Mybatis以Map返回，value存各个结果集对象，以指定的字段名作为key

迷南。 2022-05-23 11:11 628阅读 0赞

数据库建表语句:

CREATE TABLE `Products` (
      `prod_id` char(10) COLLATE utf8_unicode_ci NOT NULL,
      `vend_id` char(10) COLLATE utf8_unicode_ci NOT NULL,
      `prod_name` char(255) COLLATE utf8_unicode_ci NOT NULL,
      `prod_price` decimal(8,2) NOT NULL,
      `prod_desc` text COLLATE utf8_unicode_ci,
      PRIMARY KEY (`prod_id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

数据库数据:

INSERT INTO sqls.Products (prod_id, vend_id, prod_name, prod_price, prod_desc) VALUES ('BNBG01', 'DLL01', 'Fish bean bag toy', 3.49, 'Fish bean bag toy, complete with bean bag worms with which to feed it');
    INSERT INTO sqls.Products (prod_id, vend_id, prod_name, prod_price, prod_desc) VALUES ('BNBG02', 'DLL01', 'Bird bean bag toy', 3.49, 'Bird bean bag toy, eggs are not included');
    INSERT INTO sqls.Products (prod_id, vend_id, prod_name, prod_price, prod_desc) VALUES ('BNBG03', 'DLL01', 'Rabbit bean bag toy', 3.49, 'Rabbit bean bag toy, comes with bean bag carrots');
    INSERT INTO sqls.Products (prod_id, vend_id, prod_name, prod_price, prod_desc) VALUES ('BR01', 'BRS01', '8 inch teddy bear', 5.99, '8 inch teddy bear, comes with cap and jacket');
    INSERT INTO sqls.Products (prod_id, vend_id, prod_name, prod_price, prod_desc) VALUES ('BR02', 'BRS01', '12 inch teddy bear', 8.99, '12 inch teddy bear, comes with cap and jacket');
    INSERT INTO sqls.Products (prod_id, vend_id, prod_name, prod_price, prod_desc) VALUES ('BR03', 'BRS01', '18 inch teddy bear', 11.99, '18 inch teddy bear, comes with cap and jacket');
    INSERT INTO sqls.Products (prod_id, vend_id, prod_name, prod_price, prod_desc) VALUES ('RGAN01', 'DLL01', 'Raggedy Ann', 4.99, '18 inch Raggedy Ann doll');
    INSERT INTO sqls.Products (prod_id, vend_id, prod_name, prod_price, prod_desc) VALUES ('RYL01', 'FNG01', 'King doll', 9.49, '12 inch king doll with royal garments and crown');
    INSERT INTO sqls.Products (prod_id, vend_id, prod_name, prod_price, prod_desc) VALUES ('RYL02', 'FNG01', 'Queen doll', 9.49, '12 inch queen doll with royal garments and crown');

映射文件:

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.heiketu.testpackage.mapper.ProductsMapper">
        
        <select id="getResultUseMapValue" resultType="com.heiketu.testpackage.pojo.Product">
            SELECT * FROM Products
        </select>
    </mapper>

映射接口:

public interface ProductsMapper { 
        //结果集以Map形式返回，且对应的value为每一个Product对象
        @MapKey("prodId")
        Map<String,Product> getResultUseMapValue();
    }

实体类对象:

public class Product { 
    
      private String prodId;
      private String vendId;
      private String prodName;
      private Double prodPrice;
      private String prodDesc;
    
    
        @Override
        public String toString() { 
            return "Product{" +
                    "prodId='" + prodId + '\'' +
                    ", vendId='" + vendId + '\'' +
                    ", prodName='" + prodName + '\'' +
                    ", prodPrice=" + prodPrice +
                    ", prodDesc='" + prodDesc + '\'' +
                    '}';
        }
    
        public String getProdId() { 
            return prodId;
        }
    
        public void setProdId(String prodId) { 
            this.prodId = prodId;
        }
    
        public String getVendId() { 
            return vendId;
        }
    
        public void setVendId(String vendId) { 
            this.vendId = vendId;
        }
    
        public String getProdName() { 
            return prodName;
        }
    
        public void setProdName(String prodName) { 
            this.prodName = prodName;
        }
    
        public Double getProdPrice() { 
            return prodPrice;
        }
    
        public void setProdPrice(Double prodPrice) { 
            this.prodPrice = prodPrice;
        }
    
        public String getProdDesc() { 
            return prodDesc;
        }
    
        public void setProdDesc(String prodDesc) { 
            this.prodDesc = prodDesc;
        }
    }

测试代码:

SqlSession sqlSession = null;
    
    try { 
        String configFile = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(configFile);
        SqlSessionFactory build = new SqlSessionFactoryBuilder().build(inputStream);
        sqlSession = build.openSession();
    
        //以Map形式返回
        ProductsMapper mapper = sqlSession.getMapper(ProductsMapper.class);
        Map<String, Product> resultUseMapValue = mapper.getResultUseMapValue();
        System.out.println(resultUseMapValue);
    
    } catch (IOException e) { 
        e.printStackTrace();
    }finally { 
        sqlSession.close();
    }

**`该测试已经在mybaits配置文件中开启驼峰命名法规则`**

测试结果:

{ RGAN01=Product{ prodId='RGAN01', vendId='DLL01', prodName='Raggedy Ann', prodPrice=4.99, prodDesc='18 inch Raggedy Ann doll'}, BNBG01=Product{ prodId='BNBG01', vendId='DLL01', prodName='Fish bean bag toy', prodPrice=3.49, prodDesc='Fish bean bag toy, complete with bean bag worms with which to feed it'}, BNBG02=Product{ prodId='BNBG02', vendId='DLL01', prodName='Bird bean bag toy', prodPrice=3.49, prodDesc='Bird bean bag toy, eggs are not included'}, RYL02=Product{ prodId='RYL02', vendId='FNG01', prodName='Queen doll', prodPrice=9.49, prodDesc='12 inch queen doll with royal garments and crown'}, RYL01=Product{ prodId='RYL01', vendId='FNG01', prodName='King doll', prodPrice=9.49, prodDesc='12 inch king doll with royal garments and crown'}, BR03=Product{ prodId='BR03', vendId='BRS01', prodName='18 inch teddy bear', prodPrice=11.99, prodDesc='18 inch teddy bear, comes with cap and jacket'}, BR02=Product{ prodId='BR02', vendId='BRS01', prodName='12 inch teddy bear', prodPrice=8.99, prodDesc='12 inch teddy bear, comes with cap and jacket'}, BNBG03=Product{ prodId='BNBG03', vendId='DLL01', prodName='Rabbit bean bag toy', prodPrice=3.49, prodDesc='Rabbit bean bag toy, comes with bean bag carrots'}, BR01=Product{ prodId='BR01', vendId='BRS01', prodName='8 inch teddy bear', prodPrice=5.99, prodDesc='8 inch teddy bear, comes with cap and jacket'}}

**`总结:`**`如果想返回值的key为实体类的主键名，value为各个实体类对象，那么需要在mapper的映射文件中resultType设置为实体类全路径名。在映射接口文件的抽象类方法上加上@MayKey注解并指定以哪个属性名作为key的值。`