webutils.java

Spring API核心源代码 Spring API核心源代码 Spring API核心源代码

	 * @param value the value of the session attribute
	 */
	public static void setSessionAttribute(HttpServletRequest request, String name, Object value) {
		Assert.notNull(request, "Request must not be null");
		if (value != null) {
			request.getSession().setAttribute(name, value);
		}
		else {
			HttpSession session = request.getSession(false);
			if (session != null) {
				session.removeAttribute(name);
			}
		}
	}

	/**
	 * Get the specified session attribute, creating and setting a new attribute if
	 * no existing found. The given class needs to have a public no-arg constructor.
	 * Useful for on-demand state objects in a web tier, like shopping carts.
	 * @param session current HTTP session
	 * @param name the name of the session attribute
	 * @param clazz the class to instantiate for a new attribute
	 * @return the value of the session attribute, newly created if not found
	 * @throws IllegalArgumentException if the session attribute could not be instantiated
	 */
	public static Object getOrCreateSessionAttribute(HttpSession session, String name, Class clazz)
			throws IllegalArgumentException {

		Assert.notNull(session, "Session must not be null");
		Object sessionObject = session.getAttribute(name);
		if (sessionObject == null) {
			try {
				sessionObject = clazz.newInstance();
			}
			catch (InstantiationException ex) {
				throw new IllegalArgumentException(
				    "Could not instantiate class [" + clazz.getName() +
				    "] for session attribute '" + name + "': " + ex.getMessage());
			}
			catch (IllegalAccessException ex) {
				throw new IllegalArgumentException(
				    "Could not access default constructor of class [" + clazz.getName() +
				    "] for session attribute '" + name + "': " + ex.getMessage());
			}
			session.setAttribute(name, sessionObject);
		}
		return sessionObject;
	}

	/**
	 * Return the best available mutex for the given session:
	 * that is, an object to synchronize on for the given session.
	 * <p>Returns the session mutex attribute if available; usually,
	 * this means that the HttpSessionMutexListener needs to be defined
	 * in <code>web.xml</code>. Falls back to the HttpSession itself
	 * if no mutex attribute found.
	 * <p>The session mutex is guaranteed to be the same object during
	 * the entire lifetime of the session, available under the key defined
	 * by the <code>SESSION_MUTEX_ATTRIBUTE</code> constant. It serves as a
	 * safe reference to synchronize on for locking on the current session.
	 * <p>In many cases, the HttpSession reference itself is a safe mutex
	 * as well, since it will always be the same object reference for the
	 * same active logical session. However, this is not guaranteed across
	 * different servlet containers; the only 100% safe way is a session mutex.
	 * @param session the HttpSession to find a mutex for
	 * @return the mutex object (never <code>null</code>)
	 * @see #SESSION_MUTEX_ATTRIBUTE
	 * @see HttpSessionMutexListener
	 */
	public static Object getSessionMutex(HttpSession session) {
		Assert.notNull(session, "Session must not be null");
		Object mutex = session.getAttribute(SESSION_MUTEX_ATTRIBUTE);
		if (mutex == null) {
			mutex = session;
		}
		return mutex;
	}


	/**
	 * Determine whether the given request is an include request,
	 * that is, not a top-level HTTP request coming in from the outside.
	 * <p>Checks the presence of the "javax.servlet.include.request_uri"
	 * request attribute. Could check any request attribute that is only
	 * present in an include request.
	 * @param request current servlet request
	 * @return whether the given request is an include request
	 */
	public static boolean isIncludeRequest(ServletRequest request) {
		return (request.getAttribute(INCLUDE_REQUEST_URI_ATTRIBUTE) != null);
	}

	/**
	 * Expose the current request URI and paths as {@link javax.servlet.http.HttpServletRequest}
	 * attributes under the keys defined in the Servlet 2.4 specification,
	 * for containers that implement 2.3 or an earlier version of the Servlet API:
	 * <code>javax.servlet.forward.request_uri</code>,
	 * <code>javax.servlet.forward.context_path</code>,
	 * <code>javax.servlet.forward.servlet_path</code>,
	 * <code>javax.servlet.forward.path_info</code>,
	 * <code>javax.servlet.forward.query_string</code>.
	 * <p>Does not override values if already present, to not cause conflicts
	 * with the attributes exposed by Servlet 2.4+ containers themselves.
	 * @param request current servlet request
	 */
	public static void exposeForwardRequestAttributes(HttpServletRequest request) {
		if (request.getAttribute(FORWARD_REQUEST_URI_ATTRIBUTE) == null) {
			request.setAttribute(FORWARD_REQUEST_URI_ATTRIBUTE, request.getRequestURI());
		}
		if (request.getAttribute(FORWARD_CONTEXT_PATH_ATTRIBUTE) == null) {
			request.setAttribute(FORWARD_CONTEXT_PATH_ATTRIBUTE, request.getContextPath());
		}
		if (request.getAttribute(FORWARD_SERVLET_PATH_ATTRIBUTE) == null) {
			request.setAttribute(FORWARD_SERVLET_PATH_ATTRIBUTE, request.getServletPath());
		}
		if (request.getAttribute(FORWARD_PATH_INFO_ATTRIBUTE) == null) {
			request.setAttribute(FORWARD_PATH_INFO_ATTRIBUTE, request.getPathInfo());
		}
		if (request.getAttribute(FORWARD_QUERY_STRING_ATTRIBUTE) == null) {
			request.setAttribute(FORWARD_QUERY_STRING_ATTRIBUTE, request.getQueryString());
		}
	}

	/**
	 * Expose the given Map as request attributes, using the keys as attribute names
	 * and the values as corresponding attribute values. Keys need to be Strings.
	 * @param request current HTTP request
	 * @param attributes the attributes Map
	 * @throws IllegalArgumentException if an invalid key is found in the Map
	 */
	public static void exposeRequestAttributes(ServletRequest request, Map attributes)
			throws IllegalArgumentException {

		Assert.notNull(request, "Request must not be null");
		Iterator it = attributes.entrySet().iterator();
		while (it.hasNext()) {
			Map.Entry entry = (Map.Entry) it.next();
			if (!(entry.getKey() instanceof String)) {
				throw new IllegalArgumentException(
						"Invalid key [" + entry.getKey() + "] in attributes Map - only Strings allowed as attribute keys");
			}
			request.setAttribute((String) entry.getKey(), entry.getValue());
		}
	}

	/**
	 * Retrieve the first cookie with the given name. Note that multiple
	 * cookies can have the same name but different paths or domains.
	 * @param request current servlet request
	 * @param name cookie name
	 * @return the first cookie with the given name, or <code>null</code> if none is found
	 */
	public static Cookie getCookie(HttpServletRequest request, String name) {
		Assert.notNull(request, "Request must not be null");
		Cookie cookies[] = request.getCookies();
		if (cookies != null) {
			for (int i = 0; i < cookies.length; i++) {
				if (name.equals(cookies[i].getName())) {
					return cookies[i];
				}
			}
		}
		return null;
	}

	/**
	 * Check if a specific input type="submit" parameter was sent in the request,
	 * either via a button (directly with name) or via an image (name + ".x" or
	 * name + ".y").
	 * @param request current HTTP request
	 * @param name name of the parameter
	 * @return if the parameter was sent
	 * @see #SUBMIT_IMAGE_SUFFIXES
	 */
	public static boolean hasSubmitParameter(ServletRequest request, String name) {
		Assert.notNull(request, "Request must not be null");
		if (request.getParameter(name) != null) {
			return true;
		}
		for (int i = 0; i < SUBMIT_IMAGE_SUFFIXES.length; i++) {
			String suffix = SUBMIT_IMAGE_SUFFIXES[i];
			if (request.getParameter(name + suffix) != null) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Return a map containing all parameters with the given prefix.
	 * Maps single values to String and multiple values to String array.
	 * <p>For example, with a prefix of "spring_", "spring_param1" and
	 * "spring_param2" result in a Map with "param1" and "param2" as keys.
	 * <p>Similar to Servlet 2.3's <code>ServletRequest.getParameterMap</code>,
	 * but more flexible and compatible with Servlet 2.2.
	 * @param request HTTP request in which to look for parameters
	 * @param prefix the beginning of parameter names
	 * (if this is null or the empty string, all parameters will match)
	 * @return map containing request parameters <b>without the prefix</b>,
	 * containing either a String or a String array as values
	 * @see javax.servlet.ServletRequest#getParameterNames
	 * @see javax.servlet.ServletRequest#getParameterValues
	 * @see javax.servlet.ServletRequest#getParameterMap
	 */
	public static Map getParametersStartingWith(ServletRequest request, String prefix) {
		Assert.notNull(request, "Request must not be null");
		Enumeration paramNames = request.getParameterNames();
		Map params = new TreeMap();
		if (prefix == null) {
			prefix = "";
		}
		while (paramNames != null && paramNames.hasMoreElements()) {
			String paramName = (String) paramNames.nextElement();
			if ("".equals(prefix) || paramName.startsWith(prefix)) {
				String unprefixed = paramName.substring(prefix.length());
				String[] values = request.getParameterValues(paramName);
				if (values == null || values.length == 0) {
					// Do nothing, no values found at all.
				}
				else if (values.length > 1) {
					params.put(unprefixed, values);
				}
				else {
					params.put(unprefixed, values[0]);
				}
			}
		}
		return params;
	}

	/**
	 * Extract the URL filename from the given request URL path.
	 * Correctly resolves nested paths such as "/products/view.html" as well.
	 * @param urlPath the request URL path (e.g. "/index.html")
	 * @return the extracted URI filename (e.g. "index")
	 */
	public static String extractFilenameFromUrlPath(String urlPath) {
		int begin = urlPath.lastIndexOf('/') + 1;
		int end = urlPath.indexOf(';');
		if (end == -1) {
			end = urlPath.indexOf('?');
			if (end == -1) {
				end = urlPath.length();
			}
		}
		String filename = urlPath.substring(begin, end);
		int dotIndex = filename.lastIndexOf('.');
		if (dotIndex != -1) {
			filename = filename.substring(0, dotIndex);
		}
		return filename;
	}

}