easydo-mes-server/easydo-common/src/main/java/easydo/technology/utils/PageUtil.java

/*
 *  Copyright 2019-2020 Zheng Jie
 *
 *  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 easydo.technology.utils;

import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.core.metadata.OrderItem;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;

import java.util.*;

/**
 * 分页工具
 * 
 * @author Zheng Jie
 * @date 2018-12-10
 */
public class PageUtil {

    /**
     * List 分页
     */
    public static <T> List<T> toPage(int page, int size, List<T> list) {
        int fromIndex = page * size;
        int toIndex = page * size + size;
        if (fromIndex > list.size()) {
            return new ArrayList<>();
        } else if (toIndex >= list.size()) {
            return list.subList(fromIndex, list.size());
        } else {
            return list.subList(fromIndex, toIndex);
        }
    }

    /**
     * Page 数据处理，预防redis反序列化报错
     */
    public static <T> Map<String, Object> toPage(Page<T> page) {
        Map<String, Object> map = new LinkedHashMap<>(2);
        map.put("content", page.getContent());
        map.put("totalElements", page.getTotalElements());
        return map;
    }

    /**
     * 自定义分页
     */
    public static Map<String, Object> toPage(Object object, Object totalElements) {
        Map<String, Object> map = new LinkedHashMap<>(2);
        map.put("content", object);
        map.put("totalElements", totalElements);
        return map;
    }

    public static <T> IPage<T> toMybatisPage(Pageable pageable) {
        return toMybatisPage(pageable, false);
    }

    public static <T> IPage<T> toMybatisPage(Pageable pageable, boolean ignoreOrderBy) {
        com.baomidou.mybatisplus.extension.plugins.pagination.Page<T> page = new com.baomidou.mybatisplus.extension.plugins.pagination.Page<>(
                pageable.getPageNumber() + 1, pageable.getPageSize());
        if (!ignoreOrderBy) {
            for (Sort.Order order : pageable.getSort()) {
                OrderItem orderItem = new OrderItem();
                orderItem.setAsc(order.isAscending());
                orderItem.setColumn(
                        com.baomidou.mybatisplus.core.toolkit.StringUtils.camelToUnderline(order.getProperty()));
                page.addOrder(orderItem);
            }
        }
        return page;
    }
}