springMVC源码分析--AbstractControllerUrlHandlerMapping（六）

港控/mmm° 2022-07-13 02:08 224阅读 0赞

上一篇博客[springMVC源码分析--AbstractDetectingUrlHandlerMapping（五）][springMVC_--AbstractDetectingUrlHandlerMapping]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。

![Image 1][]

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);
    
    }

[springMVC_--AbstractDetectingUrlHandlerMapping]: http://blog.csdn.net/qq924862077/article/details/53760824
[Image 1]: