Mybatis3.2不支援Ant萬用字元TypeAliasesPackage掃描的解決方案

摘要： 業務場景 業務場景：首先專案進行分散式拆分之後，按照模組再分為為api層和service層，web層。 其中訂單業務的實體類放在com.muses.taoshop.item.entity，而使用者相關的實體類放在com.muses.taoshop.user.entity。所...

業務場景

業務場景：首先專案進行分散式拆分之後，按照模組再分為為api層和service層，web層。

其中訂單業務的實體類放在com.muses.taoshop.item.entity，而使用者相關的實體類放在com.muses.taoshop.user.entity。所以就這樣，通過萬用字元方式去setTypeAliasesPackage ，com.muses.taoshop.*.entity

Ant萬用字元的3中風格：

(1) ?：匹配檔名中的一個字元 eg: com/test/entity? 匹配 com/test/entityaa

(2) * : 匹配檔名中的任意字元 eg: com/*/entity 匹配 com/test/entity

(3) ** ： 匹配檔名中的多重路徑 eg: com/**/entity 匹配 com/test/test1/entity

mybatis配置類寫在common工程，資料庫操作有些是可以共用的，不需要每個web工程都進行重複配置。

所以寫了個Mybatis配置類：

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

/**
* 設定主資料來源名稱
*/
public static final String DATA_SOURCE_NAME = "shop";

/**
* 載入配置檔案資訊
*/
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";

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

}

貼一下配置類程式碼，主要關注： factoryBean.setTypeAliasesPackage(ENTITY_PACKAGES);之前的寫法是這樣的。ENTITY_PACKAGES是個常量：public static final String ENTITY_PACKAGES = "com.muses.taoshop.*.entity"; ，ps：注意了，這裡用了萬用字元

package com.muses.taoshop.common.core.database.config;
//省略jar進入程式碼
@MapperScan(
basePackages = MAPPER_PACKAGES,
annotationClass = MybatisRepository.class,
sqlSessionFactoryRef = SQL_SESSION_FACTORY
)
@EnableTransactionManagement
@Configuration
public class MybatisConfig {
//省略其它程式碼，主要看sqlSessionFactory配置
@Primary
@Bean(name = SQL_SESSION_FACTORY)
public SqlSessionFactory sqlSessionFactory(@Qualifier(DATA_SOURCE_NAME)DataSource dataSource)throws Exception{
//SpringBoot預設使用DefaultVFS進行掃描，但是沒有掃描到jar裡的實體類
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();
//設定一下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方法裡進行TypeAliasesPackage設定，(讓Mybatis能夠掃描到實體類，在xml檔案裡就不需要寫全實體類的全包名了。)factoryBean.setTypeAliasesPackage(ENTITY_PACKAGES);

但是執行之後都會報錯，提示實體類不能掃描到，因為我的service工程裡都是這樣寫的，ResultType進行用別名ItemCategory，例子：

<!-- 獲取所有的商品品類資訊-->
<select id="listCategory" resultType="ItemCategory">
SELECT 
<include refid="BaseColumnList" />
FROM item_category t
</select>

原始碼簡單分析

針對上面的業務場景，首先的分析一下，我們知道Mybatis的執行都會通過SQLSessionFactory去呼叫，呼叫前都是先用SqlSessionFactoryBean的setTypeAliasesPackage可以看一下SqlSessionFactoryBean的原始碼：

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

我們看一下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;
//建立一個XMLConfigBuilder讀取配置檔案的一些資訊
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);//新增Properties屬性
}
} 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);
}
/*
重點看這裡，其它原始碼先不看，這裡獲取到typeAliasesPackage字串之後，呼叫tokenizeToStringArray進行字串分隔返回一個數組，`String CONFIG_LOCATION_DELIMITERS = ",; \t\n";`
*/
if (hasLength(this.typeAliasesPackage)) {
String[] typeAliasPackageArray = tokenizeToStringArray(this.typeAliasesPackage,
ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
for (String packageToScan : typeAliasPackageArray) {//遍歷，註冊到configuration物件上
configuration.getTypeAliasRegistry().registerAliases(packageToScan,
typeAliasesSuperType == null ? Object.class : typeAliasesSuperType);
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Scanned package: '" + packageToScan + "' for aliases");
}
}
}
...
//省略其它程式碼
}

然後可以看到註冊所有別名的方法 ，registerAliases是怎麼做的？

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

要掃描註冊所有的別名之前先要掃描包下面的所有類 ：

public void registerAliases(String packageName, Class<?> superType) {
ResolverUtil<Class<?>> resolverUtil = new ResolverUtil();
resolverUtil.find(new IsA(superType), packageName);
//通過ResolverUtil獲取到的所有類都賦值給一個集合
Set<Class<? extends Class<?>>> typeSet = resolverUtil.getClasses();
/*遍歷集合，然後一個個註冊*/
Iterator var5 = typeSet.iterator();
while(var5.hasNext()) {
Class<?> type = (Class)var5.next();
if (!type.isAnonymousClass() && !type.isInterface() && !type.isMemberClass()) {
this.registerAlias(type);
}
}

}

ResolverUtil是怎麼通過packageName去查詢的呢，可以再繼續跟一下

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

try {
//VFS類用單例模式實現，先獲取集合
List<String> children = VFS.getInstance().list(path);
Iterator var5 = children.iterator();
//遍歷,.class檔案的選出來
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;
}

獲取packPath只是獲取一下相對路徑

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

校驗方法addIfMatching：

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

Class<?> type = loader.loadClass(externalName);//通過類載入器載入類
if (test.matches(type)) {//校驗是否符合
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類具體是怎麼setInstance的？繼續跟：

//這裡的關鍵點就是getResources，Thread.currentThread().getContextClassLoader().getResources()，其實總結一下Mybatis的類掃描還是要依賴與jdk提供的類載入器
 protected static List<URL> getResources(String path) throws IOException {
 //獲取到資源路徑以列表形式放在集合裡
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();
//遍歷封裝成列表
while(var3.hasNext()) {
URL url = (URL)var3.next();
names.addAll(this.list(url, path));
}

return names;
}

ok，本部落格只是稍微跟一下原始碼，並沒有對Mybatis的原始碼進行比較系統更高層次的分析。

跟了一下原始碼知道，稍微總結一下Mybatis對別名的註冊是先將從sqlSessionFactoryBean類set的別名報名進行tokenizeToStringArray拆分成陣列，然後將包名陣列丟給ResolverUtil類和VFS等類進行一系列類載入遍歷，之後將 resolverUtil.getClasses()獲取的類都賦值給Set<Class<? extends Class<?>>> typeSet 一個集合。其中也是依賴與類載入器。

支援Ant萬用字元方式setTypeAliasesPackage解決方案

從這個原始碼比較簡單的分析過程，我們並沒有找到支援所謂萬用字元的方法，通過類載入的話也是要傳個相對路徑去遍歷，不過我上面描述的業務場景是要相容萬用字元的情況的，一般不會去改包名，假如這個專案有一定規模的話。

下面給出我的解決方案：

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;

}

寫一個掃描類，程式碼參考Hibernate的AnnotationSessionFactoryBean原始碼

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的掃描類
 * </pre>
 *
 * @author nicky
 * @version 1.00.00
 * <pre>
 * 修改記錄
 *修改後版本:修改人：修改日期: 2018.12.01 18:23修改內容:
 * </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 {
//載入所有的資源
Resource[] resources = resourcePatternResolver.getResources(PACKAGE_PATTERN);
MetadataReaderFactory readerFactory = new CachingMetadataReaderFactory(resourcePatternResolver);
//遍歷資源
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);
}
//集合不為空的情況，拼裝一下資料
if (!CollectionUtils.isEmpty(packageNames)) {
typeAliasesPackage = StringUtils.join(packageNames.toArray() , ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
}else{
LOGGER.info("set empty,size:{} "+packageNames.size());
}
return typeAliasesPackage;
}


}

然後剛才的Mybatis配置類改一下，主要改 String typeAliasesPackage = packageScanner.getTypeAliasesPackages();通過掃描類去獲取一下，重點程式碼在TypeAliasesPackageScanner 掃描類

package com.muses.taoshop.common.core.database.config;
//省略jar進入程式碼
@MapperScan(
basePackages = MAPPER_PACKAGES,
annotationClass = MybatisRepository.class,
sqlSessionFactoryRef = SQL_SESSION_FACTORY
)
@EnableTransactionManagement
@Configuration
public class MybatisConfig {
//省略其它程式碼，主要看sqlSessionFactory配置
@Primary
@Bean(name = SQL_SESSION_FACTORY)
public SqlSessionFactory sqlSessionFactory(@Qualifier(DATA_SOURCE_NAME)DataSource dataSource)throws Exception{
//SpringBoot預設使用DefaultVFS進行掃描，但是沒有掃描到jar裡的實體類
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();
//設定一下TypeAliasesPackage
factoryBean.setTypeAliasesPackage(typeAliasesPackage);
SqlSessionFactory sqlSessionFactory = factoryBean.getObject();
return sqlSessionFactory;
}catch (Exception e){
e.printStackTrace();
throw new RuntimeException();
}
}