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@@ -0,0 +1,161 @@
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+/*
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+ * Copyright 2002-2023 the original author or authors.
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+ *
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+ * Licensed under the Apache License, Version 2.0 (the "License");
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+ * you may not use this file except in compliance with the License.
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+ * You may obtain a copy of the License at
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+ *
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+ * https://www.apache.org/licenses/LICENSE-2.0
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+ *
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+ * Unless required by applicable law or agreed to in writing, software
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+ * distributed under the License is distributed on an "AS IS" BASIS,
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+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+ * See the License for the specific language governing permissions and
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+ * limitations under the License.
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+ */
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+
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+package org.springframework.web.context.request;
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+
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+import com.alibaba.ttl.TransmittableThreadLocal;
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+import jakarta.faces.context.FacesContext;
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+import org.springframework.lang.Nullable;
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+import org.springframework.util.ClassUtils;
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+
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+/**
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+ * Holder class to expose the web request in the form of a thread-bound
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+ * {@link RequestAttributes} object. The request will be inherited
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+ * by any child threads spawned by the current thread if the
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+ * {@code inheritable} flag is set to {@code true}.
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+ *
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+ * <p>Use {@link RequestContextListener} or
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+ * {@link org.springframework.web.filter.RequestContextFilter} to expose
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+ * the current web request. Note that
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+ * already exposes the current request by default.
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+ *
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+ * 修改 spring 上下文存储方式 将 ThreadLocal 替换为 TransmittableThreadLocal
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+ * 支持线程上下文切换变量传递 异步获取 spring 上下文
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+ *
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+ * @author Juergen Hoeller
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+ * @author Rod Johnson
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+ * @since 2.0
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+ * @see RequestContextListener
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+ * @see org.springframework.web.filter.RequestContextFilter
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+ */
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+public abstract class RequestContextHolder {
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+
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+ private static final boolean jsfPresent =
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+ ClassUtils.isPresent("jakarta.faces.context.FacesContext", RequestContextHolder.class.getClassLoader());
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+
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+ // ThreadLocal 替换为 TransmittableThreadLocal
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+ private static final ThreadLocal<RequestAttributes> requestAttributesHolder =
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+ new TransmittableThreadLocal<>();
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+
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+ private static final ThreadLocal<RequestAttributes> inheritableRequestAttributesHolder =
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+ new TransmittableThreadLocal<>();
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+
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+
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+ /**
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+ * Reset the RequestAttributes for the current thread.
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+ */
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+ public static void resetRequestAttributes() {
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+ requestAttributesHolder.remove();
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+ inheritableRequestAttributesHolder.remove();
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+ }
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+
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+ /**
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+ * Bind the given RequestAttributes to the current thread,
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+ * <i>not</i> exposing it as inheritable for child threads.
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+ * @param attributes the RequestAttributes to expose
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+ * @see #setRequestAttributes(RequestAttributes, boolean)
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+ */
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+ public static void setRequestAttributes(@Nullable RequestAttributes attributes) {
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+ setRequestAttributes(attributes, false);
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+ }
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+
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+ /**
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+ * Bind the given RequestAttributes to the current thread.
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+ * @param attributes the RequestAttributes to expose,
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+ * or {@code null} to reset the thread-bound context
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+ * @param inheritable whether to expose the RequestAttributes as inheritable
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+ * for child threads (using an {@link InheritableThreadLocal})
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+ */
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+ public static void setRequestAttributes(@Nullable RequestAttributes attributes, boolean inheritable) {
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+ if (attributes == null) {
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+ resetRequestAttributes();
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+ }
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+ else {
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+ if (inheritable) {
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+ inheritableRequestAttributesHolder.set(attributes);
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+ requestAttributesHolder.remove();
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+ }
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+ else {
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+ requestAttributesHolder.set(attributes);
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+ inheritableRequestAttributesHolder.remove();
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+ }
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+ }
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+ }
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+
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+ /**
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+ * Return the RequestAttributes currently bound to the thread.
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+ * @return the RequestAttributes currently bound to the thread,
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+ * or {@code null} if none bound
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+ */
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+ @Nullable
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+ public static RequestAttributes getRequestAttributes() {
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+ RequestAttributes attributes = requestAttributesHolder.get();
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+ if (attributes == null) {
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+ attributes = inheritableRequestAttributesHolder.get();
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+ }
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+ return attributes;
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+ }
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+
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+ /**
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+ * Return the RequestAttributes currently bound to the thread.
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+ * <p>Exposes the previously bound RequestAttributes instance, if any.
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+ * Falls back to the current JSF FacesContext, if any.
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+ * @return the RequestAttributes currently bound to the thread
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+ * @throws IllegalStateException if no RequestAttributes object
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+ * is bound to the current thread
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+ * @see #setRequestAttributes
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+ * @see ServletRequestAttributes
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+ * @see FacesRequestAttributes
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+ * @see jakarta.faces.context.FacesContext#getCurrentInstance()
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+ */
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+ public static RequestAttributes currentRequestAttributes() throws IllegalStateException {
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+ RequestAttributes attributes = getRequestAttributes();
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+ if (attributes == null) {
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+ if (jsfPresent) {
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+ attributes = FacesRequestAttributesFactory.getFacesRequestAttributes();
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+ }
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+ if (attributes == null) {
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+ throw new IllegalStateException("No thread-bound request found: " +
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+ "Are you referring to request attributes outside of an actual web request, " +
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+ "or processing a request outside of the originally receiving thread? " +
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+ "If you are actually operating within a web request and still receive this message, " +
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+ "your code is probably running outside of DispatcherServlet: " +
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+ "In this case, use RequestContextListener or RequestContextFilter to expose the current request.");
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+ }
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+ }
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+ return attributes;
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+ }
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+
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+
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+ /**
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+ * Inner class to avoid hard-coded JSF dependency.
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+ */
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+ private static class FacesRequestAttributesFactory {
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+
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+ @Nullable
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+ public static RequestAttributes getFacesRequestAttributes() {
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+ try {
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+ FacesContext facesContext = FacesContext.getCurrentInstance();
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+ return (facesContext != null ? new FacesRequestAttributes(facesContext) : null);
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+ }
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+ catch (NoClassDefFoundError err) {
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+ // typically for com/sun/faces/util/Util if only the JSF API jar is present
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+ return null;
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+ }
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+ }
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+ }
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+
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+}
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疯狂的狮子Li