JspContext.class);
            result = page.findAttribute(key);

            if (result == null) {
                boolean resolveClass = true;
                // Performance short-cut available when running on Tomcat
                if (AST_IDENTIFIER_KEY != null) {
                    // Tomcat will set this key to Boolean.TRUE if the
                    // identifier is a stand-alone identifier (i.e.
                    // identifier) rather than part of an AstValue (i.e.
                    // identifier.something). Imports do not need to be
                    // checked if this is a stand-alone identifier
                    Boolean value = (Boolean) context.getContext(AST_IDENTIFIER_KEY);
                    if (value != null && value.booleanValue()) {
                        resolveClass = false;
                    }
                }
                // This might be the name of an imported class
                ImportHandler importHandler = context.getImportHandler();
                if (importHandler != null) {
                    Class<?> clazz = null;
                    if (resolveClass) {
                        clazz = importHandler.resolveClass(key);
                    }
                    if (clazz != null) {
                        result = new ELClass(clazz);
                    }
                    if (result == null) {
                        // This might be the name of an imported static field
                        clazz = importHandler.resolveStatic(key);
                        if (clazz != null) {
                            try {
                                result = clazz.getField(key).get(null);
                            } catch (IllegalArgumentException | IllegalAccessException |
                                    NoSuchFieldException | SecurityException e) {
                                // Most (all?) of these should have been
                                // prevented by the checks when the import
                                // was defined.
                            }
                        }
                    }
                }
            }
        }
    }

    return result;
}
 

/**
 * If the base object is <code>null</code>, searches the page, 
 * request, session and application scopes for an attribute with
 * the given name and returns it, or <code>null</code> if no
 * attribute exists with the current name.
 *
 * <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 resolve.
 * @return If the <code>propertyResolved</code> property of 
 *     <code>ELContext</code> was set to <code>true</code>, then
 *     the scoped attribute; otherwise undefined.
 * @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 Object getValue(ELContext context,
                       Object base,
                       Object property) {

    if (context == null) {
        throw new NullPointerException();
    }

    if (base == null) {
        context.setPropertyResolved(true);
        if (property instanceof String) {
            String attribute = (String) property;
            PageContext ctxt = (PageContext)
                                   context.getContext(JspContext.class);
            return ctxt.findAttribute(attribute);
        }
    }
    return null;
}
 

/**
 * Find attribute value.
 * 
 * @param <T>
 *
 * @param pageContext
 *            the page context
 * @param attributeName
 *            the version name in scope
 * @param scope
 *            the version search scope
 * @return 如果 <code>pageContext</code> 是null,抛出 {@link NullPointerException}<br>
 *         如果 <code>attributeName</code> 是null,抛出 {@link NullPointerException}<br>
 *         如果 <code>attributeName</code> 是blank,抛出 {@link IllegalArgumentException}<br>
 *         如果 <code>scope</code> 是null或者 blank,将会调用 {@link javax.servlet.jsp.JspContext#findAttribute(String)}<br>
 *         如果 <code>scope</code> 不是null或者 blank,将会调用 {@link javax.servlet.jsp.JspContext#getAttribute(String, int)}<br>
 * @since 1.12.8
 */
@SuppressWarnings("unchecked")
public static <T> T findAttributeValue(PageContext pageContext,String attributeName,String scope){
    Validate.notNull(pageContext, "pageContext can't be null!");
    Validate.notBlank(attributeName, "attributeName can't be blank!");

    //---------------------------------------------------------------

    //没有指定scope 那么从pageContext中查找
    if (isNullOrEmpty(scope)){
        return (T) pageContext.findAttribute(attributeName);
    }

    //如果指定了, 那么从指定的scope中获取
    return (T) pageContext.getAttribute(attributeName, TagUtils.getScope(scope));
}