前言

有一些使用场景比较简单不需要搭建 mysql 等比较重型的服务，使用小而轻巧的内存数据库也能满足要求，本文将实战操作纯内存型数据库 H2。

H2 数据库特性：

非常快、开源、支持 JDBC AP
嵌入式和服务式模式，内存型数据库
基于浏览器控制台的应用程序，不需要安装第三方工具
占用空间小，jar 仅仅只有 2MB 大小

下面是 H2 和其他数据库之间的对比：

实战演练

代码结构

pom.xml 配置

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.example</groupId>
        <artifactId>springboot-learning-parents</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <groupId>springboot-demo</groupId>
    <artifactId>springboot-h2</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>springboot-h2</name>
    <url>https://gitee.com/leo825/springboot-learning-parents.git</url>
    <description>springboot集成h2纯内存型数据库</description>
    <properties>
        <start-class>com.demo.SpringbootH2Application</start-class>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <mybatisplus.version>3.5.1</mybatisplus.version>
        <freemaker.version>2.3.31</freemaker.version>
        <mysql.version>8.0.28</mysql.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <!-- mybatis-plus 所需依赖  -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>${mybatisplus.version}</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>${mybatisplus.version}</version>
        </dependency>
        <dependency>
            <groupId>org.freemarker</groupId>
            <artifactId>freemarker</artifactId>
            <version>2.3.31</version>
        </dependency>

        <!-- 使用h2内存数据库 -->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

application.yml 配置

#端口，项目上下文
server:
  port: 8080
  servlet:
    context-path: /springboot-h2

spring:
  datasource:
    username: leo825
    password: 1WSX@357wj
    # 如果需要数据本地化，则改成 file 方式
    # jdbc:h2:file:D:/program/sqlite3/db/testDB;AUTO_SERVER=TRUE;DB_CLOSE_DELAY=-1
    url: jdbc:h2:mem:testDB;DB_CLOSE_DELAY=-1
    driver-class-name: org.h2.Driver
    # 初始化表
    schema: classpath:schema.sql
    # 初始化数据
    data: classpath:data.sql
    initialization-mode: always
    continue-on-error: true
    # 开启这个配置就可以通过 web 页面访问了，例如：http://localhost:8080/springboot-h2/h2-console
    h2:
      console:
        enabled: true
        settings:
          # 开启h2 console 跟踪 方便调试  默认 false
          trace: true
          # 允许console 远程访问 默认false
          web-allow-others: true
          # h2 访问路径上下文
          path: /h2-console


# mybatis-plus 配置
mybatis-plus:
  mapper-locations: classpath*:/mapper/**/*.xml
  #实体扫描，多个package用逗号或者分号分隔
  typeAliasesPackage: com.dmo.entity
  global-config:
    #数据库相关配置
    db-config:
      #主键类型  AUTO:"数据库ID自增", INPUT:"用户输入ID", ID_WORKER:"全局唯一ID (数字类型唯一ID)", UUID:"全局唯一ID UUID";
      id-type: AUTO
      #字段策略 IGNORED:"忽略判断",NOT_NULL:"非 NULL 判断"),NOT_EMPTY:"非空判断"
      field-strategy: NOT_NULL
      #驼峰下划线转换
      column-underline: true
      logic-delete-value: -1
      logic-not-delete-value: 0
    banner: false
  #原生配置
  configuration:
    # 打印sql
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
    map-underscore-to-camel-case: true
    cache-enabled: false
    call-setters-on-nulls: true
    jdbc-type-for-null: 'null'

# 日志输出配置
logging:
  level:
    root: INFO
    org:
      springframework:
        security: WARN
        web: ERROR
  file:
    path: ./logs
    name: './logs/springboot-sqlite.log'
  pattern:
    file: '%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50}:%L - %msg%n'
    console: '%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50}:%L - %msg%n'

data.sql

insert into t_user(id, username, pwd, create_time, update_time) values (0,'zhhangsan','1222', {ts '2022-07-27 18:47:52.69'}, {ts '2022-07-27 18:47:52.69'})

base

Result.java

package com.demo.base;

public class Result<T> {
    private Integer code;
    private String msg;
    private String message;
    private T data;


    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }

    public Result ok(T t){
        this.setCode(1000);
        this.setMsg("成功");
        this.setMessage("成功");
        this.setData(t);
        return this;
    }

    public Result fail(String msg){
        this.setCode(1001);
        this.setMsg(msg);
        this.setMessage(msg);
        return this;
    }


    public Result() {
    }

    public Result(Integer code, String msg) {
        this.code = code;
        this.msg = msg;
        this.setMessage(msg);
    }

    public Result(Integer code, String msg, T data) {
        this.code = code;
        this.msg = msg;
        this.data = data;
        this.setMessage(msg);
    }

}

entity

User.java

package com.demo.entity;

import com.baomidou.mybatisplus.annotation.*;
import com.fasterxml.jackson.annotation.JsonFormat;

import java.io.Serializable;
import java.util.Date;

/**
 * <p>
 * 用户表
 * </p>
 *
 * @author Leo825
 * @since 2022-07-05
 */
@TableName("t_user")
public class User implements Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * 用户主键
     */
    @TableId(value = "id", type = IdType.AUTO)
    private Integer id;

    /**
     * 用户名称
     */
    private String username;

    /**
     * 密码
     */
    private String pwd;

    /**
     * 创建时间，MyMetaObjectHandler 配合使用，入库的时候自动填充
     */
    @TableField(value = "create_time", fill = FieldFill.INSERT)
    @JsonFormat(timezone = "GMT+8", pattern = "yyyy-MM-dd HH:mm:ss")
    private Date createTime;

    /**
     * 修改时间，MyMetaObjectHandler 配合使用，入库的时候自动填充
     */
    @TableField(value = "update_time", fill = FieldFill.INSERT_UPDATE)
    @JsonFormat(timezone = "GMT+8", pattern = "yyyy-MM-dd HH:mm:ss")
    private Date updateTime;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }
    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }
    public Date getUpdateTime() {
        return updateTime;
    }

    public void setUpdateTime(Date updateTime) {
        this.updateTime = updateTime;
    }

    @Override
    public String toString() {
        return "User{" +
            "id=" + id +
            ", username=" + username +
            ", pwd=" + pwd +
            ", createTime=" + createTime +
            ", updateTime=" + updateTime +
        "}";
    }
}

mapper

package com.demo.service.impl;

import com.demo.entity.User;
import com.demo.mapper.UserMapper;
import com.demo.service.IUserService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;

/**
 * <p>
 * 用户表 服务实现类
 * </p>
 *
 * @author Leo825
 * @since 2022-07-05
 */
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {
}

service

package com.demo.service;

import com.demo.entity.User;
import com.baomidou.mybatisplus.extension.service.IService;

/**
 * <p>
 * 用户表 服务类
 * </p>
 *
 * @author Leo825
 * @since 2022-07-05
 */
public interface IUserService extends IService<User> {

}

impl 实现类：

package com.demo.service.impl;

import com.demo.entity.User;
import com.demo.mapper.UserMapper;
import com.demo.service.IUserService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;

/**
 * <p>
 * 用户表 服务实现类
 * </p>
 *
 * @author Leo825
 * @since 2022-07-05
 */
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements IUserService {

}

config

MybatisPlusConfig.java

package com.demo.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * mybatisplus 配置
 */
@Configuration
public class MybatisPlusConfig {
    /**
     * 老版本，目前已失效
     * @return
     */
    /**@Bean
    public PaginationInterceptor paginationInterceptor() {
    PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
    return paginationInterceptor;
    }*/


    /**
     * 新的分页插件,一缓和二缓遵循mybatis的规则,
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.H2));
        return interceptor;
    }
}

MyMetaObjectHandler.java

package com.demo.config;

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;

import java.util.Date;

/**
 * 填充公共字段
 *
 */
@Slf4j
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
    @Override
    public void insertFill(MetaObject metaObject) {
        log.info("start insert fill...");
        this.setFieldValByName("createTime", new Date(), metaObject);
        this.setFieldValByName("updateTime", new Date(), metaObject);
    }

    @Override
    public void updateFill(MetaObject metaObject) {
        log.info("start update fill...");
        this.setFieldValByName("updateTime",  new Date(), metaObject);
    }
}

controller

package com.demo.controller;


import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.demo.base.Result;
import com.demo.entity.User;
import com.demo.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * controller 测试
 *
 */
@RestController
@RequestMapping("/user")
public class UserController {

    /**
     * 构造方法注入
     */
    @Autowired
    IUserService userService;


    /**
     * 保存数据
     *
     * @return
     */
    @GetMapping("/save")
    public Result save() {
        User user = new User();
        user.setId(10);
        user.setUsername("miaolinlin");
        user.setPwd("121212");
        userService.save(user);
        return new Result().ok(user);
    }

    /**
     * 修改数据
     *
     * @param id
     * @return
     */
    @GetMapping("/update")
    public Result update(Integer id) {
        User user = new User();
        user.setId(id);
        user.setPwd("1111111111");
        userService.updateById(user);
        return new Result().ok("{}");
    }

    @GetMapping("/list")
    public Result list() {
        // 返回所有
        List<User> list = userService.list();
        return new Result().ok(list);
    }

    @GetMapping("/listByContion")
    public Result listByContion() {
        /**
         * 条件查询， 通过QueryWrapper来实现查询的条件：
         * eq: 代表相等
         * like: 模糊匹配
         * orderBy: 排序
         * in, notin
         * 大于，小于，between等
         */
        List<User> list = userService.list(new LambdaQueryWrapper<User>()
                // 查询年龄=11的
                .eq(User::getUsername, "miao")
                // 模糊匹配
                .like(User::getPwd, "%111%")
                // 排序，按照创建时间
                .orderByDesc(User::getCreateTime)
        );
        return new Result().ok(list);
    }

    /**
     * 根据id获取数据
     *
     * @param id
     * @return
     */
    @GetMapping("/getById")
    public Result getById(Integer id) {
        User user = userService.getById(id);
        return new Result().ok(user);
    }

    /**
     * 删除数据
     *
     * @param id
     * @return
     */
    @GetMapping("/delete")
    public Result delete(Integer id) {
        userService.removeById(id);
        return new Result().ok("success");
    }

    /**
     * 分页查询
     *
     * @param pageNum
     * @param pageSize
     * @param name
     * @return
     */
    @GetMapping("/page")
    public Result page(int pageNum, int pageSize, String name) {
        IPage<User> page = new Page<>(pageNum, pageSize);

        IPage<User> page1 = userService.page(page, new LambdaQueryWrapper<User>()
                // 主要演示这里可以加条件。在name不为空的时候执行
                .like(StringUtils.isNotEmpty(name), User::getUsername, "%" + name + "%"));

        return new Result().ok(page1);
    }
}