org.springframework.web.util
Class WebUtils

java.lang.Object
  org.springframework.web.util.WebUtils

public abstract class WebUtils

extends java.lang.Object

Miscellaneous utilities for web applications. Used by various framework classes.

Author:

Rod Johnson, Juergen Hoeller

Field Summary

static java.lang.String	DEFAULT_CHARACTER_ENCODING Default character encoding to use when request.getCharacterEncoding returns null, according to the Servlet spec.
static java.lang.String	DEFAULT_WEB_APP_ROOT_KEY Default web app root key: "webapp.root"
static java.lang.String[]	SUBMIT_IMAGE_SUFFIXES Name suffixes in case of image buttons
static java.lang.String	TEMP_DIR_CONTEXT_ATTRIBUTE Standard Servlet spec context attribute that specifies a temporary directory for the current web application, of type java.io.File
static java.lang.String	WEB_APP_ROOT_KEY_PARAM Web app root key parameter at the servlet context level (i.e.

Constructor Summary

WebUtils()

Method Summary

static javax.servlet.http.Cookie	getCookie(javax.servlet.http.HttpServletRequest request, java.lang.String name) Retrieve the first cookie with the given name.
static java.lang.Object	getOrCreateSessionAttribute(javax.servlet.http.HttpSession session, java.lang.String name, java.lang.Class clazz) Get the specified session attribute, creating and setting a new attribute if no existing found.
static java.util.Map	getParametersStartingWith(javax.servlet.ServletRequest request, java.lang.String base) Convenience method to return a map from un-prefixed property names to values.
static java.lang.Object	getRequiredSessionAttribute(javax.servlet.http.HttpServletRequest request, java.lang.String name) Check the given request for a session attribute of the given name.
static java.lang.Object	getSessionAttribute(javax.servlet.http.HttpServletRequest request, java.lang.String name) Check the given request for a session attribute of the given name.
static java.io.File	getTempDir(javax.servlet.ServletContext servletContext) Return the temporary directory for the current web application, as provided by the servlet container.
static boolean	hasSubmitParameter(javax.servlet.ServletRequest request, java.lang.String name) Checks 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").
static void	setSessionAttribute(javax.servlet.http.HttpServletRequest request, java.lang.String name, java.lang.Object value) Set the session attribute with the given name to the given value.
static void	setWebAppRootSystemProperty(javax.servlet.ServletContext servletContext) Set a system property to the web application root directory.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_CHARACTER_ENCODING

public static final java.lang.String DEFAULT_CHARACTER_ENCODING

Default character encoding to use when request.getCharacterEncoding returns null, according to the Servlet spec.

See Also:

ServletRequest.getCharacterEncoding(), Constant Field Values

TEMP_DIR_CONTEXT_ATTRIBUTE

public static final java.lang.String TEMP_DIR_CONTEXT_ATTRIBUTE

Standard Servlet spec context attribute that specifies a temporary directory for the current web application, of type java.io.File

See Also:

Constant Field Values

WEB_APP_ROOT_KEY_PARAM

public static final java.lang.String WEB_APP_ROOT_KEY_PARAM

Web app root key parameter at the servlet context level (i.e. web.xml): "webAppRootKey".

See Also:

Constant Field Values

DEFAULT_WEB_APP_ROOT_KEY

public static final java.lang.String DEFAULT_WEB_APP_ROOT_KEY

Default web app root key: "webapp.root"

See Also:

Constant Field Values

SUBMIT_IMAGE_SUFFIXES

public static final java.lang.String[] SUBMIT_IMAGE_SUFFIXES

Name suffixes in case of image buttons

Constructor Detail

WebUtils

public WebUtils()

Method Detail

setWebAppRootSystemProperty

public static void setWebAppRootSystemProperty(javax.servlet.ServletContext servletContext)
                                        throws java.lang.IllegalStateException

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 toolkits that support substition with System.getProperty values, like Log4J's "${key}" syntax within log file locations.

Parameters:

servletContext - the servlet context of the web application

Throws:

java.lang.IllegalStateException - if the system property is already set, or if the WAR file is not expanded

See Also:

WEB_APP_ROOT_KEY_PARAM, DEFAULT_WEB_APP_ROOT_KEY, WebAppRootListener, Log4jWebConfigurer

getTempDir

public static java.io.File getTempDir(javax.servlet.ServletContext servletContext)

Return the temporary directory for the current web application, as provided by the servlet container.

Parameters:

servletContext - the servlet context of the web application

Returns:

the File representing the temporary directory

getSessionAttribute

public static java.lang.Object getSessionAttribute(javax.servlet.http.HttpServletRequest request,
                                                   java.lang.String name)

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!

Parameters:

request - current HTTP request

name - the name of the session attribute

Returns:

the value of the session attribute, or null if not found

getRequiredSessionAttribute

public static java.lang.Object getRequiredSessionAttribute(javax.servlet.http.HttpServletRequest request,
                                                           java.lang.String name)
                                                    throws java.lang.IllegalStateException

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!

Parameters:

request - current HTTP request

name - the name of the session attribute

Returns:

the value of the session attribute, or null if not found

Throws:

java.lang.IllegalStateException - if the session attribute could not be found

setSessionAttribute

public static void setSessionAttribute(javax.servlet.http.HttpServletRequest request,
                                       java.lang.String name,
                                       java.lang.Object value)

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!

Parameters:

request - current HTTP request

name - the name of the session attribute

getOrCreateSessionAttribute

public static java.lang.Object getOrCreateSessionAttribute(javax.servlet.http.HttpSession session,
                                                           java.lang.String name,
                                                           java.lang.Class clazz)
                                                    throws java.lang.IllegalArgumentException

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.

Parameters:

session - current HTTP session

name - the name of the session attribute

clazz - the class to instantiate for a new attribute

Returns:

the value of the session attribute, newly created if not found

Throws:

java.lang.IllegalArgumentException - if the session attribute could not be instantiated

getCookie

public static javax.servlet.http.Cookie getCookie(javax.servlet.http.HttpServletRequest request,
                                                  java.lang.String name)

Retrieve the first cookie with the given name. Note that multiple cookies can have the same name but different paths or domains.

Parameters:

name - cookie name

Returns:

the first cookie with the given name, or null if none is found

getParametersStartingWith

public static java.util.Map getParametersStartingWith(javax.servlet.ServletRequest request,
                                                      java.lang.String base)

Convenience method to return a map from un-prefixed property names to values. E.g. with a prefix of price, price_1, price_2 produce a properties object with mappings for 1, 2 to the same values. Maps single values to String and multiple values to String array.

Parameters:

request - HTTP request in which to look for parameters

base - beginning of parameter name (if this is null or the empty string, all parameters will match)

Returns:

map containing request parameters without the prefix, containing either a String or a String[] as values

hasSubmitParameter

public static boolean hasSubmitParameter(javax.servlet.ServletRequest request,
                                         java.lang.String name)

Checks 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").

Parameters:

request - current HTTP request

name - name of the parameter

Returns:

if the parameter was sent

See Also:

SUBMIT_IMAGE_SUFFIXES