org.mytms.common.dao.querydsl.QSort.java Source code

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Here is the source code for org.mytms.common.dao.querydsl.QSort.java

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/*
 * Copyright 2013-2017 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
 *
 *      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.mytms.common.dao.querydsl;

import org.mytms.common.data.Sort;
import com.querydsl.core.types.Expression;
import com.querydsl.core.types.OrderSpecifier;
import com.querydsl.core.types.Path;
import org.springframework.util.Assert;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

/**
 * Sort option for queries that wraps a Querydsl {@link OrderSpecifier}.
 * 
 * @author Thomas Darimont
 * @author Christoph Strobl
 */
public class QSort extends Sort implements Serializable {

    private static final long serialVersionUID = -6701117396842171930L;
    private static final QSort UNSORTED = new QSort();

    private final List<OrderSpecifier<?>> orderSpecifiers;

    /**
     * Creates a new {@link QSort} instance with the given {@link OrderSpecifier}s.
     * 
     * @param orderSpecifiers must not be {@literal null} .
     */
    public QSort(OrderSpecifier<?>... orderSpecifiers) {
        this(Arrays.asList(orderSpecifiers));
    }

    /**
     * Creates a new {@link QSort} instance with the given {@link OrderSpecifier}s.
     * 
     * @param orderSpecifiers must not be {@literal null}.
     */
    public QSort(List<OrderSpecifier<?>> orderSpecifiers) {

        super(toOrders(orderSpecifiers));

        this.orderSpecifiers = orderSpecifiers;
    }

    public static QSort by(OrderSpecifier<?>... orderSpecifiers) {
        return new QSort(orderSpecifiers);
    }

    public static QSort unsorted() {
        return UNSORTED;
    }

    /**
     * Converts the given {@link OrderSpecifier}s into a list of {@link Order}s.
     * 
     * @param orderSpecifiers must not be {@literal null} or empty.
     * @return
     */
    private static List<Order> toOrders(List<OrderSpecifier<?>> orderSpecifiers) {

        Assert.notNull(orderSpecifiers, "Order specifiers must not be null!");

        return orderSpecifiers.stream().map(QSort::toOrder).collect(Collectors.toList());
    }

    /**
     * Converts the given {@link OrderSpecifier} into an {@link Order}.
     * 
     * @param orderSpecifier must not be {@literal null}.
     * @return
     */
    private static Order toOrder(OrderSpecifier<?> orderSpecifier) {

        Assert.notNull(orderSpecifier, "Order specifier must not be null!");

        Expression<?> target = orderSpecifier.getTarget();

        Object targetElement = target instanceof Path ? preparePropertyPath((Path<?>) target) : target;

        Assert.notNull(targetElement, "Target element must not be null!");

        return new Order(targetElement.toString())
                .with(orderSpecifier.isAscending() ? Direction.ASC : Direction.DESC);
    }

    /**
     * @return the orderSpecifier
     */
    public List<OrderSpecifier<?>> getOrderSpecifiers() {
        return orderSpecifiers;
    }

    /**
     * Returns a new {@link QSort} consisting of the {@link OrderSpecifier}s of the current {@code QSort} combined with
     * the ones from the given {@code QSort}.
     * 
     * @param sort can be {@literal null}.
     * @return
     */
    public QSort and(QSort sort) {
        return sort == null ? this : and(sort.getOrderSpecifiers());
    }

    /**
     * Returns a new {@link QSort} consisting of the {@link OrderSpecifier}s of the current {@link QSort} combined with
     * the given ones.
     * 
     * @param orderSpecifiers must not be {@literal null} or empty.
     * @return
     */
    public QSort and(List<OrderSpecifier<?>> orderSpecifiers) {

        Assert.notEmpty(orderSpecifiers, "OrderSpecifiers must not be null or empty!");

        List<OrderSpecifier<?>> newOrderSpecifiers = new ArrayList<>(this.orderSpecifiers);
        newOrderSpecifiers.addAll(orderSpecifiers);

        return new QSort(newOrderSpecifiers);
    }

    /**
     * Returns a new {@link QSort} consisting of the {@link OrderSpecifier}s of the current {@link QSort} combined with
     * the given ones.
     * 
     * @param orderSpecifiers must not be {@literal null} or empty.
     * @return
     */
    public QSort and(OrderSpecifier<?>... orderSpecifiers) {

        Assert.notEmpty(orderSpecifiers, "OrderSpecifiers must not be null or empty!");
        return and(Arrays.asList(orderSpecifiers));
    }

    /**
     * Recursively creates a dot-separated entityPath for the property entityPath.
     * 
     * @param path must not be {@literal null}.
     * @return
     */
    private static String preparePropertyPath(Path<?> path) {

        Path<?> root = path.getRoot();

        return root == null || path.equals(root) ? path.toString()
                : path.toString().substring(root.toString().length() + 1);
    }
}