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.accumulo.test.util; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.OutputStream; import java.io.Serializable; import java.util.Base64; import java.util.Objects; import org.apache.hadoop.io.Writable; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Partially based from {@link org.apache.commons.lang3.SerializationUtils}. * * <p> * For serializing and de-serializing objects. */ public class SerializationUtil { private static final Logger log = LoggerFactory.getLogger(SerializationUtil.class); private SerializationUtil() { } /** * Create a new instance of a class whose name is given, as a descendent of a given subclass. */ public static <E> E subclassNewInstance(String classname, Class<E> parentClass) { Class<?> c; try { c = Class.forName(classname); } catch (ClassNotFoundException e) { throw new IllegalArgumentException("Can't find class: " + classname, e); } Class<? extends E> cm; try { cm = c.asSubclass(parentClass); } catch (ClassCastException e) { throw new IllegalArgumentException(classname + " is not a subclass of " + parentClass.getName(), e); } try { return cm.newInstance(); } catch (InstantiationException | IllegalAccessException e) { throw new IllegalArgumentException("can't instantiate new instance of " + cm.getName(), e); } } public static String serializeWritableBase64(Writable writable) { byte[] b = serializeWritable(writable); return Base64.getEncoder().encodeToString(b); } public static void deserializeWritableBase64(Writable writable, String str) { byte[] b = Base64.getDecoder().decode(str); deserializeWritable(writable, b); } public static String serializeBase64(Serializable obj) { byte[] b = serialize(obj); return Base64.getEncoder().encodeToString(b); } public static Object deserializeBase64(String str) { byte[] b = Base64.getDecoder().decode(str); return deserialize(b); } // Interop with Hadoop Writable // ----------------------------------------------------------------------- public static byte[] serializeWritable(Writable writable) { ByteArrayOutputStream baos = new ByteArrayOutputStream(512); serializeWritable(writable, baos); return baos.toByteArray(); } public static void serializeWritable(Writable obj, OutputStream outputStream) { Objects.requireNonNull(obj); Objects.requireNonNull(outputStream); DataOutputStream out = null; try { out = new DataOutputStream(outputStream); obj.write(out); } catch (IOException ex) { throw new RuntimeException(ex); } finally { if (out != null) try { out.close(); } catch (IOException e) { log.error("cannot close", e); } } } public static void deserializeWritable(Writable writable, InputStream inputStream) { Objects.requireNonNull(writable); Objects.requireNonNull(inputStream); DataInputStream in = null; try { in = new DataInputStream(inputStream); writable.readFields(in); } catch (IOException ex) { throw new RuntimeException(ex); } finally { if (in != null) try { in.close(); } catch (IOException e) { log.error("cannot close", e); } } } public static void deserializeWritable(Writable writable, byte[] objectData) { Objects.requireNonNull(objectData); deserializeWritable(writable, new ByteArrayInputStream(objectData)); } // Serialize // ----------------------------------------------------------------------- /** * Serializes an {@code Object} to the specified stream. * <p> * The stream will be closed once the object is written. This avoids the need for a finally clause, and maybe also exception handling, in the application * code. * <p> * The stream passed in is not buffered internally within this method. This is the responsibility of your application if desired. * * @param obj * the object to serialize to bytes, may be null * @param outputStream * the stream to write to, must not be null * @throws IllegalArgumentException * if {@code outputStream} is {@code null} */ public static void serialize(Serializable obj, OutputStream outputStream) { Objects.requireNonNull(outputStream); ObjectOutputStream out = null; try { out = new ObjectOutputStream(outputStream); out.writeObject(obj); } catch (IOException ex) { throw new RuntimeException(ex); } finally { if (out != null) try { out.close(); } catch (IOException e) { log.error("cannot close", e); } } } /** * Serializes an {@code Object} to a byte array for storage/serialization. * * @param obj * the object to serialize to bytes * @return a byte[] with the converted Serializable */ public static byte[] serialize(Serializable obj) { ByteArrayOutputStream baos = new ByteArrayOutputStream(512); serialize(obj, baos); return baos.toByteArray(); } // Deserialize // ----------------------------------------------------------------------- /** * Deserializes an {@code Object} from the specified stream. * <p> * The stream will be closed once the object is written. This avoids the need for a finally clause, and maybe also exception handling, in the application * code. * <p> * The stream passed in is not buffered internally within this method. This is the responsibility of your application if desired. * * @param inputStream * the serialized object input stream, must not be null * @return the deserialized object * @throws IllegalArgumentException * if {@code inputStream} is {@code null} */ public static Object deserialize(InputStream inputStream) { Objects.requireNonNull(inputStream); ObjectInputStream in = null; try { in = new ObjectInputStream(inputStream); return in.readObject(); } catch (ClassNotFoundException | IOException ex) { throw new RuntimeException(ex); } finally { if (in != null) try { in.close(); } catch (IOException e) { log.error("cannot close", e); } } } /** * Deserializes a single {@code Object} from an array of bytes. * * @param objectData * the serialized object, must not be null * @return the deserialized object * @throws IllegalArgumentException * if {@code objectData} is {@code null} */ public static Object deserialize(byte[] objectData) { Objects.requireNonNull(objectData); return deserialize(new ByteArrayInputStream(objectData)); } }