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本文主要研究下spring mvc的No thread-bound request found异常

该错误信息在RequestContextHolder这个类中，详细如下：
spring-web-4.3.7.RELEASE-sources.jar!/org/springframework/web/context/request/RequestContextHolder.java

public abstract class RequestContextHolder  {
    private static final boolean jsfPresent =
            ClassUtils.isPresent("javax.faces.context.FacesContext", RequestContextHolder.class.getClassLoader());
    private static final ThreadLocal<RequestAttributes> requestAttributesHolder =
            new NamedThreadLocal<RequestAttributes>("Request attributes");
    private static final ThreadLocal<RequestAttributes> inheritableRequestAttributesHolder =
            new NamedInheritableThreadLocal<RequestAttributes>("Request context");
     * 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/DispatcherPortlet: " +
                        "In this case, use RequestContextListener or RequestContextFilter to expose the current request.");
        return attributes;
     * Return the RequestAttributes currently bound to the thread.
     * @return the RequestAttributes currently bound to the thread,
     * or {@code null} if none bound
    public static RequestAttributes getRequestAttributes() {
        RequestAttributes attributes = requestAttributesHolder.get();
        if (attributes == null) {
            attributes = inheritableRequestAttributesHolder.get();
        return attributes;
    //...
在非web下访问了RequestContextHolder.currentRequestAttributes()导致，因此在service层方法里头调用该方法要慎重，为了避免出错，可以再封装一下
    public RequestAttributes getRequestAttributesSafely(){
        RequestAttributes requestAttributes = null;
            requestAttributes = RequestContextHolder.currentRequestAttributes();
        }catch (IllegalStateException e){
            requestAttributes = new NonWebRequestAttributes();
        return requestAttributes;
NonWebRequestAttributes实现RequestAttributes接口，重写的方法都为空即可