Java tutorial
/* * Copyright 2002-2017 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 * * https://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.mvc.support; import java.util.Collection; import java.util.Map; import org.springframework.lang.Nullable; import org.springframework.ui.ModelMap; import org.springframework.validation.DataBinder; /** * A {@link ModelMap} implementation of {@link RedirectAttributes} that formats * values as Strings using a {@link DataBinder}. Also provides a place to store * flash attributes so they can survive a redirect without the need to be * embedded in the redirect URL. * * @author Rossen Stoyanchev * @since 3.1 */ @SuppressWarnings("serial") public class RedirectAttributesModelMap extends ModelMap implements RedirectAttributes { @Nullable private final DataBinder dataBinder; private final ModelMap flashAttributes = new ModelMap(); /** * Default constructor without a DataBinder. * Attribute values are converted to String via {@link #toString()}. */ public RedirectAttributesModelMap() { this(null); } /** * Constructor with a DataBinder. * @param dataBinder used to format attribute values as Strings */ public RedirectAttributesModelMap(@Nullable DataBinder dataBinder) { this.dataBinder = dataBinder; } /** * Return the attributes candidate for flash storage or an empty Map. */ @Override public Map<String, ?> getFlashAttributes() { return this.flashAttributes; } /** * {@inheritDoc} * <p>Formats the attribute value as a String before adding it. */ @Override public RedirectAttributesModelMap addAttribute(String attributeName, @Nullable Object attributeValue) { super.addAttribute(attributeName, formatValue(attributeValue)); return this; } @Nullable private String formatValue(@Nullable Object value) { if (value == null) { return null; } return (this.dataBinder != null ? this.dataBinder.convertIfNecessary(value, String.class) : value.toString()); } /** * {@inheritDoc} * <p>Formats the attribute value as a String before adding it. */ @Override public RedirectAttributesModelMap addAttribute(Object attributeValue) { super.addAttribute(attributeValue); return this; } /** * {@inheritDoc} * <p>Each attribute value is formatted as a String before being added. */ @Override public RedirectAttributesModelMap addAllAttributes(@Nullable Collection<?> attributeValues) { super.addAllAttributes(attributeValues); return this; } /** * {@inheritDoc} * <p>Each attribute value is formatted as a String before being added. */ @Override public RedirectAttributesModelMap addAllAttributes(@Nullable Map<String, ?> attributes) { if (attributes != null) { attributes.forEach(this::addAttribute); } return this; } /** * {@inheritDoc} * <p>Each attribute value is formatted as a String before being merged. */ @Override public RedirectAttributesModelMap mergeAttributes(@Nullable Map<String, ?> attributes) { if (attributes != null) { attributes.forEach((key, attribute) -> { if (!containsKey(key)) { addAttribute(key, attribute); } }); } return this; } @Override public Map<String, Object> asMap() { return this; } /** * {@inheritDoc} * <p>The value is formatted as a String before being added. */ @Override public Object put(String key, @Nullable Object value) { return super.put(key, formatValue(value)); } /** * {@inheritDoc} * <p>Each value is formatted as a String before being added. */ @Override public void putAll(@Nullable Map<? extends String, ? extends Object> map) { if (map != null) { map.forEach((key, value) -> put(key, formatValue(value))); } } @Override public RedirectAttributes addFlashAttribute(String attributeName, @Nullable Object attributeValue) { this.flashAttributes.addAttribute(attributeName, attributeValue); return this; } @Override public RedirectAttributes addFlashAttribute(Object attributeValue) { this.flashAttributes.addAttribute(attributeValue); return this; } }