mybatis有结果返回null

本是古典何须时尚 2021-11-16 09:52 432阅读 0赞

解决：application.yml 中mybatis此项（解决驼峰及数据库字段有下划线问题）

map-underscore-to-camel-case: true

问题：

mybatis debug模式有结果，但返回时绑定不上，返回null

2019-07-02 21:30:01.000  INFO 13908 --- [nio-8705-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 6 ms
    before:UserDto{id='null', name='aaa'}
    
    Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@365ae636] was not registered for synchronization because synchronization is not active
    2019-07-02 21:30:05.548  INFO 13908 --- [nio-8705-exec-1] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
    2019-07-02 21:30:06.108  INFO 13908 --- [nio-8705-exec-1] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
    JDBC Connection [HikariProxyConnection@1029331665 wrapping com.mysql.jdbc.JDBC4Connection@6a9043f2] will not be managed by Spring
    ==>  Preparing: select id as USER_ID from t_user where name=? 
    ==> Parameters: aaa(String)
    <==    Columns: USER_ID
    <==        Row: 111
    <==      Total: 1
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@365ae636]
    after:null
    2019-07-02 21:36:12.590  WARN 13908 --- [l-1 housekeeper] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Thread starvation or clock leap detected (housekeeper delta=6m6s378ms486µs221ns).

mapper.xml

<?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.example.mybatistest.mapper.ISelectIdMapper">
    <select id="selectId" resultType="com.example.mybatistest.mapper.UserDto" parameterType="com.example.mybatistest.mapper.UserDto">
        select id as USER_ID from t_user where name=#{name}
    </select>
    </mapper>

service.java

package com.example.mybatistest.service.impl;
    
    import com.example.mybatistest.mapper.ISelectIdMapper;
    import com.example.mybatistest.mapper.UserDto;
    import com.example.mybatistest.service.IQueryIdByName;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    /**
     * @Title:
     * @Auther: test
     * @Date: 2019/6/24 17:25
     * @Version: 1.0
     * @Description:
     */
    @Service
    public class QueryIdByNameImpl implements IQueryIdByName {
        @Autowired
        private ISelectIdMapper selectIdMapper;
    
        @Override
        public String queryIdByName(String name) {
            UserDto userDto=new UserDto();
            userDto.setName(name);
            System.out.println("before:"+userDto);
    
            userDto=selectIdMapper.selectId(userDto);
            System.out.println("after:"+userDto);
            return ((UserDto) userDto).toString();
        }
    }

dto.java

package com.example.mybatistest.mapper;
    
    /**
     * @Title:
     * @Auther: test
     * @Date: 2019/7/2 20:55
     * @Version: 1.0
     * @Description:
     */
    public class UserDto {
        private String userId;
        private String name;
    
        public String getUserId() {
            return userId;
        }
    
        public void setUserId(String userId) {
            this.userId = userId;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        @Override
        public String toString() {
            return "UserDto{" +
                    "id='" + userId + '\'' +
                    ", name='" + name + '\'' +
                    '}';
        }
    }

yml配置

spring:
      application:
        name: service-mybatistest
      datasource:
        # 数据库配置
        url: jdbc:mysql://192.168.1.1:3306/test?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=UTF-8&useSSL=false&autoReconnect=true&failOverReadOnly=false&maxReconnects=10
        username: test
        password: test
        driverClassName: com.mysql.jdbc.Driver
    server:
      port: 8705
    mybatis:
      configuration:
     #下面这项要开启
        map-underscore-to-camel-case: true
        log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
      mapper-locations: classpath:mappers/*.xml
    eureka:
      client:
        serviceUrl:
          #指向注册中心
          defaultZone: http://192.168.111.133:8888/eureka/
      instance:
        # 每间隔1s，向服务端发送一次心跳，证明自己依然”存活“
        lease-renewal-interval-in-seconds: 1
        # 告诉服务端，如果我2s之内没有给你发心跳，就代表我“死”了，将我踢出掉。
        lease-expiration-duration-in-seconds: 2

转载于:https://www.cnblogs.com/pu20065226/p/11123354.html