Add README to servletrequest-propagation module.

This fixes #12.

Author: sjoerdtalsma

servletrequest-propagation/README.md

@@ -0,0 +1,31 @@
+[![Released Version][maven-img]][maven] 
+
+# ServletRequest propagation library
+
+Adding the `servletrequest-propagation` jar to your classpath
+provides static access to the current `ServletRequest`
+via the `ServletRequestContextManager.currentServletRequest()` method
+if the `ServletRequestContextFilter` was applied to the inbound request.
+
+## How to use this library
+
+1. Add it to your classpath.
+  ```xml
+  <dependency>
+      <groupId>nl.talsmasoftware.context</groupId>
+      <artifactId>servletrequest-propagation</artifactId>
+      <version>[see maven-central version above]</version>
+  </dependency>
+  ```
+
+2. Include the `ServletRequestContextFilter` in your application.
+
+Done!
+
+Now the `ServletRequestContextManager.currentServletRequest()` is propagated into each
+snapshot created by the `ContextManagers.createSnapshot()` method.
+This includes all usages of the `ContextAwareExecutorService`.
+
+
+  [maven-img]: https://img.shields.io/maven-central/v/nl.talsmasoftware.context/servletrequest-propagation.svg
+  [maven]: http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22nl.talsmasoftware.context%22%20AND%20a%3A%22servletrequest-propagation%22

servletrequest-propagation/src/main/java/nl/talsmasoftware/context/servletrequest/ServletRequestContextManager.java

@@ -27,6 +27,16 @@
  */
 public final class ServletRequestContextManager implements ContextManager<ServletRequest> {
 
+    /**
+     * Static utility method to obtain the current {@link ServletRequest} (if available).
+     *
+     * @return The current ServletRequest if available, or <code>null</code> otherwise.
+     */
+    public static ServletRequest currentServletRequest() {
+        Context<ServletRequest> current = ServletRequestContext.current();
+        return current == null ? null : current.getValue();
+    }
+
     public Context<ServletRequest> initializeNewContext(ServletRequest value) {
         return new ServletRequestContext(value);
     }