Spring Boot 整合 MyBatis

如果不需要自定义druid则跳过druid部分即可

创建一个Spring Boot项目，引入以下依赖：

Maven导入相关依赖：

<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.2.8</version>
</dependency>

配置数据库连接信息

application.yml:

spring:
  datasource:
    username: root
    password: 123456
    #?serverTimezone=UTC解决时区的报错
    url: jdbc:mysql://localhost:3306/mybatis_blog?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource  #自定义数据源
    #Spring Boot 默认是不注入这些属性值的，需要自己绑定
    #druid 数据源专有配置
    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
 
      #配置监控统计拦截的filters，stat:监控统计、log4j：日志记录、wall：防御sql注入
    #如果允许时报错  java.lang.ClassNotFoundException: org.apache.log4j.Priority
    #则导入 log4j 依赖即可，Maven 地址：https://mvnrepository.com/artifact/log4j/log4j
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

编写配置文件（使我们自定义的Druid属性生效）

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
 
import javax.sql.DataSource;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
 
@Configuration
public class DruidConfig {
 
    /*
    将自定义的 Druid数据源添加到容器中，不再让 Spring Boot 自动创建
    绑定全局配置文件中的 druid 数据源属性到 com.alibaba.druid.pool.DruidDataSource从而让它们生效
    @ConfigurationProperties(prefix = "spring.datasource")：作用就是将 全局配置文件中
    前缀为 spring.datasource的属性值注入到 com.alibaba.druid.pool.DruidDataSource 的同名参数中
    */
    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DataSource druidDataSource() {
        return new DruidDataSource();
    }
 
    @Bean
    public ServletRegistrationBean statViewServlet() {
        ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
        // 这些参数可以在 com.alibaba.druid.support.http.StatViewServlet
        // 的父类 com.alibaba.druid.support.http.ResourceServlet 中找到
        Map<String, String> initParams = new HashMap<>();
        initParams.put("loginUsername", "hloong"); //后台管理界面的登录账号
        initParams.put("loginPassword", "123456"); //后台管理界面的登录密码
        //后台允许谁可以访问
        //initParams.put("allow", "localhost")：表示只有本机可以访问
        //initParams.put("allow", "")：为空或者为null时，表示允许所有访问
        initParams.put("allow", "");
        //deny：Druid 后台拒绝谁访问
        //initParams.put("test", "服务器地址");表示禁止此ip访问
        //设置初始化参数
        bean.setInitParameters(initParams);
        return bean;
    }
 
    //配置 Druid 监控 之 web 监控的 filter
//WebStatFilter：用于配置Web和Druid数据源之间的管理关联监控统计
    @Bean
    public FilterRegistrationBean webStatFilter() {
        FilterRegistrationBean bean = new FilterRegistrationBean();
        bean.setFilter(new WebStatFilter());
 
        //exclusions：设置哪些请求进行过滤排除掉，从而不进行统计
        Map<String, String> initParams = new HashMap<>();
        initParams.put("exclusions", "*.js,*.css,/druid/*,/jdbc/*");
        bean.setInitParameters(initParams);
 
        //"/*" 表示过滤所有请求
        bean.setUrlPatterns(Arrays.asList("/*"));
        return bean;
    }
}

测试数据库是否连接成功

import com.alibaba.druid.pool.DruidDataSource;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
 
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
 
@SpringBootTest
class DemoApplicationTests {
    //DI注入数据源
    @Autowired
    DataSource dataSource;
 
    @Test
    void contextLoads() throws SQLException {
 
        //看一下默认数据源
        System.out.println(dataSource.getClass());
 
        //获得连接
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        DruidDataSource druidDataSource = (DruidDataSource) dataSource;
        System.out.println("druidDataSource 数据源最大连接数：" + druidDataSource.getMaxActive());
        System.out.println("druidDataSource 数据源初始化连接数：" + druidDataSource.getInitialSize());
 
        //关闭连接
        connection.close();
    }
}

创建实体类

User:

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
 
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private Integer id;
    private String name;
    private String pwd;
}

创建mapper目录以及对应的 Mapper 接口

package com.hloong.demo.mapper;
 
import com.hloong.demo.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;
 
import java.util.List;
 
@Mapper
@Repository
public interface UserMapper {
 
    //获取所有用户信息
    public List<User> getUsers();
 
    //根据id查找指定用户
    public User getUserById(Integer id);
}

在resources目录下创建对应的Mapper映射文件

编写UserMapper:

<?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.hloong.demo.mapper.UserMapper">
 
    <select id="getUsers" resultType="User">
 select * from user
 </select>
 
    <select id="getUserById" parameterType="int" resultType="User">
select * from user where id = #{id}
</select>
</mapper>

以上三步可以采用MyBatisX自动生成

编写Controller进行测试

package com.hloong.demo.controller;

import com.hloong.demo.mapper.UserMapper;
import com.hloong.demo.pojo.User;
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;
 
import java.util.List;
 
@RestController
public class UserController {
 
    @Autowired
    UserMapper userMapper;
 
    @GetMapping("/getUsers")
    public List<User> getUsers(){
        return userMapper.getUsers();
    }
 
    @GetMapping("/getUser/{id}")
    public User getUserById(@PathVariable("id") Integer id){
        return userMapper.getUserById(id);
    }
}

配置类别名和绑定Mapper

在application.yml加上以下代码：

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mybatis:
  type-aliases-package: com.hloong.demo.pojo
  mapper-locations: classpath:mapper/*.xml