~~~ //Class 和 MapperProxyFactory 做映射 package org.apache.ibatis.binding; import java.util.Collection; import java.util.Collections; import java.util.HashMap; import java.util.Map; import java.util.Set; import org.apache.ibatis.builder.annotation.MapperAnnotationBuilder; import org.apache.ibatis.io.ResolverUtil; import org.apache.ibatis.session.Configuration; import org.apache.ibatis.session.SqlSession; /** * @author Clinton Begin * @author Eduardo Macarron * @author Lasse Voss */ public class MapperRegistry { //配置信息相關 private final Configuration config; //將 Class和 MapperProxyFactory 做映射 //每個Class 只能做一次映射 private final Map<Class<?>, MapperProxyFactory<?>> knownMappers = new HashMap<>(); public MapperRegistry(Configuration config) { this.config = config; } @SuppressWarnings("unchecked") public <T> T getMapper(Class<T> type, SqlSession sqlSession) { //獲取 Class 對應 的MapperProxyFactory final MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory<T>) knownMappers.get(type); if (mapperProxyFactory == null) { throw new BindingException("Type " + type + " is not known to the MapperRegistry."); } try { //反射實例化 return mapperProxyFactory.newInstance(sqlSession); } catch (Exception e) { throw new BindingException("Error getting mapper instance. Cause: " + e, e); } } public <T> boolean hasMapper(Class<T> type) { //是否包含key return knownMappers.containsKey(type); } public <T> void addMapper(Class<T> type) { if (type.isInterface()) { if (hasMapper(type)) { throw new BindingException("Type " + type + " is already known to the MapperRegistry."); } boolean loadCompleted = false; try { //Class 和 MapperProxyFactory 做映射 knownMappers.put(type, new MapperProxyFactory<>(type)); // It's important that the type is added before the parser is run // otherwise the binding may automatically be attempted by the // mapper parser. If the type is already known, it won't try. MapperAnnotationBuilder parser = new MapperAnnotationBuilder(config, type); //解析 parser.parse(); loadCompleted = true; } finally { if (!loadCompleted) { knownMappers.remove(type); } } } } /** * @since 3.2.2 */ public Collection<Class<?>> getMappers() { //不可修改的集合，獲取所有key return Collections.unmodifiableCollection(knownMappers.keySet()); } /** * @since 3.2.2 */ public void addMappers(String packageName, Class<?> superType) { ResolverUtil<Class<?>> resolverUtil = new ResolverUtil<>(); resolverUtil.find(new ResolverUtil.IsA(superType), packageName); Set<Class<? extends Class<?>>> mapperSet = resolverUtil.getClasses(); for (Class<?> mapperClass : mapperSet) { addMapper(mapperClass); } } /** * @since 3.2.2 */ public void addMappers(String packageName) { addMappers(packageName, Object.class); } } ~~~