不好意思，Mybatis Plus 该换了！

Bertha 。 2023-10-16 12:17 6阅读 0赞

来源：[http://juejin.cn/post/6886019929519177735][http_juejin.cn_post_6886019929519177735]

使用fluent mybatis可以不用写具体的xml文件，通过java api可以构造出比较复杂的业务sql语句，做到代码逻辑和sql逻辑的合一。

不再需要在Dao中组装查询或更新操作，在xml或mapper中再组装参数。那对比原生Mybatis, Mybatis Plus或者其他框架，FluentMybatis提供了哪些便利呢？

### **Part1 仓库地址** ###

> 详细的API及用法，可参考官方仓库  
> [https://gitee.com/fluent-mybatis/fluent-mybatis][https_gitee.com_fluent-mybatis_fluent-mybatis]

### **Part2 需求场景设置** ###

我们通过一个比较典型的业务需求来具体实现和对比下，假如有学生成绩表结构如下:

create table `student_score`
    (
        id           bigint auto_increment comment '主键ID' primary key,
        student_id   bigint            not null comment '学号',
        gender_man   tinyint default 0 not null comment '性别, 0:女; 1:男',
        school_term  int               null comment '学期',
        subject      varchar(30)       null comment '学科',
        score        int               null comment '成绩',
        gmt_create   datetime          not null comment '记录创建时间',
        gmt_modified datetime          not null comment '记录最后修改时间',
        is_deleted   tinyint default 0 not null comment '逻辑删除标识'
    ) engine = InnoDB default charset=utf8;

现在有需求:

**统计2000年三门学科('英语', '数学', '语文')及格分数按学期,学科统计最低分，最高分和平均分, 且样本数需要大于1条,统计结果按学期和学科排序**

我们可以写SQL语句如下

select school_term,
           subject,
           count(score) as count,
           min(score)   as min_score,
           max(score)   as max_score,
           avg(score)   as max_score
    from student_score
    where school_term >= 2000
      and subject in ('英语', '数学', '语文')
      and score >= 60
      and is_deleted = 0
    group by school_term, subject
    having count(score) > 1
    order by school_term, subject;

那上面的需求，分别用fluent mybatis, 原生mybatis 和 Mybatis plus来实现一番。

推荐一个开源免费的 Spring Boot 实战项目：

> [https://github.com/javastacks/spring-boot-best-practice][https_github.com_javastacks_spring-boot-best-practice]

### **Part3 三者实现对比** ###

### **1使用fluent mybatis 来实现上面的功能** ###

![cd370fecd1705ebfb941ee36e15c11c3.png][]

我们可以看到fluent api的能力，以及IDE对代码的渲染效果。插播一条：如果你近期准备面试跳槽，建议在[Java面试库][Java]小程序在线刷题，涵盖 2000+ 道 Java 面试题，几乎覆盖了所有主流技术面试题。

### **2、换成mybatis原生实现效果** ###

定义Mapper接口

public interface MyStudentScoreMapper {
        List<Map<String, Object>> summaryScore(SummaryQuery paras);
    }

定义接口需要用到的参数实体 SummaryQuery

@Data
    @Accessors(chain = true)
    public class SummaryQuery {
        private Integer schoolTerm;
    
        private List<String> subjects;
    
        private Integer score;
    
        private Integer minCount;
    }

定义实现业务逻辑的mapper xml文件

<select id="summaryScore" resultType="map" parameterType="cn.org.fluent.mybatis.springboot.demo.mapper.SummaryQuery">
        select school_term,
        subject,
        count(score) as count,
        min(score) as min_score,
        max(score) as max_score,
        avg(score) as max_score
        from student_score
        where school_term >= #{schoolTerm}
        and subject in
        <foreach collection="subjects" item="item" open="(" close=")" separator=",">
            #{item}
        </foreach>
        and score >= #{score}
        and is_deleted = 0
        group by school_term, subject
        having count(score) > #{minCount}
        order by school_term, subject
    </select>

实现业务接口(这里是测试类, 实际应用中应该对应Dao类)

@RunWith(SpringRunner.class)
    @SpringBootTest(classes = QuickStartApplication.class)
    public class MybatisDemo {
        @Autowired
        private MyStudentScoreMapper mapper;
    
        @Test
        public void mybatis_demo() {
            // 构造查询参数
            SummaryQuery paras = new SummaryQuery()
                .setSchoolTerm(2000)
                .setSubjects(Arrays.asList("英语", "数学", "语文"))
                .setScore(60)
                .setMinCount(1);
    
            List<Map<String, Object>> summary = mapper.summaryScore(paras);
            System.out.println(summary);
        }
    }

总之，直接使用mybatis，实现步骤还是相当的繁琐，效率太低。那换成mybatis plus的效果怎样呢？

推荐一个开源免费的 Spring Boot 实战项目：

> [https://github.com/javastacks/spring-boot-best-practice][https_github.com_javastacks_spring-boot-best-practice]

### **3、换成mybatis plus实现效果** ###

mybatis plus的实现比mybatis会简单比较多，实现效果如下

![d0f290f8d2c49929a797e1073013f737.png][]

如红框圈出的，写mybatis plus实现用到了比较多字符串的硬编码（可以用Entity的get lambda方法部分代替字符串编码）。字符串的硬编码，会给开发同学造成不小的使用门槛，个人觉的主要有2点：

1.  字段名称的记忆和敲码困难
2.  Entity属性跟随数据库字段发生变更后的运行时错误

其他框架，比如TkMybatis在封装和易用性上比mybatis plus要弱，就不再比较了。插播一条：如果你近期准备面试跳槽，建议在[Java面试库][Java]小程序在线刷题，涵盖 2000+ 道 Java 面试题，几乎覆盖了所有主流技术面试题。

### **Part4 生成代码编码比较** ###

### **4、fluent mybatis生成代码设置** ###

public class AppEntityGenerator {
        static final String url = "jdbc:mysql://localhost:3306/fluent_mybatis_demo?useSSL=false&useUnicode=true&characterEncoding=utf-8";
    
        public static void main(String[] args) {
            FileGenerator.build(Abc.class);
        }
    
        @Tables(
            /** 数据库连接信息 **/
            url = url, username = "root", password = "password",
            /** Entity类parent package路径 **/
            basePack = "cn.org.fluent.mybatis.springboot.demo",
            /** Entity代码源目录 **/
            srcDir = "spring-boot-demo/src/main/java",
            /** Dao代码源目录 **/
            daoDir = "spring-boot-demo/src/main/java",
            /** 如果表定义记录创建，记录修改，逻辑删除字段 **/
            gmtCreated = "gmt_create", gmtModified = "gmt_modified", logicDeleted = "is_deleted",
            /** 需要生成文件的表 ( 表名称:对应的Entity名称 ) **/
            tables = @Table(value = {"student_score"})
        )
        static class Abc {
        }
    }

### **5、mybatis plus代码生成设置** ###

public class CodeGenerator {
    
        static String dbUrl = "jdbc:mysql://localhost:3306/fluent_mybatis_demo?useSSL=false&useUnicode=true&characterEncoding=utf-8";
    
        @Test
        public void generateCode() {
            GlobalConfig config = new GlobalConfig();
            DataSourceConfig dataSourceConfig = new DataSourceConfig();
            dataSourceConfig.setDbType(DbType.MYSQL)
                .setUrl(dbUrl)
                .setUsername("root")
                .setPassword("password")
                .setDriverName(Driver.class.getName());
            StrategyConfig strategyConfig = new StrategyConfig();
            strategyConfig
                .setCapitalMode(true)
                .setEntityLombokModel(false)
                .setNaming(NamingStrategy.underline_to_camel)
                .setColumnNaming(NamingStrategy.underline_to_camel)
                .setEntityTableFieldAnnotationEnable(true)
                .setFieldPrefix(new String[]{"test_"})
                .setInclude(new String[]{"student_score"})
                .setLogicDeleteFieldName("is_deleted")
                .setTableFillList(Arrays.asList(
                    new TableFill("gmt_create", FieldFill.INSERT),
                    new TableFill("gmt_modified", FieldFill.INSERT_UPDATE)));
    
            config
                .setActiveRecord(false)
                .setIdType(IdType.AUTO)
                .setOutputDir(System.getProperty("user.dir") + "/src/main/java/")
                .setFileOverride(true);
    
            new AutoGenerator().setGlobalConfig(config)
                .setDataSource(dataSourceConfig)
                .setStrategy(strategyConfig)
                .setPackageInfo(
                    new PackageConfig()
                        .setParent("com.mp.demo")
                        .setController("controller")
                        .setEntity("entity")
                ).execute();
        }
    }

### **Part5 FluentMybatis特性一览** ###

### **Part6三者对比总结** ###

看完3个框架对同一个功能点的实现, 各位看官肯定会有自己的判断，笔者这里也总结了一份比较。

<table> 
 <tbody> 
  <tr> 
   <th>-</th> 
   <th>Mybatis Plus</th> 
   <th>Fluent Mybatis</th> 
  </tr> 
  <tr> 
   <td>代码生成</td> 
   <td>生成 Entity</td> 
   <td>生成Entity, 再通过编译生成 Mapper, Query, Update 和 SqlProvider</td> 
  </tr> 
  <tr> 
   <td>Generator易用性</td> 
   <td>低</td> 
   <td>高</td> 
  </tr> 
  <tr> 
   <td>和Mybatis的共生关系</td> 
   <td>需替换原有的SqlSessionFactoryBean</td> 
   <td>对Mybatis没有任何修改,原来怎么用还是怎么用</td> 
  </tr> 
  <tr> 
   <td>动态SQL构造方式</td> 
   <td>应用启动时, 根据Entity注解信息构造动态xml片段，注入到Mybatis解析器</td> 
   <td>应用编译时，根据Entity注解，编译生成对应方法的SqlProvider，利用mybatis的Mapper上@InsertProvider @SelectProvider @UpdateProvider注解关联</td> 
  </tr> 
  <tr> 
   <td>动态SQL结果是否容易DEBUG跟踪</td> 
   <td>不容易debug</td> 
   <td>容易，直接定位到SQLProvider方法上，设置断点即可</td> 
  </tr> 
  <tr> 
   <td>动态SQL构造</td> 
   <td>通过硬编码字段名称, 或者利用Entity的get方法的lambda表达式</td> 
   <td>通过编译手段生成对应的方法名，直接调用方法即可</td> 
  </tr> 
  <tr> 
   <td>字段变更后的错误发现</td> 
   <td>通过get方法的lambda表达的可以编译发现，通过字段编码的无法编译发现</td> 
   <td>编译时便可发现</td> 
  </tr> 
  <tr> 
   <td>不同字段动态SQL构造方法</td> 
   <td>通过接口参数方式</td> 
   <td>通过接口名称方式, FluentAPI的编码效率更高</td> 
  </tr> 
  <tr> 
   <td>语法渲染特点</td> 
   <td>无</td> 
   <td>通过关键变量select, update, set, and, or可以利用IDE语法渲染, 可读性更高</td> 
  </tr> 
 </tbody> 
</table>

[http_juejin.cn_post_6886019929519177735]: https://link.zhihu.com/?target=http%3A//juejin.cn/post/6886019929519177735
[https_gitee.com_fluent-mybatis_fluent-mybatis]: https://link.zhihu.com/?target=https%3A//gitee.com/fluent-mybatis/fluent-mybatis
[https_github.com_javastacks_spring-boot-best-practice]: https://link.zhihu.com/?target=https%3A//github.com/javastacks/spring-boot-best-practice
[cd370fecd1705ebfb941ee36e15c11c3.png]: https://img-blog.csdnimg.cn/img_convert/cd370fecd1705ebfb941ee36e15c11c3.png
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