mybatis genertor 实践及遇到的问题

xiaoxiao2024-11-11 71

参考： Spring boot Mybatis 整合（完整版）——没有坑点，一次成功 https://blog.csdn.net/Winter_chen001/article/details/77249029

https://blog.csdn.net/pucao_cug/article/details/64499355 https://blog.csdn.net/Winter_chen001/article/details/80010967 https://blog.csdn.net/qq_40307945/article/details/81351302

Mybatis Generator最完整配置详解 https://www.jianshu.com/p/e09d2370b796

文章目录

问题1 Invalid bound statement问题2 Unsatisfied dependency expressed through.。。指定generatedKey与否insert与insertseletive的区别Mybatis中updateByPrimaryKeySelective和updateByPrimaryKey更新区别

问题1 Invalid bound statement

Springboot mybatis集成 Invalid bound statement (not found) https://blog.csdn.net/qq_35981283/article/details/78590090

mybatis.typeAliasesPackage=/*pojo,entity,model 包名/ mybatis.mapperLocations=classpath:mapper/*.xml /*resource 下的mybatis xml*/

注意拼写，mapping、mapper。

问题2 Unsatisfied dependency expressed through.。。

关于SpringBoot bean无法注入的问题（与文件包位置有关）改变自动扫描的包 https://blog.csdn.net/u014695188/article/details/52263903

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘adminController’: Unsatisfied dependency expressed through field ‘adminService’; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘adminServiceImpl’: Unsatisfied dependency expressed through field ‘adminMapper’; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘adminMapper’ defined in file [D:\Development\IdeaProjects\oj\target\classes\com\simon\oj\dao\AdminMapper.class]: Unsatisfied dependency expressed through bean property ‘sqlSessionFactory’; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘sqlSessionFactory’ defined in class path resource [org/mybatis/spring/boot/autoconfigure/MybatisAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.ibatis.session.SqlSessionFactory]: Factory method ‘sqlSessionFactory’ threw exception; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: ‘file [D:\Development\IdeaProjects\oj\target\classes\mapper\AdminMapper.xml]’; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is ‘file [D:\Development\IdeaProjects\oj\target\classes\mapper\AdminMapper.xml]’. Cause: java.lang.IllegalArgumentException: Result Maps collection already contains value for com.simon.oj.dao.AdminMapper.BaseResultMap

根据错误最根本的信息Result Maps collection already contains ，定位问题其实是xml中有重名的对象。重名是因为在使用mybatis-generator时不小心多运行了一次生成，导致了mapper.xml中的内容重复。 Mybatis异常-Result Maps collection already contains value for xxx https://blog.csdn.net/loongshawn/article/details/51656699

selectAll

<property name="selectAllOrderByClause" value="age desc,username asc"/>

没有selectAll ，因为runtime 不是 MyBatis3Simple

MyBatis3 MyBatis3Simple

<context id="MySqlContext" targetRuntime="MyBatis3Simple" defaultModelType="flat"> context的targetRuntime属性设置为MyBatis3Simple是为了避免生成Example相关的代码和方法。如果需要则改为Mybatis3. defaultModelType="flat"目的是使每个表只生成一个实体类来自MyBatis学习笔记（五）：代码生成器 https://zjxkenshine.github.io/2018/03/29/MyBatis学习笔记（五）：代码生成器/

实际尝试的时候，当<table>标签下有<property>标签，且<property>标签在<generatedKey>后面的时候，会报如下错误：

The content of element type “table” must match “(property*,generatedKey?,domainObjectRenamingRule?,columnRenamingRule?,(columnOverride|ignoreColumn|ignoreColumnsByRegex)*)”.

错误时因为没有按顺序！！！ https://blog.csdn.net/Jalon2015/article/details/49422973 先写<property>，后写<generatedKey>，就好了。

The <table> Element http://www.mybatis.org/generator/configreference/table.html The <generatedKey> Element http://www.mybatis.org/generator/configreference/generatedKey.html

实际上，只要runtime选择了MyBatis3Simple，就会自动有selectAll 方法生成。

<context id="DB2Tables" targetRuntime="MyBatis3Simple">模式下生成的Mapper

public interface AdminMapper { int deleteByPrimaryKey(String idadmin); int insert(Admin record); Admin selectByPrimaryKey(String idadmin); List<Admin> selectAll(); int updateByPrimaryKey(Admin record); }

<context id="DB2Tables" targetRuntime="MyBatis3">模式下生成的Mapper

public interface AdminMapper { int deleteByPrimaryKey(String idadmin); int insert(Admin record); int insertSelective(Admin record); Admin selectByPrimaryKey(String idadmin); int updateByPrimaryKeySelective(Admin record); int updateByPrimaryKey(Admin record); }

指定generatedKey与否

在generatorConfig的table标签下，有没有<generatedKey column="idadmin" sqlStatement="JDBC" identity="true"/> 区别如下。有，insert的时候，不插入主键字段，因为主键自增。

<?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.simon.oj.dao.AdminMapper"> <resultMap id="BaseResultMap" type="com.simon.oj.pojo.Admin"> <id column="idadmin" jdbcType="VARCHAR" property="idadmin" /> <result column="password" jdbcType="VARCHAR" property="password" /> <result column="permission" jdbcType="INTEGER" property="permission" /> </resultMap> <delete id="deleteByPrimaryKey" parameterType="java.lang.String"> delete from admin where idadmin = #{idadmin,jdbcType=VARCHAR} </delete> <insert id="insert" keyColumn="idadmin" keyProperty="idadmin" parameterType="com.simon.oj.pojo.Admin" useGeneratedKeys="true"> insert into admin (password, permission) values (#{password,jdbcType=VARCHAR}, #{permission,jdbcType=INTEGER}) </insert> <update id="updateByPrimaryKey" parameterType="com.simon.oj.pojo.Admin"> update admin set password = #{password,jdbcType=VARCHAR}, permission = #{permission,jdbcType=INTEGER} where idadmin = #{idadmin,jdbcType=VARCHAR} </update> <select id="selectByPrimaryKey" parameterType="java.lang.String" resultMap="BaseResultMap"> select idadmin, password, permission from admin where idadmin = #{idadmin,jdbcType=VARCHAR} </select> <select id="selectAll" resultMap="BaseResultMap"> select idadmin, password, permission from admin order by idadmin desc </select> </mapper>

无，insert的时候插入主键在内的三个字段。

<?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.simon.oj.dao.AdminMapper"> <resultMap id="BaseResultMap" type="com.simon.oj.pojo.Admin"> <id column="idadmin" jdbcType="VARCHAR" property="idadmin" /> <result column="password" jdbcType="VARCHAR" property="password" /> <result column="permission" jdbcType="INTEGER" property="permission" /> </resultMap> <delete id="deleteByPrimaryKey" parameterType="java.lang.String"> delete from admin where idadmin = #{idadmin,jdbcType=VARCHAR} </delete> <insert id="insert" parameterType="com.simon.oj.pojo.Admin"> insert into admin (idadmin, password, permission ) values (#{idadmin,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, #{permission,jdbcType=INTEGER} ) </insert> <update id="updateByPrimaryKey" parameterType="com.simon.oj.pojo.Admin"> update admin set password = #{password,jdbcType=VARCHAR}, permission = #{permission,jdbcType=INTEGER} where idadmin = #{idadmin,jdbcType=VARCHAR} </update> <select id="selectByPrimaryKey" parameterType="java.lang.String" resultMap="BaseResultMap"> select idadmin, password, permission from admin where idadmin = #{idadmin,jdbcType=VARCHAR} </select> <select id="selectAll" resultMap="BaseResultMap"> select idadmin, password, permission from admin order by idadmin desc </select> </mapper>

目前使用的时mybatis3simple，如果使用mybatis3生成，如何进行更复杂的查询。

不用Simple模式 Mybatis-Generator 进阶用法快速开发跟sql说再见 https://www.jianshu.com/p/0155be036298 MyBatis的Mapper接口以及Example的实例函数及详解 https://blog.csdn.net/biandous/article/details/65630783 [mybatis]Example的用法 https://blog.csdn.net/zhemeban/article/details/71901759

Example类用法 https://blog.csdn.net/biandous/article/details/65630783 =====####注意。example没加条件：没写example.createCriteria(); 执行查询：selectByExample(example).====就会查询全部。

拓展：如何使用动态SQL语句？ https://blog.csdn.net/chiclewu/article/details/17082555

insert与insertseletive的区别

对于insert: //插入一条数据 //支持Oracle序列,UUID,类似Mysql的INDENTITY自动增长(自动回写) //优先使用传入的参数值,参数值空时,才会使用序列、UUID,自动增长但是要注意假如数据库字段有default，default是不会起作用的对于InsertSelective: //插入一条数据,只插入不为null的字段,不会影响有默认值的字段 //支持Oracle序列,UUID,类似Mysql的INDENTITY自动增长(自动回写) //优先使用传入的参数值,参数值空时,才会使用序列、UUID,自动增长 insertSelective不会忽略default，即为空的字段default自动填充作者：russ44 来源：原文：https://blog.csdn.net/russ44/article/details/79041944

Mybatis中updateByPrimaryKeySelective和updateByPrimaryKey更新区别

https://blog.csdn.net/shixiansen6535/article/details/81535980 insert 带Selective，只插入对应字段， insert不带Selective，插入对应字段，没插入的字段置为null （我使用的场景下，insert不带Selective，把其他置为null，后续update不带selective就可以更新null字段，所以无需Selective） update 带selective 字段不为空再更新 update 不带selective 直接更新全部（我使用场景下，本来就第一次insert之后没有填满，需要update补全的字段，所以无需加Selective）

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