SpringBoot和Mybatis的整合

以前用Spring構建一個項目，配置文件太過麻煩而且很容易出錯，而用SpringBoot，只需要填寫必要的配置文件，可以很輕鬆整合Mybatis。下面開啓SpringBoot之旅吧!

1、pom.xml引入相關依賴

<?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>com.jlu</groupId>
    <artifactId>springboot_mybatis</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springboot_mybatis</name>
    <description>Demo project for Spring Boot</description>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.10.RELEASE</version>
    <relativePath/> 
</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-jdbc</artifactId>
    </dependency>
    <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>1.3.1</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <!--引入druid-->
    <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.1.8</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>net.minidev</groupId>
        <artifactId>json-smart</artifactId>
        <version>2.2.1</version>
    </dependency>
</dependencies>

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


</project>

2、使用yaml配置文件比XML更加簡潔明瞭。application.yml

spring:
  datasource:
#   數據源基本配置
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://192.168.0.113:3306/mybatis
    type: com.alibaba.druid.pool.DruidDataSource
#   數據源其他配置
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true
#   配置監控統計攔截的filters，去掉後監控界面sql無法統計，'wall'用於防火牆
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500
    #建表時用
#    schema:
#         - classpath:sql/department.sql
#         - classpath:sql/employee.sql

#-----以下是xml配置文件方式開發-------------
mybatis:
  # 指定全局配置文件位置
  config-location: classpath:mybatis/mybatis-config.xml
  # 指定sql映射文件位置
  mapper-locations: classpath:mybatis/mapper/*.xml

如果想要自動建表，可在要第一次運行前將schema打開，建表sql放到指定路徑下

3、實體類:Department(註解版測試用)和Employee(註解+XML配置版測試用)

public class Department {

    private Integer id;
    private String departmentName;
    
    //getters sttters toString...

}

public class Employee {

    private Integer id;
    private String lastName;
    private Integer gender;
    private String email;
    private Integer dId;

    //getters setters toString...
}

4、整合Druid數據源

@Configuration
public class DruidConfig {
    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DataSource druid() {
        return new DruidDataSource();
    }
    //配置Druid的監控
    //1、配置一個管理後臺的Servlet
    @Bean
    public ServletRegistrationBean statViewServlet() {
        ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
        Map<String, String> initParams = new HashMap<>();
        initParams.put("loginUsername", "admin");
        initParams.put("loginPassword", "123456");
        initParams.put("allow", "");//默認就是允許所有訪問
        initParams.put("deny", "192.168.0.113");
        bean.setInitParameters(initParams);
        return bean;
    }
    //2、配置一個web監控的filter
    @Bean
    public FilterRegistrationBean webStatFilter() {
        FilterRegistrationBean bean = new FilterRegistrationBean();
        bean.setFilter(new WebStatFilter());
        Map<String, String> initParams = new HashMap<>();
        initParams.put("exclusions", "*.js,*.css,/druid/*");
        bean.setInitParameters(initParams);
        bean.setUrlPatterns(Arrays.asList("/*"));
        return bean;
    }
}

5、實體類對應的Mapper

  DepartmentMapper:

//@Mapper指定這是一個操作數據庫的mapper
//@Mapper
public interface DepartmentMapper {

    @Select("select * from department where id=#{id}")
    public Department getDeptById(Integer id);

    @Delete("delete from department where id=#{id}")
    public int deleteDeptById(Integer id);

    //useGeneratedKeys：開啓自增主鍵，keyProperty：Department中哪個屬性與主鍵映射
    @Options(useGeneratedKeys = true,keyProperty = "id")
    @Insert("insert into department(department_name) values(#{departmentName})")
    public int insertDept(Department department);

    @Update("update department set department_name=#{departmentName} where id=#{id}")
    public int updateDept(Department department);
}

     EmplyeeMapper:

//@Mapper或者@MapperScan將接口掃描裝配到容器中
public interface EmployeeMapper {

    public Employee getEmpById(Integer id);

    public void insertEmp(Employee employee);
}

注意mapper接口中如果不標明@Mapper，也可在主程序類裏用@MapperScan註解掃描包

//使用MapperScan批量掃描所有的Mapper接口；
@MapperScan(value = "com.jlu.springboot.mapper")
@SpringBootApplication
public class SpringBoot06DataMybatisApplication {
public static void main(String[] args) {    
SpringApplication.run(SpringBoot06DataMybatisApplication.class, args);        
}    
}

 

---

第①方式：全註解版

1、編寫controller：

@RestController
public class DeptController {
    @Autowired
    DepartmentMapper departmentMapper;
 
    //根據id查詢部門信息
    @GetMapping("/dept/{id}")
    public Department getDepartment(@PathVariable("id") Integer id){
        return departmentMapper.getDeptById(id);
    }
    //插入數據，並返回部門信息
    @GetMapping("/dept")
    public Department insertDept(Department department){
        departmentMapper.insertDept(department);
        return department;
    }  

}

2、mapper接口

//@Mapper指定這是一個操作數據庫的mapper
//@Mapper
public interface DepartmentMapper {

    @Select("select * from department where id=#{id}")
    public Department getDeptById(Integer id);

    @Delete("delete from department where id=#{id}")
    public int deleteDeptById(Integer id);

    //useGeneratedKeys：開啓自增主鍵，keyProperty：Department中哪個屬性與主鍵映射
    @Options(useGeneratedKeys = true,keyProperty = "id")
    @Insert("insert into department(department_name) values(#{departmentName})")
    public int insertDept(Department department);

    @Update("update department set department_name=#{departmentName} where id=#{id}")
    public int updateDept(Department department);
}

 3、啓動和測試：

訪問http://localhost:8080/dept?departmentName=研發部（其中id是自增長，mapper中用@Options註解標明），向數據庫插入一條數據

頁面返回數據：{"id":1,"departmentName":"研發部"}

訪問http://localhost:8080/dept/1，查詢id爲1的數據---{"id":1,"departmentName":"研發部"}

問題：

當實體類屬性departmentName和表字段depaartment_name不一致時，訪問http://localhost:8080/dept/1（返回的jsons數據{"id":1,"departmentName":NULL}）。由於用全註解版，不能用XML配置開啓駝峯命名規則，我們有2中辦法解決這問題。

其一可以用@Results註解指定映射關係如下：

    @Results({
            @Result(property = "departmentName", column = "department_name")
    })
    @Select("select * from department where id=#{id}")
    public Department getDeptById(Integer id);

 其二我們可以編寫一個自定義MyBatis的配置規則配置類；給容器中添加一個ConfigurationCustomizer；開啓駝峯命名規則

（值得注意的是如果application.yml中引入了配置文件這個就沒用了？）

@org.springframework.context.annotation.Configuration
public class MyBatisConfig {
    @Bean
    public ConfigurationCustomizer configurationCustomizer() {
        return new ConfigurationCustomizer() {
            @Override
            public void customize(Configuration configuration) {
               //全局開啓駝峯命名規則
                configuration.setMapUnderscoreToCamelCase(true);
            }
        };
    }
}

---

第②種方式：XML

1、controller

@RestController
public class DeptController {
   
    @Autowired
    EmployeeMapper employeeMapper;

    //數據插入略...
    //根據id查詢僱員信息
    @GetMapping("/emp/{id}")
    public Employee getEmp(@PathVariable("id") Integer id){
        return employeeMapper.getEmpById(id);
    }

}

2、mapper接口：

//@Mapper或者@MapperScan將接口掃描裝配到容器中
public interface EmployeeMapper {

    public Employee getEmpById(Integer id);

    public void insertEmp(Employee employee);
}

3、SQL映射文件和mapper全局配置文件 

類路徑下/mybaties/mapper/Employeemapper.xml

<?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.jlu.springboot.mapper.EmployeeMapper">

    <select id="getEmpById" resultType="com.jlu.springboot.bean.Employee">
        SELECT * FROM employee WHERE id=#{id}
    </select>

    <insert id="insertEmp">
        INSERT INTO employee(lastName,email,gender,d_id) VALUES (#{lastName},#{email},#{gender},#{dId})
    </insert>
</mapper>

類路徑下/mybaties/mybatis-config.xml

<?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>

    <settings>
        <!--mybatis開啓駝峯映射規則，數據庫字段自動映射爲實體類屬性-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>

4、在application.yml在全局配置文件中

5、啓動和測試

 訪問http://localhost:8080/emp/1，查詢id爲1的數據

{"id":1,"lastName":"zhangSan",gender:0,email:"[email protected]",dId:1}