最近學(xué)習(xí)spring data JPA 時(shí)候要用到分頁(yè)功能，但是發(fā)現(xiàn)網(wǎng)上所有教程都是通過(guò)new PageRequest()方法解決分頁(yè)，實(shí)際使用中發(fā)現(xiàn)已經(jīng)過(guò)時(shí)

替代的方法是不要new PageRequest，而是直接用 PageRequest.of這個(gè)方法 根據(jù)你的需求選擇入?yún)?/p>3. 對(duì)比

原來(lái)：

@Override@Transactional(readOnly = true) // 只讀事務(wù)public Page<People> getPage(Integer pageNum, Integer pageLimit) {Pageable pageable =new PageRequest(pageNum - 1,pageLimit);return emr.findAll(pageable);}

現(xiàn)在：

@Override@Transactional(readOnly = true) // 只讀事務(wù)public Page<People> getPage(Integer pageNum, Integer pageLimit) {Pageable pageable =PageRequest.of(pageNum - 1,pageLimit);return emr.findAll(pageable)；}pageRequest隨著spring版本的更新變動(dòng)

2x版本：

/* * Copyright 2008-2019 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.data.domain;import org.springframework.data.domain.Sort.Direction;import org.springframework.lang.Nullable;import org.springframework.util.Assert;/** * Basic Java Bean implementation of {@code Pageable}. * * @author Oliver Gierke * @author Thomas Darimont */public class PageRequest extends AbstractPageRequest {private static final long serialVersionUID = -4541509938956089562L;private final Sort sort;/** * Creates a new {@link PageRequest} with sort parameters applied. * * @param page zero-based page index, must not be negative. * @param size the size of the page to be returned, must be greater than 0. * @param sort must not be {@literal null}, use {@link Sort#unsorted()} instead. */protected PageRequest(int page, int size, Sort sort) {super(page, size);Assert.notNull(sort, 'Sort must not be null!');this.sort = sort;}/** * Creates a new unsorted {@link PageRequest}. * * @param page zero-based page index, must not be negative. * @param size the size of the page to be returned, must be greater than 0. * @since 2.0 */public static PageRequest of(int page, int size) {return of(page, size, Sort.unsorted());}/** * Creates a new {@link PageRequest} with sort parameters applied. * * @param page zero-based page index. * @param size the size of the page to be returned. * @param sort must not be {@literal null}, use {@link Sort#unsorted()} instead. * @since 2.0 */public static PageRequest of(int page, int size, Sort sort) {return new PageRequest(page, size, sort);}/** * Creates a new {@link PageRequest} with sort direction and properties applied. * * @param page zero-based page index, must not be negative. * @param size the size of the page to be returned, must be greater than 0. * @param direction must not be {@literal null}. * @param properties must not be {@literal null}. * @since 2.0 */public static PageRequest of(int page, int size, Direction direction, String... properties) {return of(page, size, Sort.by(direction, properties));}/* * (non-Javadoc) * @see org.springframework.data.domain.Pageable#getSort() */public Sort getSort() {return sort;}/* * (non-Javadoc) * @see org.springframework.data.domain.Pageable#next() */@Overridepublic Pageable next() {return new PageRequest(getPageNumber() + 1, getPageSize(), getSort());}/* * (non-Javadoc) * @see org.springframework.data.domain.AbstractPageRequest#previous() */@Overridepublic PageRequest previous() {return getPageNumber() == 0 ? this : new PageRequest(getPageNumber() - 1, getPageSize(), getSort());}/* * (non-Javadoc) * @see org.springframework.data.domain.Pageable#first() */@Overridepublic Pageable first() {return new PageRequest(0, getPageSize(), getSort());}/* * (non-Javadoc) * @see java.lang.Object#equals(java.lang.Object) */@Overridepublic boolean equals(@Nullable Object obj) {if (this == obj) {return true;}if (!(obj instanceof PageRequest)) {return false;}PageRequest that = (PageRequest) obj;return super.equals(that) && this.sort.equals(that.sort);}/* * (non-Javadoc) * @see java.lang.Object#hashCode() */@Overridepublic int hashCode() {return 31 * super.hashCode() + sort.hashCode();}/* * (non-Javadoc) * @see java.lang.Object#toString() */@Overridepublic String toString() {return String.format('Page request [number: %d, size %d, sort: %s]', getPageNumber(), getPageSize(), sort);}}

1x版本：

/* * Copyright 2008-2019 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.data.domain;import org.springframework.data.domain.Sort.Direction;/** * Basic Java Bean implementation of {@code Pageable}. * * @author Oliver Gierke * @author Thomas Darimont */public class PageRequest extends AbstractPageRequest {private static final long serialVersionUID = -4541509938956089562L;private final Sort sort;/** * Creates a new {@link PageRequest}. Pages are zero indexed, thus providing 0 for {@code page} will return the first * page. * * @param page zero-based page index. * @param size the size of the page to be returned. */public PageRequest(int page, int size) {this(page, size, null);}/** * Creates a new {@link PageRequest} with sort parameters applied. * * @param page zero-based page index. * @param size the size of the page to be returned. * @param direction the direction of the {@link Sort} to be specified, can be {@literal null}. * @param properties the properties to sort by, must not be {@literal null} or empty. */public PageRequest(int page, int size, Direction direction, String... properties) {this(page, size, new Sort(direction, properties));}/** * Creates a new {@link PageRequest} with sort parameters applied. * * @param page zero-based page index. * @param size the size of the page to be returned. * @param sort can be {@literal null}. */public PageRequest(int page, int size, Sort sort) {super(page, size);this.sort = sort;}/* * (non-Javadoc) * @see org.springframework.data.domain.Pageable#getSort() */public Sort getSort() {return sort;}/* * (non-Javadoc) * @see org.springframework.data.domain.Pageable#next() */public Pageable next() {return new PageRequest(getPageNumber() + 1, getPageSize(), getSort());}/* * (non-Javadoc) * @see org.springframework.data.domain.AbstractPageRequest#previous() */public PageRequest previous() {return getPageNumber() == 0 ? this : new PageRequest(getPageNumber() - 1, getPageSize(), getSort());}/* * (non-Javadoc) * @see org.springframework.data.domain.Pageable#first() */public Pageable first() {return new PageRequest(0, getPageSize(), getSort());}/* * (non-Javadoc) * @see java.lang.Object#equals(java.lang.Object) */@Overridepublic boolean equals(final Object obj) {if (this == obj) {return true;}if (!(obj instanceof PageRequest)) {return false;}PageRequest that = (PageRequest) obj;boolean sortEqual = this.sort == null ? that.sort == null : this.sort.equals(that.sort);return super.equals(that) && sortEqual;}/* * (non-Javadoc) * @see java.lang.Object#hashCode() */@Overridepublic int hashCode() {return 31 * super.hashCode() + (null == sort ? 0 : sort.hashCode());}/* * (non-Javadoc) * @see java.lang.Object#toString() */@Overridepublic String toString() {return String.format('Page request [number: %d, size %d, sort: %s]', getPageNumber(), getPageSize(),sort == null ? null : sort.toString());}}

2x版本常用創(chuàng)建實(shí)例方式：

調(diào)用靜態(tài)方法

從源碼中看到2x版本的構(gòu)造器是使用protected修飾的,所有無(wú)法通過(guò)new的方式去創(chuàng)建實(shí)例,只能通過(guò)調(diào)用static修飾的方法進(jìn)行創(chuàng)建。

1x版本常用創(chuàng)建實(shí)例方式：

直接調(diào)用構(gòu)造器即可

因?yàn)?x版本使用的是public修飾的構(gòu)造器，所以可以直接使用構(gòu)造器創(chuàng)建實(shí)例。

剛使用spring自帶的分頁(yè)工具Pageable入的坑，自己記錄一下，希望能給大家一個(gè)參考，也希望大家多多支持好吧啦網(wǎng)。