Class FlashMap

java.lang.Object

java.util.AbstractMap<String,Object>

java.util.HashMap<String,Object>

org.springframework.web.servlet.FlashMap

All Implemented Interfaces:

Serializable, Cloneable, Comparable<FlashMap>, Map<String,Object>

public final class FlashMap
extends HashMap<String,Object>
implements Comparable<FlashMap>

A FlashMap provides a way for one request to store attributes intended for use in another. This is most commonly needed when redirecting from one URL to another -- for example, the Post/Redirect/Get pattern. A FlashMap is saved before the redirect (typically in the session) and is made available after the redirect and removed immediately.

A FlashMap can be set up with a request path and request parameters to help identify the target request. Without this information, a FlashMap is made available to the next request, which may or may not be the intended recipient. On a redirect, the target URL is known and a FlashMap can be updated with that information. This is done automatically when the org.springframework.web.servlet.view.RedirectView is used.

Note: annotated controllers will usually not use FlashMap directly. See org.springframework.web.servlet.mvc.support.RedirectAttributes for an overview of using flash attributes in annotated controllers.

Since:

3.1

Author:

Rossen Stoyanchev

See Also:

• FlashMapManager
• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class AbstractMap

AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface Map

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor	Description
FlashMap()

Method Summary

Modifier and Type	Method	Description
FlashMap	addTargetRequestParam(String name, String value)	Provide a request parameter identifying the request for this FlashMap.
FlashMap	addTargetRequestParams(@Nullable MultiValueMap<String,String> params)	Provide request parameters identifying the request for this FlashMap.
int	compareTo(FlashMap other)	Compare two FlashMaps and prefer the one that specifies a target URL path or has more target URL parameters.
boolean	equals(@Nullable Object other)
long	getExpirationTime()	Return the expiration time for the FlashMap or -1 if the expiration period has not started.
MultiValueMap<String,String>	getTargetRequestParams()	Return the parameters identifying the target request, or an empty map.
@Nullable String	getTargetRequestPath()	Return the target URL path (or null if none specified).
int	hashCode()
boolean	isExpired()	Return whether this instance has expired depending on the amount of elapsed time since the call to startExpirationPeriod(int).
void	setExpirationTime(long expirationTime)	Set the expiration time for the FlashMap.
void	setTargetRequestPath(@Nullable String path)	Provide a URL path to help identify the target request for this FlashMap.
void	startExpirationPeriod(int timeToLive)	Start the expiration period for this instance.
String	toString()

Methods inherited from class HashMap

clear, clone, compute, computeIfAbsent, computeIfPresent, containsKey, containsValue, entrySet, forEach, get, getOrDefault, isEmpty, keySet, merge, newHashMap, put, putAll, putIfAbsent, remove, remove, replace, replace, replaceAll, size, values

Methods inherited from class Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

FlashMap

public FlashMap()

Method Details

setTargetRequestPath

public void setTargetRequestPath(@Nullable String path)

Provide a URL path to help identify the target request for this FlashMap.

The path may be absolute (for example, "/application/resource") or relative to the current request (for example, "../resource").

getTargetRequestPath

public @Nullable String getTargetRequestPath()

Return the target URL path (or null if none specified).

addTargetRequestParams

public FlashMap addTargetRequestParams(@Nullable MultiValueMap<String,String> params)

Provide request parameters identifying the request for this FlashMap.

Parameters:

params - a Map with the names and values of expected parameters

addTargetRequestParam

public FlashMap addTargetRequestParam(String name,
 String value)

Provide a request parameter identifying the request for this FlashMap.

Parameters:

name - the expected parameter name (skipped if empty)

value - the expected value (skipped if empty)

getTargetRequestParams

public MultiValueMap<String,String> getTargetRequestParams()

Return the parameters identifying the target request, or an empty map.

startExpirationPeriod

public void startExpirationPeriod(int timeToLive)

Start the expiration period for this instance.

Parameters:

timeToLive - the number of seconds before expiration

setExpirationTime

public void setExpirationTime(long expirationTime)

Set the expiration time for the FlashMap. This is provided for serialization purposes but can also be used instead startExpirationPeriod(int).

Since:

4.2

getExpirationTime

public long getExpirationTime()

Return the expiration time for the FlashMap or -1 if the expiration period has not started.

Since:

4.2

isExpired

public boolean isExpired()

Return whether this instance has expired depending on the amount of elapsed time since the call to startExpirationPeriod(int).

compareTo

public int compareTo(FlashMap other)

Compare two FlashMaps and prefer the one that specifies a target URL path or has more target URL parameters. Before comparing FlashMap instances ensure that they match a given request.

Specified by:

compareTo in interface Comparable<FlashMap>

equals

public boolean equals(@Nullable Object other)

Specified by:

equals in interface Map<String,Object>

Overrides:

equals in class AbstractMap<String,Object>

hashCode

public int hashCode()

Specified by:

hashCode in interface Map<String,Object>

Overrides:

hashCode in class AbstractMap<String,Object>

toString

public String toString()

Overrides:

toString in class AbstractMap<String,Object>