1 共通代码

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
import org.hibernate.query.internal.NativeQueryImpl;
import org.hibernate.transform.Transformers;
public class UserDao{
    @PersistenceContext
    private EntityManager entityManager;
}

2 createQuery()

使用HQL语句实现查询，以hibernate生成的Bean为对象装入list返回 。

EntityManager entityManager;
String hql="Select * From User";
List<User> userList=entityManager.createQuery(hql);

3 createNativeQuery()

使用SQL语句实现查询。

3.1 查询List

    /**
     * 得到用户信息
     */
    public List<SysUserDto> getUserList(String username, String jobNumer) {
        String sql="select t1.user_id userId,t1.user_name userName,t1.postid postId,t1.jobnumer jobNumer,t1.dept_id deptId,t4.dept_name deptName " +
                " from sys_user t1" ;
        List<Object> params = new ArrayList<>();
        if(com.pit.common.utils.StringUtils.isNotBlank(username)){
            sql+=" and t1.user_name like ?";
            params.add("%"+username+"%");
        }
        if(com.pit.common.utils.StringUtils.isNotBlank(jobNumer)){
            sql+=" and t1.jonumer like ?";
            params.add("%"+jobNumer+"%");
        }
        Query contentQuery = entityManager.createNativeQuery(sql.toString());
        for (int i = 0; i < params.size(); i++) {
            contentQuery.setParameter(i + 1, params.get(i));
        }
        contentQuery.unwrap(NativeQueryImpl.class).setResultTransformer(Transformers.aliasToBean(SysUserDto.class));
        List<SysUserDto> results = contentQuery.getResultList();
        return results;
    }

3.2 查询数量

    /**
     * 得到用户信息数量
     */
    public int getUserListCount( String username, String jobNumer) {
        String sql="select count(*) " +
                " from sys_user t1" ;
        List<Object> params = new ArrayList<>();
        if(com.pit.common.utils.StringUtils.isNotBlank(username)){
            sql+=" and t1.user_name like ?";
            params.add("%"+username+"%");
        }
        if(com.pit.common.utils.StringUtils.isNotBlank(jobNumer)){
            sql+=" and t1.jobnumer like ?";
            params.add("%"+jobNumer+"%");
        }
        Query contentQuery = entityManager.createNativeQuery(sql.toString());
        for (int i = 0; i < params.size(); i++) {
            contentQuery.setParameter(i + 1, params.get(i));
        }
        Object result = contentQuery.getSingleResult();
        int count = 0;
        if (null != result  && !"".equals(result.toString())) {
            count = Integer.parseInt(result.toString());
        }
        return count;
    }