Spring Boot 应用系列 2 -- Spring Boot 2 整合MyBatis和Druid

本系列将分别演示单数据源和多数据源的配置和应用，本文先演示单数据源(MySQL)的配置。

1. pom.xml文件配置

需要在dependencies节点添加：

<!-- MySQL -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.12</version>
</dependency>
<!-- MySQL end -->

<!-- Connection Pool -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.10</version>
</dependency>
<!-- Connection Pool end -->

<!-- MyBatis -->
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.2</version>
</dependency>
<!-- MyBatis end -->

2. 因为是单数据源，为了方便起见，我们把数据源和连接池全部放到application.yml里，当然数据源的配置也可以另起一个新文件。

 1 server:
 2   port: 9007
 3   
 4 spring:
 5   datasource:
 6     name: devutility-test-database-mybatis-springboot
 7     type: com.alibaba.druid.pool.DruidDataSource
 8     druid:
 9       driver-class-name: com.mysql.cj.jdbc.Driver
10       url: ${DB_URL:jdbc:mysql://127.0.0.1:3306/Test}?useUnicode=true&useSSL=false
11       username: ${DB_UID:tester}
12       password: ${DB_PWD:tester}
13       initial-size: 1
14       min-idle: 1
15       max-active: 20
16       max-wait: 60000
17       time-between-eviction-runs-millis: 60000
18       min-evictable-idle-time-millis: 300000
19       validation-query: SELECT 'x'
20       test-while-idle: true
21       test-on-borrow: false
22       test-on-return: false
23       pool-prepared-statements: false
24       max-pool-prepared-statement-per-connection-size: 20
25       filters: stat
26 mybatis:
27   mapper-locations: classpath:mappers/*.xml
28   type-aliases-package: devutility.test.database.mybatis.springboot.entities

第27行定义了mapper的xml文件的地址；

第28行定义了实体类的包，在mapper的xml文件中可以只写实体类名而不必写全实体类的命名空间。

3. MyBatis相关配置

MyBatis的配置主要涉及到mapper的xml文件，mapper的接口文件，以及数据库相关的实体类的定义。

(1) 首先定义一个客户实体类：

package devutility.test.database.mybatis.springboot.entities;

public class Customer extends BaseEntity {
    private long id;
    private String name1;
    private String address1;
    private String city;
    private int state;
    private int zip;
    private String phone;
    private String email;

(2) 定义mapper的xml文件，也叫XML映射文件，存放于src/main/resources/mappers目录下。

<?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="devutility.test.database.mybatis.springboot.mappers.CustomerMapper">
    <select id="get" resultType="Customer">
        select * from Customer where id = #{id};
    </select>
</mapper>

XML映射文件的定义规则可以参考MyBatis官网，此处我们仅实现一个根据主键查询Customer的功能。

(3) 定义Mapper接口：

package devutility.test.database.mybatis.springboot.mappers;

import org.apache.ibatis.annotations.Mapper;

import devutility.test.database.mybatis.springboot.entities.Customer;

@Mapper
public interface CustomerMapper {
    Customer get(long id);
}

4. 应用

package devutility.test.database.mybatis.springboot.controllers;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import devutility.test.database.mybatis.springboot.entities.Customer;
import devutility.test.database.mybatis.springboot.mappers.CustomerMapper;

@RestController
@RequestMapping("/customer")
public class CustomerController {
    @Autowired
    private CustomerMapper customerMapper;

    @RequestMapping("/get")
    public Customer get(long id) {
        return customerMapper.get(id);
    }
}

Demo地址