SimpleSpecification.java

package cn.timer.api.config.specification;

import java.util.List;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;

import org.springframework.data.jpa.domain.Specification;

public class SimpleSpecification<T> implements Specification<T> {

	private static final long serialVersionUID = 9090560756576906120L;
	
	/**
	 * 查询的条件列表，是一组列表
	 */
	private List<SpecificationOperator> opers;

	public SimpleSpecification(List<SpecificationOperator> opers) {
		this.opers = opers;
	}

	@Override
	public Predicate toPredicate(Root<T> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
		int index = 0;
		// 通过resultPre来组合多个条件
		Predicate resultPre = null;
		for (SpecificationOperator op : opers) {
			if (index++ == 0) {
				resultPre = generatePredicate(root, criteriaBuilder, op);
				continue;
			}
			Predicate pre = generatePredicate(root, criteriaBuilder, op);
			if (pre == null)
				continue;
			if ("and".equalsIgnoreCase(op.getJoin())) {
				resultPre = criteriaBuilder.and(resultPre, pre);
			} else if ("or".equalsIgnoreCase(op.getJoin())) {
				resultPre = criteriaBuilder.or(resultPre, pre);
			}
		}
		return resultPre;
	}

	/**
	 * 根据不同的操作符返回特定的查询
	 */
	private Predicate generatePredicate(Root<T> root, CriteriaBuilder criteriaBuilder, SpecificationOperator op) {
		if ("=".equalsIgnoreCase(op.getOper())) {
			System.out.println(op.getKey() + "," + op.getValue());
			return criteriaBuilder.equal(root.get(op.getKey()), op.getValue());
		} else if (">=".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.ge(root.get(op.getKey()), (Number) op.getValue());
		} else if ("<=".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.le(root.get(op.getKey()), (Number) op.getValue());
		} else if (">".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.gt(root.get(op.getKey()), (Number) op.getValue());
		} else if ("<".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.lt(root.get(op.getKey()), (Number) op.getValue());
		} else if (":".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.like(root.get(op.getKey()), "%" + op.getValue() + "%");
		} else if ("l:".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.like(root.get(op.getKey()), op.getValue() + "%");
		} else if (":l".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.like(root.get(op.getKey()), "%" + op.getValue());
		} else if ("null".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.isNull(root.get(op.getKey()));
		} else if ("!null".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.isNotNull(root.get(op.getKey()));
		} else if ("!=".equalsIgnoreCase(op.getOper())) {
			return criteriaBuilder.notEqual(root.get(op.getKey()), op.getValue());
		}
		return null;
	}

}