feat(GrpcServlet): ability override method name

servlet/src/main/java/io/grpc/servlet/GrpcServlet.java

@@ -28,6 +28,10 @@
  * A simple servlet backed by a gRPC server. Must set {@code asyncSupported} to true. The {@code
  * /contextRoot/urlPattern} must match the gRPC services' path, which is
  * "/full-service-name/short-method-name".
+ * If you use application server and want to get access to grpc from non root path
+ * for example {@code /deployment-name/full-service-name/short-method-name}
+ * you must override {@link #getMethod(HttpServletRequest)}.
+ * <a href=https://github.com/grpc/grpc-java/pull/11825>More info</a>.
  *
  * <p>The API is experimental. The authors would like to know more about the real usecases. Users
  * are welcome to provide feedback by commenting on
@@ -58,6 +62,10 @@ private static ServletAdapter loadServices(List<? extends BindableService> binda
     return serverBuilder.buildServletAdapter();
   }
 
+  protected String getMethod(HttpServletRequest req) {
+    return req.getRequestURI().substring(1); // remove the leading "/"
+  }
+
   @Override
   protected final void doGet(HttpServletRequest request, HttpServletResponse response)
       throws IOException {
@@ -67,7 +75,7 @@ protected final void doGet(HttpServletRequest request, HttpServletResponse respo
   @Override
   protected final void doPost(HttpServletRequest request, HttpServletResponse response)
       throws IOException {
-    servletAdapter.doPost(request, response);
+    servletAdapter.doPost(getMethod(request), request, response);
   }
 
   @Override

servlet/src/main/java/io/grpc/servlet/ServletAdapter.java

@@ -59,10 +59,11 @@
  * process it, and transforms the gRPC response into {@link HttpServletResponse}. An adapter can be
  * instantiated by {@link ServletServerBuilder#buildServletAdapter()}.
  *
- * <p>In a servlet, calling {@link #doPost(HttpServletRequest, HttpServletResponse)} inside {@link
- * javax.servlet.http.HttpServlet#doPost(HttpServletRequest, HttpServletResponse)} makes the servlet
- * backed by the gRPC server associated with the adapter. The servlet must support Asynchronous
- * Processing and must be deployed to a container that supports servlet 4.0 and enables HTTP/2.
+ * <p>In a servlet, calling {@link #doPost(String, HttpServletRequest, HttpServletResponse)} inside 
+ * {@link javax.servlet.http.HttpServlet#doPost(HttpServletRequest, HttpServletResponse)} makes
+ * the servlet backed by the gRPC server associated with the adapter. The servlet must support 
+ * Asynchronous Processing and must be deployed to a container that supports servlet 4.0
+ * and enables HTTP/2.
  *
  * <p>The API is experimental. The authors would like to know more about the real usecases. Users
  * are welcome to provide feedback by commenting on
@@ -103,14 +104,19 @@ public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOExc
     resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, "GET method not supported");
   }
 
+  public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+    doPost(req.getRequestURI().substring(1), req, resp);
+  }
+
   /**
    * Call this method inside {@link javax.servlet.http.HttpServlet#doPost(HttpServletRequest,
    * HttpServletResponse)} to serve gRPC POST request.
    *
    * <p>Do not modify {@code req} and {@code resp} before or after calling this method. However,
    * calling {@code resp.setBufferSize()} before invocation is allowed.
    */
-  public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+  public void doPost(String method, HttpServletRequest req, HttpServletResponse resp)
+      throws IOException {
     checkArgument(req.isAsyncSupported(), "servlet does not support asynchronous operation");
     checkArgument(ServletAdapter.isGrpc(req), "the request is not a gRPC request");
 
@@ -119,7 +125,6 @@ public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOEx
 
     AsyncContext asyncCtx = req.startAsync(req, resp);
 
-    String method = req.getRequestURI().substring(1); // remove the leading "/"
     Metadata headers = getHeaders(req);
 
     if (logger.isLoggable(FINEST)) {