Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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 org.apache.slider.server.appmaster.web.view; import com.google.inject.Inject; import org.apache.hadoop.yarn.webapp.hamlet.Hamlet; import org.apache.hadoop.yarn.webapp.view.HtmlBlock; import org.apache.slider.server.appmaster.state.StateAccessForProviders; import org.apache.slider.server.appmaster.web.WebAppApi; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * */ public class ClusterSpecificationBlock extends HtmlBlock { private static final Logger log = LoggerFactory.getLogger(ClusterSpecificationBlock.class); private StateAccessForProviders appState; @Inject public ClusterSpecificationBlock(WebAppApi slider) { this.appState = slider.getAppState(); } @Override protected void render(Block html) { doRender(html); } // An extra method to make testing easier since you can't make an instance of Block protected void doRender(Hamlet html) { html.div("cluster_json").h2("JSON Cluster Specification").pre()._(getJson())._()._(); } /** * Get the JSON, catching any exceptions and returning error text instead * @return */ private String getJson() { return appState.getClusterStatus().toString(); } }