# Class InputSource

java.lang.Object
org.xml.sax.InputSource

public class InputSource extends Object
A single input source for an XML entity.

This class allows a SAX application to encapsulate information about an input source in a single object, which may include a public identifier, a system identifier, a byte stream (possibly with a specified encoding), and/or a character stream.

There are two places that the application can deliver an input source to the parser: as the argument to the Parser.parse method, or as the return value of the EntityResolver.resolveEntity method.

The SAX parser will use the InputSource object to determine how to read XML input. If there is a character stream available, the parser will read that stream directly, disregarding any text encoding declaration found in that stream. If there is no character stream, but there is a byte stream, the parser will use that byte stream, using the encoding specified in the InputSource or else (if no encoding is specified) autodetecting the character encoding using an algorithm such as the one in the XML specification. If neither a character stream nor a byte stream is available, the parser will attempt to open a URI connection to the resource identified by the system identifier.

An InputSource object belongs to the application: the SAX parser shall never modify it in any way (it may modify a copy if necessary). However, standard processing of both byte and character streams is to close them on as part of end-of-parse cleanup, so applications should not attempt to re-use such streams after they have been handed to a parser.

Since:
  1.4, SAX 1.0
See Also:
  - `XMLReader.parse(org.xml.sax.InputSource)`
  - `EntityResolver.resolveEntity(String, String)`
  - `InputStream`
  - `Reader`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `InputSource()`
  Zero-argument default constructor.
  `InputSource(InputStream byteStream)`
  Create a new input source with a byte stream.
  `InputSource(Reader characterStream)`
  Create a new input source with a character stream.
  `InputSource(String systemId)`
  Create a new input source with a system identifier.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `InputStream`
  `getByteStream()`
  Get the byte stream for this input source.
  `Reader`
  `getCharacterStream()`
  Get the character stream for this input source.
  `String`
  `getEncoding()`
  Get the character encoding for a byte stream or URI.
  `String`
  `getPublicId()`
  Get the public identifier for this input source.
  `String`
  `getSystemId()`
  Get the system identifier for this input source.
  `boolean`
  `isEmpty()`
  Indicates whether the `InputSource` object is empty.
  `void`
  `setByteStream(InputStream byteStream)`
  Set the byte stream for this input source.
  `void`
  `setCharacterStream(Reader characterStream)`
  Set the character stream for this input source.
  `void`
  `setEncoding(String encoding)`
  Set the character encoding, if known.
  `void`
  `setPublicId(String publicId)`
  Set the public identifier for this input source.
  `void`
  `setSystemId(String systemId)`
  Set the system identifier for this input source.

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### InputSource

    public InputSource()
    Zero-argument default constructor.
    See Also:
      - `setPublicId(String)`
      - `setSystemId(String)`
      - `setByteStream(InputStream)`
      - `setCharacterStream(Reader)`
      - `setEncoding(String)`

  - ### InputSource

    public InputSource(String systemId)
    Create a new input source with a system identifier.

    Applications may use setPublicId to include a public identifier as well, or setEncoding to specify the character encoding, if known.

    If the system identifier is a URL, it must be fully resolved (it may not be a relative URL).

    Parameters:
      `systemId` - The system identifier (URI).
    See Also:
      - `setPublicId(String)`
      - `setSystemId(String)`
      - `setByteStream(InputStream)`
      - `setEncoding(String)`
      - `setCharacterStream(Reader)`

  - ### InputSource

    public InputSource(InputStream byteStream)
    Create a new input source with a byte stream.

    Application writers should use setSystemId() to provide a base for resolving relative URIs, may use setPublicId to include a public identifier, and may use setEncoding to specify the object's character encoding.

    Parameters:
      `byteStream` - The raw byte stream containing the document.
    See Also:
      - `setPublicId(String)`
      - `setSystemId(String)`
      - `setEncoding(String)`
      - `setByteStream(InputStream)`
      - `setCharacterStream(Reader)`

  - ### InputSource

    public InputSource(Reader characterStream)
    Create a new input source with a character stream.

    Application writers should use setSystemId() to provide a base for resolving relative URIs, and may use setPublicId to include a public identifier.

    The character stream shall not include a byte order mark.

    Parameters:
      `characterStream` - the character stream
    See Also:
      - `setPublicId(String)`
      - `setSystemId(String)`
      - `setByteStream(InputStream)`
      - `setCharacterStream(Reader)`

- ## Method Details

  - ### setPublicId

    public void setPublicId(String publicId)
    Set the public identifier for this input source.

    The public identifier is always optional: if the application writer includes one, it will be provided as part of the location information.

    Parameters:
      `publicId` - The public identifier as a string.
    See Also:
      - `getPublicId()`
      - `Locator.getPublicId()`
      - `SAXParseException.getPublicId()`

  - ### getPublicId

    public String getPublicId()
    Get the public identifier for this input source.
    Returns:
      The public identifier, or null if none was supplied.
    See Also:
      - `setPublicId(String)`

  - ### setSystemId

    public void setSystemId(String systemId)
    Set the system identifier for this input source.

    The system identifier is optional if there is a byte stream or a character stream, but it is still useful to provide one, since the application can use it to resolve relative URIs and can include it in error messages and warnings (the parser will attempt to open a connection to the URI only if there is no byte stream or character stream specified).

    If the application knows the character encoding of the object pointed to by the system identifier, it can register the encoding using the setEncoding method.

    If the system identifier is a URL, it must be fully resolved (it may not be a relative URL).

    Parameters:
      `systemId` - The system identifier as a string.
    See Also:
      - `setEncoding(String)`
      - `getSystemId()`
      - `Locator.getSystemId()`
      - `SAXParseException.getSystemId()`

  - ### getSystemId

    public String getSystemId()
    Get the system identifier for this input source.

    The getEncoding method will return the character encoding of the object pointed to, or null if unknown.

    If the system ID is a URL, it will be fully resolved.

    Returns:
      The system identifier, or null if none was supplied.
    See Also:
      - `setSystemId(String)`
      - `getEncoding()`

  - ### setByteStream

    public void setByteStream(InputStream byteStream)
    Set the byte stream for this input source.

    The SAX parser will ignore this if there is also a character stream specified, but it will use a byte stream in preference to opening a URI connection itself.

    If the application knows the character encoding of the byte stream, it should set it with the setEncoding method.

    Parameters:
      `byteStream` - A byte stream containing an XML document or other entity.
    See Also:
      - `setEncoding(String)`
      - `getByteStream()`
      - `getEncoding()`
      - `InputStream`

  - ### getByteStream

    public InputStream getByteStream()
    Get the byte stream for this input source.

    The getEncoding method will return the character encoding for this byte stream, or null if unknown.

    Returns:
      The byte stream, or null if none was supplied.
    See Also:
      - `getEncoding()`
      - `setByteStream(InputStream)`

  - ### setEncoding

    public void setEncoding(String encoding)
    Set the character encoding, if known.

    The encoding must be a string acceptable for an XML encoding declaration (see section 4.3.3 of the XML 1.0 recommendation).

    This method has no effect when the application provides a character stream.

    Parameters:
      `encoding` - A string describing the character encoding.
    See Also:
      - `setSystemId(String)`
      - `setByteStream(InputStream)`
      - `getEncoding()`

  - ### getEncoding

    public String getEncoding()
    Get the character encoding for a byte stream or URI. This value will be ignored when the application provides a character stream.
    Returns:
      The encoding, or null if none was supplied.
    See Also:
      - `setByteStream(InputStream)`
      - `getSystemId()`
      - `getByteStream()`

  - ### setCharacterStream

    public void setCharacterStream(Reader characterStream)
    Set the character stream for this input source.

    If there is a character stream specified, the SAX parser will ignore any byte stream and will not attempt to open a URI connection to the system identifier.

    Parameters:
      `characterStream` - The character stream containing the XML document or other entity.
    See Also:
      - `getCharacterStream()`
      - `Reader`

  - ### getCharacterStream

    public Reader getCharacterStream()
    Get the character stream for this input source.
    Returns:
      The character stream, or null if none was supplied.
    See Also:
      - `setCharacterStream(Reader)`

  - ### isEmpty

    public boolean isEmpty()
    Indicates whether the `InputSource` object is empty. Empty is defined as follows:
    - All of the input sources, including the public identifier, system identifier, byte stream, and character stream, are `null`.
    - The public identifier and system identifier are `null`, and byte and character stream are either `null` or contain no byte or character.

      Note that this method will reset the byte stream if it is provided, or the character stream if the byte stream is not provided.

    In case of error while checking the byte or character stream, the method will return false to allow the XML processor to handle the error.

    Returns:
      true if the `InputSource` object is empty, false otherwise