架构师之hibernate实体注解------实体如何用setResultTransformer转换?

1.前言.

当你用hibernate查出数据,但是类型不是原来的类型怎么办,新增的实体类还用不用,答案是可以用的.用query.setResultTransformer(Transformers.aliasToBean(AA.class));这种形式可以解决查出来的数据不能使用的问题.

2.代码

(1)查询dao
 String sql = "select USER_ID,USERNAME from test where USER_ID= :id";
        Query query = getCurrentSession().createSQLQuery(sql);//.addScalar("MODULE_ID", LongType.INSTANCE);
        query.setBigDecimal("id", new BigDecimal("1"));
        query.setResultTransformer(Transformers.aliasToBean(UserEntity.class));
        List<UserEntity> list=null;
        list=query.list();
        return list;

(2)实体类

package com.test.ljn.sample.domain;

import java.math.BigDecimal;
import java.math.BigInteger;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

import com.test.ljn.base.domain.IBean;

import javax.persistence.Table;

import org.hibernate.annotations.PolymorphismType;
import org.hibernate.annotations.Polymorphism;

@Entity
@Table(name = "test_USER")
@Polymorphism(type = PolymorphismType.EXPLICIT)
public class UserEntity  implements IBean<Long> {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	/** 模块ID */
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "USER_ID", unique = true, nullable = false)
    private BigInteger USER_ID;

    /** 父模块ID */
    @Column(name = "USERNAME")
    private String USERNAME;



	public BigInteger getUSER_ID() {
		return USER_ID;
	}

	public void setUSER_ID(BigInteger uSER_ID) {
		USER_ID = uSER_ID;
	}

	public String getUSERNAME() {
		return USERNAME;
	}

	public void setUSERNAME(String uSERNAME) {
		USERNAME = uSERNAME;
	}


    
}

3.需要注意的.

(1)这种转换实体类很严格,必须连属性名字要和数据库字段高度一致(注解此时没很大作用用.

(2)实体类可以比表字段少一些字段.