Springboot : RequestContextHolder_springboot requestcontextholder

前言

• springboot 2.0.0.RELEASE
• sping-web 提供了 RequestContextHolder 。RequestContextHolder 让开发者可以在请求的任意位置获取到 request、response、session 等。
• 因 RequestContextHolder 是 sping-web 提供的，所以 springboot 中也可以使用。

获取请求参数

RequestAttributes requestAttributes = RequestContextHolder.currentRequestAttributes();
//RequestAttributes requestAttributes =  RequestContextHolder.getRequestAttributes();

//获取请求参数
String str = (String) requestAttributes.getAttribute("name", RequestAttributes.SCOPE_REQUEST);
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从SESSION取值

RequestAttributes requestAttributes = RequestContextHolder.currentRequestAttributes();

//从session里面获取对应的值
String str = (String) requestAttributes.getAttribute("name", RequestAttributes.SCOPE_SESSION);
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获取request、response、session

ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
HttpServletRequest request = attributes.getRequest();
HttpServletResponse response = attributes.getResponse();
HttpSession session = attributes.getRequest().getSession();
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getRequestAttributes vs currentRequestAttributes

	/**
	 * Return the RequestAttributes currently bound to the thread.
	 * @return the RequestAttributes currently bound to the thread,
	 * or {@code null} if none bound
	 */
	@Nullable
	public static RequestAttributes getRequestAttributes() {
		RequestAttributes attributes = requestAttributesHolder.get();
		if (attributes == null) {
			attributes = inheritableRequestAttributesHolder.get();
		}
		return attributes;
	}
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	/**
	 * Return the RequestAttributes currently bound to the thread.
	 * <p>Exposes the previously bound RequestAttributes instance, if any.
	 * Falls back to the current JSF FacesContext, if any.
	 * @return the RequestAttributes currently bound to the thread
	 * @throws IllegalStateException if no RequestAttributes object
	 * is bound to the current thread
	 * @see #setRequestAttributes
	 * @see ServletRequestAttributes
	 * @see FacesRequestAttributes
	 * @see javax.faces.context.FacesContext#getCurrentInstance()
	 */
	public static RequestAttributes currentRequestAttributes() throws IllegalStateException {
		RequestAttributes attributes = getRequestAttributes();
		if (attributes == null) {
			if (jsfPresent) {
				attributes = FacesRequestAttributesFactory.getFacesRequestAttributes();
			}
			if (attributes == null) {
				throw new IllegalStateException("No thread-bound request found: " +
						"Are you referring to request attributes outside of an actual web request, " +
						"or processing a request outside of the originally receiving thread? " +
						"If you are actually operating within a web request and still receive this message, " +
						"your code is probably running outside of DispatcherServlet: " +
						"In this case, use RequestContextListener or RequestContextFilter to expose the current request.");
			}
		}
		return attributes;
	}
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