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The Spring Framework WebUtils.java source code
/*
* Copyright 2002-2008 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.util;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;
import javax.servlet.ServletContext;
import javax.servlet.ServletRequest;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* Miscellaneous utilities for web applications.
* Used by various framework classes.
*
* @author Rod Johnson
* @author Juergen Hoeller
*/
public abstract class WebUtils {
/**
* Standard Servlet 2.3+ spec request attributes for include URI and paths.
* <p>If included via a RequestDispatcher, the current resource will see the
* originating request. Its own URI and paths are exposed as request attributes.
*/
public static final String INCLUDE_REQUEST_URI_ATTRIBUTE = "javax.servlet.include.request_uri";
public static final String INCLUDE_CONTEXT_PATH_ATTRIBUTE = "javax.servlet.include.context_path";
public static final String INCLUDE_SERVLET_PATH_ATTRIBUTE = "javax.servlet.include.servlet_path";
public static final String INCLUDE_PATH_INFO_ATTRIBUTE = "javax.servlet.include.path_info";
public static final String INCLUDE_QUERY_STRING_ATTRIBUTE = "javax.servlet.include.query_string";
/**
* Standard Servlet 2.4+ spec request attributes for forward URI and paths.
* <p>If forwarded to via a RequestDispatcher, the current resource will see its
* own URI and paths. The originating URI and paths are exposed as request attributes.
*/
public static final String FORWARD_REQUEST_URI_ATTRIBUTE = "javax.servlet.forward.request_uri";
public static final String FORWARD_CONTEXT_PATH_ATTRIBUTE = "javax.servlet.forward.context_path";
public static final String FORWARD_SERVLET_PATH_ATTRIBUTE = "javax.servlet.forward.servlet_path";
public static final String FORWARD_PATH_INFO_ATTRIBUTE = "javax.servlet.forward.path_info";
public static final String FORWARD_QUERY_STRING_ATTRIBUTE = "javax.servlet.forward.query_string";
/**
* Prefix of the charset clause in a content type String: ";charset="
*/
public static final String CONTENT_TYPE_CHARSET_PREFIX = ";charset=";
/**
* Default character encoding to use when <code>request.getCharacterEncoding
* returns <code>null, according to the Servlet spec.
* @see ServletRequest#getCharacterEncoding
*/
public static final String DEFAULT_CHARACTER_ENCODING = "ISO-8859-1";
/**
* Standard Servlet spec context attribute that specifies a temporary
* directory for the current web application, of type <code>java.io.File.
*/
public static final String TEMP_DIR_CONTEXT_ATTRIBUTE = "javax.servlet.context.tempdir";
/**
* HTML escape parameter at the servlet context level
* (i.e. a context-param in <code>web.xml): "defaultHtmlEscape".
*/
public static final String HTML_ESCAPE_CONTEXT_PARAM = "defaultHtmlEscape";
/**
* Web app root key parameter at the servlet context level
* (i.e. a context-param in <code>web.xml): "webAppRootKey".
*/
public static final String WEB_APP_ROOT_KEY_PARAM = "webAppRootKey";
/** Default web app root key: "webapp.root" */
public static final String DEFAULT_WEB_APP_ROOT_KEY = "webapp.root";
/** Name suffixes in case of image buttons */
public static final String[] SUBMIT_IMAGE_SUFFIXES = {".x", ".y"};
/** Key for the mutex session attribute */
public static final String SESSION_MUTEX_ATTRIBUTE = WebUtils.class.getName() + ".MUTEX";
/**
* Set a system property to the web application root directory.
* The key of the system property can be defined with the "webAppRootKey"
* context-param in <code>web.xml. Default is "webapp.root".
* <p>Can be used for tools that support substition with System.getProperty
* values, like log4j's "${key}" syntax within log file locations.
* @param servletContext the servlet context of the web application
* @throws IllegalStateException if the system property is already set,
* or if the WAR file is not expanded
* @see #WEB_APP_ROOT_KEY_PARAM
* @see #DEFAULT_WEB_APP_ROOT_KEY
* @see WebAppRootListener
* @see Log4jWebConfigurer
*/
public static void setWebAppRootSystemProperty(ServletContext servletContext) throws IllegalStateException {
Assert.notNull(servletContext, "ServletContext must not be null");
String root = servletContext.getRealPath("/");
if (root == null) {
throw new IllegalStateException(
"Cannot set web app root system property when WAR file is not expanded");
}
String param = servletContext.getInitParameter(WEB_APP_ROOT_KEY_PARAM);
String key = (param != null ? param : DEFAULT_WEB_APP_ROOT_KEY);
String oldValue = System.getProperty(key);
if (oldValue != null && !StringUtils.pathEquals(oldValue, root)) {
throw new IllegalStateException(
"Web app root system property already set to different value: '" +
key + "' = [" + oldValue + "] instead of [" + root + "] - " +
"Choose unique values for the 'webAppRootKey' context-param in your web.xml files!");
}
System.setProperty(key, root);
servletContext.log("Set web app root system property: '" + key + "' = [" + root + "]");
}
/**
* Remove the system property that points to the web app root directory.
* To be called on shutdown of the web application.
* @param servletContext the servlet context of the web application
* @see #setWebAppRootSystemProperty
*/
public static void removeWebAppRootSystemProperty(ServletContext servletContext) {
Assert.notNull(servletContext, "ServletContext must not be null");
String param = servletContext.getInitParameter(WEB_APP_ROOT_KEY_PARAM);
String key = (param != null ? param : DEFAULT_WEB_APP_ROOT_KEY);
System.getProperties().remove(key);
}
/**
* Return whether default HTML escaping is enabled for the web application,
* i.e. the value of the "defaultHtmlEscape" context-param in <code>web.xml
* (if any). Falls back to <code>false in case of no explicit default given.
* @param servletContext the servlet context of the web application
* @return whether default HTML escaping is enabled (default is false)
*/
public static boolean isDefaultHtmlEscape(ServletContext servletContext) {
if (servletContext == null) {
return false;
}
String param = servletContext.getInitParameter(HTML_ESCAPE_CONTEXT_PARAM);
return Boolean.valueOf(param).booleanValue();
}
/**
* Return whether default HTML escaping is enabled for the web application,
* i.e. the value of the "defaultHtmlEscape" context-param in <code>web.xml
* (if any).
* <p>This method differentiates between no param specified at all and
* an actual boolean value specified, allowing to have a context-specific
* default in case of no setting at the global level.
* @param servletContext the servlet context of the web application
* @return whether default HTML escaping is enabled (null = no explicit default)
*/
public static Boolean getDefaultHtmlEscape(ServletContext servletContext) {
if (servletContext == null) {
return null;
}
Assert.notNull(servletContext, "ServletContext must not be null");
String param = servletContext.getInitParameter(HTML_ESCAPE_CONTEXT_PARAM);
return (StringUtils.hasText(param)? Boolean.valueOf(param) : null);
}
/**
* Return the temporary directory for the current web application,
* as provided by the servlet container.
* @param servletContext the servlet context of the web application
* @return the File representing the temporary directory
*/
public static File getTempDir(ServletContext servletContext) {
Assert.notNull(servletContext, "ServletContext must not be null");
return (File) servletContext.getAttribute(TEMP_DIR_CONTEXT_ATTRIBUTE);
}
/**
* Return the real path of the given path within the web application,
* as provided by the servlet container.
* <p>Prepends a slash if the path does not already start with a slash,
* and throws a FileNotFoundException if the path cannot be resolved to
* a resource (in contrast to ServletContext's <code>getRealPath,
* which returns null).
* @param servletContext the servlet context of the web application
* @param path the path within the web application
* @return the corresponding real path
* @throws FileNotFoundException if the path cannot be resolved to a resource
* @see javax.servlet.ServletContext#getRealPath
*/
public static String getRealPath(ServletContext servletContext, String path) throws FileNotFoundException {
Assert.notNull(servletContext, "ServletContext must not be null");
// Interpret location as relative to the web application root directory.
if (!path.startsWith("/")) {
path = "/" + path;
}
String realPath = servletContext.getRealPath(path);
if (realPath == null) {
throw new FileNotFoundException(
"ServletContext resource [" + path + "] cannot be resolved to absolute file path - " +
"web application archive not expanded?");
}
return realPath;
}
/**
* Determine the session id of the given request, if any.
* @param request current HTTP request
* @return the session id, or <code>null if none
*/
public static String getSessionId(HttpServletRequest request) {
Assert.notNull(request, "Request must not be null");
HttpSession session = request.getSession(false);
return (session != null ? session.getId() : null);
}
/**
* Check the given request for a session attribute of the given name.
* Returns null if there is no session or if the session has no such attribute.
* Does not create a new session if none has existed before!
* @param request current HTTP request
* @param name the name of the session attribute
* @return the value of the session attribute, or <code>null if not found
*/
public static Object getSessionAttribute(HttpServletRequest request, String name) {
Assert.notNull(request, "Request must not be null");
HttpSession session = request.getSession(false);
return (session != null ? session.getAttribute(name) : null);
}
/**
* Check the given request for a session attribute of the given name.
* Throws an exception if there is no session or if the session has no such
* attribute. Does not create a new session if none has existed before!
* @param request current HTTP request
* @param name the name of the session attribute
* @return the value of the session attribute, or <code>null if not found
* @throws IllegalStateException if the session attribute could not be found
*/
public static Object getRequiredSessionAttribute(HttpServletRequest request, String name)
throws IllegalStateException {
Object attr = getSessionAttribute(request, name);
if (attr == null) {
throw new IllegalStateException("No session attribute '" + name + "' found");
}
return attr;
}
/**
* Set the session attribute with the given name to the given value.
* Removes the session attribute if value is null, if a session existed at all.
* Does not create a new session if not necessary!
* @param request current HTTP request
* @param name the name of the session attribute
* @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. 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 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)
* @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>javax.servlet.forward.context_path,
* <code>javax.servlet.forward.servlet_path,
* <code>javax.servlet.forward.path_info,
* <code>javax.servlet.forward.query_string.
* <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
*/
public static void exposeRequestAttributes(ServletRequest request, Map attributes) {
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 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.
* @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,
* 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;
}
/**
* Return the target page specified in the request.
* @param request current servlet request
* @param paramPrefix the parameter prefix to check for
* (e.g. "_target" for parameters like "_target1" or "_target2")
* @param currentPage the current page, to be returned as fallback
* if no target page specified
* @return the page specified in the request, or current page if not found
*/
public static int getTargetPage(ServletRequest request, String paramPrefix, int currentPage) {
Enumeration paramNames = request.getParameterNames();
while (paramNames.hasMoreElements()) {
String paramName = (String) paramNames.nextElement();
if (paramName.startsWith(paramPrefix)) {
for (int i = 0; i < WebUtils.SUBMIT_IMAGE_SUFFIXES.length; i++) {
String suffix = WebUtils.SUBMIT_IMAGE_SUFFIXES[i];
if (paramName.endsWith(suffix)) {
paramName = paramName.substring(0, paramName.length() - suffix.length());
}
}
return Integer.parseInt(paramName.substring(paramPrefix.length()));
}
}
return currentPage;
}
/**
* 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;
}
}
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