## javax.mail
Interface Part

All Known Subinterfaces:
  MimePart

All Known Implementing Classes:
  BodyPart, Message, MessageHeaders, MimeBodyPart, MimeMessage, POP3Message, PreencodedMimeBodyPart, SMTPMessage

    public interface Part

The `Part` interface is the common base interface for Messages and BodyParts.

Part consists of a set of attributes and a "Content".

Attributes:

The JavaMail API defines a set of standard Part attributes that are considered to be common to most existing Mail systems. These attributes have their own settor and gettor methods. Mail systems may support other Part attributes as well, these are represented as name-value pairs where both the name and value are Strings.

Content:

The data type of the "content" is returned by the `getContentType()` method. The MIME typing system is used to name data types.

The "content" of a Part is available in various formats:

- As a DataHandler - using the `getDataHandler()` method. The "content" of a Part is also available through a `javax.activation.DataHandler` object. The DataHandler object allows clients to discover the operations available on the content, and to instantiate the appropriate component to perform those operations.
- As an input stream - using the `getInputStream()` method. Any mail-specific encodings are decoded before this stream is returned.
- As a Java object - using the `getContent()` method. This method returns the "content" as a Java object. The returned object is of course dependent on the content itself. In particular, a "multipart" Part's content is always a Multipart or subclass thereof. That is, `getContent()` on a "multipart" type Part will always return a Multipart (or subclass) object.

Part provides the `writeTo()` method that streams out its bytestream in mail-safe form suitable for transmission. This bytestream is typically an aggregation of the Part attributes and its content's bytestream.

Message and BodyPart implement the Part interface. Note that in MIME parlance, Part models an Entity (RFC 2045, Section 2.4).

Field Summary
`static java.lang.String` `ATTACHMENT` This part should be presented as an attachment.
`static java.lang.String` `INLINE` This part should be presented inline.

Method Summary
`void` `addHeader(java.lang.String header_name, java.lang.String header_value)` Add this value to the existing values for this header_name.
`java.util.Enumeration` `getAllHeaders()` Return all the headers from this part as an Enumeration of Header objects.
`java.lang.Object` `getContent()` Return the content as a Java object.
`java.lang.String` `getContentType()` Returns the Content-Type of the content of this part.
`javax.activation.DataHandler` `getDataHandler()` Return a DataHandler for the content within this part.
`java.lang.String` `getDescription()` Return a description String for this part.
`java.lang.String` `getDisposition()` Return the disposition of this part.
`java.lang.String` `getFileName()` Get the filename associated with this part, if possible.
`java.lang.String[]` `getHeader(java.lang.String header_name)` Get all the headers for this header name.
`java.io.InputStream` `getInputStream()` Return an input stream for this part's "content".
`int` `getLineCount()` Return the number of lines in the content of this part.
`java.util.Enumeration` `getMatchingHeaders(java.lang.String[] header_names)` Return matching headers from this part as an Enumeration of Header objects.
`java.util.Enumeration` `getNonMatchingHeaders(java.lang.String[] header_names)` Return non-matching headers from this envelope as an Enumeration of Header objects.
`int` `getSize()` Return the size of the content of this part in bytes.
`boolean` `isMimeType(java.lang.String mimeType)` Is this Part of the specified MIME type? This method compares only the `primaryType` and `subType`.
`void` `removeHeader(java.lang.String header_name)` Remove all headers with this name.
`void` `setContent(Multipart mp)` This method sets the given Multipart object as this message's content.
`void` `setContent(java.lang.Object obj, java.lang.String type)` A convenience method for setting this part's content.
`void` `setDataHandler(javax.activation.DataHandler dh)` This method provides the mechanism to set this part's content.
`void` `setDescription(java.lang.String description)` Set a description String for this part.
`void` `setDisposition(java.lang.String disposition)` Set the disposition of this part.
`void` `setFileName(java.lang.String filename)` Set the filename associated with this part, if possible.
`void` `setHeader(java.lang.String header_name, java.lang.String header_value)` Set the value for this header_name.
`void` `setText(java.lang.String text)` A convenience method that sets the given String as this part's content with a MIME type of "text/plain".
`void` `writeTo(java.io.OutputStream os)` Output a bytestream for this Part.

Field Detail

### ATTACHMENT

    static final java.lang.String ATTACHMENT

  This part should be presented as an attachment.

  See Also:
    `getDisposition()`, `setDisposition(java.lang.String)`, Constant Field Values

### INLINE

    static final java.lang.String INLINE

  This part should be presented inline.

  See Also:
    `getDisposition()`, `setDisposition(java.lang.String)`, Constant Field Values

Method Detail

### getSize

    int getSize()
                throws MessagingException

  Return the size of the content of this part in bytes. Return -1 if the size cannot be determined.

  Note that the size may not be an exact measure of the content size and may or may not account for any transfer encoding of the content. The size is appropriate for display in a user interface to give the user a rough idea of the size of this part.

  Returns:
    size of content in bytes
  Throws:
    `MessagingException`

### getLineCount

    int getLineCount()
                     throws MessagingException

  Return the number of lines in the content of this part. Return -1 if the number cannot be determined. Note that this number may not be an exact measure of the content length and may or may not account for any transfer encoding of the content.

  Returns:
    number of lines in the content.
  Throws:
    `MessagingException`

### getContentType

    java.lang.String getContentType()
                                    throws MessagingException

  Returns the Content-Type of the content of this part. Returns null if the Content-Type could not be determined.

  The MIME typing system is used to name Content-types.

  Returns:
    The ContentType of this part
  Throws:
    `MessagingException`
  See Also:
    `DataHandler`

### isMimeType

    boolean isMimeType(java.lang.String mimeType)
                       throws MessagingException

  Is this Part of the specified MIME type? This method compares only the `primaryType` and `subType`. The parameters of the content types are ignored.

  For example, this method will return `true` when comparing a Part of content type "text/plain" with "text/plain; charset=foobar".

  If the `subType` of `mimeType` is the special character '*', then the subtype is ignored during the comparison.

  Throws:
    `MessagingException`

### getDisposition

    java.lang.String getDisposition()
                                    throws MessagingException

  Return the disposition of this part. The disposition describes how the part should be presented to the user. (See RFC 2183.) The return value should be considered without regard to case. For example:

  >      String disp = part.getDisposition();
  >      if (disp == null || disp.equalsIgnoreCase(Part.ATTACHMENT))
  >             // treat as attachment if not first part

  Returns:
    disposition of this part, or null if unknown
  Throws:
    `MessagingException`
  See Also:
    `ATTACHMENT`, `INLINE`, `getFileName()`

### setDisposition

    void setDisposition(java.lang.String disposition)
                        throws MessagingException

  Set the disposition of this part.

  Parameters:
    `disposition` - disposition of this part
  Throws:
    `MessagingException`
    `IllegalWriteException` - if the underlying implementation does not support modification of this header
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder
  See Also:
    `ATTACHMENT`, `INLINE`, `setFileName(java.lang.String)`

### getDescription

    java.lang.String getDescription()
                                    throws MessagingException

  Return a description String for this part. This typically associates some descriptive information with this part. Returns null if none is available.

  Returns:
    description of this part
  Throws:
    `MessagingException`

### setDescription

    void setDescription(java.lang.String description)
                        throws MessagingException

  Set a description String for this part. This typically associates some descriptive information with this part.

  Parameters:
    `description` - description of this part
  Throws:
    `MessagingException`
    `IllegalWriteException` - if the underlying implementation does not support modification of this header
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder

### getFileName

    java.lang.String getFileName()
                                 throws MessagingException

  Get the filename associated with this part, if possible. Useful if this part represents an "attachment" that was loaded from a file. The filename will usually be a simple name, not including directory components.

  Returns:
    Filename to associate with this part
  Throws:
    `MessagingException`

### setFileName

    void setFileName(java.lang.String filename)
                     throws MessagingException

  Set the filename associated with this part, if possible. Useful if this part represents an "attachment" that was loaded from a file. The filename will usually be a simple name, not including directory components.

  Parameters:
    `filename` - Filename to associate with this part
  Throws:
    `IllegalWriteException` - if the underlying implementation does not support modification of this header
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder
    `MessagingException`

### getInputStream

    java.io.InputStream getInputStream()
                                       throws java.io.IOException,
                                              MessagingException

  Return an input stream for this part's "content". Any mail-specific transfer encodings will be decoded before the input stream is provided.

  This is typically a convenience method that just invokes the DataHandler's `getInputStream()` method.

  Returns:
    an InputStream
  Throws:
    `java.io.IOException` - this is typically thrown by the DataHandler. Refer to the documentation for javax.activation.DataHandler for more details.
    `MessagingException`
  See Also:
    `getDataHandler()`, `DataHandler.getInputStream()`

### getDataHandler

    javax.activation.DataHandler getDataHandler()
                                                throws MessagingException

  Return a DataHandler for the content within this part. The DataHandler allows clients to operate on as well as retrieve the content.

  Returns:
    DataHandler for the content
  Throws:
    `MessagingException`

### getContent

    java.lang.Object getContent()
                                throws java.io.IOException,
                                       MessagingException

  Return the content as a Java object. The type of the returned object is of course dependent on the content itself. For example, the object returned for "text/plain" content is usually a String object. The object returned for a "multipart" content is always a Multipart subclass. For content-types that are unknown to the DataHandler system, an input stream is returned as the content

  This is a convenience method that just invokes the DataHandler's getContent() method

  Returns:
    Object
  Throws:
    `MessagingException`
    `java.io.IOException` - this is typically thrown by the DataHandler. Refer to the documentation for javax.activation.DataHandler for more details.
  See Also:
    `DataHandler.getContent()`

### setDataHandler

    void setDataHandler(javax.activation.DataHandler dh)
                        throws MessagingException

  This method provides the mechanism to set this part's content. The DataHandler wraps around the actual content.

  Parameters:
    `dh` - The DataHandler for the content.
  Throws:
    `MessagingException`
    `IllegalWriteException` - if the underlying implementation does not support modification of existing values
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder

### setContent

    void setContent(java.lang.Object obj,
                    java.lang.String type)
                    throws MessagingException

  A convenience method for setting this part's content. The part internally wraps the content in a DataHandler.

  Note that a DataContentHandler class for the specified type should be available to the JavaMail implementation for this to work right. i.e., to do `setContent(foobar, "application/x-foobar")`, a DataContentHandler for "application/x-foobar" should be installed. Refer to the Java Activation Framework for more information.

  Parameters:
    `obj` - A java object.
    `type` - MIME type of this object.
  Throws:
    `IllegalWriteException` - if the underlying implementation does not support modification of existing values
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder
    `MessagingException`

### setText

    void setText(java.lang.String text)
                 throws MessagingException

  A convenience method that sets the given String as this part's content with a MIME type of "text/plain".

  Parameters:
    `text` - The text that is the Message's content.
  Throws:
    `IllegalWriteException` - if the underlying implementation does not support modification of existing values
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder
    `MessagingException`

### setContent

    void setContent(Multipart mp)
                    throws MessagingException

  This method sets the given Multipart object as this message's content.

  Parameters:
    `mp` - The multipart object that is the Message's content
  Throws:
    `IllegalWriteException` - if the underlying implementation does not support modification of existing values
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder
    `MessagingException`

### writeTo

    void writeTo(java.io.OutputStream os)
                 throws java.io.IOException,
                        MessagingException

  Output a bytestream for this Part. This bytestream is typically an aggregration of the Part attributes and an appropriately encoded bytestream from its 'content'.

  Classes that implement the Part interface decide on the appropriate encoding algorithm to be used.

  The bytestream is typically used for sending.

  Throws:
    `java.io.IOException` - if an error occurs writing to the stream or if an error is generated by the javax.activation layer.
    `MessagingException` - if an error occurs fetching the data to be written
  See Also:
    `DataHandler.writeTo(java.io.OutputStream)`

### getHeader

    java.lang.String[] getHeader(java.lang.String header_name)
                                 throws MessagingException

  Get all the headers for this header name. Returns `null` if no headers for this header name are available.

  Parameters:
    `header_name` - the name of this header
  Returns:
    the value fields for all headers with this name
  Throws:
    `MessagingException`

### setHeader

    void setHeader(java.lang.String header_name,
                   java.lang.String header_value)
                   throws MessagingException

  Set the value for this header_name. Replaces all existing header values with this new value.

  Parameters:
    `header_name` - the name of this header
    `header_value` - the value for this header
  Throws:
    `MessagingException`
    `IllegalWriteException` - if the underlying implementation does not support modification of existing values
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder

### addHeader

    void addHeader(java.lang.String header_name,
                   java.lang.String header_value)
                   throws MessagingException

  Add this value to the existing values for this header_name.

  Parameters:
    `header_name` - the name of this header
    `header_value` - the value for this header
  Throws:
    `MessagingException`
    `IllegalWriteException` - if the underlying implementation does not support modification of existing values
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder

### removeHeader

    void removeHeader(java.lang.String header_name)
                      throws MessagingException

  Remove all headers with this name.

  Parameters:
    `header_name` - the name of this header
  Throws:
    `MessagingException`
    `IllegalWriteException` - if the underlying implementation does not support modification of existing values
    `java.lang.IllegalStateException` - if this Part is obtained from a READ_ONLY folder

### getAllHeaders

    java.util.Enumeration getAllHeaders()
                                        throws MessagingException

  Return all the headers from this part as an Enumeration of Header objects.

  Returns:
    enumeration of Header objects
  Throws:
    `MessagingException`

### getMatchingHeaders

    java.util.Enumeration getMatchingHeaders(java.lang.String[] header_names)
                                             throws MessagingException

  Return matching headers from this part as an Enumeration of Header objects.

  Returns:
    enumeration of Header objects
  Throws:
    `MessagingException`

### getNonMatchingHeaders

    java.util.Enumeration getNonMatchingHeaders(java.lang.String[] header_names)
                                                throws MessagingException

  Return non-matching headers from this envelope as an Enumeration of Header objects.

  Returns:
    enumeration of Header objects
  Throws:
    `MessagingException`