SpringBoot自学好几天 中途开始写笔记 SpringBoot数据访问 整合MyBatis(二) 20190221

一、对数据库操作

注意注意：上一步自动创建数据表 这一步 需要把sql文件删除 或者把配置文件改成 initialization-mode: never

1. 新建mapper 注解 @Mapper

package com.example.springboot.mapper;

import com.example.springboot.bean.Department;
import org.apache.ibatis.annotations.*;

/**
 * @author LM
 * @create 2019-02-21 20:45
 */
@Mapper
public interface DepartmentMapper {

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

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

    @Insert("insert into department (departmentname ) values(#{departmentName})")
    public int insertDept(Department department);

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

2. 新建controller测试

package com.example.springboot.controller;

import com.example.springboot.bean.Department;
import com.example.springboot.mapper.DepartmentMapper;
import org.apache.ibatis.annotations.Options;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author LM
 * @create 2019-02-21 20:57
 *
 * 简化一下：这里就不写service层了 为了方便测试  开发不能这样
 */
@RestController
public class DeptController {

    @Autowired
    DepartmentMapper departmentMapper;

    @GetMapping("/dept/{id}")
    public Department getDepartment(@PathVariable("id") Integer id){
        return departmentMapper.getDeptById(id);
    }
    //option指定了 自增属性会封装到department中
    @Options(useGeneratedKeys = true,keyProperty = "id")
    @GetMapping("/dept")
    public Department insertDept(Department department){
          departmentMapper.insertDept(department);
          return department;
    }
}

4. 访问页面
   新增：
   http://127.0.0.1:8080/dept/?departmentName=AA
   
   查询：
   http://127.0.0.1:8080/dept/1
   
   查看数据库数据：
   
5. 考虑问题 修改mybatis相关规则 添加ConfigurationCustomizer

package com.example.springboot.config;

import org.mybatis.spring.boot.autoconfigure.ConfigurationCustomizer;
import org.springframework.context.annotation.Bean;


/**
 * @author LM
 * @create 2019-02-21 21:18
 */
@org.springframework.context.annotation.Configuration
public class MyBatisConfig {

    @Bean
    public ConfigurationCustomizer  configurationCustomizer(){
        return new ConfigurationCustomizer() {
            @Override
            public void customize(org.apache.ibatis.session.Configuration configuration) {
                //开启驼峰命名法
                configuration.setMapUnderscoreToCamelCase(true);
            }
        };
    }
}

7. 每个mapper写一个 @Mapper注解 比较麻烦 可以统一配置
   方法： 在SpringBootMybatis02Application上加注解

@MapperScan(value = "com.example.springboot.mapper")
@SpringBootApplication
public class SpringBootMybatis02Application {

    public static void main(String[] args) {
        SpringApplication.run(SpringBootMybatis02Application.class, args);
    }

}

@Mapper已经不需要了

二、 配置文件的方式 SQL

1. 创建新Mapper

/**
 * @author LM
 * @create 2019-02-21 21:26
 * @Mapper 或者 用 @MapperScan方式 将接口扫描到容器中 之前已经配置了@MapperScan所以这里不用配置了
 */

public interface EmployeeMapper {
    public  Employee getEmpById(Integer id);
    public void insertEmp(Employee employee);
}

2. 创建sql映射文件
   官网有配置文件的参考 点击进入
   namespace绑定接口！！
   mybatis-config.xml

<configuration>

configuration>

EmployeeMapper.xml

<mapper namespace="com.example.springboot.mapper.EmployeeMapper">

    
    <select id="getEmpById" resultType="com.example.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>

3. 项目配置文件配置
   application.yml

mybatis:
  config-location: classpath:mybatis/mybatis-config.xml #指定全局配置文件
  mapper-locations: classpath:mybatis/mapper/*.xml #指定sql编写文件

4. 测试

package com.example.springboot.controller;

import com.example.springboot.bean.Employee;
import com.example.springboot.mapper.EmployeeMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author LM
 * @create 2019-02-21 21:50
 */
@RestController
public class EmployeeController {

    @Autowired
    EmployeeMapper employeeMapper;

    @GetMapping("/emp/{id}")
    public Employee getEmp(@PathVariable("id") Integer id){
        return employeeMapper.getEmpById(id);
    }

}

问题：dId字段是空的 因为我们没有开启驼峰命名法
http://www.mybatis.org/mybatis-3/configuration.html#settings
mybatis-config.xml

<configuration>
        <settings>
            <setting name="mapUnderscoreToCamelCase" value="true"/>
        settings>
configuration>

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