ContextLoader and FrameworkServlet support "contextId" parameter for custom serialization id

Author: jhoeller

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/FrameworkServlet.java

@@ -33,6 +33,7 @@
 import org.springframework.context.i18n.LocaleContext;
 import org.springframework.context.i18n.LocaleContextHolder;
 import org.springframework.context.i18n.SimpleLocaleContext;
+import org.springframework.util.ObjectUtils;
 import org.springframework.web.context.ConfigurableWebApplicationContext;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.request.RequestAttributes;
@@ -121,6 +122,9 @@ public abstract class FrameworkServlet extends HttpServletBean {
 	/** WebApplicationContext implementation class to create */
 	private Class contextClass = DEFAULT_CONTEXT_CLASS;
 
+	/** WebApplicationContext id to assign */
+	private String contextId;
+
 	/** Namespace for this servlet */
 	private String namespace;
 
@@ -185,6 +189,21 @@ public Class getContextClass() {
 		return this.contextClass;
 	}
 
+	/**
+	 * Specify a custom WebApplicationContext id,
+	 * to be used as serialization id for the underlying BeanFactory.
+	 */
+	public void setContextId(String contextId) {
+		this.contextId = contextId;
+	}
+
+	/**
+	 * Return the custom WebApplicationContext id, if any.
+	 */
+	public String getContextId() {
+		return this.contextId;
+	}
+
 	/**
 	 * Set a custom namespace for this servlet,
 	 * to be used for building a default context config location.
@@ -413,23 +432,29 @@ protected WebApplicationContext createWebApplicationContext(ApplicationContext p
 				(ConfigurableWebApplicationContext) BeanUtils.instantiateClass(contextClass);
 
 		// Assign the best possible id value.
-		ServletContext sc = getServletContext();
-		if (sc.getMajorVersion() == 2 && sc.getMinorVersion() < 5) {
-			// Servlet <= 2.4: resort to name specified in web.xml, if any.
-			String servletContextName = sc.getServletContextName();
-			if (servletContextName != null) {
-				wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX + servletContextName +
-						"." + getServletName());
+		if (this.contextId != null) {
+			wac.setId(this.contextId);
+		}
+		else {
+			// Generate default id...
+			ServletContext sc = getServletContext();
+			if (sc.getMajorVersion() == 2 && sc.getMinorVersion() < 5) {
+				// Servlet <= 2.4: resort to name specified in web.xml, if any.
+				String servletContextName = sc.getServletContextName();
+				if (servletContextName != null) {
+					wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX + servletContextName +
+							"." + getServletName());
+				}
+				else {
+					wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX + getServletName());
+				}
 			}
 			else {
-				wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX + getServletName());
+				// Servlet 2.5's getContextPath available!
+				wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
+						ObjectUtils.getDisplayString(sc.getContextPath()) + "/" + getServletName());
 			}
 		}
-		else {
-			// Servlet 2.5's getContextPath available!
-			wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX + sc.getContextPath() +
-					"/" + getServletName());
-		}
 
 		wac.setParent(parent);
 		wac.setServletContext(getServletContext());

org.springframework.web/src/main/java/org/springframework/web/context/ContextLoader.java

@@ -77,11 +77,18 @@
 public class ContextLoader {
 
 	/**
-	 * Config param for the root WebApplicationContext implementation class to
-	 * use: "<code>contextClass</code>"
+	 * Config param for the root WebApplicationContext implementation class to use:
+	 * "<code>contextClass</code>"
 	 */
 	public static final String CONTEXT_CLASS_PARAM = "contextClass";
 
+	/**
+	 * Config param for the root WebApplicationContext id,
+	 * to be used as serialization id for the underlying BeanFactory:
+	 * "<code>contextId</code>"
+	 */
+	public static final String CONTEXT_ID_PARAM = "contextId";
+
 	/**
 	 * Name of servlet context parameter (i.e., "<code>contextConfigLocation</code>")
 	 * that can specify the config location for the root context, falling back
@@ -251,21 +258,20 @@ protected WebApplicationContext createWebApplicationContext(ServletContext sc, A
 				(ConfigurableWebApplicationContext) BeanUtils.instantiateClass(contextClass);
 
 		// Assign the best possible id value.
-		if (sc.getMajorVersion() == 2 && sc.getMinorVersion() < 5) {
-			// Servlet <= 2.4: resort to name specified in web.xml, if any.
-			String servletContextName = sc.getServletContextName();
-			wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
-					ObjectUtils.getDisplayString(servletContextName));
+		String idParam = sc.getInitParameter(CONTEXT_ID_PARAM);
+		if (idParam != null) {
+			wac.setId(idParam);
 		}
 		else {
-			// Servlet 2.5's getContextPath available!
-			try {
-				String contextPath = (String) ServletContext.class.getMethod("getContextPath").invoke(sc);
+			// Generate default id...
+			if (sc.getMajorVersion() == 2 && sc.getMinorVersion() < 5) {
+				// Servlet <= 2.4: resort to name specified in web.xml, if any.
 				wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
-						ObjectUtils.getDisplayString(contextPath));
+						ObjectUtils.getDisplayString(sc.getServletContextName()));
 			}
-			catch (Exception ex) {
-				throw new IllegalStateException("Failed to invoke Servlet 2.5 getContextPath method", ex);
+			else {
+				wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
+						ObjectUtils.getDisplayString(sc.getContextPath()));
 			}
 		}