Mybatis实体类对象入参查询笔记

Myth丶恋晨 2022-05-23 07:12 156阅读 0赞

测试实体类对象结构如下:

/** 使用lobmok插件 */
    @Getter
    @Setter
    @NoArgsConstructor
    @ToString
    @EqualsAndHashCode
    public class Vendor { 
        private String vend_id;
        private String vend_name;
        private String vend_address;
        private String vend_city;
        private String vend_state;
        private String vend_zip;
        private String vend_country;
    }

XML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.mybatis.mapper.VendorMapper">  
      <select id="findByVendorEntity" parameterType="vendor" resultType="vendor">
      	select * from Vendors where vend_id = #{vend_id} and vend_name = #{vend_name}
      </select>
    </mapper>

接口文件

public interface VendorMapper { 
    	//通过Vendor对象查询
    	Vendors findByVendorEntity(Vendor vendor);
    }

测试文件内容:

try {
    			String resource = "mybatis-config.xml";
    			InputStream resourceAsStream = Resources.getResourceAsStream(resource);
    			SqlSessionFactory build = new SqlSessionFactoryBuilder().build(resourceAsStream,"development2");
    			//获取SQLSession
    			SqlSession openSession = build.openSession();
    			
    			VendorMapper mapper = openSession.getMapper(VendorMapper.class);
    			Vendor vendor = new Vendor();
    			vendor.setId("BRE02");
    			vendor.setName("Bear Emporium");
    			
    			Vendor findByVendorEntity = mapper.findByVendorEntity(vendor);
    			System.out.println(findByVendorEntity);
    		} catch (IOException e) {
    			System.out.println("加载配置文件失败");
    			e.printStackTrace();
    		}

笔记:

当对象作为参数传入查询时(不一定指定`parameterType`属性值为实体对象的别名或全路径名,typeHandler貌似会自动识别),SQL查询语句的`#{}`中内容需要与实体类的字段属性一一对应(并非实体类的属性一定是数据库表中的字段,只要填入的值对应即可。mybatis查询条件是看sql语句的where后的查询条件)，如果表达式中的值没有对应，则会报错。  
错误示例如下:

`....Cause:org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ids' in 'class com.mybatis.beans.Vendors' ....Cause:org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'ids' in 'class com.mybatis.beans.Vendors'...`