org.springframework.web.servlet.FlashMap Maven / Gradle / Ivy
/*
* Copyright 2002-2014 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.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.
*
* 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.
*
*
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 implements Comparable {
private String targetRequestPath;
private final MultiValueMap targetRequestParams = new LinkedMultiValueMap();
private long expirationStartTime;
private int timeToLive;
/**
* Provide a URL path to help identify the target request for this FlashMap.
* The path may be absolute (e.g. /application/resource) or relative to the
* current request (e.g. ../resource).
* @param path the URI path
*/
public void setTargetRequestPath(String path) {
this.targetRequestPath = path;
}
/**
* Return the target URL path or {@code null}.
*/
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 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 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.expirationStartTime = System.currentTimeMillis();
this.timeToLive = timeToLive;
}
/**
* Whether this instance has expired depending on the amount of elapsed
* time since the call to {@link #startExpirationPeriod}.
*/
public boolean isExpired() {
if (this.expirationStartTime != 0) {
return (System.currentTimeMillis() - this.expirationStartTime > this.timeToLive * 1000);
}
else {
return false;
}
}
/**
* 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 String toString() {
StringBuilder sb = new StringBuilder();
sb.append("FlashMap [attributes=").append(super.toString());
sb.append(", targetRequestPath=").append(this.targetRequestPath);
sb.append(", targetRequestParams=").append(this.targetRequestParams).append("]");
return sb.toString();
}
}