# Package org.apache.poi.hpsf

Processes streams in the Horrible Property Set Format (HPSF) in POI filesystems.

See: Description

- Class Summary
  Class | Description
  --- | ---
  Array |
  Blob |
  ClassID | Represents a class ID (16 bytes).
  ClipboardData |
  CodePageString |
  Currency |
  CustomProperties | Maintains the instances of `CustomProperty` that belong to a `DocumentSummaryInformation`.
  CustomProperty | This class represents custom properties in the document summary information stream.
  Date |
  Decimal |
  DocumentSummaryInformation | Convenience class representing a DocumentSummary Information stream in a Microsoft Office document.
  Filetime | The Windows FILETIME structure holds a date and time associated with a file.
  GUID |
  HPSFPropertiesOnlyDocument | A version of `POIDocument` which allows access to the HPSF Properties, but no other document contents.
  IndirectPropertyName |
  Property | A property in a `Section` of a `PropertySet`.
  PropertySet | Represents a property set in the Horrible Property Set Format (HPSF).
  PropertySetFactory | Factory class to create instances of `SummaryInformation`, `DocumentSummaryInformation` and `PropertySet`.
  Section | Represents a section in a `PropertySet`.
  SummaryInformation | Convenience class representing a Summary Information stream in a Microsoft Office document.
  Thumbnail | Class to manipulate data in the Clipboard Variant (`VT_CF`) format.
  TypedPropertyValue |
  UnicodeString |
  Variant | The `Variant` types as defined by Microsoft's COM.
  VariantBool |
  VariantSupport | Supports reading and writing of variant data.
  Vector | Holder for vector-type properties
  VersionedStream |

- Enum Summary
  Enum | Description
  --- | ---
  ClassIDPredefined |

- Exception Summary
  Exception | Description
  --- | ---
  HPSFException | This exception is the superclass of all other checked exceptions thrown in this package.
  HPSFRuntimeException | This exception is the superclass of all other unchecked exceptions thrown in this package.
  IllegalPropertySetDataException | This exception is thrown when there is an illegal value set in a `PropertySet`.
  IllegalVariantTypeException | This exception is thrown if HPSF encounters a variant type that is illegal in the current context.
  MarkUnsupportedException | This exception is thrown if an `InputStream` does not support the `InputStream.mark(int)` operation.
  MissingSectionException | This exception is thrown if one of the `PropertySet`'s convenience methods does not find a required `Section`.
  NoFormatIDException | This exception is thrown if a `PropertySet` is to be written but does not have a formatID set (see `Section.setFormatID(ClassID)` or `Section.setFormatID(byte[])`.
  NoPropertySetStreamException | This exception is thrown if a format error in a property set stream is detected or when the input data do not constitute a property set stream.
  NoSingleSectionException | This exception is thrown if one of the `PropertySet`'s convenience methods that require a single `Section` is called and the `PropertySet` does not contain exactly one `Section`.
  ReadingNotSupportedException | This exception is thrown when HPSF tries to read a (yet) unsupported variant type.
  UnexpectedPropertySetTypeException | This exception is thrown if a certain type of property set is expected (e.g.
  UnsupportedVariantTypeException | This exception is thrown if HPSF encounters a variant type that isn't supported yet.
  VariantTypeException | This exception is thrown if HPSF encounters a problem with a variant type.
  WritingNotSupportedException | This exception is thrown when trying to write a (yet) unsupported variant type.

## Package org.apache.poi.hpsf Description

Processes streams in the Horrible Property Set Format (HPSF) in POI filesystems. Microsoft Office documents, i.e. POI filesystems, usually contain meta data like author, title, last saving time etc. These items are called properties and stored in property set streams along with the document itself. These streams are commonly named `\005SummaryInformation` and `\005DocumentSummaryInformation`. However, a POI filesystem may contain further property sets of other names or types.

In order to extract the properties from a POI filesystem, a property set stream's contents must be parsed into a `PropertySet` instance. Its subclasses `SummaryInformation` and `DocumentSummaryInformation` deal with the well-known property set streams `\005SummaryInformation` and `\005DocumentSummaryInformation`. (However, the streams' names are irrelevant. What counts is the property set's first section's format ID - see below.)

The factory method `PropertySetFactory.create(org.apache.poi.poifs.filesystem.DirectoryEntry, java.lang.String)` creates a PropertySet instance. This method always returns the most specific property set: If it identifies the stream data as a Summary Information or as a Document Summary Information it returns an instance of the corresponding class, else the general PropertySet.

A PropertySet contains a list of `Sections` which can be retrieved with `PropertySet.getSections()`. Each Section contains a `Property` array which can be retrieved with `Section.getProperties()`. Since the vast majority of PropertySets contains only a single Section, the convenience method `PropertySet.getProperties()` returns the properties of a PropertySets Section (throwing a `NoSingleSectionException` if the PropertySet contains more (or less) than exactly one Section).

Each Property has an ID, a type, and a value which can be retrieved with `Property.getID()`, `Property.getType()`, and `Property.getValue()`, respectively. The value's class depends on the property's type. The current implementation does not yet support all property types and restricts the values' classes to String, Integer and Date. A value of a yet unknown type is returned as a byte array containing the values origin bytes from the property set stream.

To retrieve the value of a specific Property, use `Section.getProperty(long)` or `Section.getPropertyIntValue(long)`.

The SummaryInformation and DocumentSummaryInformation classes provide convenience methods for retrieving well-known properties. For example, an application that wants to retrieve a document's title string just calls `SummaryInformation.getTitle()` instead of going through the hassle of first finding out what the title's property ID is and then using this ID to get the property's value.

See Also:
  [MS-OLEPS] Object Linking and Embedding (OLE) Property Set Data Structures

Copyright 2020 The Apache Software Foundation or its licensors, as applicable.