MyBatis-Plus 源码解说

fl_zxf2024-06-15 21:19

归档

总说明

单元测试

添加方法-UT

  • 参考：com.baomidou.mybatisplus.core.MybatisXMLConfigBuilderTest
java 复制代码 
    @Test
    void parse() throws IOException {
        ResourceLoader loader = new DefaultResourceLoader();
        Resource resource = loader.getResource("classpath:/MybatisXMLConfigBuilderTest.xml");
        MybatisXMLConfigBuilder builder = new MybatisXMLConfigBuilder(resource.getInputStream(), null); // ref: sign_c_110 | sign_cm_110
        Configuration configuration = builder.parse(); // ref: sign_m_110
        MappedStatement mappedStatement = configuration.getMappedStatement(..."EntityMapper.selectCount");
    }

    interface EntityMapper extends BaseMapper<Entity> { }

    @TableName(autoResultMap = true)
    static class Entity {
        private Long id;
        private String name;
    }
  • MybatisXMLConfigBuilderTest.xml
xml 复制代码 
<configuration>
    <mappers>
        <mapper class="com.baomidou.mybatisplus.core.MybatisXMLConfigBuilderTest$EntityMapper"/>
    </mappers>
</configuration>

完整测试

  • 参考：com.baomidou.mybatisplus.test.MybatisTest
java 复制代码 
    private static SqlSessionFactory sqlSessionFactory;

    @BeforeAll
    public static void init() throws IOException, SQLException {
        Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
        sqlSessionFactory = new MybatisSqlSessionFactoryBuilder().build(reader);    // 关键部分

        Configuration configuration = sqlSessionFactory.getConfiguration();
        TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();
        typeHandlerRegistry.register(AgeEnum.class, MybatisEnumTypeHandler.class);  // 注册枚举类型处理器

        DataSource dataSource = sqlSessionFactory.getConfiguration().getEnvironment().getDataSource();
        Connection connection = dataSource.getConnection();                         // 获取连接执行脚本
        ScriptRunner scriptRunner = new ScriptRunner(connection);
        scriptRunner.runScript(Resources.getResourceAsReader("h2/user.ddl.sql"));
    }

    @Test
    void test() {
        try (SqlSession sqlSession = sqlSessionFactory.openSession(true)) {
            H2UserMapper mapper = sqlSession.getMapper(H2UserMapper.class); // 添加 Mapper, ref: sign_m_130
            mapper.myInsertWithNameVersion("test", 2);
            H2User h2User = new H2User(...);
            mapper.insert(h2User);
        }
    }

Spring 测试

  • 参考：com.baomidou.mybatisplus.test.h2.H2StudentMapperTest
java 复制代码 
@TestMethodOrder(MethodOrderer.OrderAnnotation.class)
@ExtendWith(SpringExtension.class)
@ContextConfiguration(locations = {"classpath:h2/spring-test-h2.xml"})
class H2StudentMapperTest {
    @Resource
    protected H2StudentMapper studentMapper;

    @Test
    void testIn() {
        LambdaQueryWrapper<H2Student> wrapper = Wrappers.<H2Student>lambdaQuery()
            .in(H2Student::getName, Arrays.asList("a", "b"));
        List<H2Student> list = studentMapper.selectList(wrapper);
    }
}

原理

添加方法

java 复制代码 
// sign_c_110
// 从 MyBatis 的 XMLConfigBuilder 复制过来的, 使用自己的 MybatisConfiguration 而不是 Configuration
public class MybatisXMLConfigBuilder extends BaseBuilder {
    // sign_cm_110
    private MybatisXMLConfigBuilder(XPathParser parser, String environment, Properties props) {
        super(new MybatisConfiguration()); // 传自己的 MybatisConfiguration 实例，ref: sign_c_120
        ...
    }

    // sign_m_110
    public Configuration parse() {
        ...
        parseConfiguration(parser.evalNode("/configuration")); // ref: sign_m_111
        return configuration;
    }

    // sign_m_111
    private void parseConfiguration(XNode root) {
        try {
            // (类似的) 参考：[MyBatis-创建-SqlSessionFactory sign_m_121]
            ...
            mapperElement(root.evalNode("mappers")); // ref: sign_m_112
        } ... // catch
    }

    // sign_m_112  解析 Mapper 配置
    private void mapperElement(XNode parent) throws Exception {
        if (parent != null) {
            for (XNode child : parent.getChildren()) {
                if ("package".equals(child.getName())) {
                    ...
                } else {
                    String resource = child.getStringAttribute("resource");
                    String url = child.getStringAttribute("url");
                    String mapperClass = child.getStringAttribute("class");
                    if (resource != null && url == null && mapperClass == null) {
                        ...
                    } else if (resource == null && url != null && mapperClass == null) {
                        ...
                    } else if (resource == null && url == null && mapperClass != null) {
                        Class<?> mapperInterface = Resources.classForName(mapperClass);
                        configuration.addMapper(mapperInterface); // 注册 Mappger, ref: sign_m_120
                    } ... // else {}
                }
            }
        }
    }
}
  • com.baomidou.mybatisplus.core.MybatisConfiguration
java 复制代码 
// sign_c_120 替换默认的 Configuration 类
public class MybatisConfiguration extends Configuration {
    // Mapper 注册
    protected MybatisMapperRegistry mybatisMapperRegistry = new MybatisMapperRegistry(this); // ref: sign_c_130 | sign_cm_130

    // sign_m_120  注册 Mappger
    @Override
    public <T> void addMapper(Class<T> type) {
        mybatisMapperRegistry.addMapper(type); // ref: sign_m_130
    }
}
java 复制代码 
// sign_c_130  继承自 MapperRegistry
public class MybatisMapperRegistry extends MapperRegistry {
    private Configuration config; // 实际是 MybatisConfiguration 实例，ref: sign_c_120
    private Map<Class<?>, MybatisMapperProxyFactory<?>> knownMappers = new ConcurrentHashMap<>();

    // sign_cm_130
    public MybatisMapperRegistry(Configuration config) {
        super(config);
        this.config = config;
    }

    // sign_m_130
    @Override
    public <T> void addMapper(Class<T> type) {
        if (type.isInterface()) {
            ...
            try {
                knownMappers.put(type, new MybatisMapperProxyFactory<>(type)); // 会在 getMapper(T) 时调用，参考：[MyBatis-获取-Mapper sign_m_330]
                MybatisMapperAnnotationBuilder parser = new MybatisMapperAnnotationBuilder(config, type); // ref: sign_c_140 | sign_cm_140
                parser.parse(); // ref: sign_m_140
            } ... // finally {}
        }
    }
}
  • com.baomidou.mybatisplus.core.MybatisMapperAnnotationBuilder
java 复制代码 
// sign_c_140
public class MybatisMapperAnnotationBuilder extends MapperAnnotationBuilder {
    private static Set<Class<? extends Annotation>> statementAnnotationTypes = 
        Stream.of(
            Select.class, Update.class, Insert.class, Delete.class, 
            SelectProvider.class, UpdateProvider.class, InsertProvider.class, DeleteProvider.class
        ).collect(Collectors.toSet());
    
    // sign_cm_140
    public MybatisMapperAnnotationBuilder(Configuration configuration, Class<?> type) {
        super(configuration, type); // configuration 为 MybatisConfiguration 实例，ref: sign_c_120
        this.assistant = new MybatisMapperBuilderAssistant(configuration, resource);
        ...
    }

    // sign_m_140
    @Override
    public void parse() {
        String resource = type.toString();
        if (!configuration.isResourceLoaded(resource)) {
            ... // MyBatis 那套解析逻辑
            try {
                if (GlobalConfigUtils.isSupperMapperChildren(configuration, type)) { // 判断 type 是不是继承 Mapper 接口
                    // 自己继承 BaseMapper，就会进入此逻辑
                    parserInjector(); // 注入基础方法，ref: sign_m_141
                }
            } ... // catch
        }
        ...
    }

    // sign_m_141 注入基础方法
    void parserInjector() {
        GlobalConfigUtils.getSqlInjector(configuration) // 返回 DefaultSqlInjector 实例, ref: sign_c_150
            .inspectInject(assistant, type); // 解析 BaseMapper 基础方法，ref: sign_m_160
    }
}
  • com.baomidou.mybatisplus.core.injector.DefaultSqlInjector
java 复制代码 
// sign_c_150  SQL 默认注入器
public class DefaultSqlInjector extends AbstractSqlInjector {
    // sign_m_150
    @Override
    public List<AbstractMethod> getMethodList(Class<?> mapperClass, TableInfo tableInfo) {
        Stream.Builder<AbstractMethod> builder = Stream.<AbstractMethod>builder()
            .add(new Insert())
            .add(new Delete())
            .add(new Update())
            .add(new SelectCount()) // ref: sign_c_180
            .add(new SelectMaps())
            .add(new SelectObjs())
            .add(new SelectList());
        if (tableInfo.havePK()) {
            builder.add(new DeleteById())
                .add(new DeleteBatchByIds())
                .add(new UpdateById())
                .add(new SelectById())
                .add(new SelectBatchByIds());
        } ... // else
        return builder.build().collect(toList());
    }
}
  • com.baomidou.mybatisplus.core.injector.AbstractSqlInjector
java 复制代码 
// sign_c_160  SQL 自动注入器
public abstract class AbstractSqlInjector implements ISqlInjector {
    // sign_m_160  将 BaseMapper 的基础方法转成 SQL 语句注入到 configuration (MyBatis) 中去
    @Override
    public void inspectInject(MapperBuilderAssistant builderAssistant, Class<?> mapperClass) {
        Class<?> modelClass = ReflectionKit.getSuperClassGenericType(mapperClass, Mapper.class, 0); // 获取实体类
        if (modelClass != null) {
            ... // 是否已注册判断处理

                // 初始化表信息(读取：表名、主键、字段等)
                TableInfo tableInfo = TableInfoHelper.initTableInfo(builderAssistant, modelClass);
                List<AbstractMethod> methodList = this.getMethodList(mapperClass, tableInfo); // ref: sign_m_150
                if (CollectionUtils.isNotEmpty(methodList)) {
                    // 循环注入自定义方法
                    methodList.forEach(m -> m.inject(builderAssistant, mapperClass, modelClass, tableInfo)); // ref: sign_m_170
                } ... // else
        }
    }
}
java 复制代码 
public abstract class AbstractMethod implements Constants {
    // sign_m_170 注入自定义方法
    public void inject(MapperBuilderAssistant builderAssistant, Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
        this.configuration = builderAssistant.getConfiguration();
        this.builderAssistant = builderAssistant;
        this.languageDriver = configuration.getDefaultScriptingLanguageInstance();
        /* 注入自定义方法 */
        injectMappedStatement(mapperClass, modelClass, tableInfo); // 以 SelectCount 为例，ref: sign_c_180 | sign_m_180
    }

    // sign_m_171
    protected MappedStatement addSelectMappedStatementForOther(Class<?> mapperClass, String id, SqlSource sqlSource,
                                                               Class<?> resultType) {
        return addMappedStatement( // ref: sign_m_172
            mapperClass, id, sqlSource, SqlCommandType.SELECT, ...
        ); 
    }

    // sign_m_172  添加 MappedStatement 到 Mybatis 容器
    protected MappedStatement addMappedStatement(
        Class<?> mapperClass, String id, SqlSource sqlSource,
        SqlCommandType sqlCommandType, ...
    ) {
        ... // 判断是否已添加处理
        // 构建 MappedStatement 并添加到 configuration
        return builderAssistant.addMappedStatement(...); // 参考：[MyBatis-创建-SqlSessionFactory sign_m_150]
    }
}
  • com.baomidou.mybatisplus.core.injector.methods.SelectCount
java 复制代码 
// sign_c_180
public class SelectCount extends AbstractMethod {
    // sign_m_180  拼接 SQL 语句注入到 configuration (MyBatis) 中去
    @Override
    public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
        SqlMethod sqlMethod = SqlMethod.SELECT_COUNT;
        String sql = String.format(
            sqlMethod.getSql(), // "<script>%s SELECT COUNT(%s) AS total FROM %s %s %s\n</script>"
            /*
            <if test="ew != null and ew.sqlFirst != null">
                ${ew.sqlFirst}
            </if>
            */
            sqlFirst(),
            /*
            <choose>
                <when test="ew != null and ew.sqlSelect != null">
                    ${ew.sqlSelect}
                </when>
                <otherwise>*</otherwise>
            </choose>
            */
            sqlCount(), 
            tableInfo.getTableName(), // 表名：entity
            /*
            <if test="ew != null">
                <bind name="_sgEs_" value="ew.sqlSegment != null and ew.sqlSegment != ''"/>
                <where>
                    <if test="ew.entity != null">
                        <if test="ew.entity.id != null">id=#{ew.entity.id}</if>
                        <if test="ew.entity['name'] != null"> AND name=#{ew.entity.name}</if>
                    </if>
                    <if test="_sgEs_ and ew.nonEmptyOfNormal">
                        AND ${ew.sqlSegment}
                    </if>
                </where>
                <if test="_sgEs_ and ew.emptyOfNormal">
                    ${ew.sqlSegment}
                </if>
            </if>
            */
            sqlWhereEntityWrapper(true, tableInfo),
            /*
            <if test="ew != null and ew.sqlComment != null">
                ${ew.sqlComment}
            </if>
            */
            sqlComment()
        );
        SqlSource sqlSource = super.createSqlSource(configuration, sql, modelClass);
        return this.addSelectMappedStatementForOther(mapperClass, methodName, sqlSource, Long.class); // ref: sign_m_171
    }
}
  • com.baomidou.mybatisplus.core.injector.methods.SelectList
java 复制代码 
    public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
        SqlMethod sqlMethod = SqlMethod.SELECT_COUNT;
        String.format(
            sqlMethod.getSql(), // "<script>%s SELECT %s FROM %s %s %s %s\n</script>"
            /*
            <if test="ew != null and ew.sqlFirst != null">
                ${ew.sqlFirst}
            </if>
            */
            sqlFirst(), 
            /*
            <choose>
                <when test="ew != null and ew.sqlSelect != null">
                    ${ew.sqlSelect}
                </when>
                <otherwise>test_id,name,age,price,test_type,`desc`,version,deleted,last_updated_dt</otherwise>
            </choose>
            */
            sqlSelectColumns(tableInfo, true), 
            tableInfo.getTableName(), // 表名：entity
            /*
            <where>
                deleted=0
                <if test="ew != null">
                    <bind name="_sgEs_" value="ew.sqlSegment != null and ew.sqlSegment != ''"/>
                    <if test="ew.entity != null">
                        <if test="ew.entity.testId != null"> AND test_id=#{ew.entity.testId}</if>
                        <if test="ew.entity['name'] != null"> AND name=#{ew.entity.name}</if>
                        <if test="ew.entity['age'] != null"> AND age=#{ew.entity.age}</if>
                        <if test="ew.entity['price'] != null"> AND price=#{ew.entity.price}</if>
                        <if test="ew.entity['testType'] != null"> AND test_type=#{ew.entity.testType}</if>
                        <if test="ew.entity['desc'] != null"> AND `desc`=#{ew.entity.desc}</if>
                        <if test="ew.entity['testDate'] != null"> AND test_date=#{ew.entity.testDate}</if>
                        <if test="ew.entity['version'] != null"> AND version=#{ew.entity.version}</if>
                        <if test="ew.entity['lastUpdatedDt'] != null"> AND last_updated_dt=#{ew.entity.lastUpdatedDt}</if>
                    </if>
                    <if test="_sgEs_ and ew.nonEmptyOfNormal">
                        AND ${ew.sqlSegment}
                    </if>
                    <if test="_sgEs_ and ew.emptyOfNormal">
                        ${ew.sqlSegment}
                    </if>
                </if>
            </where>
            */
            sqlWhereEntityWrapper(true, tableInfo), 
            sqlOrderBy(tableInfo), // 空
            /*
            <if test="ew != null and ew.sqlComment != null">
                ${ew.sqlComment}
            </if>
            */
            sqlComment()
        );
        SqlSource sqlSource = super.createSqlSource(configuration, sql, modelClass);
        return this.addSelectMappedStatementForOther(mapperClass, methodName, sqlSource, Long.class); // ref: sign_m_171
    }
总结
  • 大部分扩展自 MyBatis 已有类，扩展的类使用 Mybatis 前缀

Spring 集成

  • 单测关键类：
    • com.baomidou.mybatisplus.test.h2.config.DBConfig
    • com.baomidou.mybatisplus.test.h2.config.MybatisPlusConfig
  • Spring-Boot 关键类:
    • com.baomidou.mybatisplus.autoconfigure.MybatisPlusAutoConfiguration
    • 数据源（连接池）通过 # sqlSessionFactory(DataSource) 方法设置
  • 注解扫描：

SQL 格式化

  • org.apache.ibatis.executor.CachingExecutor #query(MS, p, RB, RH) 调用
  • org.apache.ibatis.mapping.MappedStatement #getBoundSql 主要逻辑在这里
相关推荐
敲代码的小王！1 小时前
mybatisplus介绍以及使用（下）
java·数据库·mybatis
陈逸轩*^_^*13 小时前
Mybatis详细教程 （万字详解)
mybatis
晚睡早起₍˄·͈༝·͈˄*₎◞ ̑̑14 小时前
苍穹外卖学习笔记(十三)
java·笔记·学习·mybatis
十十一丶17 小时前
Mybatis(进阶部分)
java·tomcat·mybatis
爱上语文19 小时前
Springboot综合练习
java·spring boot·后端·spring·mybatis
《小书生》21 小时前
Mybatis 9种动态 sql 标签使用
java·sql·mybatis
为java添砖加瓦2 天前
【读写分离？聊聊Mysql多数据源实现读写分离的几种方案】
java·数据库·spring boot·后端·mysql·spring·mybatis
The best are water2 天前
jeesite集成redis，redis工具类
redis·spring·mybatis
程序猿小D2 天前
第二百五十五节 JPA教程 - JPA 多对多连接表示例
java·开发语言·数据库·mysql·servlet·mybatis·jpa
hhzz2 天前
Spring Boot 整合MyBatis-Plus 实现多层次树结构的异步加载功能
spring boot·后端·mybatis
热门推荐
01【案例教程】LoadRunner订票系统WebTours部署02组基轨迹建模 GBTM的介绍与实现（Stata 或 R）032024年高教社杯数学建模国赛C题超详细解题思路分析04RAG 实践- Ollama+RagFlow 部署本地知识库05yolov8实战第五天——yolov8+ffmpg实时视频流检测并进行实时推流——（推流，保姆教学）06【2024数模国赛赛题思路公开】国赛B题思路丨附可运行代码丨无偿自提07Ubuntu24.04安装中文输入法08软件工程从理论到实践客观题汇总(头歌第一章至第八章)09【2024高教社杯全国大学生数学建模竞赛】B题 生产过程中的决策问题——解题思路 代码 论文10npm使用国内淘宝镜像（最新地址）