SpringBoot整合MyBatis源码
SpringBoot如何整合MyBatis
导包
代码
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.3</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.24</version>
</dependency>
<dependency>
<groupId>cn.hutool</groupId>
<artifactId>hutool-all</artifactId>
<version>5.8.3</version>
</dependency>
配置application.yml
代码
server:
port: 9090
servlet:
encoding:
charset: UTF-8
context-path: /visual-web
spring:
application:
name: visual-web
datasource:
type: com.zaxxer.hikari.HikariDataSource
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://IP1:3360/db?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT&allowPublicKeyRetrieval=true
username: root
password: pwd
hikari:
connection-timeout: 10000
validation-timeout: 3000
idle-timeout: 60000
login-timeout: 5
max-lifetime: 60000
maximum-pool-size: 10
minimum-idle: 5
read-only: false
mybatis:
type-aliases-package: com.sunpeiyu.visualweb.entity
mapper-locations: classpath:com/sunpeiyu/visualweb/mapper/*.xml
编写Mapper和XML
代码
<?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.sunpeiyu.visualweb.dao.MenuMapper">
<select id="selectMenuList" resultType="com.sunpeiyu.visualweb.entity.MenuEntity">
select menu_id as menuId, menu_name as menuName,
menu_path as menuPath, menu_label as menuLabel,
menu_url as menuUrl, menu_index as menuIndex, menu_icon as menuIcon
from menu
</select>
</mapper>
@Repository
@Mapper
public interface MenuMapper {
/**
* 查询所有的菜单
* @return
*/
List<MenuEntity> selectMenuList();
}
service层
代码
@Service
public class MenuServiceImpl {
@Autowired
private MenuMapper menuMapper;
public List<MenuDTO> listMenu() {
List<MenuEntity> menuEntityList = menuMapper.selectMenuList();
return CopyUtils.copyListByShallow(menuEntityList, MenuDTO.class);
}
}
controller层
代码
@RequestMapping("/menu")
@RestController
public class MenuController {
@Autowired
private MenuServiceImpl menuService;
@GetMapping("/list")
public List<MenuDTO> list() {
return menuService.listMenu();
}
}
流程图
mybatis源码阅读思考
- mybatis如何加载mapper中java接口和xml文件的。
- mybatis如何解析xml文件中的sql语句。
- mybatis的mapper中只有java接口，没有实现类，如何进行实现类调用。
- mybatis中的拦截器的源码如何实现的。
- mybatis中的xml文件和java接口如何做到一一对应的。
自动装配Spring.factories文件中EnableAutoConfiguration对应的值MybatisAutoConfiguration
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.mybatis.spring.boot.autoconfigure.MybatisLanguageDriverAutoConfiguration,\
org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration
代码
@Configuration
@ConditionalOnClass({SqlSessionFactory.class, SqlSessionFactoryBean.class})
@ConditionalOnSingleCandidate(DataSource.class)
@EnableConfigurationProperties({MybatisProperties.class})
@AutoConfigureAfter({DataSourceAutoConfiguration.class, MybatisLanguageDriverAutoConfiguration.class})
public class MybatisAutoConfiguration implements InitializingBean {
private static final Logger logger = LoggerFactory.getLogger(MybatisAutoConfiguration.class);
private final MybatisProperties properties;
private final Interceptor[] interceptors;
private final TypeHandler[] typeHandlers;
private final LanguageDriver[] languageDrivers;
private final ResourceLoader resourceLoader;
private final DatabaseIdProvider databaseIdProvider;
private final List<ConfigurationCustomizer> configurationCustomizers;
public MybatisAutoConfiguration(MybatisProperties properties, ObjectProvider<Interceptor[]> interceptorsProvider, ObjectProvider<TypeHandler[]> typeHandlersProvider, ObjectProvider<LanguageDriver[]> languageDriversProvider, ResourceLoader resourceLoader, ObjectProvider<DatabaseIdProvider> databaseIdProvider, ObjectProvider<List<ConfigurationCustomizer>> configurationCustomizersProvider) {
this.properties = properties;
this.interceptors = (Interceptor[])interceptorsProvider.getIfAvailable();
this.typeHandlers = (TypeHandler[])typeHandlersProvider.getIfAvailable();
this.languageDrivers = (LanguageDriver[])languageDriversProvider.getIfAvailable();
this.resourceLoader = resourceLoader;
this.databaseIdProvider = (DatabaseIdProvider)databaseIdProvider.getIfAvailable();
this.configurationCustomizers = (List)configurationCustomizersProvider.getIfAvailable();
}
public void afterPropertiesSet() {
this.checkConfigFileExists();
}
private void checkConfigFileExists() {
if (this.properties.isCheckConfigLocation() && StringUtils.hasText(this.properties.getConfigLocation())) {
Resource resource = this.resourceLoader.getResource(this.properties.getConfigLocation());
Assert.state(resource.exists(), "Cannot find config location: " + resource + " (please add config file or check your Mybatis configuration)");
}
}
@Bean
@ConditionalOnMissingBean
public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
SqlSessionFactoryBean factory = new SqlSessionFactoryBean();
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());
}
Set<String> factoryPropertyNames = (Set)Stream.of((new BeanWrapperImpl(SqlSessionFactoryBean.class)).getPropertyDescriptors()).map(FeatureDescriptor::getName).collect(Collectors.toSet());
Class<? extends LanguageDriver> defaultLanguageDriver = this.properties.getDefaultScriptingLanguageDriver();
if (factoryPropertyNames.contains("scriptingLanguageDrivers") && !ObjectUtils.isEmpty(this.languageDrivers)) {
factory.setScriptingLanguageDrivers(this.languageDrivers);
if (defaultLanguageDriver == null && this.languageDrivers.length == 1) {
defaultLanguageDriver = this.languageDrivers[0].getClass();
}
}
if (factoryPropertyNames.contains("defaultScriptingLanguageDriver")) {
factory.setDefaultScriptingLanguageDriver(defaultLanguageDriver);
}
return factory.getObject();
}
private void applyConfiguration(SqlSessionFactoryBean factory) {
org.apache.ibatis.session.Configuration configuration = this.properties.getConfiguration();
if (configuration == null && !StringUtils.hasText(this.properties.getConfigLocation())) {
configuration = new org.apache.ibatis.session.Configuration();
}
if (configuration != null && !CollectionUtils.isEmpty(this.configurationCustomizers)) {
Iterator var3 = this.configurationCustomizers.iterator();
while(var3.hasNext()) {
ConfigurationCustomizer customizer = (ConfigurationCustomizer)var3.next();
customizer.customize(configuration);
}
}
factory.setConfiguration(configuration);
}
@Bean
@ConditionalOnMissingBean
public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
ExecutorType executorType = this.properties.getExecutorType();
return executorType != null ? new SqlSessionTemplate(sqlSessionFactory, executorType) : new SqlSessionTemplate(sqlSessionFactory);
}
@Configuration
@Import({MybatisAutoConfiguration.AutoConfiguredMapperScannerRegistrar.class})
@ConditionalOnMissingBean({MapperFactoryBean.class, MapperScannerConfigurer.class})
public static class MapperScannerRegistrarNotFoundConfiguration implements InitializingBean {
public MapperScannerRegistrarNotFoundConfiguration() {
}
public void afterPropertiesSet() {
MybatisAutoConfiguration.logger.debug("Not found configuration for registering mapper bean using @MapperScan, MapperFactoryBean and MapperScannerConfigurer.");
}
}
public static class AutoConfiguredMapperScannerRegistrar implements BeanFactoryAware, ImportBeanDefinitionRegistrar {
private BeanFactory beanFactory;
public AutoConfiguredMapperScannerRegistrar() {
}
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
if (!AutoConfigurationPackages.has(this.beanFactory)) {
MybatisAutoConfiguration.logger.debug("Could not determine auto-configuration package, automatic mapper scanning disabled.");
} else {
MybatisAutoConfiguration.logger.debug("Searching for mappers annotated with @Mapper");
List<String> packages = AutoConfigurationPackages.get(this.beanFactory);
if (MybatisAutoConfiguration.logger.isDebugEnabled()) {
packages.forEach((pkg) -> {
MybatisAutoConfiguration.logger.debug("Using auto-configuration base package '{}'", pkg);
});
}
BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(MapperScannerConfigurer.class);
builder.addPropertyValue("processPropertyPlaceHolders", true);
builder.addPropertyValue("annotationClass", Mapper.class);
builder.addPropertyValue("basePackage", StringUtils.collectionToCommaDelimitedString(packages));
BeanWrapper beanWrapper = new BeanWrapperImpl(MapperScannerConfigurer.class);
Stream.of(beanWrapper.getPropertyDescriptors()).filter((x) -> {
return x.getName().equals("lazyInitialization");
}).findAny().ifPresent((x) -> {
builder.addPropertyValue("lazyInitialization", "${mybatis.lazy-initialization:false}");
});
registry.registerBeanDefinition(MapperScannerConfigurer.class.getName(), builder.getBeanDefinition());
}
}
public void setBeanFactory(BeanFactory beanFactory) {
this.beanFactory = beanFactory;
}
}
}
Mybatis中的关键bean
关键1，SqlSessionFactory类，根据mapper配置文件解析出dao与具体jdbc操作、resultMap与实体类等的映射关系
关键2，SqlSessionTemplate类，实现了CRUD操作
关键3，AutoConfiguredMapperScannerRegistrar类，扫描@Mapper注解的类
注册SqlSessionFactory类，根据mapper配置文件解析出dao与具体jdbc操作、resultMap与实体类等的映射关系
@Bean
@ConditionalOnMissingBean
public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
// 设置数据源DataSource
SqlSessionFactoryBean factory = new SqlSessionFactoryBean();
factory.setDataSource(dataSource);
factory.setVfs(SpringBootVFS.class);
// 设置总配置文件，mybatis-config.xml
if (StringUtils.hasText(this.properties.getConfigLocation())) {
factory.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation()));
}
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);
}
// 设置mybatis自动扫描到自定义的POJO
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);
}
// 设置mapper-locations，扫描mapper的xml文件
if (!ObjectUtils.isEmpty(this.properties.resolveMapperLocations())) {
factory.setMapperLocations(this.properties.resolveMapperLocations());
}
Set<String> factoryPropertyNames = Stream
.of(new BeanWrapperImpl(SqlSessionFactoryBean.class).getPropertyDescriptors()).map(PropertyDescriptor::getName)
.collect(Collectors.toSet());
Class<? extends LanguageDriver> defaultLanguageDriver = this.properties.getDefaultScriptingLanguageDriver();
if (factoryPropertyNames.contains("scriptingLanguageDrivers") && !ObjectUtils.isEmpty(this.languageDrivers)) {
// Need to mybatis-spring 2.0.2+
factory.setScriptingLanguageDrivers(this.languageDrivers);
if (defaultLanguageDriver == null && this.languageDrivers.length == 1) {
defaultLanguageDriver = this.languageDrivers[0].getClass();
}
}
if (factoryPropertyNames.contains("defaultScriptingLanguageDriver")) {
// Need to mybatis-spring 2.0.2+
factory.setDefaultScriptingLanguageDriver(defaultLanguageDriver);
}
// 创建SqlSessionFactory对象
return factory.getObject();
}
factory.getObject();实例化SqlSessionFactory对象
@Override
public SqlSessionFactory getObject() throws Exception {
if (this.sqlSessionFactory == null) {
afterPropertiesSet();
}
return this.sqlSessionFactory;
}
@Override
public void afterPropertiesSet() throws Exception {
notNull(dataSource, "Property 'dataSource' is required");
notNull(sqlSessionFactoryBuilder, "Property 'sqlSessionFactoryBuilder' is required");
state((configuration == null && configLocation == null) || !(configuration != null && configLocation != null),
"Property 'configuration' and 'configLocation' can not specified with together");
this.sqlSessionFactory = buildSqlSessionFactory();
}
委派给buildSqlSessionFactory()方法，构建SqlSessionFactory对象
- 解析this.typeAliasesPackage，扫描到自定义的POJO，存放到this.typeAliases
- 遍历mapper-locations，扫描mapper的所有xml文件，解析xml文件
protected SqlSessionFactory buildSqlSessionFactory() throws Exception {
final Configuration targetConfiguration;
XMLConfigBuilder xmlConfigBuilder = null;
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 XMLConfigBuilder(this.configLocation.getInputStream(), null, this.configurationProperties);
targetConfiguration = xmlConfigBuilder.getConfiguration();
} else {
LOGGER.debug(
() -> "Property 'configuration' or 'configLocation' not specified, using default MyBatis Configuration");
targetConfiguration = new Configuration();
Optional.ofNullable(this.configurationProperties).ifPresent(targetConfiguration::setVariables);
}
Optional.ofNullable(this.objectFactory).ifPresent(targetConfiguration::setObjectFactory);
Optional.ofNullable(this.objectWrapperFactory).ifPresent(targetConfiguration::setObjectWrapperFactory);
Optional.ofNullable(this.vfs).ifPresent(targetConfiguration::setVfsImpl);
// 扫描到自定义的POJO，存放到this.typeAliases
if (hasLength(this.typeAliasesPackage)) {
scanClasses(this.typeAliasesPackage, this.typeAliasesSuperType).stream()
.filter(clazz -> !clazz.isAnonymousClass()).filter(clazz -> !clazz.isInterface())
.filter(clazz -> !clazz.isMemberClass()).forEach(targetConfiguration.getTypeAliasRegistry()::registerAlias);
}
if (!isEmpty(this.typeAliases)) {
Stream.of(this.typeAliases).forEach(typeAlias -> {
targetConfiguration.getTypeAliasRegistry().registerAlias(typeAlias);
LOGGER.debug(() -> "Registered type alias: '" + typeAlias + "'");
});
}
if (!isEmpty(this.plugins)) {
Stream.of(this.plugins).forEach(plugin -> {
targetConfiguration.addInterceptor(plugin);
LOGGER.debug(() -> "Registered plugin: '" + plugin + "'");
});
}
if (hasLength(this.typeHandlersPackage)) {
scanClasses(this.typeHandlersPackage, TypeHandler.class).stream().filter(clazz -> !clazz.isAnonymousClass())
.filter(clazz -> !clazz.isInterface()).filter(clazz -> !Modifier.isAbstract(clazz.getModifiers()))
.forEach(targetConfiguration.getTypeHandlerRegistry()::register);
}
if (!isEmpty(this.typeHandlers)) {
Stream.of(this.typeHandlers).forEach(typeHandler -> {
targetConfiguration.getTypeHandlerRegistry().register(typeHandler);
LOGGER.debug(() -> "Registered type handler: '" + typeHandler + "'");
});
}
targetConfiguration.setDefaultEnumTypeHandler(defaultEnumTypeHandler);
if (!isEmpty(this.scriptingLanguageDrivers)) {
Stream.of(this.scriptingLanguageDrivers).forEach(languageDriver -> {
targetConfiguration.getLanguageRegistry().register(languageDriver);
LOGGER.debug(() -> "Registered scripting language driver: '" + languageDriver + "'");
});
}
Optional.ofNullable(this.defaultScriptingLanguageDriver)
.ifPresent(targetConfiguration::setDefaultScriptingLanguage);
if (this.databaseIdProvider != null) {// fix #64 set databaseId before parse mapper xmls
try {
targetConfiguration.setDatabaseId(this.databaseIdProvider.getDatabaseId(this.dataSource));
} catch (SQLException e) {
throw new NestedIOException("Failed getting a databaseId", e);
}
}
Optional.ofNullable(this.cache).ifPresent(targetConfiguration::addCache);
if (xmlConfigBuilder != null) {
try {
xmlConfigBuilder.parse();
LOGGER.debug(() -> "Parsed configuration file: '" + this.configLocation + "'");
} catch (Exception ex) {
throw new NestedIOException("Failed to parse config resource: " + this.configLocation, ex);
} finally {
ErrorContext.instance().reset();
}
}
targetConfiguration.setEnvironment(new Environment(this.environment,
this.transactionFactory == null ? new SpringManagedTransactionFactory() : this.transactionFactory,
this.dataSource));
// 遍历mapper-locations，扫描mapper的所有xml文件
if (this.mapperLocations != null) {
if (this.mapperLocations.length == 0) {
LOGGER.warn(() -> "Property 'mapperLocations' was specified but matching resources are not found.");
} else {
for (Resource mapperLocation : this.mapperLocations) {
if (mapperLocation == null) {
continue;
}
try {
XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(mapperLocation.getInputStream(),
targetConfiguration, mapperLocation.toString(), targetConfiguration.getSqlFragments());
// 解析mapper的xml文件
xmlMapperBuilder.parse();
} catch (Exception e) {
throw new NestedIOException("Failed to parse mapping resource: '" + mapperLocation + "'", e);
} finally {
ErrorContext.instance().reset();
}
LOGGER.debug(() -> "Parsed mapper file: '" + mapperLocation + "'");
}
}
} else {
LOGGER.debug(() -> "Property 'mapperLocations' was not specified.");
}
return this.sqlSessionFactoryBuilder.build(targetConfiguration);
}
注册SqlSessionFactory类逻辑
自动装配的逻辑中使用ConfigurationClassPostProcessor这个处理@Configuration注解的后置处理器，使用registerBeanDefinition方法，将当前的SqlSessionFactory类放入beanDefinitionMap中。
注册SqlSessionTemplate类，实现了CRUD操作
@Bean
@ConditionalOnMissingBean
public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
ExecutorType executorType = this.properties.getExecutorType();
return executorType != null ? new SqlSessionTemplate(sqlSessionFactory, executorType) : new SqlSessionTemplate(sqlSessionFactory);
}
注册SqlSessionTemplate类逻辑
自动装配的逻辑中使用ConfigurationClassPostProcessor这个处理@Configuration注解的后置处理器，使用registerBeanDefinition方法，将当前的SqlSessionTemplate类放入beanDefinitionMap中。
注册AutoConfiguredMapperScannerRegistrar类来扫描被@Mapper标注的类
注入AutoConfiguredMapperScannerRegistrar类
在自动装配的源码中ConfigurationClassParser.processImports(configClass, sourceClass, getImports(sourceClass), filter, true)，执行@Import注解的同时也会批量注册实现了ImportBeanDefinitionRegistrar接口的类
default方法，就是实现了ImportBeanDefinitionRegistra接口的类，只要实例化就是会执行registerBeanDefinitions方法
public interface ImportBeanDefinitionRegistrar {
default void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry,
BeanNameGenerator importBeanNameGenerator) {
registerBeanDefinitions(importingClassMetadata, registry);
}
default void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
}
}
AutoConfiguredMapperScannerRegistrar.registerBeanDefinitions方法
该方法的执行，找到并且解析注解@Mapper注解，扫描包路径basePackage配置下的bean，然后又注册了重要的类MapperScannerConfigurer。
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
//这个是判断beanFactory中是否存在AutoConfigurationPackages的bean，这里是存在的
if (!AutoConfigurationPackages.has(this.beanFactory)) {
logger.debug("Could not determine auto-configuration package, automatic mapper scanning disabled.");
return;
}
logger.debug("Searching for mappers annotated with @Mapper");
// 这里获取要扫描的包名，这里会是com.sunpeiyu.visualweb.mapper，其实也就是我们在哪里找mapper
List<String> packages = AutoConfigurationPackages.get(this.beanFactory);
if (logger.isDebugEnabled()) {
packages.forEach(pkg -> logger.debug("Using auto-configuration base package '{}'", pkg));
}
//下面这些代码主要就是定义一个bean的定义，添加到BeanFactory中
BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(MapperScannerConfigurer.class);
builder.addPropertyValue("processPropertyPlaceHolders", true);
//这就是要扫描的注解类型，就是@Mapper
builder.addPropertyValue("annotationClass", Mapper.class);
//这里是要扫描的包的路径
builder.addPropertyValue("basePackage", StringUtils.collectionToCommaDelimitedString(packages));
BeanWrapper beanWrapper = new BeanWrapperImpl(MapperScannerConfigurer.class);
Set<String> propertyNames = Stream.of(beanWrapper.getPropertyDescriptors()).map(PropertyDescriptor::getName)
.collect(Collectors.toSet());
if (propertyNames.contains("lazyInitialization")) {
// Need to mybatis-spring 2.0.2+
builder.addPropertyValue("lazyInitialization", "${mybatis.lazy-initialization:false}");
}
if (propertyNames.contains("defaultScope")) {
// Need to mybatis-spring 2.0.6+
builder.addPropertyValue("defaultScope", "${mybatis.mapper-default-scope:}");
}
// 注册MapperScannerConfigurer到this.beanDefinitionMap
registry.registerBeanDefinition(MapperScannerConfigurer.class.getName(), builder.getBeanDefinition());
}
MapperScannerConfigurer扫描mapper，将mapper注册到beanDefinitionMap中
MapperScannerConfigurer定义
MapperScannerConfigurer执行增加bean的入口方法
执行postProcessBeanDefinitionRegistry方法：
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
if (this.processPropertyPlaceHolders) {
//这个是主要设置一些属性，比如上面包名，要扫描的注解类名称等等
processPropertyPlaceHolders();
}
//这个类看名字，大家都知道是干什么的了。主要就是扫描mapper注解的类
ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);
scanner.setAddToConfig(this.addToConfig);
scanner.setAnnotationClass(this.annotationClass);
scanner.setMarkerInterface(this.markerInterface);
scanner.setSqlSessionFactory(this.sqlSessionFactory);
scanner.setSqlSessionTemplate(this.sqlSessionTemplate);
scanner.setSqlSessionFactoryBeanName(this.sqlSessionFactoryBeanName);
scanner.setSqlSessionTemplateBeanName(this.sqlSessionTemplateBeanName);
scanner.setResourceLoader(this.applicationContext);
scanner.setBeanNameGenerator(this.nameGenerator);
scanner.setMapperFactoryBeanClass(this.mapperFactoryBeanClass);
if (StringUtils.hasText(lazyInitialization)) {
scanner.setLazyInitialization(Boolean.valueOf(lazyInitialization));
}
if (StringUtils.hasText(defaultScope)) {
scanner.setDefaultScope(defaultScope);
}
//这里是设置要扫描的注解类，这里会设置@Mapper
scanner.registerFilters();
//这里就是要根据传入的包名去做扫描了，这里的this.basePackage就是上面说的com.example.springbootmybatis
scanner.scan(
StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS));
}
包名遍历扫描，将包含的mapper转成BeanDefinition，并且将mapper的bean存放到beanDefinitionMap中
public int scan(String... basePackages) {
int beanCountAtScanStart = this.registry.getBeanDefinitionCount();
// 在这里进行mapper的扫描
doScan(basePackages);
// Register annotation config processors, if necessary.
if (this.includeAnnotationConfig) {
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}
return (this.registry.getBeanDefinitionCount() - beanCountAtScanStart);
}
@Override
public Set<BeanDefinitionHolder> doScan(String... basePackages) {
//首先会进入这里，我们进去看看
Set<BeanDefinitionHolder> beanDefinitions = super.doScan(basePackages);
if (beanDefinitions.isEmpty()) {
LOGGER.warn(() -> "No MyBatis mapper was found in '" + Arrays.toString(basePackages)
+ "' package. Please check your configuration.");
} else {
//我们会走到这里，这个方法也比较重要，我们进去看看
processBeanDefinitions(beanDefinitions);
}
return beanDefinitions;
}
protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
Assert.notEmpty(basePackages, "At least one base package must be specified");
Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
//根据传入的包名遍历
for (String basePackage : basePackages) {
//这里就是扫描类路径下的mapper注解类了。
//比如我这里的传入的包名是com.example.springbootmybatis,就会被转换成classpath*:com/example/springbootmybatis/**/*.class这个路径进行解析查找，将找到的类作为BeanDefinition的定义，返回
Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
for (BeanDefinition candidate : candidates) {
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
candidate.setScope(scopeMetadata.getScopeName());
//获取bean的名字
String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
//这里candidate的类型是ScannedGenericBeanDefinition,所以会进入这个if分支，这个没啥，就是设置一些bean初始化相关属性，不关注了
if (candidate instanceof AbstractBeanDefinition) {
postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
}
//也会进入这个if分支，这个也不进去看了
if (candidate instanceof AnnotatedBeanDefinition) {
AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
}
//这个是判断beanFactory是否包含beanName的bean的定义，不包含就会进入分支，这个分支也没啥特殊的，就是把bean的定义添加到beanFactory中
if (checkCandidate(beanName, candidate)) {
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
definitionHolder =
AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
beanDefinitions.add(definitionHolder);
registerBeanDefinition(definitionHolder, this.registry);
}
}
}
return beanDefinitions;
}
设置beanDefinition
填充beanDefinition中，的beanClass为MapperFactoryBean类，并且设置注入方式为通过类型注入。
private void processBeanDefinitions(Set<BeanDefinitionHolder> beanDefinitions) {
......
//这里是给bean定义的添加一个构造方法参数，就是我们扫描出来mapper注解类的类名，我这里是com.example.springbootmybatis.mapper.UserMapper。这个是为后续选择哪个构造方法服务的
definition.getConstructorArgumentValues().addGenericArgumentValue(beanClassName); // issue #59
//这个就是设置对应bean定义存放的实际类，
//这里设置成了org.mybatis.spring.mapper.MapperFactoryBean这个类，这注意这个类实现了FactoryBean接口
definition.setBeanClass(this.mapperFactoryBeanClass);
......
if (!explicitFactoryUsed) {
LOGGER.debug(() -> "Enabling autowire by type for MapperFactoryBean with name '" + holder.getBeanName() + "'.");
//这句也比较重要，代表属性注入模式
definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);
}
......
}
}
实例化@Mapper类的bean对象
AbstractBeanFactory.doGetBean方法
protected <T> T doGetBean(
String name, @Nullable Class<T> requiredType, @Nullable Object[] args, boolean typeCheckOnly)
throws BeansException {
......
//由于我们的是单例对象，会走到这个分支
if (mbd.isSingleton()) {
sharedInstance = getSingleton(beanName, () -> {
try {
//在这个方法中会创建bean对象，我们下面看看这个方法
return createBean(beanName, mbd, args);
}
catch (BeansException ex) {
destroySingleton(beanName);
throw ex;
}
});
// 由于我们的sharedInstance对象是，
// 所以在这里最终会调用到FactoryBeanRegistrySupport的doGetObjectFromFactoryBean方法，
// 返回真正的userMapper的bean对象，也就是调用MapperFactoryBean的getObject()方法
beanInstance = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
}
AbstractAutowireCapableBeanFactory.doCreateBean方法
Mybatis如何加载mapper-locations配置下的xml文件
Mybatis如何加载@Mapper注解的dao
参考
https://blog.51cto.com/u_15069485/4082734
https://blog.csdn.net/caoyuanyenang/article/details/115936875
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