Spring Boot 教程 Mybatis 1. 什麼是Mybatis? MyBatis 是一款優秀的持久層框架，它支持自定義 SQL、存儲過程以及高級映射。MyBatis 免除了幾乎所有的 JDBC 代碼以及設置參數和獲取結果集的工作。MyBatis 可以通過簡單的 XML 或註解來配置和映射原 ...

Spring Boot 教程 - Mybatis

1. 什麼是Mybatis?

MyBatis 是一款優秀的持久層框架，它支持自定義 SQL、存儲過程以及高級映射。MyBatis 免除了幾乎所有的 JDBC 代碼以及設置參數和獲取結果集的工作。MyBatis 可以通過簡單的 XML 或註解來配置和映射原始類型、介面和 Java POJO（Plain Old Java Objects，普通老式 Java 對象）為資料庫中的記錄。

2. Spring Boot 整合 Mybatis

2.1 引入maven坐標

<!--springboot父工程-->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <dependencies>
        <!--springboot框架web組件-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.2.2.RELEASE</version>
        </dependency>
        <!--mybatis整合springboot組件-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.0</version>
        </dependency>
        <!--mysql資料庫連接驅動-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.18</version>
        </dependency>
        <!--lombok組件-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.10</version>
        </dependency>
    </dependencies>

    <build>
        <!--springboot的maven插件-->
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <compilerArgs>
                        <arg>-parameters</arg>
                    </compilerArgs>
                </configuration>
            </plugin>
        </plugins>
    </build>

2.2 編寫代碼

2.2.1 創建如圖所示的目錄結構

記得兩個mapper文件的路徑要一致，在編譯之後mybatis的映射文件和介面文件才會在同一個目錄下。

2.2.2 代碼編寫

2.2.2.1 創建配置文件和啟動類

application.yml：

butterflytri:
  databaseurl-port: 127.0.0.1:3306 # 資料庫埠
  database-name: student_db # 資料庫名
server:
  port: 8080 # 應用埠
  servlet:
    context-path: /butterflytri # 應用映射
spring:
  application:
    name: mybatis # 應用名稱
  datasource:
    url: jdbc:mysql://${butterflytri.databaseurl-port}/${butterflytri.database-name}?useUnicode=true&characterEncoding=UTF-8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: root
mybatis:
  type-aliases-package: org.wjf.entity # entity別名
  mapper-locations: classpath:org/wjf/mapper/*Mapper.xml # mapper映射包掃描

啟動類MybatisApplication.java：

package org.butterflytri;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * @author: WJF
 * @date: 2020/5/16
 * @description: MybatisApplication
 */
@SpringBootApplication
public class MybatisApplication {

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

}

2.2.2.2 創建實體類Student

在entity包下創建Student.java實體類。

package org.butterflytri.entity;

import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

import java.io.Serializable;

/**
 * @author: WJF
 * @date: 2020/5/16
 * @description: Student
 */

@ToString
@Getter
@Setter
public class Student implements Serializable {

    private Long id;

    private String studentName;

    private String studentNo;

    private String sex;

    private Integer age;

}

2.2.2.3 編寫mybatis介面文件

在mapper包下創建StudentMapper.java介面。

package org.butterflytri.mapper;

import org.apache.ibatis.annotations.Mapper;
import org.butterflytri.entity.Student;

import java.util.List;

/**
 * @author: WJF
 * @date: 2020/5/16
 * @description:
 */
@Mapper
public interface StudentMapper {

    /**
     * 查詢所有學生信息
     * @return List<Student>
     */
    List<Student> findAll();

    /**
     * 通過id查詢學生信息
     * @param id
     * @return Student
     */
    Student findOne(Long id);

    /**
     * 通過學號查詢學生信息
     * @param studentNo
     * @return Student
     */
    Student findByStudentNo(String studentNo);

}

2.2.2.4 創建mybatis映射文件

在mapper包下創建StudentMapper.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="org.butterflytri.mapper.StudentMapper">
    <sql id="propertyMapper">
        `ID` AS id,
        `STUDENT_NAME` AS studentName,
        `STUDENT_NO` AS studentNo,
        `SEX` AS sex,
        `AGE` AS age
    </sql>
    <select id="findAll" resultType="org.butterflytri.entity.Student">
        SELECT
            <include refid="propertyMapper"></include>
        FROM
            `t_student`
    </select>
    <select id="findOne" parameterType="java.lang.Long" resultType="org.butterflytri.entity.Student">
        SELECT
            <include refid="propertyMapper"></include>
        FROM
            `t_student`
        WHERE
            `ID` = #{id}
    </select>
    <select id="findByStudentNo" parameterType="java.lang.String" resultType="org.butterflytri.entity.Student">
        SELECT
            <include refid="propertyMapper"></include>
        FROM
            `t_student`
        WHERE
            `STUDENT_NO` = #{studentNo}
    </select>
</mapper>

2.2.2.5 Service層

在service包下創建StudentService.java介面，在impl包下創建StudentServiceImpl.Java類並繼承StudentService.Java介面。

StudentService.java：

package org.butterflytri.service;

import org.butterflytri.entity.Student;

import java.util.List;

/**
 * @author: WJF
 * @date: 2020/5/16
 * @description: StudentService
 */

public interface StudentService {

    public List<Student> findAll();

    public Student findOne(Long id);

    public Student findByStudentNo(String studentNo);
}

StudentServiceImpl.java：

package org.butterflytri.service.impl;

import org.butterflytri.entity.Student;
import org.butterflytri.mapper.StudentMapper;
import org.butterflytri.service.StudentService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.List;

/**
 * @author: WJF
 * @date: 2020/5/16
 * @description: StudentServiceImpl
 */
@Service
public class StudentServiceImpl implements StudentService {

    @Resource
    private StudentMapper studentMapper;

    @Override
    public List<Student> findAll() {
        return studentMapper.findAll();
    }

    @Override
    public Student findOne(Long id) {
        return studentMapper.findOne(id);
    }

    @Override
    public Student findByStudentNo(String studentNo) {
        return studentMapper.findByStudentNo(studentNo);
    }
}

2.2.2.6 Controller層

在controller包下創建StudentController.java控制器類。

package org.butterflytri.controller;

import org.butterflytri.entity.Student;
import org.butterflytri.service.StudentService;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.List;

/**
 * @author: WJF
 * @date: 2020/5/16
 * @description: StudentController
 */
@RestController
@RequestMapping("/student")
public class StudentController {

    @Resource
    private StudentService studentService;

    @RequestMapping("/findAll")
    public List<Student> findAll() {
        return studentService.findAll();
    }

    @RequestMapping("/findOne")
    public Student findOne(Long id) {
        return studentService.findOne(id);
    }

    @RequestMapping("/findByStudentNo")
    public Student findByStudentNo(String studentNo) {
        return studentService.findByStudentNo(studentNo);
    }

}