Spring Data JPA原生SQL查询

package com.wanda.cms.dao.repository;import org.springframework.stereotype.Repository;import javax.persistence.EntityManager;import javax.persistence.PersistenceContext;import javax.persistence.Query;import java.math.BigInteger;import java.util.*;

/** * 构建复杂查询 * @author lchb */@Repositorypublic class NativeQueryRepository{

    @PersistenceContext    private EntityManager entityManager;

    /**     * 根据sql查询     * @param sql     * @param resultClass     * @param <T>     * @return     */    public <T> List<T> findBySql(String sql,Class resultClass){        Query nativeQuery=null;        if(resultClass!=null && !resultClass.equals(Object.class)) {            nativeQuery = entityManager.createNativeQuery(sql, resultClass);        }else{            nativeQuery = entityManager.createNativeQuery(sql);        }

        List rows = nativeQuery.getResultList();        List<T> resultList=new ArrayList<T>();        for (Object obj : rows) {            T row=(T)obj;            resultList.add(row);        }        return resultList;    }

    /**     * 根据参数查询     * @param sql     * @param parameters     * @param resultClass     * @param <T>     * @return     */    public <T> List<T> findBySql(String sql,Map<String,Object> parameters,Class resultClass){        Query nativeQuery=null;        if(resultClass!=null && !resultClass.equals(Object.class)) {            nativeQuery = entityManager.createNativeQuery(sql, resultClass);        }else{            nativeQuery = entityManager.createNativeQuery(sql);        }

        Iterator<Map.Entry<String,Object>> entries = parameters.entrySet().iterator();        while (entries.hasNext()) {            Map.Entry<String,Object> entry = entries.next();            nativeQuery.setParameter(entry.getKey(),entry.getValue());        }

        List rows = nativeQuery.getResultList();        List<T> resultList=new ArrayList<T>();        for (Object obj : rows) {            T row=(T)obj;            resultList.add(row);        }        return resultList;    }

    public Integer findCountBySql(String sql,Map<String,Object> parameters){        List<Object> list=this.findBySql(sql,parameters,Object.class);        BigInteger total=(BigInteger)list.get(0);        return total.intValue();    }

}