Mybatis系列之全局扫描ant通配符格式的包名

SmileNicky

发布于 2022-05-07 16:32:30

3670

发布于 2022-05-07 16:32:30

业务场景

业务场景：首先项目进行分布式拆分之后，按照模块再分为为api层和service层，web层。其中订单业务的实体类放在com.muses.taoshop.item.entity，而用户相关的实体类放在com.muses.taoshop.user.entity。所以就这样，通过通配符方式去setTypeAliasesPackage ，com.muses.taoshop.*.entity

Ant通配符的3中风格： (1) ?：匹配文件名中的一个字符 eg: com/test/entity? 匹配 com/test/entityaa (2) * : 匹配文件名中的任意字符 eg: com/*/entity 匹配 com/test/entity (3) ** ：匹配文件名中的多重路径 eg: com/**/entity 匹配 com/test/test1/entity

mybatis配置类写在common工程，数据库操作有些是可以共用的，不需要每个web工程都进行重复配置。所以写了个Mybatis配置类：

package com.muses.taoshop.common.core.database.config;
public class BaseConfig {

    /**
     * 设置主数据源名称
     */
    public static final String DATA_SOURCE_NAME = "shop";

    /**
     * 加载配置文件信息
     */
    public static final String DATA_SOURCE_PROPERTIES = "spring.datasource.shop";

    /**
     * repository 所在包
     */
    public static final String REPOSITORY_PACKAGES = "com.muses.taoshop.**.repository";

    /**
     * mapper 所在包
     */
    public static final String MAPPER_PACKAGES = "com.muses.taoshop.**.mapper";

    /**
     * 实体类 所在包
     */
    public static final String ENTITY_PACKAGES = "com.muses.taoshop.*.entity";
...

}

贴一下配置类代码，主要关注： factoryBean.setTypeAliasesPackage(ENTITY_PACKAGES);之前的写法是这样的。ENTITY_PACKAGES是个常量：public static final String ENTITY_PACKAGES = "com.muses.taoshop.*.entity";，ps：注意了，这里用了通配符

package com.muses.taoshop.common.core.database.config;
//省略代码
@MapperScan(
        basePackages = MAPPER_PACKAGES,
        annotationClass = MybatisRepository.class,
        sqlSessionFactoryRef = SQL_SESSION_FACTORY
)
@EnableTransactionManagement
@Configuration
public class MybatisConfig {
	//省略其它代码，主要看sqlSessionFactory配置
    @Primary
    @Bean(name = SQL_SESSION_FACTORY)
    public SqlSessionFactory sqlSessionFactory(@Qualifier(DATA_SOURCE_NAME)DataSource dataSource)throws Exception{
        //SpringBoot默认使用DefaultVFS进行扫描，但是没有扫描到jar里的实体类
        VFS.addImplClass(SpringBootVFS.class);
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        factoryBean.setDataSource(dataSource);
        //factoryBean.setConfigLocation(new ClassPathResource("mybatis-config.xml"));
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        try{
            factoryBean.setMapperLocations(resolver.getResources("classpath*:/mybatis/*Mapper.xml"));
            //String typeAliasesPackage = packageScanner.getTypeAliasesPackages();
            //设置一下TypeAliasesPackage
            factoryBean.setTypeAliasesPackage(ENTITY_PACKAGES);
            SqlSessionFactory sqlSessionFactory = factoryBean.getObject();
            return sqlSessionFactory;
        }catch (Exception e){
            e.printStackTrace();
            throw new RuntimeException();
        }
    }

...

}

ps:原先做法：在sqlSessionFactory方法里进行TypeAliasesPackage设置，(让Mybatis能够扫描到实体类，在xml文件里就不需要写全实体类的全包名了。)factoryBean.setTypeAliasesPackage(ENTITY_PACKAGES);

但是运行之后都会报错，提示实体类不能扫描到，因为我的service工程里都是这样写的，ResultType进行用别名ItemCategory，例子：

 <!-- 获取所有的商品品类信息-->
    <select id="listCategory" resultType="ItemCategory">
        SELECT 
        <include refid="BaseColumnList" />
        FROM item_category t
    </select>

源码简单分析

针对上面的业务场景，首先的分析一下，我们知道Mybatis的执行都会通过SQLSessionFactory去调用，调用前都是先用SqlSessionFactoryBean的setTypeAliasesPackage可以看一下SqlSessionFactoryBean的源码：

/**
   * Packages to search for type aliases.
   *
   * @since 1.0.1
   *
   * @param typeAliasesPackage package to scan for domain objects
   *
   */
  public void setTypeAliasesPackage(String typeAliasesPackage) {
    this

我们看一下SqlSessionFactoryBean的初步Build方法：

/**
   * Build a {@code SqlSessionFactory} instance.
   *
   * The default implementation uses the standard MyBatis {@code XMLConfigBuilder} API to build a
   * {@code SqlSessionFactory} instance based on an Reader.
   * Since 1.3.0, it can be specified a {@link Configuration} instance directly(without config file).
   *
   * @return SqlSessionFactory
   * @throws IOException if loading the config file failed
   */
  protected SqlSessionFactory buildSqlSessionFactory() throws IOException {

    Configuration configuration;
//创建一个XMLConfigBuilder读取配置文件的一些信息
    XMLConfigBuilder xmlConfigBuilder = null;
    if (this.configuration != null) {
      configuration = this.configuration;
      if (configuration.getVariables() == null) {
        configuration.setVariables(this.configurationProperties);
      } else if (this.configurationProperties != null) {
        configuration.getVariables().putAll(this.configurationProperties);//添加Properties属性
      }
    } else if (this.configLocation != null) {
      xmlConfigBuilder = new XMLConfigBuilder(this.configLocation.getInputStream(), null, this.configurationProperties);
      configuration = xmlConfigBuilder.getConfiguration();
    } else {
      if (LOGGER.isDebugEnabled()) {
        LOGGER.debug("Property 'configuration' or 'configLocation' not specified, using default MyBatis Configuration");
      }
      configuration = new Configuration();
      if (this.configurationProperties != null) {
        configuration.setVariables(this.configurationProperties);
      }
    }

    if (this.objectFactory != null) {
      configuration.setObjectFactory(this.objectFactory);
    }

    if (this.objectWrapperFactory != null) {
      configuration.setObjectWrapperFactory(this.objectWrapperFactory);
    }

    if (this.vfs != null) {
      configuration.setVfsImpl(this.vfs);
    }
/*
重点看这里，其它源码先不看，这里获取到typeAliasesPackage字符串之后，调用tokenizeToStringArray进行字符串分隔返回一个数组，`String CONFIG_LOCATION_DELIMITERS = ",; \t\n";`
*/
    if (hasLength(this.typeAliasesPackage)) {
      String[] typeAliasPackageArray = tokenizeToStringArray(this.typeAliasesPackage,
          ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
      for (String packageToScan : typeAliasPackageArray) {//遍历，注册到configuration对象上
        configuration.getTypeAliasRegistry().registerAliases(packageToScan,
                typeAliasesSuperType == null ? Object.class : typeAliasesSuperType);
        if (LOGGER.isDebugEnabled()) {
          LOGGER.debug("Scanned package: '" + packageToScan + "' for aliases");
        }
      }
    }
    ...
    //省略其它代码
}

然后可以看到注册所有别名的方法，registerAliases是怎么做的？

configuration.getTypeAliasRegistry().registerAliases(packageToScan,
                typeAliasesSuperType == null ? Object.class : typeAliasesSuperType);

要扫描注册所有的别名之前先要扫描包下面的所有类：

public void registerAliases(String packageName, Class<?> superType) {
        ResolverUtil<Class<?>> resolverUtil = new ResolverUtil();
        resolverUtil.find(new IsA(superType), packageName);
       	//通过ResolverUtil获取到的所有类都赋值给一个集合
        Set<Class<? extends Class<?>>> typeSet = resolverUtil.getClasses();
        /*遍历集合，然后一个个注册*/
        Iterator var5 = typeSet.iterator();
        while(var5.hasNext()) {
            Class<?> type = (Class)var5.next();
            if (!type.isAnonymousClass() && !type.isInterface() && !type.isMemberClass()) {
                this.registerAlias(type);
            }
        }

    }

ResolverUtil是怎么通过packageName去查找的呢，可以再继续跟一下

 public ResolverUtil<T> find(ResolverUtil.Test test, String packageName) {
 	//获取包路径
        String path = this.getPackagePath(packageName);

        try {
        //VFS类用单例模式实现，先获取集合
            List<String> children = VFS.getInstance().list(path);
            Iterator var5 = children.iterator();
	   //遍历,.class文件的选出来
            while(var5.hasNext()) {
                String child = (String)var5.next();
                if (child.endsWith(".class")) {
                    this.addIfMatching(test, child);
                }
            }
        } catch (IOException var7) {
            log.error("Could not read package: " + packageName, var7);
        }

        return this;
    }

获取packPath只是获取一下相对路径

protected String getPackagePath(String packageName) {
        return packageName == null ? null : packageName.replace('.', '/');
    }

校验方法addIfMatching：

 protected void addIfMatching(ResolverUtil.Test test, String fqn) {
        try {
            String externalName = fqn.substring(0, fqn.indexOf(46)).replace('/', '.');
            ClassLoader loader = this.getClassLoader();//类加载器
            if (log.isDebugEnabled()) {
                log.debug("Checking to see if class " + externalName + " matches criteria [" + test + "]");
            }

            Class<?> type = loader.loadClass(externalName);//通过类加载器加载类
            if (test.matches(type)) {//校验是否符合
                this.matches.add(type);
            }
        } catch (Throwable var6) {
            log.warn("Could not examine class '" + fqn + "' due to a " + var6.getClass().getName() + " with message: " + var6.getMessage());
        }

    }

VFS类具体是怎么setInstance的？继续跟：

//这里的关键点就是getResources，Thread.currentThread().getContextClassLoader().getResources()，其实总结一下Mybatis的类扫描还是要依赖与jdk提供的类加载器
 protected static List<URL> getResources(String path) throws IOException {
 //获取到资源路径以列表形式放在集合里
        return Collections.list(Thread.currentThread().getContextClassLoader().getResources(path));
    }

    ...
    public List<String> list(String path) throws IOException {
        List<String> names = new ArrayList();
        Iterator var3 = getResources(path).iterator();
	//遍历封装成列表
        while(var3.hasNext()) {
            URL url = (URL)var3.next();
            names.addAll(this.list(url, path));
        }

        return names;
    }

ok，本博客只是稍微跟一下源码，并没有对Mybatis的源码进行比较系统更高层次的分析。跟了一下源码知道，稍微总结一下Mybatis对别名的注册是先将从sqlSessionFactoryBean类set的别名报名进行tokenizeToStringArray拆分成数组，然后将包名数组丢给ResolverUtil类和VFS等类进行一系列类加载遍历，之后将 resolverUtil.getClasses()获取的类都赋值给Set<Class<? extends Class<?>>> typeSet 一个集合。其中也是依赖与类加载器。

支持Ant通配符方式setTypeAliasesPackage解决方案

从这个源码比较简单的分析过程，我们并没有找到支持所谓通配符的方法，通过类加载的话也是要传个相对路径去遍历，不过我上面描述的业务场景是要兼容通配符的情况的，一般不会去改包名，假如这个项目有一定规模的话。

下面给出我的解决方案：

package com.muses.taoshop.common.core.database.annotation;

import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.util.ClassUtils;

import static com.muses.taoshop.common.core.database.config.BaseConfig.ENTITY_PACKAGES;

public class AnnotationConstants {

    public static final String DEFAULT_RESOURCE_PATTERN = "**/*.class";

    public final static String PACKAGE_PATTERN =
            ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX
            + ClassUtils.convertClassNameToResourcePath(ENTITY_PACKAGES)
            + DEFAULT_RESOURCE_PATTERN;

}

写一个扫描类，代码参考Hibernate的AnnotationSessionFactoryBean源码

package com.muses.taoshop.common.core.database.annotation;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;

import java.io.IOException;
import java.util.*;

import org.springframework.core.io.Resource;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.core.type.classreading.MetadataReaderFactory;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import org.thymeleaf.util.StringUtils;

import static com.muses.taoshop.common.core.database.annotation.AnnotationConstants.PACKAGE_PATTERN;

/**
 * <pre>
 *  TypeAlicsesPackage的扫描类
 * </pre>
 *
 * @author nicky
 * @version 1.00.00
 * <pre>
 * 修改记录
 *    修改后版本:     修改人：  修改日期: 2018.12.01 18:23    修改内容:
 * </pre>
 */
@Component
public class TypeAliasesPackageScanner {

    protected final static Logger LOGGER = LoggerFactory.getLogger(TypeAliasesPackageScanner.class);
    private static ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
   /* private TypeFilter[] entityTypeFilters = new TypeFilter[]{new AnnotationTypeFilter(Entity.class, false),
            new AnnotationTypeFilter(Embeddable.class, false),
            new AnnotationTypeFilter(MappedSuperclass.class, false),
            new AnnotationTypeFilter(org.hibernate.annotations.Entity.class, false)};*/


    public static String getTypeAliasesPackages() {
        Set<String> packageNames = new TreeSet<String>();
        //TreeSet packageNames = new TreeSet();
        String typeAliasesPackage ="";
        try {
            //加载所有的资源
            Resource[] resources = resourcePatternResolver.getResources(PACKAGE_PATTERN);
            MetadataReaderFactory readerFactory = new CachingMetadataReaderFactory(resourcePatternResolver);
            //遍历资源
            for (Resource resource : resources) {
                if (resource.isReadable()) {
                    MetadataReader reader = readerFactory.getMetadataReader(resource);
                    String className = reader.getClassMetadata().getClassName();
                    //eg:com.muses.taoshop.item.entity.ItemBrand
                    LOGGER.info("className : {} "+className);
                    try{
                        //eg:com.muses.taoshop.item.entity
                        LOGGER.info("packageName : {} "+Class.forName(className).getPackage().getName());
                        packageNames.add(Class.forName(className).getPackage().getName());
                    }catch (ClassNotFoundException e){
                        LOGGER.error("classNotFoundException : {} "+e);
                    }
                }
            }
        } catch (IOException e) {
            LOGGER.error("ioException =>: {} " + e);
        }
        //集合不为空的情况，拼装一下数据
        if (!CollectionUtils.isEmpty(packageNames)) {
            typeAliasesPackage = StringUtils.join(packageNames.toArray() , ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
        }else{
            LOGGER.info("set empty,size:{} "+packageNames.size());
        }
        return typeAliasesPackage;
    }

    
}

然后刚才的Mybatis配置类改一下，主要改 String typeAliasesPackage = packageScanner.getTypeAliasesPackages();通过扫描类去获取一下，重点代码在TypeAliasesPackageScanner 扫描类

package com.muses.taoshop.common.core.database.config;
//省略代码
@MapperScan(
        basePackages = MAPPER_PACKAGES,
        annotationClass = MybatisRepository.class,
        sqlSessionFactoryRef = SQL_SESSION_FACTORY
)
@EnableTransactionManagement
@Configuration
public class MybatisConfig {
	//省略其它代码，主要看sqlSessionFactory配置
    @Primary
    @Bean(name = SQL_SESSION_FACTORY)
    public SqlSessionFactory sqlSessionFactory(@Qualifier(DATA_SOURCE_NAME)DataSource dataSource)throws Exception{
        //SpringBoot默认使用DefaultVFS进行扫描，但是没有扫描到jar里的实体类
        VFS.addImplClass(SpringBootVFS.class);
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        factoryBean.setDataSource(dataSource);
        //factoryBean.setConfigLocation(new ClassPathResource("mybatis-config.xml"));
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        try{
            factoryBean.setMapperLocations(resolver.getResources("classpath*:/mybatis/*Mapper.xml"));
            String typeAliasesPackage = packageScanner.getTypeAliasesPackages();
            //设置一下TypeAliasesPackage
            factoryBean.setTypeAliasesPackage(typeAliasesPackage);
            SqlSessionFactory sqlSessionFactory = factoryBean.getObject();
            return sqlSessionFactory;
        }catch (Exception e){
            e.printStackTrace();
            throw new RuntimeException();
        }
    }

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原始发表：2018-12-03，如有侵权请联系 cloudcommunity@tencent.com 删除

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