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.flume.sink.customhdfs; import com.google.common.base.Preconditions; import org.apache.flume.Context; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class SequenceFileSerializerFactory { private static final Logger logger = LoggerFactory.getLogger(SequenceFileSerializerFactory.class); /** * {@link Context} prefix */ static final String CTX_PREFIX = "writeFormat."; @SuppressWarnings("unchecked") static SequenceFileSerializer getSerializer(String formatType, Context context) { Preconditions.checkNotNull(formatType, "serialize type must not be null"); // try to find builder class in enum of known formatters SequenceFileSerializerType type; try { type = SequenceFileSerializerType.valueOf(formatType); } catch (IllegalArgumentException e) { logger.debug("Not in enum, loading builder class: {}", formatType); type = SequenceFileSerializerType.Other; } Class<? extends SequenceFileSerializer.Builder> builderClass = type.getBuilderClass(); // handle the case where they have specified their own builder in the config if (builderClass == null) { try { Class c = Class.forName(formatType); if (c != null && SequenceFileSerializer.Builder.class.isAssignableFrom(c)) { builderClass = (Class<? extends SequenceFileSerializer.Builder>) c; } else { logger.error("Unable to instantiate Builder from {}", formatType); return null; } } catch (ClassNotFoundException ex) { logger.error("Class not found: " + formatType, ex); return null; } catch (ClassCastException ex) { logger.error("Class does not extend " + SequenceFileSerializer.Builder.class.getCanonicalName() + ": " + formatType, ex); return null; } } // build the builder SequenceFileSerializer.Builder builder; try { builder = builderClass.newInstance(); } catch (InstantiationException ex) { logger.error("Cannot instantiate builder: " + formatType, ex); return null; } catch (IllegalAccessException ex) { logger.error("Cannot instantiate builder: " + formatType, ex); return null; } return builder.build(context); } }