jsgkj/gkaq/yjpt-java/trunk/java_src/com/jtgh/yjpt/common/SpecificationCreater.java

package com.jtgh.yjpt.common;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

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

import org.apache.commons.lang3.StringUtils;
import org.springframework.data.jpa.domain.Specification;

import com.jtgh.yjpt.common.PredicateModel.JoinType;

/**
 * Create Specification in the sense of Domain Driven Design
 * 
 * @author 袁晓冬
 * 
 */
public class SpecificationCreater {
	/**
	 * 根据PredicateModel集合构造查询
	 * 
	 * @param pms
	 * @param clazz
	 * @return
	 */
	public static <T> ModelSpecification<T> searchByPredicateModels(
			Collection<PredicateModel> pms) {
		return new ModelSpecification<T>(pms);
	}

	/**
	 * 根据PredicateModel集合构造查询
	 * 
	 * @param pms
	 * @param clazz
	 * @return
	 */
	public static <T> ModelSpecification<T> searchByPredicateModels_OR(
			Collection<PredicateModel> pms) {
		return new ModelSpecification<T>(pms, PredicateModel.JoinType.OR);
	}

	/**
	 * 可以处理PredicateModel模型的Specification
	 * 
	 * @author 袁晓冬
	 * 
	 * @param <T>
	 */
	public static class ModelSpecification<T> implements Specification<T> {
		private PredicateModel predicateModel;
		private List<PredicateJoin> joins = null;

		public ModelSpecification(Collection<PredicateModel> pms) {
			this.predicateModel = new PredicateModel(
					PredicateModel.JoinType.AND, pms);
		}

		/**
		 * 利用or连接查询条件
		 * 
		 * @param pms
		 * @param type
		 */
		public ModelSpecification(Collection<PredicateModel> pms, JoinType type) {
			this.predicateModel = new PredicateModel(type, pms);
		}

		public List<PredicateJoin> getJoins() {
			return joins;
		}

		public void setJoins(List<PredicateJoin> joins) {
			this.joins = joins;
		}

		@Override
		public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query,
				CriteriaBuilder cb) {
			if (null != joins && joins.size() > 0) {
				for (PredicateJoin join : joins) {
					root.join(
							root.getModel().getList(join.getField(),
									join.getClazz()), join.getType());
				}
			}
			if (predicateModel == null
					|| (predicateModel.getFieldName() == null && !predicateModel
							.hasSubPredicateModel())) {
				// 无查询条件
				return cb.conjunction();
			}
			return toPredicateFromModel(predicateModel, root, cb);
		}

		@SuppressWarnings({ "unchecked", "rawtypes" })
		private Predicate toPredicateFromModel(PredicateModel pm, Root<T> root,
				CriteriaBuilder cb) {
			if (pm.hasSubPredicateModel()) {// 处理下级模型
				List<Predicate> predicateList = new ArrayList<Predicate>();
				for (PredicateModel p : pm.getSubPms()) {
					predicateList.add(toPredicateFromModel(p, root, cb));
				}
				Predicate[] predicates = new Predicate[predicateList.size()];
				predicateList.toArray(predicates);
				switch (pm.getJoinType()) {
				case AND:
					return cb.and(predicates);
				case OR:
					return cb.or(predicates);
				default:
					return cb.and(predicates);
				}
			} else {// 无下级模型时
				// nested path translate, 如Task的名为"user.name"的filedName,
				// 转换为Task.user.name属性
				String[] names = StringUtils.split(pm.getFieldName(), ".");
				Path expression = root.get(names[0]);
				for (int i = 1; i < names.length; i++) {
					expression = expression.get(names[i]);
				}
				// logic operator
				switch (pm.getOperator()) {
				case IN:
					In in = cb.in(expression);
					Iterable<?> it = (Iterable<?>) pm.getValue();
					for (Object o : it) {
						in.value(o);
					}
					return in;
				case EQ:
					return cb.equal(expression, pm.getValue());
				case NEQ:
					return cb.notEqual(expression, pm.getValue());
				case LIKE:
					return cb.like(expression.as(String.class), "%" + pm.getValue() + "%");
				case LIKE_L:
					return cb.like(expression.as(String.class), "%" + pm.getValue());
				case LIKE_R:
					return cb.like(expression.as(String.class), pm.getValue() + "%");
				case GT:
					return cb.greaterThan(expression,
							(Comparable) pm.getValue());
				case LT:
					return cb.lessThan(expression, (Comparable) pm.getValue());
				case GTE:
					return cb.greaterThanOrEqualTo(expression,
							(Comparable) pm.getValue());
				case LTE:
					return cb.lessThanOrEqualTo(expression,
							(Comparable) pm.getValue());
				case NL:
					return cb.isNull(expression);
				case NNL:
					return cb.isNotNull(expression);
				default:
					return cb.equal(expression, pm.getValue());
				}
			}
		}
	}

}