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.poi.ddf; import java.io.PrintWriter; import java.util.Collections; import java.util.List; import java.util.Map; import java.util.function.Supplier; import org.apache.poi.common.usermodel.GenericRecord; import org.apache.poi.util.BitField; import org.apache.poi.util.BitFieldFactory; import org.apache.poi.util.GenericRecordJsonWriter; import org.apache.poi.util.GenericRecordUtil; import org.apache.poi.util.GenericRecordXmlWriter; import org.apache.poi.util.Internal; import org.apache.poi.util.LittleEndian; /** * The base abstract record from which all escher records are defined. Subclasses will need * to define methods for serialization/deserialization and for determining the record size. */ public abstract class EscherRecord implements Cloneable, GenericRecord { private static final BitField fInstance = BitFieldFactory.getInstance(0xfff0); private static final BitField fVersion = BitFieldFactory.getInstance(0x000f); private short _options; private short _recordId; /** * Create a new instance */ public EscherRecord() { // fields uninitialised } /** * Delegates to fillFields(byte[], int, EscherRecordFactory) * * @param data they bytes to serialize from * @param f the escher record factory * @return The number of bytes written. * * @see #fillFields(byte[], int, org.apache.poi.ddf.EscherRecordFactory) */ protected int fillFields(byte[] data, EscherRecordFactory f) { return fillFields(data, 0, f); } /** * The contract of this method is to deserialize an escher record including * it's children. * * @param data The byte array containing the serialized escher * records. * @param offset The offset into the byte array. * @param recordFactory A factory for creating new escher records. * @return The number of bytes written. */ public abstract int fillFields(byte[] data, int offset, EscherRecordFactory recordFactory); /** * Reads the 8 byte header information and populates the <code>options</code> * and <code>recordId</code> records. * * @param data the byte array to read from * @param offset the offset to start reading from * @return the number of bytes remaining in this record. This * may include the children if this is a container. */ protected int readHeader(byte[] data, int offset) { _options = LittleEndian.getShort(data, offset); _recordId = LittleEndian.getShort(data, offset + 2); return LittleEndian.getInt(data, offset + 4); } /** * Read the options field from header and return instance part of it. * @param data the byte array to read from * @param offset the offset to start reading from * @return value of instance part of options field */ protected static short readInstance(byte[] data, int offset) { final short options = LittleEndian.getShort(data, offset); return fInstance.getShortValue(options); } /** * Determine whether this is a container record by inspecting the option field. * * @return true is this is a container field. */ public boolean isContainerRecord() { return getVersion() == (short) 0x000f; } /** * Note that <code>options</code> is an internal field. * Use {@link #setInstance(short)} ()} and {@link #setVersion(short)} ()} to set the actual fields. * * @return The options field for this record. All records have one. */ @Internal public short getOptions() { return _options; } /** * Set the options this this record. Container records should have the * last nibble set to 0xF.<p> * * Note that {@code options} is an internal field. * Use {@link #getInstance()} and {@link #getVersion()} to access actual fields. * * @param options the record options */ @Internal public void setOptions(short options) { // call to handle correct/incorrect values setVersion(fVersion.getShortValue(options)); setInstance(fInstance.getShortValue(options)); _options = options; } /** * Serializes to a new byte array. This is done by delegating to * serialize(int, byte[]); * * @return the serialized record. * @see #serialize(int, byte[]) */ public byte[] serialize() { byte[] retval = new byte[getRecordSize()]; serialize(0, retval); return retval; } /** * Serializes to an existing byte array without serialization listener. * This is done by delegating to serialize(int, byte[], EscherSerializationListener). * * @param offset the offset within the data byte array. * @param data the data array to serialize to. * @return The number of bytes written. * * @see #serialize(int, byte[], org.apache.poi.ddf.EscherSerializationListener) */ public int serialize(int offset, byte[] data) { return serialize(offset, data, new NullEscherSerializationListener()); } /** * Serializes the record to an existing byte array. * * @param offset the offset within the byte array * @param data the data array to serialize to * @param listener a listener for begin and end serialization events. This * is useful because the serialization is * hierarchical/recursive and sometimes you need to be able * break into that. * @return the number of bytes written. */ public abstract int serialize(int offset, byte[] data, EscherSerializationListener listener); /** * Subclasses should effeciently return the number of bytes required to * serialize the record. * * @return number of bytes */ abstract public int getRecordSize(); /** * Return the current record id. * * @return The 16 bit record id. */ public short getRecordId() { return _recordId; } /** * Sets the record id for this record. * * @param recordId the record id */ public void setRecordId(short recordId) { _recordId = recordId; } /** * @return Returns the children of this record. By default this will * be an empty list. EscherCotainerRecord is the only record * that may contain children. * * @see EscherContainerRecord */ public List<EscherRecord> getChildRecords() { return Collections.emptyList(); } /** * Sets the child records for this record. By default this will throw * an exception as only EscherContainerRecords may have children. * * @param childRecords Not used in base implementation. */ public void setChildRecords(List<EscherRecord> childRecords) { throw new UnsupportedOperationException("This record does not support child records."); } /** * Escher records may need to be clonable in the future. * * @return the cloned object * * @throws CloneNotSupportedException if the subclass hasn't implemented {@link Cloneable} */ @Override public EscherRecord clone() throws CloneNotSupportedException { return (EscherRecord) super.clone(); } /** * Returns the indexed child record. * * @param index the index of the child within the child records * @return the indexed child record */ public EscherRecord getChild(int index) { return getChildRecords().get(index); } /** * The display methods allows escher variables to print the record names * according to their hierarchy. * * @param w The print writer to output to. * @param indent The current indent level. */ public void display(PrintWriter w, int indent) { for (int i = 0; i < indent * 4; i++) { w.print(' '); } w.println(getRecordName()); } /** * Subclasses should return the short name for this escher record. * * @return the short name for this escher record */ public abstract String getRecordName(); /** * Returns the instance part of the option record. * * @return The instance part of the record */ public short getInstance() { return fInstance.getShortValue(_options); } /** * Sets the instance part of record * * @param value instance part value */ public void setInstance(short value) { _options = fInstance.setShortValue(_options, value); } /** * Returns the version part of the option record. * * @return The version part of the option record */ public short getVersion() { return fVersion.getShortValue(_options); } /** * Sets the version part of record * * @param value version part value */ public void setVersion(short value) { _options = fVersion.setShortValue(_options, value); } public String toXml() { return toXml(""); } /** * @param tab - each children must be indented right relative to its parent * @return xml representation of this record */ public final String toXml(String tab) { return GenericRecordXmlWriter.marshal(this); } @Override public final String toString() { return GenericRecordJsonWriter.marshal(this); } @Override public List<? extends GenericRecord> getGenericChildren() { return getChildRecords(); } @Override public Map<String, Supplier<?>> getGenericProperties() { return GenericRecordUtil.getGenericProperties("recordId", this::getRecordId, "version", this::getVersion, "instance", this::getInstance, "options", this::getOptions, "recordSize", this::getRecordSize); } }