springMVC源码分析--AbstractControllerUrlHandlerMapping（六）

上一篇博客springMVC源码分析--AbstractDetectingUrlHandlerMapping（五）中我们介绍了AbstractDetectingUrlHandlerMapping，其定义了一个抽象方法determineUrlsForHandler在子类AbstractControllerUrlHandlerMapping中实现。

子类中AbstractControllerUrlHandlerMapping中determineUrlsForHandler的实现如下，实现原理就是根据beanName从容器中获取bean，然后调用buildUrlsForHandler完成beanName和beanClass的对应关系，其具体实现还是在其子类中实现。

	@Override
	protected String[] determineUrlsForHandler(String beanName) {
		Class<?> beanClass = getApplicationContext().getType(beanName);
		//判断是不是支持的类型
		if (isEligibleForMapping(beanName, beanClass)) {
			//模板方法，在子类实现
			return buildUrlsForHandler(beanName, beanClass);
		}
		else {
			return null;
		}
	}

抽象方法buildUrlsForHandler

protected abstract String[] buildUrlsForHandler(String beanName, Class<?> beanClass);

除此之外AbstractControllerUrlHandlerMapping还提供了一些配置，用于排除掉一些包或者一些类，可以在配置中进行配置

public void setIncludeAnnotatedControllers(boolean includeAnnotatedControllers) {
		this.predicate = (includeAnnotatedControllers ?
				new AnnotationControllerTypePredicate() : new ControllerTypePredicate());
	}

	public void setExcludedPackages(String... excludedPackages) {
		this.excludedPackages = (excludedPackages != null) ?
				new HashSet<String>(Arrays.asList(excludedPackages)) : new HashSet<String>();
	}

	public void setExcludedClasses(Class<?>... excludedClasses) {
		this.excludedClasses = (excludedClasses != null) ?
				new HashSet<Class<?>>(Arrays.asList(excludedClasses)) : new HashSet<Class<?>>();
	}

判断beanName和beanClass是否已经配置排除对应关系。

protected boolean isEligibleForMapping(String beanName, Class<?> beanClass) {
		if (beanClass == null) {
			if (logger.isDebugEnabled()) {
				logger.debug("Excluding controller bean '" + beanName + "' from class name mapping " +
						"because its bean type could not be determined");
			}
			return false;
		}
		if (this.excludedClasses.contains(beanClass)) {
			if (logger.isDebugEnabled()) {
				logger.debug("Excluding controller bean '" + beanName + "' from class name mapping " +
						"because its bean class is explicitly excluded: " + beanClass.getName());
			}
			return false;
		}
		String beanClassName = beanClass.getName();
		for (String packageName : this.excludedPackages) {
			if (beanClassName.startsWith(packageName)) {
				if (logger.isDebugEnabled()) {
					logger.debug("Excluding controller bean '" + beanName + "' from class name mapping " +
							"because its bean class is defined in an excluded package: " + beanClass.getName());
				}
				return false;
			}
		}
		//
		return isControllerType(beanClass);
	}

总结：AbstractControllerUrlHandlerMapping的实现机制就是根据beanName从容器中获取实现类beanClass，同时beanName和beanClass的对应关系的操作是在其子类中完成实现的，同时AbstractControllerUrlHandlerMapping提供了一些配置用于排除一些类的关系。

AbstractControllerUrlHandlerMapping完整源码如下：

public abstract class AbstractControllerUrlHandlerMapping extends AbstractDetectingUrlHandlerMapping  {

	private ControllerTypePredicate predicate = new AnnotationControllerTypePredicate();

	private Set<String> excludedPackages = Collections.singleton("org.springframework.web.servlet.mvc");

	private Set<Class<?>> excludedClasses = Collections.emptySet();

	public void setIncludeAnnotatedControllers(boolean includeAnnotatedControllers) {
		this.predicate = (includeAnnotatedControllers ?
				new AnnotationControllerTypePredicate() : new ControllerTypePredicate());
	}

	public void setExcludedPackages(String... excludedPackages) {
		this.excludedPackages = (excludedPackages != null) ?
				new HashSet<String>(Arrays.asList(excludedPackages)) : new HashSet<String>();
	}

	public void setExcludedClasses(Class<?>... excludedClasses) {
		this.excludedClasses = (excludedClasses != null) ?
				new HashSet<Class<?>>(Arrays.asList(excludedClasses)) : new HashSet<Class<?>>();
	}

	@Override
	protected String[] determineUrlsForHandler(String beanName) {
		Class<?> beanClass = getApplicationContext().getType(beanName);
		//判断是不是支持的类型
		if (isEligibleForMapping(beanName, beanClass)) {
			//模板方法，在子类实现
			return buildUrlsForHandler(beanName, beanClass);
		}
		else {
			return null;
		}
	}

	protected boolean isEligibleForMapping(String beanName, Class<?> beanClass) {
		if (beanClass == null) {
			if (logger.isDebugEnabled()) {
				logger.debug("Excluding controller bean '" + beanName + "' from class name mapping " +
						"because its bean type could not be determined");
			}
			return false;
		}
		if (this.excludedClasses.contains(beanClass)) {
			if (logger.isDebugEnabled()) {
				logger.debug("Excluding controller bean '" + beanName + "' from class name mapping " +
						"because its bean class is explicitly excluded: " + beanClass.getName());
			}
			return false;
		}
		String beanClassName = beanClass.getName();
		for (String packageName : this.excludedPackages) {
			if (beanClassName.startsWith(packageName)) {
				if (logger.isDebugEnabled()) {
					logger.debug("Excluding controller bean '" + beanName + "' from class name mapping " +
							"because its bean class is defined in an excluded package: " + beanClass.getName());
				}
				return false;
			}
		}
		//
		return isControllerType(beanClass);
	}

	//判断是否实现了Controller接口或者使用了@Controller
	protected boolean isControllerType(Class<?> beanClass) {
		return this.predicate.isControllerType(beanClass);
	}

	protected boolean isMultiActionControllerType(Class<?> beanClass) {
		return this.predicate.isMultiActionControllerType(beanClass);
	}

	protected abstract String[] buildUrlsForHandler(String beanName, Class<?> beanClass);

}