Import code from internal repository to git

java/com/google/domain/registry/util/HttpServletUtils.java

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+// Copyright 2016 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.domain.registry.util;
+
+import static com.google.common.net.MediaType.PLAIN_TEXT_UTF_8;
+import static com.google.domain.registry.util.PreconditionsUtils.checkArgumentNotNull;
+
+import java.io.IOException;
+
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/** Utility methods for working with {@link HttpServlet}-related classes. */
+public final class HttpServletUtils {
+
+  /**
+   * Returns the value of the given request's first {@code name} parameter, or throws
+   * {@code IllegalArgumentException} if the parameter is not present.
+   */
+  public static String getRequiredParameterValue(HttpServletRequest req, String name) {
+    return checkArgumentNotNull(req.getParameter(name), "Missing required parameter: %s", name);
+  }
+
+  /**
+   * Sets the content type on an HttpServletResponse to UTF-8, returns 200 OK status, and sends
+   * "OK".
+   */
+  public static void sendOk(HttpServletResponse rsp) throws IOException {
+    rsp.setContentType(PLAIN_TEXT_UTF_8.toString());
+    rsp.getWriter().write("OK\n");
+  }
+}