spring data jpa 分页（基于jpa-spec扩展）

功能：

分页查询、分页排序查询、普通条件查询、多表连接条件查询；查询条件类型包括枚举、日期以及java基础类型

版本：

spring data jpa:2.1.1.RELEASE

jpa-spec:3.2.3

google guava:27.0.1-jre

jdk:1.8

主扩展类：

import com.github.wenhao.jpa.PredicateBuilder;
import com.github.wenhao.jpa.Specifications;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.xxxx.xxx.common.enums.Behavior;
import com.xxxx.xxx.common.enums.DateFormat;
import com.xxxx.xxx.common.util.ReflectionUtils;
import lombok.Data;
import org.apache.commons.lang3.time.DateUtils;
import org.springframework.data.domain.*;
import org.springframework.data.jpa.domain.Specification;


import javax.persistence.criteria.Predicate;
import java.text.ParseException;
import java.util.*;
import java.util.stream.Collectors;

/**
 * 作者： [e-mail]
 * 功能：spring data jpa查询（包括分页，基于jpa-spec扩展）
 */
@Data
public class PageEntity  {

    /**页码*/
    private Integer page;
    /**展示数据数量*/
    private Integer size;
    /**要条件查询对象的class*/
    private Class clazz;
    /**查询排序*/
    private Set<Order> orders;
    /**条件查询参数*/
    private List<specificationParam> params;

    /**
     *  分页及排序
     */
    public Pageable getPageable(){
        return PageRequest.of(page,size,this.getSorts(orders));
    }

    /**
     * 排序，内部调用
     * @param orders
     * @return
     */
    private Sort getSorts(Set<Order> orders){
        List<Sort.Order> orderList = orders.stream().map(order -> new Sort.Order(order.sort,order.name)).collect(Collectors.toList());
        return Sort.by(orderList);
    }

    /**
     * 排序
     * @return
     */
    public Sort getSort(){
        List<Sort.Order> orderList = orders.stream().map(order -> new Sort.Order(order.sort,order.name)).collect(Collectors.toList());
        return Sort.by(orderList);
    }

    /**
     *  获取查询条件
     * @param clazz
     * @return
     */
    public Specification getSpecification(Class clazz) {
        this.clazz = clazz;
        Specification result = null;
        for (specificationParam sp:params) {
            if (Predicate.BooleanOperator.AND.equals(sp.getCt())){
                if(Objects.isNull(result)){
                    result  = builderBehavior(Specifications.and(),sp).build();
                }else{
                    result = result.and(builderBehavior(Specifications.and(),sp).build());
                }
            }else{
                if(Objects.isNull(result)){
                    result  = builderBehavior(Specifications.or(),sp).build();
                }else{
                    result = result.or(builderBehavior(Specifications.or(),sp).build());
                }
            }
        }
        return result;
    }

    /**
     * 匹配查询条件行为
     * @param predicateBuilder
     * @param sp
     * @return
     */
    private PredicateBuilder builderBehavior(PredicateBuilder predicateBuilder,specificationParam sp)  {
        PredicateBuilder result = null;
        sp.setParams(parseParams(sp.getName(),sp.getParams()));
        switch (sp.getBehavior()){
            case BW: result = predicateBuilder.between(sp.getName(),sp.getParams().get(0),sp.getParams().get(1));break;
            case EQ: result = predicateBuilder.eq(sp.getName(),sp.getParams().stream().toArray());break;
            case GE: result = predicateBuilder.ge(sp.getName(),(Comparable)sp.getParams().stream().findFirst().get());break;
            case GT: result = predicateBuilder.gt(sp.getName(),(Comparable)sp.getParams().stream().findFirst().get());break;
            case IN: result = predicateBuilder.in(sp.getName(),sp.getParams().stream().toArray());break;
            case LE: result = predicateBuilder.le(sp.getName(),(Comparable)sp.getParams().stream().findFirst().get());break;
            case LK: result = predicateBuilder.like(sp.getName(), sp.getParams().stream().toArray(String[]::new));break;
            case LT: result = predicateBuilder.lt(sp.getName(),(Comparable)sp.getParams().stream().findFirst().get());break;
            case NE: result = predicateBuilder.ne(sp.getName(),sp.getParams().stream().toArray());break;
            case NI: result = predicateBuilder.notIn(sp.getName(),sp.getParams().stream().toArray());break;
            case NL: result = predicateBuilder.notLike(sp.getName(), sp.getParams().stream().toArray(String[]::new));break;
        }
        return result;
    }

    /**
     * 查询条件解析
     * @param name
     * @param params
     * @return
     */
    private List<Object> parseParams(String name,List<Object> params)  {
        clazz = ReflectionUtils.getFieldClass(clazz, name);
        List<Object> resultParams = Lists.newArrayListWithCapacity(2);
        if(clazz.isEnum()){
            for (Object param:params) {
                resultParams.add(Enum.valueOf(clazz, param.toString()));
            }
        }else if(clazz.equals(Date.class)){
            try {
                for (Object param:params) {
                    String[] dateFormats = Lists.newArrayList(DateFormat.values()).stream().map(dateFormat -> dateFormat.getDateFormat()).collect(Collectors.toList()).stream().toArray(String[]::new);
                    resultParams.add(DateUtils.parseDate(param.toString(),dateFormats));
                }
            } catch (ParseException e) {
                e.printStackTrace();
            }
        }
        return Iterables.isEmpty(resultParams)?params:resultParams;
    }

    /**
     * 查询条件内部类
     */
    @Data
    static class  specificationParam{

        /**查询条件之间的关系（and/or）*/
        private Predicate.BooleanOperator ct = Predicate.BooleanOperator.AND;
        /**查询条件的行为（等于、大于、小于……）*/
        private Behavior behavior;
        /**查询条件的参数集合*/
        private List<Object> params;
        /**查询条件的name*/
        private String name;
    }

    /**
     * 排序内部类，过滤掉相同name的排序
     */
    @Data
    static class Order{
        /**排序方式（ASC/DESC）*/
        private Sort.Direction sort;
        /**排序的name*/
        private String name;
        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }
            Order order = (Order) o;
            return name.equals(order.name);
        }
        @Override
        public int hashCode() {
            return Objects.hash(name);
        }
    }

}

扩展依赖类：

public enum Behavior {
    BW,//bwteen
    EQ,//equal
    GE,//greaterThanOrEqualTo
    GT,//greaterThan
    IN,
    LE,//lessThanOrEqualTo
    LK,//like
    LT,//lessThan
    NE,//not equal
    NI,//not in
    NL;//not like
}

/**
 * 时间模板枚举
 * 这里只添加了一个例子，如果需要扩展时间模板，请自行添加
 */
public enum DateFormat {

    YEAR_MONTH_DAY_HOURS_MIN_SEC("yyyy-MM-dd HH:mm:ss");

    private String dateFormat;

    DateFormat(String dateFormat) {
        this.dateFormat = dateFormat;
    }

    public String getDateFormat(){
        return this.dateFormat;
    }
}

ReflectionUtils：https://blog.csdn.net/Mr_wangjk/article/details/86144986

参数形式：

{
	"page":1,
	"size":10,
	"params":[{
		"name":"xxx",
		"params":["2018-12-21 11:07:44"],
		"behavior":"EQ"
	}],
	"orders":[{
		"sort":"DESC",
		"name":"xx"
	}]
}