之前调试时，发现1个问题，就是mapperRegistry找不到对象

后来发现是mapper.xml的namespace里面的类名写得不对，然后来重新debug下

---

断点在

stop in org.apache.ibatis.builder.xml.XMLMapperBuilder.bindMapperForNamespace

调试

private void bindMapperForNamespace() {		// 看到这里了		String namespace = builderAssistant.getCurrentNamespace();		System.out.println("namespace--->"+namespace);		if (namespace != null) {			// 如果设置了			Class
     boundType = null;			try {				// 看看是不是类				boundType = Resources.classForName(namespace);			} catch (ClassNotFoundException e) {				// ignore, bound type is not required			}			//如果真的是类/接口			if (boundType != null) {				System.out.println("boundType--->"+boundType);				//之前没有绑定				if (!configuration.hasMapper(boundType)) {					// Spring may not know the real resource name so we set a					// flag					// to prevent loading again this resource from the mapper					// interface					// look at MapperAnnotationBuilder#loadXmlResource					//关键这里					configuration.addLoadedResource("namespace:" + namespace);					configuration.addMapper(boundType);				}			}		}	}

可以看到，关键就是

configuration.addLoadedResource("namespace:" + namespace);					configuration.addMapper(boundType);

 跟进去

第1行就是标记这个资源加载过了，见下图

319    		loadedResources.add(resource);main[1] print loadedResources loadedResources = "[mysql_mapper.xml]"main[1] step> Step completed: "thread=main", org.apache.ibatis.session.Configuration.addLoadedResource(), line=320 bci=11320    	}main[1] print loadedResources loadedResources = "[mysql_mapper.xml, namespace:interfaces.RoleMapper]"

看第2行

configuration.addMapper(boundType);

public 
    
      void addMapper(Class
     
       type) {		// 交给mapperRegistry负责		mapperRegistry.addMapper(type);	}
     
    

跟进去

public 
    
      void addMapper(Class
     
       type) {		//这里开始		//还必须是接口		if (type.isInterface()) {			//防止重复注册			if (hasMapper(type)) {				throw new BindingException("Type " + type + " is already known to the MapperRegistry.");			}			//			boolean loadCompleted = false;			try {				//开始注册				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);				parser.parse();				loadCompleted = true;			} finally {				if (!loadCompleted) {					knownMappers.remove(type);				}			}		}	}
      
     
    

这里继续跟踪

knownMappers.put(type, new MapperProxyFactory<T>(type));

/** * @author Lasse Voss */public class MapperProxyFactory
    
      {	// 接口类	private final Class
     
       mapperInterface;	// 方法容器	private final Map
      
        methodCache = new ConcurrentHashMap
       
        ();	public MapperProxyFactory(Class
        
          mapperInterface) {		// 设置接口类		this.mapperInterface = mapperInterface;		//end	}
        
       
      
     
    

---然后就剩下

MapperAnnotationBuilder parser = new MapperAnnotationBuilder(config, type);

先看MapperAnnotationBuilder parser = new MapperAnnotationBuilder(config, type);

然后就是parse解析过程了

public void parse() {		// 开始解析		String resource = type.toString();		// 如果没有加载过		if (!configuration.isResourceLoaded(resource)) {			// 进来			// 这1行不执行			loadXmlResource();			// 标记已经加载过了			configuration.addLoadedResource(resource);			//			assistant.setCurrentNamespace(type.getName());			// 继续执行			// 下面2行注释掉			parseCache();			parseCacheRef();			//正式			//获取类的方法			Method[] methods = type.getMethods();			//遍历每1个方法			for (Method method : methods) {				//				try {					// issue #237					//如果不是bridge方法					if (!method.isBridge()) {						//解析此方法						parseStatement(method);					}				} catch (IncompleteElementException e) {					configuration.addIncompleteMethod(new MethodResolver(this, method));				}			}		}		parsePendingMethods();	}

上面是注解解析的过程，暂且不表。