Spring Boot 整合 Mybatis

MyBatis 是一款优秀的持久层框架，它支持定制化 SQL 、存储过程以及高级映射。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。这里介绍 Spring Boot 整合 Mybatis 的步骤，数据库选用 MYSQL

创建 Spring Boot 项目

本博客之前已经介绍过了，这里就不在叙述

修改 pom.xml

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.2</version>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>

<dependency>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-maven-plugin</artifactId>
    <version>1.3.7</version>
</dependency>

修改 Spring Boot 配置文件

这里使用 yml 格式的配置文件，将 application.properties 改名为 application.yml,下面配置请根据自己的需求而修改

# 端口
server:
  port: 8080

# 配置数据源
spring:
  datasource:
     url: jdbc:mysql://127.0.0.1:3306/databaseName?useUnicode=true&characterEncoding=utf8
     username: root
     password: root
     driver-class-name: com.mysql.jdbc.Driver

# 打印 SQL 语句信息
logging:
 level:
   com.mysql.api: debug

debug: false

Spring Boot 会自动加载 application.yml 相关配置，数据源就会自动注入到s qlSessionFactory 中，sqlSessionFactory 会自动注入到 Mapper 中。

使用 Mybatis-generator 插件快速生成代码

配置 pom.xml

添加 Mybatis-generator 插件

<dependency>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-maven-plugin</artifactId>
    <version>1.3.7</version>
</dependency>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <fork>true</fork>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-maven-plugin</artifactId>
            <version>1.3.7</version>
            <configuration>
                <configurationFile>src/main/resources/generatorConfig.xml</configurationFile>
                <verbose>true</verbose>
                <overwrite>true</overwrite>
            </configuration>
            <executions>
                <execution>
                    <id>Generate MyBatis Artifacts</id>
                    <goals>
                        <goal>generate</goal>
                    </goals>
                </execution>
            </executions>
            <dependencies>
                <dependency>
                    <groupId>org.mybatis.generator</groupId>
                    <artifactId>mybatis-generator-core</artifactId>
                    <version>1.3.7</version>
                </dependency>
            </dependencies>
        </plugin>
    </plugins>
</build>

编写配置文件 generatorConfig.xml

在 IntelliJ IDEA 开发环境下，此文件需要放在 resource 根目录下，mybatis generator 默认加载此目录的配置文件，以下文件需要根据自己的情况进行配置

<?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>
    <!--数据库驱动jar -->
    <classPathEntry
        location="D:\.m2\repository\mysql\mysql-connector-java\5.1.33\mysql-connector-java-5.1.33.jar" />

    <context id="Tables" targetRuntime="MyBatis3">
        <!--去除注释 -->
        <commentGenerator>
            <property name="suppressDate" value="true"/>
            <property name="suppressAllComments" value="true" />
        </commentGenerator>

        <!--数据库连接 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
            connectionURL="jdbc:mysql://129.1.18.18:3306/ssm_demo" userId="root"
            password="root">
        </jdbcConnection>
        <!--默认false Java type resolver will always use java.math.BigDecimal if 
            the database column is of type DECIMAL or NUMERIC. -->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <!--生成实体类 指定包名 以及生成的地址 （可以自定义地址，但是路径不存在不会自动创建 使用Maven生成在target目录下，会自动创建） -->
        <javaModelGenerator targetPackage="com.myapp.api.entity"
                            targetProject="src/main/java">
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>
        <!--生成SQLMAP文件 -->
        <sqlMapGenerator targetPackage="mapping"
                         targetProject="src/main/resources">
            <property name="enableSubPackages" value="false" />
        </sqlMapGenerator>
        <!-- 生成DAO的包名和位置-->
        <!-- XMLMAPPER生成xml映射文件, ANNOTATEDMAPPER 生成的 dao 采用注解来写sql -->
        <javaClientGenerator type="ANNOTATEDMAPPER"
                             targetPackage="com.myapp.api.mapper"
                             targetProject="src/main/java">
            <property name="enableSubPackages" value="false" />
        </javaClientGenerator>

        <!--对应数据库表  mysql 可以加入主键自增 字段命名 忽略某字段等 -->
        <table tableName="" domainObjectName=""
            enableCountByExample="false" enableUpdateByExample="false"
            enableDeleteByExample="false" enableSelectByExample="false"
            selectByExampleQueryId="false" />
    </context>
</generatorConfiguration>

在 IntelliJ IDEA 配置

配置命令 mybatis-generator:generate -e

配置好之后点击旁边的运行按钮

当然也可以在 plugins 中找到 mybatis-generator，双击运行或右击运行都可

配置 Spring Boot 自动创建或者更新表结构

配置 pom.xml

<dependency>
    <groupId>com.gitee.sunchenbin.mybatis.actable</groupId>
    <artifactId>mybatis-enhance-actable</artifactId>
    <version>1.0.3</version>
</dependency>

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.8</version>
</dependency>
<dependency>
    <groupId>net.sf.json-lib</groupId>
    <artifactId>json-lib</artifactId>
    <version>2.4</version>
    <classifier>jdk15</classifier>
    <exclusions>
        <exclusion>
            <artifactId>commons-logging</artifactId>
            <groupId>commons-logging</groupId>
        </exclusion>
    </exclusions>
</dependency>

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.10</version>
</dependency>

配置 application.properties

mybatis.table.auto=update
mybatis.model.pack=com.myapp.api.entity
mybatis.database.type=mysql

• 当 mybatis.table.auto=create 时，系统启动后，会将所有的表删除掉，然后根据 model 中配置的结构重新建表，该操作会破坏原有数据。
• 当 mybatis.table.auto=update 时，系统会自动判断哪些表是新建的，哪些字段要修改类型等，哪些字段要删除，哪些字段要新增，该操作不会破坏原有数据。
• 当 mybatis.table.auto=none 时，系统不做任何处理。
• mybatis.model.pack 这个配置是用来配置要扫描的用于创建表的对象的包名
• mybatis.database.type 这个是用来区别数据库的，预计会支持这四种数据库 mysql/oracle/sqlserver/postgresql，但目前仅支持 mysql

编写配置文件

com.myapp.api.config/MyBatisMapperScannerConfig.java

package com.myapp.api.config;

import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@AutoConfigureAfter(MybatisTableConfig.class)
public class MyBatisMapperScannerConfig {

    @Bean
    public MapperScannerConfigurer mapperScannerConfigurer() throws Exception{
        MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
        mapperScannerConfigurer.setBasePackage("com.myapp.api.mapper.*;com.gitee.sunchenbin.mybatis.actable.dao.*");
        mapperScannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactory");
        return mapperScannerConfigurer;
    }

}

com.myapp.api.config/MybatisTableConfig.java

package com.myapp.api.config;


import com.alibaba.druid.pool.DruidDataSource;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.beans.factory.config.PropertiesFactoryBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

@Configuration
@ComponentScan(basePackages = {"com.gitee.sunchenbin.mybatis.actable.manager.*"})
public class MybatisTableConfig {

    @Value("${spring.datasource.driver-class-name}")
    private String driver;

    @Value("${spring.datasource.url}")
    private String url;

    @Value("${spring.datasource.username}")
    private String username;

    @Value("${spring.datasource.password}")
    private String password;

    @Bean
    public PropertiesFactoryBean configProperties() throws Exception{
        PropertiesFactoryBean propertiesFactoryBean = new PropertiesFactoryBean();
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        propertiesFactoryBean.setLocations(resolver.getResources("classpath*:application.properties"));
        return propertiesFactoryBean;
    }

    @Bean
    public DruidDataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(driver);
        dataSource.setUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        dataSource.setMaxActive(30);
        dataSource.setInitialSize(10);
        dataSource.setValidationQuery("SELECT 1");
        dataSource.setTestOnBorrow(true);
        return dataSource;
    }

    @Bean
    public DataSourceTransactionManager dataSourceTransactionManager() {
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dataSource());
        return dataSourceTransactionManager;
    }

    @Bean
    public SqlSessionFactoryBean sqlSessionFactory() throws Exception{
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource());
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        sqlSessionFactoryBean.setMapperLocations(resolver.getResources("classpath*:com/gitee/sunchenbin/mybatis/actable/mapping/*/*.xml"));
        sqlSessionFactoryBean.setTypeAliasesPackage("com.myapp.api.entity.*");
        return sqlSessionFactoryBean;
    }
}

注意 MyBatisMapperScannerConfig 和 MybatisTableConfig 不能合并，不然会出现 @Value 为空的错误

以上代码中的 com.myapp.api.mapper.* 、 com.myapp.api.entity.* 请根据自己的情况将其替换