spring boot + mybatis 讀取數據庫

創建數據庫

use testdb;
drop table if exists t_city;
create table t_city(
id int primary key auto_increment,
city varchar(20),
state varchar(10)
)engine = innodb default charset = utf8;

insert into t_city values(1,"zhengzhou","HN");

maven 的pom 文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>nulijiushimeili</groupId>
    <artifactId>spring-boot2-mybatis</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>spring-boot2-mybatis</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <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.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.4</version>
        </dependency>

        <!-- alibaba的druid數據庫連接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.9</version>
        </dependency>
    </dependencies>

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

</project>

spring boot 配置 application.yml

#默認使用配置
spring:
  profiles:
    active: dev

#公共配置與profiles選擇無關 mapperLocations指的路徑是src/main/resources
mybatis:
  typeAliasesPackage: com.xdd.entity
#  mapperLocations: classpath:mapper/*.xml


---

#開發配置
spring:
  profiles: dev

  datasource:
    url: jdbc:mysql://localhost:3306/testdb
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
    # 使用druid數據源
    type: com.alibaba.druid.pool.DruidDataSource

spring boot 啟動器

@SpringBootApplication
@EnableTransactionManagement //如果mybatis中service實現類中加入事務注解，需要此處添加該注解
@MapperScan("nulijiushimeili.springboot2mybatis.mapper")  //掃描的是mapper.xml中namespace指向值的包位置
public class SpringBoot2MybatisApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBoot2MybatisApplication.class, args);
    }
}

City bean

public class City {

    private String city;
    private String state;

    public City(){}

    public City(String city, String state){
        this.city = city ;
        this.state = state;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }


    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

}

mapper

@Repository
public interface CityMapper {

    @Select("select * from t_city where state = #{state}")
    City findByState(@Param("state")String state);
}

controller

@Controller
@RequestMapping(value = "/abv")
public class RegistyController {
 @Autowired
    private CityMapper cityMapper;

    @RequestMapping(value = "/read", method = RequestMethod.GET)
    @ResponseBody
    public City readMybatis(@RequestParam String state) {
        return cityMapper.findByState(state);
    }
}

測試url

http://localhost:8080/abv/read?state=HN

踩坑記

1. 數據庫的字段名和bean的字段名必須保持一致，前后台請求數據的key也必須是一致的。否則會加載不到數據
2. 映射url請求路徑不對，比如在類名上添加了@RequestMapping(),在請求的時候只寫了類名上了方法上的路徑。

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