geode-core/src/main/java/org/apache/geode/pdx/PdxReader.java

/*
 * 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.geode.pdx;

import java.util.Date;

/**
 * A PdxReader will be passed to {@link PdxSerializable#fromData(PdxReader) fromData} or
 * {@link PdxSerializer#fromData(Class, PdxReader) PdxSerializer fromData} by GemFire during
 * deserialization of a PDX. The domain class needs to deserialize field members using this
 * interface. This interface is implemented by GemFire. Each readXXX call will return the field's
 * value. If the serialized PDX does not contain the named field then a default value will be
 * returned. Standard Java defaults are used. For Objects this is <code>null</code> and for
 * primitives it is <code>0</code> or <code>0.0</code>.
 * <P>
 * You <em>must</em> read fields in the same order they were written by {@link PdxWriter}.
 * <P>
 * The methods on this interface are not thread safe so do not call them concurrently, on the same
 * instance, from more than one thread.
 *
 * @since GemFire 6.6
 */
public interface PdxReader {

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a <code>char</code>
   *         field.
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  char readChar(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>boolean</code> field.
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  boolean readBoolean(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a <code>byte</code>
   *         field.
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  byte readByte(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a <code>short</code>
   *         field.
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  short readShort(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a <code>int</code>
   *         field.
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  int readInt(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a <code>long</code>
   *         field.
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  long readLong(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a <code>float</code>
   *         field.
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  float readFloat(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>double</code> field.
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  double readDouble(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>String</code> field.
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  String readString(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not an
   *         <code>Object</code> field.
   */
  Object readObject(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>char[]</code> field.
   */
  char[] readCharArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>boolean[]</code> field.
   */
  boolean[] readBooleanArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>byte[]</code> field.
   */
  byte[] readByteArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>short[]</code> field.
   */
  short[] readShortArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a <code>int[]</code>
   *         field.
   */
  int[] readIntArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>long[]</code> field.
   */
  long[] readLongArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>float[]</code> field.
   */
  float[] readFloatArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>double[]</code> field.
   */
  double[] readDoubleArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>String[]</code> field.
   */
  String[] readStringArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>Object[]</code> field.
   */
  Object[] readObjectArray(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a
   *         <code>byte[][]</code> field.
   */
  byte[][] readArrayOfByteArrays(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   * @throws PdxFieldTypeMismatchException if the named field exists and is not a <code>Date</code>
   *         field.
   */
  Date readDate(String fieldName);

  /**
   * Checks if the named field exists and returns the result.
   * <p>
   * This can be useful when writing code that handles more than one version of a PDX class.
   *
   * @param fieldName the name of the field to check
   * @return <code>true</code> if the named field exists; otherwise <code>false</code>
   */
  boolean hasField(String fieldName);

  /**
   * Checks if the named field was {@link PdxWriter#markIdentityField(String) marked} as an identity
   * field.
   * <p>
   * Note that if no fields have been marked then all the fields are used as identity fields even
   * though this method will return <code>false</code> since none of them have been <em>marked</em>.
   *
   * @param fieldName the name of the field to check
   * @return <code>true</code> if the named field exists and was marked as an identify field;
   *         otherwise <code>false</code>
   */
  boolean isIdentityField(String fieldName);

  /**
   * Reads the named field and returns its value.
   *
   * @param fieldName the name of the field to read
   * @return the value of the field if the field exists; otherwise a default value
   * @throws PdxSerializationException if deserialization of the field fails.
   */
  Object readField(String fieldName);

  /**
   * This method returns an object that represents all the unread fields which must be passed to
   * {@link PdxWriter#writeUnreadFields(PdxUnreadFields) writeUnreadFields} in the toData code.
   * <P>
   * Note that if {@link org.apache.geode.cache.CacheFactory#setPdxIgnoreUnreadFields(boolean)
   * setPdxIgnoreUnreadFields} or
   * {@link org.apache.geode.cache.client.ClientCacheFactory#setPdxIgnoreUnreadFields(boolean)
   * client setPdxIgnoreUnreadFields} are set to <code>true</code> then this method will always
   * return an object that has no unread fields.
   *
   * @return an object that represents the unread fields.
   */
  PdxUnreadFields readUnreadFields();
}