3分钟搭建springboot+mybatis+mybatis-

此项目使用idea用Spring Initializr快速搭建，不含service和controller层，使用单元测试试通数据库查询

0）准备数据库表

数据库执行下面语句，创建d_user表

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for d_user
-- ----------------------------
DROP TABLE IF EXISTS `d_user`;
CREATE TABLE `d_user`  (
  `id` int(0) NOT NULL,
  `name` varchar(25) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
  `ip` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of d_user
-- ----------------------------
INSERT INTO `d_user` VALUES (1001, '雨欣', '100011');
INSERT INTO `d_user` VALUES (1002, '雨欣：324：324：324', '100012');

SET FOREIGN_KEY_CHECKS = 1;

如下：

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1）创建Spring Initializr

鼠标选择：file>new>project...进入创建菜单
选择Spring Initializr 修改配置值并next

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随后选择你想用的功能，本人在pom文件中添加的，此处直接略过finish

image.png
创建后结构如下：
image.png

2）mybatis-gennerator生成dao,mapper

项目生成后配置pom文件，引入需要的依赖：在pom文件的build下添加如下代码：

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

            <!--逆向工程自动生成需要            -->
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.2</version>
                <configuration>
                    <configurationFile>
                        src/main/resources/generator/genteratorCongfig.xml
                    </configurationFile>
                    <overwrite>true</overwrite>
                    <verbose>true</verbose>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>8.0.16</version>
                    </dependency>
                    <dependency>
                        <groupId>tk.mybatis</groupId>
                        <artifactId>mapper</artifactId>
                        <version>3.4.2</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
        <!-- 如果不添加此节点mybatis的mapper.xml文件都会被漏掉。 -->
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                    <include>**/*.yml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                    <include>**/*.yml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

更新pom依赖加载，在resources文件夹下添加generator文件夹，并创建config.properties；genteratorCongfig.xml；

image.png

代码直接粘贴如下：
其中config.properties文件内容如下，注意修改你的数据库配置，自动生成的mapper，dao子文件夹名称，以及生成路径

jdbc.driverClass=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai&allowMultiQueries=true
jdbc.user=root
jdbc.password=root


#模块名
moduleName=d_user
#表名
tableName=d_user
#默认路径
modelPath=com.example.demo1

其中genteratorCongfig.xml 文件内容如下

<!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/config.properties"/>

    <context id="Mysql" targetRuntime="MyBatis3Simple" defaultModelType="flat">
        <property name="beginningDelimiter" value="`"/>
        <property name="endingDelimiter" value="`"/>

        <plugin type="tk.mybatis.mapper.generator.MapperPlugin">
            <property name="mappers" value="tk.mybatis.mapper.common.Mapper"/>
            <property name="caseSensitive" value="true"/>
            <property name="lombok" value="Getter,Setter,ToString"/>
        </plugin>

        <jdbcConnection driverClass="${jdbc.driverClass}"
                        connectionURL="${jdbc.url}"
                        userId="${jdbc.user}"
                        password="${jdbc.password}">
        </jdbcConnection>

        <!--实体-->
        <javaModelGenerator targetPackage="${modelPath}.model.entity.${moduleName}"
                            targetProject="src/main/java"/>

        <!--mapper.xml-->
        <sqlMapGenerator targetPackage="mapper.${moduleName}"
                         targetProject="./src/main/resources"/>

        <!--mapper接口-->
        <javaClientGenerator targetPackage="${modelPath}.dao.${moduleName}"
                             targetProject="src/main/java"
                             type="XMLMAPPER"/>

        <!--为哪张表生成代码-->
        <table tableName="${tableName}">
            <generatedKey column="id" sqlStatement="JDBC"/>
        </table>
    </context>
</generatorConfiguration>

随后双击序号3处，等待自动生成组件，生成mapper;dao;model如下

image.png

打开生成文件，此时pom未引入相关依赖，方法报错：

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再次打开pom文件，配置如下内容：（包括了测试单元）

        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.1.5</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.16</version>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper</artifactId>
            <version>3.4.2</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>

解决报错

3)创建查询语句

创建application.yml,mybatis-config.xml文件如下：

image.png

application文件内容如下：

spring:
  application:
    name: springboot-mybatis
#  profiles:
#    active: test
  datasource:
    #MySQL数据库支持配置
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai&allowMultiQueries=true
    username: root
    password: root
    type: com.zaxxer.hikari.HikariDataSource
    hikari:
      minimum-idle: 5
      maximum-pool-size: 100
      idle-timeout: 600000
      pool-name: OrderHikariCP
      max-lifetime: 1800000
      connection-timeout: 60000
      connection-test-query: SELECT 1
server:
  port: 8088
mybatis:
  config-location: classpath:mybatis-config.xml
  type-aliases-package: org.example.common.dao.**
  mapper-locations: classpath:mapper/*/*.xml
dataType: 0

mybatis-config文件内容如下：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <properties resource="application.yml">
        <property name="dataType" value="${dataType}"/>
    </properties>
    <settings>
        <!-- 在null时也调用 setter,适应于返回Map,3.2版本以上可用 -->
        <setting name="callSettersOnNulls" value="true"/>
        <!-- 全局映射器启用缓存 -->
        <setting name="cacheEnabled" value="true"/>
        <!-- 查询时，关闭关联对象即时加载以提高性能 -->
        <setting name="lazyLoadingEnabled" value="false"/>
        <!-- 设置关联对象加载的形态，此处为按需加载字段(加载字段由SQL指定)，不会加载关联表的所有字段，以提高性能 -->
        <setting name="aggressiveLazyLoading" value="false"/>
        <!-- 对于未知的SQL查询，允许返回不同的结果集以达到通用的效果 -->
        <setting name="multipleResultSetsEnabled" value="true"/>
        <!-- 允许使用列标签代替列名 -->
        <setting name="useColumnLabel" value="true"/>
        <!-- 允许使用自定义的主键值(比如由程序生成的UUID 32位编码作为键值)，数据表的PK生成策略将被覆盖 -->
        <setting name="useGeneratedKeys" value="true"/>
        <!-- 给予被嵌套的resultMap以字段-属性的映射支持 -->
        <!--<setting name="autoMappingBehavior" value="FULL" />-->
        <!-- 对于批量更新操作缓存SQL以提高性能  -->
        <setting name="defaultExecutorType" value="SIMPLE"/>
        <!-- 数据库超过25000秒仍未响应则超时 -->
        <setting name="defaultStatementTimeout" value="25000"/>
    </settings>

</configuration>

随后在mapper中创建查询selectAllById方法：

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    DUser selectAllById(@Param("id") Integer id);

在mapper映射中添加查询语句：

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注意：resultType若为java对象，地址映射对。

  <sql id="User_Num">
    id,name,ip
  </sql>
  <!--查询-->
  <select parameterType="Integer" id="selectAllById" resultType="com.example.demo1.model.entity.d_user.DUser">
    SELECT
    <include refid="User_Num"/>
    FROM d_user WHERE id = #{id}
  </select>

再修改springboot启动项如下：

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@ComponentScan(value = {"com.example"})
@MapperScan("com.example.demomybatis.**")

修改测试启动项如下：

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@SpringBootTest
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = Demo1Application.class)
class Demo1ApplicationTests {

    @Autowired(required=true)
    DUserMapper dUserMapper;

    @Test
    void contextLoads() {
        System.out.println("here==="+dUserMapper.selectAllById(1001).getName());
    }
}

启动测试单元，查询成功。

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注意：若重新逆向工程创建项目，需要删除mapper文件，不然累加，启动报错

进阶项目---搭建dubbo项目： https://www.jianshu.com/p/be534104785b