/*
* Copyright 2002-2016 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.servlet;
import java.util.HashMap;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
/**
* 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 -- e.g. 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.
*
* <p>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
* {@code org.springframework.web.servlet.view.RedirectView} is used.
*
* <p>Note: annotated controllers will usually not use FlashMap directly.
* See {@code org.springframework.web.servlet.mvc.support.RedirectAttributes}
* for an overview of using flash attributes in annotated controllers.
*
* @author Rossen Stoyanchev
* @since 3.1
* @see FlashMapManager
*/
@SuppressWarnings("serial")
public final class FlashMap extends HashMap<String, Object> implements Comparable<FlashMap> {
private String targetRequestPath;
private final MultiValueMap<String, String> targetRequestParams = new LinkedMultiValueMap<>(4);
private long expirationTime = -1;
/**
* Provide a URL path to help identify the target request for this FlashMap.
* <p>The path may be absolute (e.g. "/application/resource") or relative to the
* current request (e.g. "../resource").
*/
public void setTargetRequestPath(String path) {
this.targetRequestPath = path;
}
/**
* Return the target URL path (or {@code null} if none specified).
*/
public String getTargetRequestPath() {
return this.targetRequestPath;
}
/**
* Provide request parameters identifying the request for this FlashMap.
* @param params a Map with the names and values of expected parameters
*/
public FlashMap addTargetRequestParams(MultiValueMap<String, String> params) {
if (params != null) {
for (String key : params.keySet()) {
for (String value : params.get(key)) {
addTargetRequestParam(key, value);
}
}
}
return this;
}
/**
* Provide a request parameter identifying the request for this FlashMap.
* @param name the expected parameter name (skipped if empty or {@code null})
* @param value the expected value (skipped if empty or {@code null})
*/
public FlashMap addTargetRequestParam(String name, String value) {
if (StringUtils.hasText(name) && StringUtils.hasText(value)) {
this.targetRequestParams.add(name, value);
}
return this;
}
/**
* Return the parameters identifying the target request, or an empty map.
*/
public MultiValueMap<String, String> getTargetRequestParams() {
return this.targetRequestParams;
}
/**
* Start the expiration period for this instance.
* @param timeToLive the number of seconds before expiration
*/
public void startExpirationPeriod(int timeToLive) {
this.expirationTime = System.currentTimeMillis() + timeToLive * 1000;
}
/**
* Set the expiration time for the FlashMap. This is provided for serialization
* purposes but can also be used instead {@link #startExpirationPeriod(int)}.
* @since 4.2
*/
public void setExpirationTime(long expirationTime) {
this.expirationTime = expirationTime;
}
/**
* Return the expiration time for the FlashMap or -1 if the expiration
* period has not started.
* @since 4.2
*/
public long getExpirationTime() {
return this.expirationTime;
}
/**
* Return whether this instance has expired depending on the amount of
* elapsed time since the call to {@link #startExpirationPeriod}.
*/
public boolean isExpired() {
return (this.expirationTime != -1 && System.currentTimeMillis() > this.expirationTime);
}
/**
* 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.
*/
@Override
public int compareTo(FlashMap other) {
int thisUrlPath = (this.targetRequestPath != null ? 1 : 0);
int otherUrlPath = (other.targetRequestPath != null ? 1 : 0);
if (thisUrlPath != otherUrlPath) {
return otherUrlPath - thisUrlPath;
}
else {
return other.targetRequestParams.size() - this.targetRequestParams.size();
}
}
@Override
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (!(other instanceof FlashMap)) {
return false;
}
FlashMap otherFlashMap = (FlashMap) other;
return (super.equals(otherFlashMap) &&
ObjectUtils.nullSafeEquals(this.targetRequestPath, otherFlashMap.targetRequestPath) &&
this.targetRequestParams.equals(otherFlashMap.targetRequestParams));
}
@Override
public int hashCode() {
int result = super.hashCode();
result = 31 * result + ObjectUtils.nullSafeHashCode(this.targetRequestPath);
result = 31 * result + this.targetRequestParams.hashCode();
return result;
}
@Override
public String toString() {
return "FlashMap [attributes=" + super.toString() + ", targetRequestPath=" +
this.targetRequestPath + ", targetRequestParams=" + this.targetRequestParams + "]";
}
}