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Library to support implementing representations for
hyper-text driven REST web services.
/*
* Copyright 2022-2024 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.hateoas;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import org.springframework.core.ParameterizedTypeReference;
import org.springframework.core.ResolvableType;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
/**
* DTO to implement binding response representations of Slice collections.
*
* @author Michael Schout
* @author Oliver Drotbohm
* @since 2.1
*/
public class SlicedModel extends CollectionModel {
public static SlicedModel NO_SLICE = new SlicedModel<>();
private final SliceMetadata metadata;
private final @Nullable ResolvableType fallbackType;
/**
* Default constructor to allow instantiation by reflection.
*/
protected SlicedModel() {
this(new ArrayList<>(), null);
}
protected SlicedModel(Collection content, @Nullable SliceMetadata metadata) {
this(content, metadata, Links.NONE);
}
protected SlicedModel(Collection content, @Nullable SliceMetadata metadata, Iterable links) {
this(content, metadata, links, null);
}
protected SlicedModel(Collection content, @Nullable SliceMetadata metadata, Iterable links,
@Nullable ResolvableType fallbackType) {
super(content, links, fallbackType);
this.metadata = metadata;
this.fallbackType = fallbackType;
}
/**
* Creates an empty {@link SlicedModel}.
*
* @param the payload type.
* @return will never be {@literal null}.
*/
public static SlicedModel empty() {
return empty(Collections.emptyList());
}
/**
* Creates an empty {@link SlicedModel} with the given fallback type.
*
* @param the payload type.
* @param fallbackElementType must not be {@literal null}.
* @param generics must not be {@literal null}.
* @return will never be {@literal null}.
* @see #withFallbackType(Class, Class...)
*/
public static SlicedModel empty(Class fallbackElementType, Class generics) {
return empty(ResolvableType.forClassWithGenerics(fallbackElementType, generics));
}
/**
* Creates an empty {@link SlicedModel} with the given fallback type.
*
* @param the payload type.
* @param fallbackElementType must not be {@literal null}.
* @return will never be {@literal null}.
* @see #withFallbackType(ParameterizedTypeReference)
*/
public static SlicedModel empty(ParameterizedTypeReference fallbackElementType) {
return empty(ResolvableType.forType(fallbackElementType));
}
/**
* Creates an empty {@link SlicedModel} with the given fallback type.
*
* @param the payload type.
* @param fallbackElementType must not be {@literal null}.
* @return will never be {@literal null}.
* @see #withFallbackType(ResolvableType)
*/
public static SlicedModel empty(ResolvableType fallbackElementType) {
return new SlicedModel<>(Collections.emptyList(), null, Collections.emptyList(), fallbackElementType);
}
/**
* Creates an empty {@link SlicedModel} with the given links.
*
* @param the payload type.
* @param links must not be {@literal null}.
* @return will never be {@literal null}.
*/
public static SlicedModel empty(Link... links) {
return empty(null, links);
}
/**
* Creates an empty {@link SlicedModel} with the given links.
*
* @param the payload type.
* @param links must not be {@literal null}.
* @return will never be {@literal null}.
*/
public static SlicedModel empty(Iterable links) {
return empty(null, links);
}
/**
* Creates an empty {@link SlicedModel} with the given {@link SliceMetadata}.
*
* @param the payload type.
* @param metadata can be {@literal null}.
* @return will never be {@literal null}.
*/
public static SlicedModel empty(@Nullable SliceMetadata metadata) {
return empty(metadata, Collections.emptyList());
}
/**
* Creates an empty {@link SlicedModel} with the given {@link SliceMetadata} and fallback type.
*
* @param the payload type.
* @param metadata can be {@literal null}.
* @param fallbackType must not be {@literal null}.
* @param generics must not be {@literal null}.
* @return will never be {@literal null}.
* @see #withFallbackType(Class, Class...)
*/
public static SlicedModel empty(@Nullable SliceMetadata metadata, Class fallbackType,
Class... generics) {
Assert.notNull(fallbackType, "Fallback type must not be null!");
Assert.notNull(generics, "Generics must not be null!");
return empty(metadata, ResolvableType.forClassWithGenerics(fallbackType, generics));
}
/**
* Creates an empty {@link SlicedModel} with the given {@link SliceMetadata} and fallback type.
*
* @param the payload type.
* @param metadata can be {@literal null}.
* @return will never be {@literal null}.
* @see #withFallbackType(ParameterizedTypeReference)
*/
public static SlicedModel empty(@Nullable SliceMetadata metadata,
ParameterizedTypeReference fallbackType) {
Assert.notNull(fallbackType, "Fallback type must not be null!");
return empty(metadata, ResolvableType.forType(fallbackType));
}
/**
* Creates an empty {@link SlicedModel} with the given {@link SliceMetadata} and fallback type.
*
* @param
* @param metadata can be {@literal null}.
* @param fallbackType must not be {@literal null}.
* @return
* @see #withFallbackType(ResolvableType)
*/
public static SlicedModel empty(@Nullable SliceMetadata metadata, ResolvableType fallbackType) {
Assert.notNull(fallbackType, "Fallback type must not be null!");
return new SlicedModel<>(Collections.emptyList(), metadata, Collections.emptyList(), fallbackType);
}
/**
* Creates an empty {@link SlicedModel} with the given {@link SliceMetadata} and links.
*
* @param
* @param metadata can be {@literal null}.
* @param links must not be {@literal null}.
* @return
*/
public static SlicedModel empty(@Nullable SliceMetadata metadata, Link... links) {
return empty(Arrays.asList(links));
}
/**
* Creates an empty {@link SlicedModel} with the given {@link SliceMetadata} and links.
*
* @param the payload type.
* @param metadata can be {@literal null}.
* @param links must not be {@literal null}.
* @return will never be {@literal null}.
*/
public static SlicedModel empty(@Nullable SliceMetadata metadata, Iterable links) {
return of(Collections.emptyList(), metadata, links);
}
/**
* Creates a new {@link SlicedModel} from the given content, {@link SliceMetadata} and {@link Link}s (optional).
*
* @param the payload type.
* @param content must not be {@literal null}.
* @param metadata can be {@literal null}.
* @return will never be {@literal null}.
*/
public static SlicedModel of(Collection content, @Nullable SliceMetadata metadata) {
return new SlicedModel<>(content, metadata);
}
/**
* Creates a new {@link SlicedModel} from the given content, {@link SliceMetadata} and {@link Link}s (optional).
*
* @param the payload type.
* @param content must not be {@literal null}.
* @param metadata can be {@literal null}.
* @param links must not be {@literal null}.
* @return will never be {@literal null}.
*/
public static SlicedModel of(Collection content, @Nullable SliceMetadata metadata, Link... links) {
return new SlicedModel<>(content, metadata, Arrays.asList(links));
}
/**
* Creates a new {@link SlicedModel} from the given content {@link SliceMetadata} and {@link Link}s.
*
* @param the payload type.
* @param content must not be {@literal null}.
* @param metadata can be {@literal null}.
* @param links must not be {@literal null}.
* @return will never be {@literal null}.
*/
public static SlicedModel of(Collection content, @Nullable SliceMetadata metadata, Iterable links) {
return new SlicedModel<>(content, metadata, links);
}
/**
* Factory method to easily create a {@link SlicedModel} instance from a set of entities and pagination metadata.
*
* @param the nested {@link EntityModel} type.
* @param the actual payload type.
* @param content must not be {@literal null}.
* @param metadata
* @return will never be {@literal null}.
*/
@SuppressWarnings("unchecked")
public static , S> SlicedModel wrap(Iterable content, SliceMetadata metadata) {
Assert.notNull(content, "Content must not be null!");
List resources = new ArrayList<>();
for (S element : content) {
resources.add((T) EntityModel.of(element));
}
return SlicedModel.of(resources, metadata);
}
/**
* Returns the pagination metadata.
*
* @return the metadata can be {@literal null}.
*/
@Nullable
@JsonProperty("page")
public SliceMetadata getMetadata() {
return metadata;
}
/**
* Returns the {@link Link} pointing to the next slice (if set).
*
* @return will never be {@literal null}.
*/
@JsonIgnore
public Optional getNextLink() {
return getLink(IanaLinkRelations.NEXT);
}
/**
* Returns the {@link Link} pointing to the previous slice (if set).
*
* @return will never be {@literal null}.
*/
@JsonIgnore
public Optional getPreviousLink() {
return getLink(IanaLinkRelations.PREV);
}
/*
* (non-Javadoc)
*
* @see org.springframework.hateoas.CollectionModel#withFallbackType(java.lang.Class,
* java.lang.Class[])
*/
@Override
public SlicedModel withFallbackType(Class type, Class... generics) {
return withFallbackType(ResolvableType.forClassWithGenerics(type, generics));
}
/*
* (non-Javadoc)
*
* @see org.springframework.hateoas.CollectionModel#withFallbackType(org.springframework.
* core.ParameterizedTypeReference)
*/
@Override
public SlicedModel withFallbackType(ParameterizedTypeReference type) {
return withFallbackType(ResolvableType.forType(type));
}
/*
* (non-Javadoc)
*
* @see org.springframework.hateoas.CollectionModel#withFallbackType(org.springframework.
* core.ResolvableType)
*/
@Override
public SlicedModel withFallbackType(ResolvableType type) {
return new SlicedModel<>(getContent(), metadata, getLinks(), type);
}
/*
* (non-Javadoc)
* @see org.springframework.hateoas.CollectionModel#toString()
*/
@Override
public String toString() {
return String.format("SlicedModel { content: %s, fallbackType: %s, metadata: %s, links: %s }", //
getContent(), fallbackType, metadata, getLinks());
}
/*
* (non-Javadoc)
* @see org.springframework.hateoas.CollectionModel#equals(java.lang.Object)
*/
@Override
public boolean equals(@Nullable Object obj) {
if (this == obj) {
return true;
}
if (obj == null || !getClass().equals(obj.getClass())) {
return false;
}
SlicedModel that = (SlicedModel) obj;
return Objects.equals(this.metadata, that.metadata) //
&& super.equals(obj);
}
/*
* (non-Javadoc)
*
* @see org.springframework.hateoas.CollectionModel#hashCode()
*/
@Override
public int hashCode() {
return super.hashCode() + Objects.hash(metadata);
}
/**
* Value object for slice metadata.
*
* @author Michael Schout
*/
public static class SliceMetadata {
@JsonProperty //
private long size;
@JsonProperty //
private long number;
protected SliceMetadata() {}
/**
* Creates a new {@link SliceMetadata} from the given size, and slice number.
*
* @param size must be greater or equal to zero.
* @param number zero-indexed slice number, greater or equal to zero.
*/
public SliceMetadata(long size, long number) {
Assert.isTrue(size > -1, "Size must not be negative!");
Assert.isTrue(number > -1, "Number must not be negative!");
this.size = size;
this.number = number;
}
/**
* Returns the requested size of the slice.
*
* @return the size a positive long.
*/
public long getSize() {
return size;
}
/**
* Returns the number of the current slice.
*
* @return the number a positive long.
*/
public long getNumber() {
return number;
}
/*
* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
return String.format("Metadata: { number: %d, size %d )", number, size);
}
/*
* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(@Nullable Object obj) {
if (this == obj) {
return true;
}
if (obj == null || !obj.getClass().equals(getClass())) {
return false;
}
SliceMetadata that = (SliceMetadata) obj;
return super.equals(that) //
&& Objects.equals(this.number, that.number) //
&& Objects.equals(this.size, that.size);
}
/*
* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
return Objects.hash(super.hashCode(), number, size);
}
}
}
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