1 前言
上次我们看了 Mybatis 是如何整合到 SpringBoot 的，那么平时我们可能直接用的就是 Mybatis-Plus，那么它又是如何结合到的 SpringBoot 的呢？原理其实是一样的，这节我们就来看看。
看的过程中，其实会深深体会 Mybatis-Plus 就是对 Mybatis 的增强，类似 SpringBoot 对 Spring 的增强。
2 环境准备
还是老样子，首先我们新建个工程，然后引入 Mybatis-Plus，大家要知道一点引入 Mybatis-Plus 的依赖，就不需要主动引入 Mybatis 的了，因为它自己会依赖的：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>42.2.7</version>
</dependency>
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.3.0</version>
</dependency>
spring.datasource.driver-class-name = org.postgresql.Driver spring.datasource.url = jdbc:postgresql://localhost:5432/test spring.datasource.username = postgres spring.datasource.password = xxx mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl mybatis-plus.mapper-locations=classpath*:/mapper/**/*.xml
还有一个变化就是我们的 Mapper 接口，可以直接继承 Plus 提供的，就可以完成基础的 CRUD：
@Mapper
public interface AccountMapper extends BaseMapper<AccountPo> {
}
效果：
3 源码分析
我们还是直接从 Starter 看起（mybatis-plus-boot-starter-3.3.0.jar / META-INF / spring.factories）：
3.1 MybatisPlusAutoConfiguration
对比着来看，Mybatis 那边是MybatisAutoConfiguration， Mybatis-Plus 是MybatisPlusAutoConfiguration：
@Configuration
@ConditionalOnClass({SqlSessionFactory.class, SqlSessionFactoryBean.class})
@ConditionalOnSingleCandidate(DataSource.class)
@EnableConfigurationProperties({MybatisPlusProperties.class})
@AutoConfigureAfter({DataSourceAutoConfiguration.class, MybatisPlusLanguageDriverAutoConfiguration.class})
public class MybatisPlusAutoConfiguration implements InitializingBean {
private static final Logger logger = LoggerFactory.getLogger(MybatisPlusAutoConfiguration.class);
private final MybatisPlusProperties properties;
对于 SqlSessionFactory 的创建，Mybatis 那边是 SqlSessionFactoryBean， Mybatis-Plus 是 MybatisSqlSessionFactoryBean：
@Bean
@ConditionalOnMissingBean
public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
MybatisSqlSessionFactoryBean factory = new MybatisSqlSessionFactoryBean();
factory.setDataSource(dataSource);
factory.setVfs(SpringBootVFS.class);
if (StringUtils.hasText(this.properties.getConfigLocation())) {
factory.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation()));
}
this.applyConfiguration(factory);
if (this.properties.getConfigurationProperties() != null) {
factory.setConfigurationProperties(this.properties.getConfigurationProperties());
}
if (!ObjectUtils.isEmpty(this.interceptors)) {
factory.setPlugins(this.interceptors);
}
if (this.databaseIdProvider != null) {
factory.setDatabaseIdProvider(this.databaseIdProvider);
}
if (StringUtils.hasLength(this.properties.getTypeAliasesPackage())) {
factory.setTypeAliasesPackage(this.properties.getTypeAliasesPackage());
}
if (this.properties.getTypeAliasesSuperType() != null) {
factory.setTypeAliasesSuperType(this.properties.getTypeAliasesSuperType());
}
if (StringUtils.hasLength(this.properties.getTypeHandlersPackage())) {
factory.setTypeHandlersPackage(this.properties.getTypeHandlersPackage());
}
if (!ObjectUtils.isEmpty(this.typeHandlers)) {
factory.setTypeHandlers(this.typeHandlers);
}
if (!ObjectUtils.isEmpty(this.properties.resolveMapperLocations())) {
factory.setMapperLocations(this.properties.resolveMapperLocations());
}
Class<? extends LanguageDriver> defaultLanguageDriver = this.properties.getDefaultScriptingLanguageDriver();
if (!ObjectUtils.isEmpty(this.languageDrivers)) {
factory.setScriptingLanguageDrivers(this.languageDrivers);
}
Optional.ofNullable(defaultLanguageDriver).ifPresent(factory::setDefaultScriptingLanguageDriver);
if (StringUtils.hasLength(this.properties.getTypeEnumsPackage())) {
factory.setTypeEnumsPackage(this.properties.getTypeEnumsPackage());
}
GlobalConfig globalConfig = this.properties.getGlobalConfig();
this.getBeanThen(MetaObjectHandler.class, globalConfig::setMetaObjectHandler);
this.getBeanThen(IKeyGenerator.class, (i) -> {
globalConfig.getDbConfig().setKeyGenerator(i);
});
this.getBeanThen(ISqlInjector.class, globalConfig::setSqlInjector);
this.getBeanThen(IdentifierGenerator.class, globalConfig::setIdentifierGenerator);
factory.setGlobalConfig(globalConfig);
return factory.getObject();
}
基本大差不差，我们看看 getObject（）方法：
public SqlSessionFactory getObject() throws Exception {
if (this.sqlSessionFactory == null) {
this.afterPropertiesSet();
}
return this.sqlSessionFactory;
}
还是继续 afterPropertiesSet（）方法：
public void afterPropertiesSet() throws Exception {
// 必须校验
Assert.notNull(this.dataSource, "Property 'dataSource' is required");
Assert.state(this.configuration == null && this.configLocation == null || this.configuration == null || this.configLocation == null, "Property 'configuration' and 'configLocation' can not specified with together");
this.sqlSessionFactory = this.buildSqlSessionFactory();
}
继续 buildSqlSessionFactory（）方法：
protected SqlSessionFactory buildSqlSessionFactory() throws Exception {
MybatisXMLConfigBuilder xmlConfigBuilder = null;
MybatisConfiguration targetConfiguration;
if (this.configuration != null) {
targetConfiguration = this.configuration;
if (targetConfiguration.getVariables() == null) {
targetConfiguration.setVariables(this.configurationProperties);
} else if (this.configurationProperties != null) {
targetConfiguration.getVariables().putAll(this.configurationProperties);
}
} else if (this.configLocation != null) {
xmlConfigBuilder = new MybatisXMLConfigBuilder(this.configLocation.getInputStream(), (String)null, this.configurationProperties);
targetConfiguration = xmlConfigBuilder.getConfiguration();
} else {
LOGGER.debug(() -> {
return "Property 'configuration' or 'configLocation' not specified, using default MyBatis Configuration";
});
targetConfiguration = new MybatisConfiguration();
Optional.ofNullable(this.configurationProperties).ifPresent(targetConfiguration::setVariables);
}
this.globalConfig = (GlobalConfig)Optional.ofNullable(this.globalConfig).orElseGet(GlobalConfigUtils::defaults);
this.globalConfig.setDbConfig((DbConfig)Optional.ofNullable(this.globalConfig.getDbConfig()).orElseGet(DbConfig::new));
targetConfiguration.setGlobalConfig(this.globalConfig);
if (StringUtils.hasLength(this.typeEnumsPackage)) {
Object classes;
if (this.typeEnumsPackage.contains("*") && !this.typeEnumsPackage.contains(",") && !this.typeEnumsPackage.contains(";")) {
classes = this.scanClasses(this.typeEnumsPackage, (Class)null);
if (((Set)classes).isEmpty()) {
LOGGER.warn(() -> {
return "Can't find class in '[" + this.typeEnumsPackage + "]' package. Please check your configuration.";
});
}
} else {
classes = new HashSet();
String[] typeEnumsPackageArray = StringUtils.tokenizeToStringArray(this.typeEnumsPackage, ",; \t\n");
com.baomidou.mybatisplus.core.toolkit.Assert.notNull(typeEnumsPackageArray, "not find typeEnumsPackage:" + this.typeEnumsPackage, new Object[0]);
Stream.of(typeEnumsPackageArray).forEach((typePackage) -> {
try {
Set<Class<?>> scanTypePackage = this.scanClasses(typePackage, (Class)null);
if (scanTypePackage.isEmpty()) {
LOGGER.warn(() -> {
return "Can't find class in '[" + typePackage + "]' package. Please check your configuration.";
});
} else {
classes.addAll(scanTypePackage);
}
} catch (IOException var4) {
throw new MybatisPlusException("Cannot scan class in '[" + typePackage + "]' package", var4);
}
});
}
TypeHandlerRegistry typeHandlerRegistry = targetConfiguration.getTypeHandlerRegistry();
((Set)classes).stream().filter(Class::isEnum).filter((cls) -> {
return IEnum.class.isAssignableFrom(cls) || MybatisEnumTypeHandler.dealEnumType(cls).isPresent();
}).forEach((cls) -> {
typeHandlerRegistry.register(cls, MybatisEnumTypeHandler.class);
});
}
Optional.ofNullable(this.objectFactory).ifPresent(targetConfiguration::setObjectFactory);
Optional.ofNullable(this.objectWrapperFactory).ifPresent(targetConfiguration::setObjectWrapperFactory);
Optional.ofNullable(this.vfs).ifPresent(targetConfiguration::setVfsImpl);
Stream var10000;
if (StringUtils.hasLength(this.typeAliasesPackage)) {
var10000 = this.scanClasses(this.typeAliasesPackage, this.typeAliasesSuperType).stream().filter((clazz) -> {
return !clazz.isAnonymousClass();
}).filter((clazz) -> {
return !clazz.isInterface();
}).filter((clazz) -> {
return !clazz.isMemberClass();
});
TypeAliasRegistry var10001 = targetConfiguration.getTypeAliasRegistry();
var10000.forEach(var10001::registerAlias);
}
if (!ObjectUtils.isEmpty(this.typeAliases)) {
Stream.of(this.typeAliases).forEach((typeAlias) -> {
targetConfiguration.getTypeAliasRegistry().registerAlias(typeAlias);
LOGGER.debug(() -> {
return "Registered type alias: '" + typeAlias + "'";
});
});
}
if (!ObjectUtils.isEmpty(this.plugins)) {
Stream.of(this.plugins).forEach((plugin) -> {
targetConfiguration.addInterceptor(plugin);
LOGGER.debug(() -> {
return "Registered plugin: '" + plugin + "'";
});
});
}
if (StringUtils.hasLength(this.typeHandlersPackage)) {
var10000 = this.scanClasses(this.typeHandlersPackage, TypeHandler.class).stream().filter((clazz) -> {
return !clazz.isAnonymousClass();
}).filter((clazz) -> {
return !clazz.isInterface();
}).filter((clazz) -> {
return !Modifier.isAbstract(clazz.getModifiers());
}).filter((clazz) -> {
return ClassUtils.getConstructorIfAvailable(clazz, new Class[0]) != null;
});
TypeHandlerRegistry var28 = targetConfiguration.getTypeHandlerRegistry();
var10000.forEach(var28::register);
}
if (!ObjectUtils.isEmpty(this.typeHandlers)) {
Stream.of(this.typeHandlers).forEach((typeHandler) -> {
targetConfiguration.getTypeHandlerRegistry().register(typeHandler);
LOGGER.debug(() -> {
return "Registered type handler: '" + typeHandler + "'";
});
});
}
if (!ObjectUtils.isEmpty(this.scriptingLanguageDrivers)) {
Stream.of(this.scriptingLanguageDrivers).forEach((languageDriver) -> {
targetConfiguration.getLanguageRegistry().register(languageDriver);
LOGGER.debug(() -> {
return "Registered scripting language driver: '" + languageDriver + "'";
});
});
}
Optional.ofNullable(this.defaultScriptingLanguageDriver).ifPresent(targetConfiguration::setDefaultScriptingLanguage);
if (this.databaseIdProvider != null) {
try {
targetConfiguration.setDatabaseId(this.databaseIdProvider.getDatabaseId(this.dataSource));
} catch (SQLException var23) {
throw new NestedIOException("Failed getting a databaseId", var23);
}
}
Optional.ofNullable(this.cache).ifPresent(targetConfiguration::addCache);
if (xmlConfigBuilder != null) {
try {
xmlConfigBuilder.parse();
LOGGER.debug(() -> {
return "Parsed configuration file: '" + this.configLocation + "'";
});
} catch (Exception var21) {
throw new NestedIOException("Failed to parse config resource: " + this.configLocation, var21);
} finally {
ErrorContext.instance().reset();
}
}
targetConfiguration.setEnvironment(new Environment(MybatisSqlSessionFactoryBean.class.getSimpleName(), (TransactionFactory)(this.transactionFactory == null ? new SpringManagedTransactionFactory() : this.transactionFactory), this.dataSource));
if (this.mapperLocations != null) {
if (this.mapperLocations.length == 0) {
LOGGER.warn(() -> {
return "Property 'mapperLocations' was specified but matching resources are not found.";
});
} else {
Resource[] var24 = this.mapperLocations;
int var27 = var24.length;
for(int var5 = 0; var5 < var27; ++var5) {
Resource mapperLocation = var24[var5];
if (mapperLocation != null) {
try {
XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(mapperLocation.getInputStream(), targetConfiguration, mapperLocation.toString(), targetConfiguration.getSqlFragments());
xmlMapperBuilder.parse();
} catch (Exception var19) {
throw new NestedIOException("Failed to parse mapping resource: '" + mapperLocation + "'", var19);
} finally {
ErrorContext.instance().reset();
}
LOGGER.debug(() -> {
return "Parsed mapper file: '" + mapperLocation + "'";
});
}
}
}
} else {
LOGGER.debug(() -> {
return "Property 'mapperLocations' was not specified.";
});
}
SqlSessionFactory sqlSessionFactory = (new MybatisSqlSessionFactoryBuilder()).build(targetConfiguration);
SqlHelper.FACTORY = sqlSessionFactory;
// 这就是我们启动的时候，打日志的源头
if (this.globalConfig.isBanner()) {
System.out.println(" _ _ |_ _ _|_. ___ _ | _ ");
System.out.println("| | |\\/|_)(_| | |_\\ |_)||_|_\\ ");
System.out.println(" / | ");
System.out.println(" " + MybatisPlusVersion.getVersion() + " ");
}
return sqlSessionFactory;
}
基本上差不多，多了一个打印启动日志的。
3.2 MybatisPlusProperties
对比着来看，Mybatis 那边是 MybatisProperties（属性是 mybatis 开头）， Mybatis-Plus 是 MybatisPlusProperties（属性是mybatis-plus 开头）：
@ConfigurationProperties(
prefix = "mybatis-plus"
)
public class MybatisPlusProperties {
private static final ResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver();
private String configLocation;
private String[] mapperLocations = new String[]{"classpath*:/mapper/**/*.xml"};
可以看到属性配置 mybatis-plus 开头，并且 mapper.xml 的位置也帮我们初始化了一个默认的目录，其它的就不细看了，本节主要看关系的串联哈。
还有 @Mapper 扫描，跟 Mybatis 一致，直接复制的：
@Configuration
@Import({MybatisPlusAutoConfiguration.AutoConfiguredMapperScannerRegistrar.class})
@ConditionalOnMissingBean({MapperFactoryBean.class, MapperScannerConfigurer.class})
public static class MapperScannerRegistrarNotFoundConfiguration implements InitializingBean {
public MapperScannerRegistrarNotFoundConfiguration() {
}
public void afterPropertiesSet() {
MybatisPlusAutoConfiguration.logger.debug("Not found configuration for registering mapper bean using @MapperScan, MapperFactoryBean and MapperScannerConfigurer.");
}
}
4 小结
好啦，就看到这里了，对比着上一节的 Mybatis 的来看。
标签：return,SpringBoot,factory,targetConfiguration,Mybatis,Plus,null,class From： https://www.cnblogs.com/kukuxjx/p/18033610