Springboot整合MyBatis進行數據庫交互

1. Mybatis訪問數據庫
   1. 註解方式
      1. 創建項目
         1. 勾選mysql Driver； JDBC API；Mybatis
      2. 配置數據源
         1. spring:
         2.   datasource:
         3.     url: jdbc:mysql://192.168.1.103:3306/jdbc?serverTimezone=Asia/Shanghai
         4.     username: root
         5.     password: yahang.521
         6.     driver-class-name: com.mysql.cj.jdbc.Driver
         7.    
         8.     # Hikari 連接池配置
         9.     hikari:
         10.       minimum-idle: 5 # 最小空閒連接數量    
         11.       idle-timeout: 180000 # 空閒連接存活最大時間，默認600000（10分鐘）    
         12.       maximum-pool-size: 10 # 連接池最大連接數，默認是10   
         13.       auto-commit: true  # 此屬性控制從池返回的連接的默認自動提交行爲,默認值：true    
         14.       pool-name: HikariPool # 連接池名稱     
         15.       max-lifetime: 1800000 # 此屬性控制池中連接的最長生命週期，值0表示無限生命週期，默認1800000即30分鐘    
         16.       connection-timeout: 30000 # 數據庫連接超時時間,默認30秒，即30000
         17.       connection-test-query: SELECT 1
      3. 創建操作不同表對應的Mapper接口
         1.      @Mapper
         2. public interface StudentMapper {
         3.    
         4.     @Select("select * from student where id=#{id}")
         5.     Student queryStudentById(Integer id);
         6.    
         7.     @Delete("delete from student where id = #{id}")
         8.     int deleteStudentById(Integer id);
         9.       
         10. }
      4. 編寫業務代碼
         1.      @Controller
         2. public class StController {
         3.    
         4.     @Autowired
         5.     private StudentMapper studentMapper;
         6.    
         7.     @ResponseBody
         8.     @RequestMapping("/getStudentById")
         9.     public Student getStudentById(Integer id) {
         10.         Student student = studentMapper.queryStudentById(id);
         11.         return student;
         12.     }
         13. }
      5. 其他
         1. 批量掃描包下的mapper類
         2. @MapperScan(value = "com.njupt.mapper")
         3. @SpringBootApplication
         4. public class MybatisApplication {
         5.      public static void main(String[] args) {
         6.            SpringApplication.run(MybatisApplication.class, args);
         7.      }
         8. }
   2. 配置文件方式
      1. 創建項目
         1. 勾選mysql Driver； JDBC API；Mybatis
      2. 配置數據源
         1. spring:
         2.   datasource:
         3.     url: jdbc:mysql://192.168.1.103:3306/jdbc?serverTimezone=Asia/Shanghai
         4.     username: root
         5.     password: yahang.521
         6.     driver-class-name: com.mysql.cj.jdbc.Driver
         7.    
         8.     # Hikari 連接池配置
         9.     hikari:
         10.       minimum-idle: 5 # 最小空閒連接數量    
         11.       idle-timeout: 180000 # 空閒連接存活最大時間，默認600000（10分鐘）    
         12.       maximum-pool-size: 10 # 連接池最大連接數，默認是10   
         13.       auto-commit: true  # 此屬性控制從池返回的連接的默認自動提交行爲,默認值：true    
         14.       pool-name: HikariPool # 連接池名稱     
         15.       max-lifetime: 1800000 # 此屬性控制池中連接的最長生命週期，值0表示無限生命週期，默認1800000即30分鐘    
         16.       connection-timeout: 30000 # 數據庫連接超時時間,默認30秒，即30000
         17.       connection-test-query: SELECT 1
      3. 在resources目錄下創建兩個目錄
         1. mybatis官方文檔:  https://mybatis.org/mybatis-3/zh/index.html
         2. resources/mybatis/config:mybatis全局配置文件目錄
            1. 新建mybatis-config.xml文件: 該文件無需配置環境，也無需引用mapper文件，直接配置就可以
               1. <?xml version="1.0" encoding="UTF-8" ?>
               2. <!DOCTYPE configuration
               3.   PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
               4.   "http://mybatis.org/dtd/mybatis-3-config.dtd">
               5. <configuration>
               6.     <settings>
               7.         <setting name="mapUnderscoreToCamelCase" value="true"/>
               8.     </settings> 
               9. </configuration>
         3. resources/mybatis/mapper：mybatis sql映射文件目錄
            1. 新建StudentMapper.xml
               1. <?xml version="1.0" encoding="UTF-8" ?>
               2. <!DOCTYPE mapper
               3.   PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
               4.   "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
               5. <mapper namespace="com.njupt.mapper.StudentMapper"> <!-- 接口全類名 -->
               6.      <select id="getStudentById" resultType="com.njupt.entities.Student">
               7.            select * from student where id=#{id}
               8.      </select>
               9. </mapper>
      4. 讓SpringBoot查找到這兩個xml文件，需要在application.yml中配置以下兩項
         1. mybatis:
         2.   config-location: classpath:mybatis/config/mybatis-config.xml
         3.   mapper-locations:
         4.   - classpath:mybatis/mapper/*.xml
      5. 創建操作不同表對應的Mapper接口
         1. public interface StudentMapper {
         2.     public Student getStudentById(Integer id);
         3. }
      6. 批量掃描包下的mapper類
         1. @SpringBootApplication
         2. @MapperScan(value = "com.njupt.mapper")
         3. public class MybatisApplication {
         4.      public static void main(String[] args) {
         5.            SpringApplication.run(MybatisApplication.class, args);
         6.      }
         7. }
      7. 編寫業務代碼
         1. @Controller
         2. public class StudentController {
         3.    
         4.     @Autowired
         5.     private StudentMapper studentMapper;
         6.     private Logger logger = LoggerFactory.getLogger(this.getClass());
         7.    
         8.     @RequestMapping("/getStudentById/{id}")
         9.     @ResponseBody
         10.     public Student getStudentById(@PathVariable("id") Integer id) {
         11.         logger.info("enter getStudentById");
         12.         return studentMapper.getStudentById(id);
         13.     }
         14. }
      8. 測試