Hibernate Criteria API根实体别名覆盖问题解析与应对策略

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;
import org.hibernate.transform.Transformers;

import javax.persistence.*;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

// 假设这是一个通用的DAO方法
public class GenericDao<T> {

    protected Session getSession() {
        // 实际应用中应从SessionFactory获取
        throw new UnsupportedOperationException("Implement getSession() method");
    }

    protected void begin() {
        // 实际应用中应开启事务
    }

    protected void commit() {
        // 实际应用中应提交事务
    }

    protected List<T> findByProjectionCriteria() {
        // 尝试设置自定义别名 "temp"
        Criteria cr = getSession().createCriteria(Vehicle.class, "temp");
        cr.setResultTransformer(Transformers.aliasToBean(Vehicle.class));

        ProjectionList projectionList = Projections.projectionList();
        projectionList.add(Projections.property("vehicleId"), "vehicleId");
        projectionList.add(Projections.property("vin"), "vin");
        projectionList.add(Projections.property("initialRegistration"), "initialRegistration");
        cr.setProjection(projectionList);

        cr.add(Restrictions.eq("vin", "WVW29343249702776"));

        begin();
        List<T> list = null;
        try {
            list = cr.list();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            commit();
        }

        if (list == null) {
            list = new ArrayList<>();
        }
        return list;
    }
}

// 实体定义
@Entity
@Table(name = "vehicle")
class Vehicle {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "vehicle_id", unique = true, nullable = false)
    private int vehicleId;

    @Column(nullable = false, length = 17)
    private String vin;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "initial_registration")
    private Date initialRegistration;

    // Getter和Setter省略
    public int getVehicleId() { return vehicleId; }
    public void setVehicleId(int vehicleId) { this.vehicleId = vehicleId; }
    public String getVin() { return vin; }
    public void setVin(String vin) { this.vin = vin; }
    public Date getInitialRegistration() { return initialRegistration; }
    public void setInitialRegistration(Date initialRegistration) { this.initialRegistration = initialRegistration; }
}

select temp.vehicle_id as y0_, temp.vin as y1_,temp.initial_registration as y2_ from vehicle temp where temp.vin=?

select this_.vehicle_id as y0_, this_.vin as y1_,this_.initial_registration as y2_ from vehicle this_ where this_.vin=?

private void createCriteriaSQLAliasMap() {
    int i = 0;
    // 遍历所有Criteria对象（包括根Criteria和关联Criteria）
    Iterator criteriaIterator = criteriaEntityNames.entrySet().iterator();
    while ( criteriaIterator.hasNext() ) {
        Map.Entry me = ( Map.Entry ) criteriaIterator.next();
        Criteria crit = ( Criteria ) me.getKey(); // Criteria对象作为key
        String alias = crit.getAlias(); // 获取用户为该Criteria设置的别名
        if ( alias == null ) {
            alias = ( String ) me.getValue(); // 如果用户未设置，则使用实体名作为别名
        }
        // 将Criteria对象及其生成的SQL别名存入map
        criteriaSQLAliasMap.put( crit, StringHelper.generateAlias( alias, i++ ) );
    }
    // 关键步骤：在这里，根Criteria的别名被强制设置为rootSQLAlias
    criteriaSQLAliasMap.put( rootCriteria, rootSQLAlias );
}

// 即使表别名是this_，以下代码通常也能正常工作
// Projections.property("vin") 会被Hibernate内部翻译为 this_.vin
projectionList.add(Projections.property("vin"), "vin");
cr.add(Restrictions.eq("vin", "WVW29343249702776"));

// HQL允许你直接在FROM子句中指定别名
String hql = "SELECT v.vehicleId, v.vin, v.initialRegistration " +
             "FROM Vehicle v WHERE v.vin = :vin";
List<Vehicle> vehicles = getSession().createQuery(hql, Vehicle.class)
                                     .setParameter("vin", "WVW29343249702776")
                                     .list();

// 原生SQL提供完全的控制
String sql = "SELECT temp.vehicle_id as vehicleId, temp.vin as vin, temp.initial_registration as initialRegistration " +
             "FROM vehicle temp WHERE temp.vin = :vin";
List<Vehicle> vehicles = getSession().createNativeQuery(sql, Vehicle.class)
                                     .setParameter("vin", "WVW29343249702776")
                                     .list();