环境准备
mysql:5.7
jdk:1.8
创建项目
通过Spring Initializr方式创建,
添加依赖包
<dependencies>
<!--SpringBoot通用依赖模块-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!--MyBatis分页插件-->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.4.1</version>
</dependency>
<!-- MyBatis 生成器 -->
<dependency>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-core</artifactId>
<version>1.3.3</version>
</dependency>
<!--Mysql数据库驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.15</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
修改.yml配置文件
server:
port: 8082
spring:
datasource:
url: jdbc:mysql://localhost:3306/mall?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
username: root
password: root_123
mybatis:
mapper-locations:
- classpath:mapper/*.xml
- classpath*:com/**/mapper/*.xml
添加代码生成器
package com.example.studyspringbootmybatis.mbg;
import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.internal.DefaultShellCallback;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
/**
* 用于生产MBG的代码
*/
public class Generator {
public static void main(String[] args) throws Exception {
//MBG 执行过程中的警告信息
List<String> warnings = new ArrayList<String>();
//当生成的代码重复时，覆盖原代码
boolean overwrite = true;
//读取我们的 MBG 配置文件
InputStream is = Generator.class.getResourceAsStream("/generatorConfig.xml");
ConfigurationParser cp = new ConfigurationParser(warnings);
Configuration config = cp.parseConfiguration(is);
is.close();
DefaultShellCallback callback = new DefaultShellCallback(overwrite);
//创建 MBG
MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
//执行生成代码
myBatisGenerator.generate(null);
//输出警告信息
for (String warning : warnings) {
System.out.println(warning);
}
}
}
#数据库配置文件generator.properties
jdbc.driverClass=com.mysql.cj.jdbc.Driver
jdbc.connectionURL=jdbc:mysql://localhost:3306/mall?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
jdbc.userId=root
jdbc.password=root_123
#代码生成配置文件generatorConfig.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
"http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
<properties resource="generator.properties"/>
<context id="MySqlContext" targetRuntime="MyBatis3" defaultModelType="flat">
<property name="beginningDelimiter" value="`"/>
<property name="endingDelimiter" value="`"/>
<property name="javaFileEncoding" value="UTF-8"/>
<!-- 为模型生成序列化方法-->
<plugin type="org.mybatis.generator.plugins.SerializablePlugin"/>
<!-- 为生成的Java模型创建一个toString方法 -->
<plugin type="org.mybatis.generator.plugins.ToStringPlugin"/>
<!--可以自定义生成model的代码注释-->
<commentGenerator type="com.example.studyspringbootmybatis.mbg.CommentGenerator">
<!-- 是否去除自动生成的注释 true：是 ： false:否 -->
<property name="suppressAllComments" value="true"/>
<property name="suppressDate" value="true"/>
<property name="addRemarkComments" value="true"/>
</commentGenerator>
<!--配置数据库连接-->
<jdbcConnection driverClass="${jdbc.driverClass}"
connectionURL="${jdbc.connectionURL}"
userId="${jdbc.userId}"
password="${jdbc.password}">
<!--解决mysql驱动升级到8.0后不生成指定数据库代码的问题-->
<property name="nullCatalogMeansCurrent" value="true" />
</jdbcConnection>
<!--指定生成model的路径-->
<javaModelGenerator targetPackage="com.example.studyspringbootmybatis.mbg.model" targetProject="study-springboot-mybatis\src\main\java"/>
<!--指定生成mapper.xml的路径-->
<sqlMapGenerator targetPackage="com.example.studyspringbootmybatis.mbg.mapper" targetProject="study-springboot-mybatis\src\main\resources"/>
<!--指定生成mapper接口的的路径-->
<javaClientGenerator type="XMLMAPPER" targetPackage="com.example.studyspringbootmybatis.mbg.mapper"
targetProject="study-springboot-mybatis\src\main\java"/>
<!--生成全部表tableName设为%-->
<table tableName="pms_brand">
<generatedKey column="id" sqlStatement="MySql" identity="true"/>
</table>
</context>
</generatorConfiguration>
创建Mybatis配置类
package com.example.studyspringbootmybatis.config;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Configuration;
/**
* MyBatis配置类
*/
@Configuration
@MapperScan("com.example.studyspringbootmybatis.mbg.mapper")
public class MyBatisConfig {
}
编写业务代码
遇到问题
Description:
The dependencies of some of the beans in the application context form a cycle:
┌──->──┐
| com.github.pagehelper.autoconfigure.PageHelperAutoConfiguration
└──<-──┘
Action:
Relying upon circular references is discouraged and they are prohibited by default. Update your application to remove the dependency cycle between beans.
As a last resort, it may be possible to break the cycle automatically by setting spring.main.allow-circular-references to true.
解决升级 Spring Boot 2.6后，因循环引用导致启动时报错的问题
原因是SprinBoot与PageHelper的版本冲突导致的，使用SpringBoot2.6及以上版本，对应的PageHelper版本应该在1.4.1及以上。
<!--分页插件PageHelper-->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.4.1</version>
</dependency>
依赖循环引用是不鼓励的，默认情况下是禁止的。更新应用程序以删除bean之间的依赖循环。
作为最后的手段，可以通过设置spring.main来自动打破循环。spring.main.allow-circular-references=true
