org.springframework.web.method.support.HandlerMethodReturnValueHandler Java Examples

@PostConstruct
public void init() {
    // 获取当前 RequestMappingHandlerAdapter 所有的 ArgumentResolver对象
    List<HandlerMethodArgumentResolver> argumentResolvers = requestMappingHandlerAdapter.getArgumentResolvers();
    List<HandlerMethodArgumentResolver> newArgumentResolvers = new ArrayList<>(argumentResolvers.size() + 1);
    // 添加 PropertiesHandlerMethodArgumentResolver 到集合第一个位置
    newArgumentResolvers.add(0, new PropertiesHandlerMethodArgumentResolver());
    // 将原 ArgumentResolver 添加到集合中
    newArgumentResolvers.addAll(argumentResolvers);
    // 重新设置 ArgumentResolver对象集合
    requestMappingHandlerAdapter.setArgumentResolvers(newArgumentResolvers);

    // 获取当前 RequestMappingHandlerAdapter 所有的 returnValueHandlers对象
    List<HandlerMethodReturnValueHandler> returnValueHandlers = requestMappingHandlerAdapter.getReturnValueHandlers();
    List<HandlerMethodReturnValueHandler> newReturnValueHandlers = new ArrayList<>(returnValueHandlers.size() + 1);
    // 添加 PropertiesHandlerMethodReturnValueHandler 到集合第一个位置
    newReturnValueHandlers.add(0, new PropertiesHandlerMethodReturnValueHandler());
    // 将原 returnValueHandlers 添加到集合中
    newReturnValueHandlers.addAll(returnValueHandlers);
    // 重新设置 ReturnValueHandlers对象集合
    requestMappingHandlerAdapter.setReturnValueHandlers(newReturnValueHandlers);
}
 

@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
    if (RequestMappingHandlerAdapter.class.isAssignableFrom(ClassUtils.getUserClass(bean))) {
        RequestMappingHandlerAdapter adapter = (RequestMappingHandlerAdapter) bean;
        List<Object> advices = getRequestResponseBodyAdviceByReflect(adapter);
        RaptorHandlerMethodProcessor raptorHandlerMethodProcessor = new RaptorHandlerMethodProcessor(raptorMessageConverter,advices);

        ArrayList<HandlerMethodArgumentResolver> argumentResolvers = new ArrayList<>(adapter.getArgumentResolvers());
        argumentResolvers.add(0, raptorHandlerMethodProcessor);
        adapter.setArgumentResolvers(argumentResolvers);

        ArrayList<HandlerMethodReturnValueHandler> returnValueHandlers = new ArrayList<>(adapter.getReturnValueHandlers());
        returnValueHandlers.add(0, raptorHandlerMethodProcessor);
        adapter.setReturnValueHandlers(returnValueHandlers);
    }
    return bean;
}
 

@Test
public void setAlwaysUseRedirectAttributes() throws Exception {
	HandlerMethodArgumentResolver redirectAttributesResolver = new RedirectAttributesMethodArgumentResolver();
	HandlerMethodArgumentResolver modelResolver = new ModelMethodProcessor();
	HandlerMethodReturnValueHandler viewHandler = new ViewNameMethodReturnValueHandler();

	this.handlerAdapter.setArgumentResolvers(Arrays.asList(redirectAttributesResolver, modelResolver));
	this.handlerAdapter.setReturnValueHandlers(Collections.singletonList(viewHandler));
	this.handlerAdapter.setIgnoreDefaultModelOnRedirect(true);
	this.handlerAdapter.afterPropertiesSet();

	this.request.setAttribute(DispatcherServlet.OUTPUT_FLASH_MAP_ATTRIBUTE, new FlashMap());

	HandlerMethod handlerMethod = handlerMethod(new RedirectAttributeController(), "handle", Model.class);
	ModelAndView mav = this.handlerAdapter.handle(request, response, handlerMethod);

	assertTrue("Without RedirectAttributes arg, model should be empty", mav.getModel().isEmpty());
}
 

@Test
public void setAlwaysUseRedirectAttributes() throws Exception {
	HandlerMethodArgumentResolver redirectAttributesResolver = new RedirectAttributesMethodArgumentResolver();
	HandlerMethodArgumentResolver modelResolver = new ModelMethodProcessor();
	HandlerMethodReturnValueHandler viewHandler = new ViewNameMethodReturnValueHandler();

	this.handlerAdapter.setArgumentResolvers(Arrays.asList(redirectAttributesResolver, modelResolver));
	this.handlerAdapter.setReturnValueHandlers(Collections.singletonList(viewHandler));
	this.handlerAdapter.setIgnoreDefaultModelOnRedirect(true);
	this.handlerAdapter.afterPropertiesSet();

	this.request.setAttribute(DispatcherServlet.OUTPUT_FLASH_MAP_ATTRIBUTE, new FlashMap());

	HandlerMethod handlerMethod = handlerMethod(new RedirectAttributeController(), "handle", Model.class);
	ModelAndView mav = this.handlerAdapter.handle(request, response, handlerMethod);

	assertTrue("Without RedirectAttributes arg, model should be empty", mav.getModel().isEmpty());
}
 

/**
 * Provide access to the shared return value handlers used by the
 * {@link RequestMappingHandlerAdapter} and the {@link ExceptionHandlerExceptionResolver}.
 * <p>This method cannot be overridden; use {@link #addReturnValueHandlers} instead.
 * @since 4.3
 */
protected final List<HandlerMethodReturnValueHandler> getReturnValueHandlers() {
	if (this.returnValueHandlers == null) {
		this.returnValueHandlers = new ArrayList<>();
		addReturnValueHandlers(this.returnValueHandlers);
	}
	return this.returnValueHandlers;
}
 

/**
 * 动态添加消息体响应切面
 * @param returnValueHandlers       响应处理器列表（需要注入 {@link org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#getReturnValueHandlers()}）
 * @param handlerExceptionResolver  异常处理解析器（需要注入 {@link org.springframework.web.servlet.HandlerExceptionResolver}）
 * @param responseBodyAdvice        ResponseBodyAdvice
 */
public static void addDynamicResponseBodyAdvice(List<HandlerMethodReturnValueHandler> returnValueHandlers, HandlerExceptionResolver handlerExceptionResolver, ResponseBodyAdvice<?> responseBodyAdvice) {
    if (CollectionUtils.isEmpty(returnValueHandlers)) {
        return;
    }
    // 下面这行添加不起作用，由于内部构建已经完成
    // adapter.setResponseBodyAdvice(Collections.singletonList(responseBodyAdvice));
    for (HandlerMethodReturnValueHandler returnValueHandler : returnValueHandlers) {
        // 只有AbstractMessageConverterMethodArgumentResolver继承类型（主要是HttpEntityMethodProcessor、RequestResponseBodyMethodProcessor）有Advice Chain
        if (returnValueHandler instanceof AbstractMessageConverterMethodArgumentResolver) {
            // TODO <mark> 由于使用底层API, 这个advice.responseBodyAdvice属性在未来版本中可能会改
            List<Object> advices = ReflectUtil.invokeFieldPath(returnValueHandler, "advice.responseBodyAdvice");
            if (CollectionUtils.isEmpty(advices)) {
                continue;
            }
            advices.add(responseBodyAdvice);
        }
    }

    // 动态添加到异常处理（因为源码流程中的异常处理是新加载的HandlerExceptionResolver，与正常响应处理不是同个处理集）
    if (handlerExceptionResolver instanceof HandlerExceptionResolverComposite) {
        // SpringMVC默认为注册HandlerExceptionResolverComposite的Bean
        List<HandlerExceptionResolver> exceptionResolvers = ((HandlerExceptionResolverComposite) handlerExceptionResolver).getExceptionResolvers();
        if (CollectionUtils.isEmpty(exceptionResolvers)) {
            return;
        }
        for (HandlerExceptionResolver exceptionResolver : exceptionResolvers) {
            if (exceptionResolver instanceof ExceptionHandlerExceptionResolver) {
                HandlerMethodReturnValueHandlerComposite returnValueHandlerComposite = ((ExceptionHandlerExceptionResolver) exceptionResolver).getReturnValueHandlers();
                if (returnValueHandlerComposite == null) {
                    return;
                }
                SpringMvcPolyfill.addDynamicResponseBodyAdvice(returnValueHandlerComposite.getHandlers(), null, responseBodyAdvice);
            }
        }
    }
}
 

private void testReturnValueHandlers(Object bean) {
	assertNotNull(bean);
	Object value = new DirectFieldAccessor(bean).getPropertyValue("customReturnValueHandlers");
	assertNotNull(value);
	assertTrue(value instanceof List);
	@SuppressWarnings("unchecked")
	List<HandlerMethodReturnValueHandler> handlers = (List<HandlerMethodReturnValueHandler>) value;
	assertEquals(2, handlers.size());
	assertEquals(TestHandlerMethodReturnValueHandler.class, handlers.get(0).getClass());
	assertEquals(TestHandlerMethodReturnValueHandler.class, handlers.get(1).getClass());
	assertNotSame(handlers.get(0), handlers.get(1));
}
 

private int indexOfType(final List<HandlerMethodReturnValueHandler> originalHandlers, Class<?> handlerClass) {
    for (int i = 0; i < originalHandlers.size(); i++) {
        final HandlerMethodReturnValueHandler valueHandler = originalHandlers.get(i);
        if (handlerClass.isAssignableFrom(valueHandler.getClass())) {
            return i;
        }
    }
    return -1;
}
 

public GuavaLFReturnValueHandler install(RequestMappingHandlerAdapter requestMappingHandlerAdapter) {
    final List<HandlerMethodReturnValueHandler> originalHandlers = new ArrayList<>(
            requestMappingHandlerAdapter.getReturnValueHandlers());

    final int deferredPos = indexOfType(originalHandlers, DeferredResultMethodReturnValueHandler.class);
    // Add our handler directly after the deferred handler.
    originalHandlers.add(deferredPos + 1, this);

    requestMappingHandlerAdapter.setReturnValueHandlers(originalHandlers);

    return this;
}
 

@Test
public void setReturnValueHandlers() {
	HandlerMethodReturnValueHandler handler = new ModelMethodProcessor();
	this.resolver.setReturnValueHandlers(Collections.singletonList(handler));
	this.resolver.afterPropertiesSet();

	assertMethodProcessorCount(RESOLVER_COUNT, 1);
}
 

/**
 * Configure the complete list of supported return value types thus
 * overriding handlers that would otherwise be configured by default.
 */
public void setReturnValueHandlers(@Nullable List<HandlerMethodReturnValueHandler> returnValueHandlers) {
	if (returnValueHandlers == null) {
		this.returnValueHandlers = null;
	}
	else {
		this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite();
		this.returnValueHandlers.addHandlers(returnValueHandlers);
	}
}
 

/**
 * Configure the complete list of supported return value types thus
 * overriding handlers that would otherwise be configured by default.
 */
public void setReturnValueHandlers(@Nullable List<HandlerMethodReturnValueHandler> returnValueHandlers) {
	if (returnValueHandlers == null) {
		this.returnValueHandlers = null;
	}
	else {
		this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite();
		this.returnValueHandlers.addHandlers(returnValueHandlers);
	}
}
 

/**
 * Return the list of return value handlers to use including built-in and
 * custom handlers provided via {@link #setReturnValueHandlers}.
 */
protected List<HandlerMethodReturnValueHandler> getDefaultReturnValueHandlers() {
	List<HandlerMethodReturnValueHandler> handlers = new ArrayList<>();

	// Single-purpose return value types
	handlers.add(new ModelAndViewMethodReturnValueHandler());
	handlers.add(new ModelMethodProcessor());
	handlers.add(new ViewMethodReturnValueHandler());
	handlers.add(new HttpEntityMethodProcessor(
			getMessageConverters(), this.contentNegotiationManager, this.responseBodyAdvice));

	// Annotation-based return value types
	handlers.add(new ModelAttributeMethodProcessor(false));
	handlers.add(new RequestResponseBodyMethodProcessor(
			getMessageConverters(), this.contentNegotiationManager, this.responseBodyAdvice));

	// Multi-purpose return value types
	handlers.add(new ViewNameMethodReturnValueHandler());
	handlers.add(new MapMethodProcessor());

	// Custom return value types
	if (getCustomReturnValueHandlers() != null) {
		handlers.addAll(getCustomReturnValueHandlers());
	}

	// Catch-all
	handlers.add(new ModelAttributeMethodProcessor(true));

	return handlers;
}
 

private int indexOfType(final List<HandlerMethodReturnValueHandler> originalHandlers, Class<?> handlerClass) {
    for (int i = 0; i < originalHandlers.size(); i++) {
        final HandlerMethodReturnValueHandler valueHandler = originalHandlers.get(i);
        if (handlerClass.isAssignableFrom(valueHandler.getClass())) {
            return i;
        }
    }
    return -1;
}
 

/**
 * Configure the complete list of supported return value types thus
 * overriding handlers that would otherwise be configured by default.
 */
public void setReturnValueHandlers(@Nullable List<HandlerMethodReturnValueHandler> returnValueHandlers) {
	if (returnValueHandlers == null) {
		this.returnValueHandlers = null;
	}
	else {
		this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite();
		this.returnValueHandlers.addHandlers(returnValueHandlers);
	}
}
 

/**
 * Provide access to the shared return value handlers used by the
 * {@link RequestMappingHandlerAdapter} and the
 * {@link ExceptionHandlerExceptionResolver}. This method cannot be
 * overridden, use {@link #addReturnValueHandlers(List)} instead.
 * @since 4.3
 */
protected final List<HandlerMethodReturnValueHandler> getReturnValueHandlers() {
	if (this.returnValueHandlers == null) {
		this.returnValueHandlers = new ArrayList<HandlerMethodReturnValueHandler>();
		addReturnValueHandlers(this.returnValueHandlers);
	}
	return this.returnValueHandlers;
}
 

@Test
public void setCustomReturnValueHandlers() {
	HandlerMethodReturnValueHandler handler = new ViewNameMethodReturnValueHandler();
	this.handlerAdapter.setCustomReturnValueHandlers(Collections.singletonList(handler));
	this.handlerAdapter.afterPropertiesSet();

	assertTrue(this.handlerAdapter.getReturnValueHandlers().contains(handler));
	assertMethodProcessorCount(RESOLVER_COUNT, INIT_BINDER_RESOLVER_COUNT, HANDLER_COUNT + 1);
}
 

/**
 * Configure the complete list of supported return value types thus
 * overriding handlers that would otherwise be configured by default.
 */
public void setReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
	if (returnValueHandlers == null) {
		this.returnValueHandlers = null;
	}
	else {
		this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite();
		this.returnValueHandlers.addHandlers(returnValueHandlers);
	}
}
 

private void decorateHandlers(List<HandlerMethodReturnValueHandler> handlers) {

			for (HandlerMethodReturnValueHandler handler : handlers) {
				if (handler instanceof RequestResponseBodyMethodProcessor) {
					ResponseBodyWrapHandler decorator = new ResponseBodyWrapHandler(handler);
					int index = handlers.indexOf(handler);
					handlers.set(index, decorator);
					break;
				}
			}

		}
 

@Override
public void afterPropertiesSet() {
	// Do this first, it may add ResponseBodyAdvice beans
	initExceptionHandlerAdviceCache();

	if (this.argumentResolvers == null) {
		List<HandlerMethodArgumentResolver> resolvers = getDefaultArgumentResolvers();
		this.argumentResolvers = new HandlerMethodArgumentResolverComposite().addResolvers(resolvers);
	}
	if (this.returnValueHandlers == null) {
		List<HandlerMethodReturnValueHandler> handlers = getDefaultReturnValueHandlers();
		this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite().addHandlers(handlers);
	}
}
 

/**
 * Provide access to the shared return value handlers used by the
 * {@link RequestMappingHandlerAdapter} and the {@link ExceptionHandlerExceptionResolver}.
 * <p>This method cannot be overridden; use {@link #addReturnValueHandlers} instead.
 * @since 4.3
 */
protected final List<HandlerMethodReturnValueHandler> getReturnValueHandlers() {
	if (this.returnValueHandlers == null) {
		this.returnValueHandlers = new ArrayList<>();
		addReturnValueHandlers(this.returnValueHandlers);
	}
	return this.returnValueHandlers;
}
 

@Test
public void setCustomReturnValueHandlers() {
	HandlerMethodReturnValueHandler handler = new ViewNameMethodReturnValueHandler();
	this.resolver.setCustomReturnValueHandlers(Collections.singletonList(handler));
	this.resolver.afterPropertiesSet();

	assertTrue(this.resolver.getReturnValueHandlers().getHandlers().contains(handler));
	assertMethodProcessorCount(RESOLVER_COUNT, HANDLER_COUNT + 1);
}
 

@Test
public void setReturnValueHandlers() {
	HandlerMethodReturnValueHandler handler = new ModelMethodProcessor();
	this.resolver.setReturnValueHandlers(Collections.singletonList(handler));
	this.resolver.afterPropertiesSet();

	assertMethodProcessorCount(RESOLVER_COUNT, 1);
}
 

@Test
public void setCustomReturnValueHandlers() {
	HandlerMethodReturnValueHandler handler = new ViewNameMethodReturnValueHandler();
	this.handlerAdapter.setCustomReturnValueHandlers(Collections.singletonList(handler));
	this.handlerAdapter.afterPropertiesSet();

	assertTrue(this.handlerAdapter.getReturnValueHandlers().contains(handler));
	assertMethodProcessorCount(RESOLVER_COUNT, INIT_BINDER_RESOLVER_COUNT, HANDLER_COUNT + 1);
}
 

@Test
public void setReturnValueHandlers() {
	HandlerMethodReturnValueHandler handler = new ModelMethodProcessor();
	this.handlerAdapter.setReturnValueHandlers(Collections.singletonList(handler));
	this.handlerAdapter.afterPropertiesSet();

	assertMethodProcessorCount(RESOLVER_COUNT, INIT_BINDER_RESOLVER_COUNT, 1);
}
 

private void testReturnValueHandlers(Object bean) {
	assertNotNull(bean);
	Object value = new DirectFieldAccessor(bean).getPropertyValue("customReturnValueHandlers");
	assertNotNull(value);
	assertTrue(value instanceof List);
	@SuppressWarnings("unchecked")
	List<HandlerMethodReturnValueHandler> handlers = (List<HandlerMethodReturnValueHandler>) value;
	assertEquals(2, handlers.size());
	assertEquals(TestHandlerMethodReturnValueHandler.class, handlers.get(0).getClass());
	assertEquals(TestHandlerMethodReturnValueHandler.class, handlers.get(1).getClass());
	assertNotSame(handlers.get(0), handlers.get(1));
}
 

/**
 * 反射获取HandlerMethodReturnValueHandler集合
 */
private List<HandlerMethodReturnValueHandler>
    findHandlerMethodReturnValueHandlers(RequestMappingHandlerAdapter requestMappingHandlerAdapter)
        throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
    Field returnValueHandlerCompositeField =
        ReflectionUtils.findField(RequestMappingHandlerAdapter.class, "returnValueHandlers");
    returnValueHandlerCompositeField.setAccessible(true);
    Field modifiersField = Field.class.getDeclaredField("modifiers");
    modifiersField.setAccessible(true);
    modifiersField.setInt(returnValueHandlerCompositeField,
        returnValueHandlerCompositeField.getModifiers() & ~Modifier.FINAL);
    HandlerMethodReturnValueHandlerComposite returnValueHandlerComposite =
        (HandlerMethodReturnValueHandlerComposite)ReflectionUtils.getField(returnValueHandlerCompositeField,
            requestMappingHandlerAdapter);
    Field returnValueHandlersField =
        ReflectionUtils.findField(HandlerMethodReturnValueHandlerComposite.class, "returnValueHandlers");
    returnValueHandlersField.setAccessible(true);
    Field returnValueHandlerModifiersField = Field.class.getDeclaredField("modifiers");
    returnValueHandlerModifiersField.setAccessible(true);
    returnValueHandlerModifiersField.setInt(returnValueHandlersField,
        returnValueHandlersField.getModifiers() & ~Modifier.FINAL);
    List<HandlerMethodReturnValueHandler> returnValueHandlers =
        (List<HandlerMethodReturnValueHandler>)ReflectionUtils.getField(returnValueHandlersField,
            returnValueHandlerComposite);
    return returnValueHandlers;

}
 

@Bean
public WebMvcConfigurationSupport rxJavaWebMvcConfiguration() {
    return new WebMvcConfigurationSupport(){
        @Override
        protected void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
            super.addReturnValueHandlers(returnValueHandlers);
            returnValueHandlers.addAll(handlers);
        }
    };
}
 

/**
 * Configure the complete list of supported return value types thus
 * overriding handlers that would otherwise be configured by default.
 */
public void setReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
	if (returnValueHandlers == null) {
		this.returnValueHandlers = null;
	}
	else {
		this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite();
		this.returnValueHandlers.addHandlers(returnValueHandlers);
	}
}
 

/**
 * Return the list of return value handlers to use including built-in and
 * custom handlers provided via {@link #setReturnValueHandlers}.
 */
protected List<HandlerMethodReturnValueHandler> getDefaultReturnValueHandlers() {
	List<HandlerMethodReturnValueHandler> handlers = new ArrayList<HandlerMethodReturnValueHandler>();

	// Single-purpose return value types
	handlers.add(new ModelAndViewMethodReturnValueHandler());
	handlers.add(new ModelMethodProcessor());
	handlers.add(new ViewMethodReturnValueHandler());
	handlers.add(new HttpEntityMethodProcessor(
			getMessageConverters(), this.contentNegotiationManager, this.responseBodyAdvice));

	// Annotation-based return value types
	handlers.add(new ModelAttributeMethodProcessor(false));
	handlers.add(new RequestResponseBodyMethodProcessor(
			getMessageConverters(), this.contentNegotiationManager, this.responseBodyAdvice));

	// Multi-purpose return value types
	handlers.add(new ViewNameMethodReturnValueHandler());
	handlers.add(new MapMethodProcessor());

	// Custom return value types
	if (getCustomReturnValueHandlers() != null) {
		handlers.addAll(getCustomReturnValueHandlers());
	}

	// Catch-all
	handlers.add(new ModelAttributeMethodProcessor(true));

	return handlers;
}