org.springframework.web.util.WebUtils Maven / Gradle / Ivy
/*
* Copyright 2002-2005 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.StringUtils;
/**
* Miscellaneous utilities for web applications.
* Used by various framework classes.
*
* @author Rod Johnson
* @author Juergen Hoeller
*/
public abstract class WebUtils {
/**
* Default character encoding to use when request.getCharacterEncoding
* returns 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 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 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 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"};
/**
* 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 web.xml. Default is "webapp.root".
* 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 {
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) {
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 web.xml (if any).
* @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) {
String param = servletContext.getInitParameter(HTML_ESCAPE_CONTEXT_PARAM);
return Boolean.valueOf(param).booleanValue();
}
/**
* 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) {
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.
*
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 getRealPath,
* which returns null).
* @param servletContext the servlet context of 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 {
// 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 null if none
*/
public static String getSessionId(HttpServletRequest request) {
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 null if not found
*/
public static Object getSessionAttribute(HttpServletRequest request, String name) {
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 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
*/
public static void setSessionAttribute(HttpServletRequest request, String name, Object value) {
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 {
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;
}
/**
* 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 {
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 name cookie name
* @return the first cookie with the given name, or null if none is found
*/
public static Cookie getCookie(HttpServletRequest request, String name) {
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) {
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.
*
For example, with a prefix of "spring_", "spring_param1" and
* "spring_param2" result in a Map with "param1" and "param2" as keys.
*
Similar to Servlet 2.3's ServletRequest.getParameterMap,
* 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 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) {
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) {
// do nothing, no values found at all
}
else if (values.length > 1) {
params.put(unprefixed, values);
}
else {
params.put(unprefixed, values[0]);
}
}
}
return params;
}
}