public class DataFlavor extends Object implements Externalizable, Cloneable
A DataFlavor
provides meta information about data. DataFlavor
is typically used to access data on the clipboard, or during a drag and drop operation.
An instance of DataFlavor
encapsulates a content type as defined in RFC 2045 and RFC 2046. A content type is typically referred to as a MIME type.
A content type consists of a media type (referred to as the primary type), a subtype, and optional parameters. See RFC 2045 for details on the syntax of a MIME type.
The JRE data transfer implementation interprets the parameter "class" of a MIME type as a representation class. The representation class reflects the class of the object being transferred. In other words, the representation class is the type of object returned by Transferable.getTransferData(java.awt.datatransfer.DataFlavor)
. For example, the MIME type of imageFlavor
is "image/x-java-image;class=java.awt.Image"
, the primary type is image
, the subtype is x-java-image
, and the representation class is java.awt.Image
. When getTransferData
is invoked with a DataFlavor
of imageFlavor
, an instance of java.awt.Image
is returned. It's important to note that DataFlavor
does no error checking against the representation class. It is up to consumers of DataFlavor
, such as Transferable
, to honor the representation class.
Note, if you do not specify a representation class when creating a DataFlavor
, the default representation class is used. See appropriate documentation for DataFlavor
's constructors.
Also, DataFlavor
instances with the "text" primary MIME type may have a "charset" parameter. Refer to RFC 2046 and selectBestTextFlavor(java.awt.datatransfer.DataFlavor[])
for details on "text" MIME types and the "charset" parameter.
Equality of DataFlavors
is determined by the primary type, subtype, and representation class. Refer to equals(DataFlavor)
for details. When determining equality, any optional parameters are ignored. For example, the following produces two DataFlavors
that are considered identical:
DataFlavor flavor1 = new DataFlavor(Object.class, "X-test/test; class=<java.lang.Object>; foo=bar"); DataFlavor flavor2 = new DataFlavor(Object.class, "X-test/test; class=<java.lang.Object>; x=y"); // The following returns true. flavor1.equals(flavor2);As mentioned,
flavor1
and flavor2
are considered identical. As such, asking a Transferable
for either DataFlavor
returns the same results. For more information on the using data transfer with Swing see the How to Use Drag and Drop and Data Transfer, section in Java Tutorial.
public static final DataFlavor stringFlavor
The DataFlavor
representing a Java Unicode String class, where:
representationClass = java.lang.String mimeType = "application/x-java-serialized-object"
public static final DataFlavor imageFlavor
The DataFlavor
representing a Java Image class, where:
representationClass = java.awt.Image mimeType = "image/x-java-image"
@Deprecated public static final DataFlavor plainTextFlavor
Deprecated. as of 1.3. Use DataFlavor.getReaderForText(Transferable)
instead of Transferable.getTransferData(DataFlavor.plainTextFlavor)
.
The DataFlavor
representing plain text with Unicode encoding, where:
representationClass = InputStream mimeType = "text/plain; charset=unicode"This
DataFlavor
has been deprecated because (1) Its representation is an InputStream, an 8-bit based representation, while Unicode is a 16-bit character set; and (2) The charset "unicode" is not well-defined. "unicode" implies a particular platform's implementation of Unicode, not a cross-platform implementation. public static final String javaSerializedObjectMimeType
A MIME Content-Type of application/x-java-serialized-object represents a graph of Java object(s) that have been made persistent. The representation class associated with this DataFlavor
identifies the Java type of an object returned as a reference from an invocation java.awt.datatransfer.getTransferData
.
public static final DataFlavor javaFileListFlavor
To transfer a list of files to/from Java (and the underlying platform) a DataFlavor
of this type/subtype and representation class of java.util.List
is used. Each element of the list is required/guaranteed to be of type java.io.File
.
public static final String javaJVMLocalObjectMimeType
To transfer a reference to an arbitrary Java object reference that has no associated MIME Content-type, across a Transferable
interface WITHIN THE SAME JVM, a DataFlavor
with this type/subtype is used, with a representationClass
equal to the type of the class/interface being passed across the Transferable
.
The object reference returned from Transferable.getTransferData
for a DataFlavor
with this MIME Content-Type is required to be an instance of the representation Class of the DataFlavor
.
public static final String javaRemoteObjectMimeType
In order to pass a live link to a Remote object via a Drag and Drop ACTION_LINK
operation a Mime Content Type of application/x-java-remote-object should be used, where the representation class of the DataFlavor
represents the type of the Remote
interface to be transferred.
public static DataFlavor selectionHtmlFlavor
Represents a piece of an HTML markup. The markup consists of the part selected on the source side. Therefore some tags in the markup may be unpaired. If the flavor is used to represent the data in a Transferable
instance, no additional changes will be made. This DataFlavor instance represents the same HTML markup as DataFlavor instances which content MIME type does not contain document parameter and representation class is the String class.
representationClass = String mimeType = "text/html"
public static DataFlavor fragmentHtmlFlavor
Represents a piece of an HTML markup. If possible, the markup received from a native system is supplemented with pair tags to be a well-formed HTML markup. If the flavor is used to represent the data in a Transferable
instance, no additional changes will be made.
representationClass = String mimeType = "text/html"
public static DataFlavor allHtmlFlavor
Represents a piece of an HTML markup. If possible, the markup received from a native system is supplemented with additional tags to make up a well-formed HTML document. If the flavor is used to represent the data in a Transferable
instance, no additional changes will be made.
representationClass = String mimeType = "text/html"
public DataFlavor()
Constructs a new DataFlavor
. This constructor is provided only for the purpose of supporting the Externalizable
interface. It is not intended for public (client) use.
public DataFlavor(Class<?> representationClass, String humanPresentableName)
Constructs a DataFlavor
that represents a Java class.
The returned DataFlavor
will have the following characteristics:
representationClass = representationClass mimeType = application/x-java-serialized-object
representationClass
- the class used to transfer data in this flavorhumanPresentableName
- the human-readable string used to identify this flavor; if this parameter is null
then the value of the the MIME Content Type is usedNullPointerException
- if representationClass
is nullpublic DataFlavor(String mimeType, String humanPresentableName)
Constructs a DataFlavor
that represents a MimeType
.
The returned DataFlavor
will have the following characteristics:
If the mimeType
is "application/x-java-serialized-object; class=<representation class>", the result is the same as calling new DataFlavor(Class:forName(<representation class>)
.
Otherwise:
representationClass = InputStream mimeType = mimeType
mimeType
- the string used to identify the MIME type for this flavor; if the the mimeType
does not specify a "class=" parameter, or if the class is not successfully loaded, then an IllegalArgumentException
is thrownhumanPresentableName
- the human-readable string used to identify this flavor; if this parameter is null
then the value of the the MIME Content Type is usedIllegalArgumentException
- if mimeType
is invalid or if the class is not successfully loadedNullPointerException
- if mimeType
is nullpublic DataFlavor(String mimeType, String humanPresentableName, ClassLoader classLoader) throws ClassNotFoundException
Constructs a DataFlavor
that represents a MimeType
.
The returned DataFlavor
will have the following characteristics:
If the mimeType is "application/x-java-serialized-object; class=<representation class>", the result is the same as calling new DataFlavor(Class:forName(<representation class>)
.
Otherwise:
representationClass = InputStream mimeType = mimeType
mimeType
- the string used to identify the MIME type for this flavorhumanPresentableName
- the human-readable string used to identify this flavorclassLoader
- the class loader to useClassNotFoundException
- if the class is not loadedIllegalArgumentException
- if mimeType
is invalidNullPointerException
- if mimeType
is nullpublic DataFlavor(String mimeType) throws ClassNotFoundException
Constructs a DataFlavor
from a mimeType
string. The string can specify a "class=<fully specified Java class name>" parameter to create a DataFlavor
with the desired representation class. If the string does not contain "class=" parameter, java.io.InputStream
is used as default.
mimeType
- the string used to identify the MIME type for this flavor; if the class specified by "class=" parameter is not successfully loaded, then an ClassNotFoundException
is thrownClassNotFoundException
- if the class is not loadedIllegalArgumentException
- if mimeType
is invalidNullPointerException
- if mimeType
is nullprotected static final Class<?> tryToLoadClass(String className, ClassLoader fallback) throws ClassNotFoundException
Tries to load a class from: the bootstrap loader, the system loader, the context loader (if one is present) and finally the loader specified.
className
- the name of the class to be loadedfallback
- the fallback loaderClassNotFoundException
- if class is not foundpublic String toString()
String representation of this DataFlavor
and its parameters. The resulting String
contains the name of the DataFlavor
class, this flavor's MIME type, and its representation class. If this flavor has a primary MIME type of "text", supports the charset parameter, and has an encoded representation, the flavor's charset is also included. See selectBestTextFlavor
for a list of text flavors which support the charset parameter.
toString
in class Object
DataFlavor
selectBestTextFlavor(java.awt.datatransfer.DataFlavor[])
public static final DataFlavor getTextPlainUnicodeFlavor()
Returns a DataFlavor
representing plain text with Unicode encoding, where:
representationClass = java.io.InputStream mimeType = "text/plain; charset=<platform default Unicode encoding>"Sun's implementation for Microsoft Windows uses the encoding
utf-16le
. Sun's implementation for Solaris and Linux uses the encoding iso-10646-ucs-2
. DataFlavor
representing plain text with Unicode encodingpublic static final DataFlavor selectBestTextFlavor(DataFlavor[] availableFlavors)
Selects the best text DataFlavor
from an array of
DataFlavor
s. Only DataFlavor.stringFlavor
, and equivalent flavors, and flavors that have a primary MIME type of "text", are considered for selection.
Flavors are first sorted by their MIME types in the following order:
For example, "text/sgml" will be selected over "text/html", and DataFlavor.stringFlavor
will be chosen over DataFlavor.plainTextFlavor
.
If two or more flavors share the best MIME type in the array, then that MIME type will be checked to see if it supports the charset parameter.
The following MIME types support, or are treated as though they support, the charset parameter:
DataFlavor
which uses that MIME type. If so, the JRE will assume from that point on that the MIME type supports the charset parameter and will not check again. If the parameter is not explicitly listed, the JRE will assume from that point on that the MIME type does not support the charset parameter and will not check again. Because this check is performed on an arbitrarily chosen DataFlavor
, developers must ensure that all DataFlavor
s with a "text/<other>" MIME type specify the charset parameter if it is supported by that MIME type. Developers should never rely on the JRE to substitute the platform's default charset for a "text/<other>" DataFlavor. Failure to adhere to this restriction will lead to undefined behavior. If the best MIME type in the array does not support the charset parameter, the flavors which share that MIME type will then be sorted by their representation classes in the following order: java.io.InputStream
, java.nio.ByteBuffer
, [B
, <all others>.
If two or more flavors share the best representation class, or if no flavor has one of the three specified representations, then one of those flavors will be chosen non-deterministically.
If the best MIME type in the array does support the charset parameter, the flavors which share that MIME type will then be sorted by their representation classes in the following order: java.io.Reader
, java.lang.String
, java.nio.CharBuffer
, [C
, <all others>.
If two or more flavors share the best representation class, and that representation is one of the four explicitly listed, then one of those flavors will be chosen non-deterministically. If, however, no flavor has one of the four specified representations, the flavors will then be sorted by their charsets. Unicode charsets, such as "UTF-16", "UTF-8", "UTF-16BE", "UTF-16LE", and their aliases, are considered best. After them, the platform default charset and its aliases are selected. "US-ASCII" and its aliases are worst. All other charsets are chosen in alphabetical order, but only charsets supported by this implementation of the Java platform will be considered.
If two or more flavors share the best charset, the flavors will then again be sorted by their representation classes in the following order: java.io.InputStream
, java.nio.ByteBuffer
, [B
, <all others>.
If two or more flavors share the best representation class, or if no flavor has one of the three specified representations, then one of those flavors will be chosen non-deterministically.
availableFlavors
- an array of available DataFlavor
snull
, if availableFlavors
is null
, has zero length, or contains no text flavorspublic Reader getReaderForText(Transferable transferable) throws UnsupportedFlavorException, IOException
Gets a Reader for a text flavor, decoded, if necessary, for the expected charset (encoding). The supported representation classes are java.io.Reader
, java.lang.String
, java.nio.CharBuffer
, [C
, java.io.InputStream
, java.nio.ByteBuffer
, and [B
.
Because text flavors which do not support the charset parameter are encoded in a non-standard format, this method should not be called for such flavors. However, in order to maintain backward-compatibility, if this method is called for such a flavor, this method will treat the flavor as though it supports the charset parameter and attempt to decode it accordingly. See selectBestTextFlavor
for a list of text flavors which do not support the charset parameter.
transferable
- the Transferable
whose data will be requested in this flavorReader
to read the Transferable
's dataIllegalArgumentException
- if the representation class is not one of the seven listed aboveIllegalArgumentException
- if the Transferable
has null
dataNullPointerException
- if the Transferable
is null
UnsupportedEncodingException
- if this flavor's representation is java.io.InputStream
, java.nio.ByteBuffer
, or [B
and this flavor's encoding is not supported by this implementation of the Java platformUnsupportedFlavorException
- if the Transferable
does not support this flavorIOException
- if the data cannot be read because of an I/O errorselectBestTextFlavor(java.awt.datatransfer.DataFlavor[])
public String getMimeType()
Returns the MIME type string for this DataFlavor
.
public Class<?> getRepresentationClass()
Returns the Class
which objects supporting this DataFlavor
will return when this DataFlavor
is requested.
Class
which objects supporting this DataFlavor
will return when this DataFlavor
is requestedpublic String getHumanPresentableName()
Returns the human presentable name for the data format that this DataFlavor
represents. This name would be localized for different countries.
DataFlavor
representspublic String getPrimaryType()
Returns the primary MIME type for this DataFlavor
.
DataFlavor
public String getSubType()
Returns the sub MIME type of this DataFlavor
.
DataFlavor
public String getParameter(String paramName)
Returns the human presentable name for this DataFlavor
if paramName
equals "humanPresentableName". Otherwise returns the MIME type value associated with paramName
.
paramName
- the parameter name requestednull
if there is no associated valuepublic void setHumanPresentableName(String humanPresentableName)
Sets the human presentable name for the data format that this DataFlavor
represents. This name would be localized for different countries.
humanPresentableName
- the new human presentable namepublic boolean equals(Object o)
Indicates whether some other object is "equal to" this one.
The equals
method implements an equivalence relation on non-null object references:
x
, x.equals(x)
should return true
. x
and y
, x.equals(y)
should return true
if and only if y.equals(x)
returns true
. x
, y
, and z
, if x.equals(y)
returns true
and y.equals(z)
returns true
, then x.equals(z)
should return true
. x
and y
, multiple invocations of x.equals(y)
consistently return true
or consistently return false
, provided no information used in equals
comparisons on the objects is modified. x
, x.equals(null)
should return false
. The equals
method for class Object
implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x
and y
, this method returns true
if and only if x
and y
refer to the same object (x == y
has the value true
).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden, so as to maintain the general contract for the hashCode
method, which states that equal objects must have equal hash codes.
The equals comparison for the DataFlavor
class is implemented as follows: Two DataFlavor
s are considered equal if and only if their MIME primary type and subtype and representation class are equal. Additionally, if the primary type is "text", the subtype denotes a text flavor which supports the charset parameter, and the representation class is not java.io.Reader
, java.lang.String
, java.nio.CharBuffer
, or [C
, the charset
parameter must also be equal. If a charset is not explicitly specified for one or both DataFlavor
s, the platform default encoding is assumed. See selectBestTextFlavor
for a list of text flavors which support the charset parameter.
equals
in class Object
o
- the Object
to compare with this
true
if that
is equivalent to this DataFlavor
; false
otherwiseselectBestTextFlavor(java.awt.datatransfer.DataFlavor[])
public boolean equals(DataFlavor that)
This method has the same behavior as equals(Object)
. The only difference being that it takes a DataFlavor
instance as a parameter.
that
- the DataFlavor
to compare with this
true
if that
is equivalent to this DataFlavor
; false
otherwiseselectBestTextFlavor(java.awt.datatransfer.DataFlavor[])
@Deprecated public boolean equals(String s)
Deprecated. As inconsistent with hashCode()
contract, use isMimeTypeEqual(String)
instead.
Compares only the mimeType
against the passed in String
and representationClass
is not considered in the comparison. If representationClass
needs to be compared, then equals(new DataFlavor(s))
may be used.
s
- the mimeType
to compare.s
is null
public int hashCode()
Returns hash code for this DataFlavor
. For two equal DataFlavor
s, hash codes are equal. For the String
that matches DataFlavor.equals(String)
, it is not guaranteed that DataFlavor
's hash code is equal to the hash code of the String
.
hashCode
in class Object
DataFlavor
Object.equals(java.lang.Object)
, System.identityHashCode(java.lang.Object)
public boolean match(DataFlavor that)
Identical to equals(DataFlavor)
.
that
- the DataFlavor
to compare with this
true
if that
is equivalent to this DataFlavor
; false
otherwiseselectBestTextFlavor(java.awt.datatransfer.DataFlavor[])
public boolean isMimeTypeEqual(String mimeType)
Returns whether the string representation of the MIME type passed in is equivalent to the MIME type of this DataFlavor
. Parameters are not included in the comparison.
mimeType
- the string representation of the MIME typeDataFlavor
; false otherwiseNullPointerException
- if mimeType is null
public final boolean isMimeTypeEqual(DataFlavor dataFlavor)
Compares the mimeType
of two DataFlavor
objects. No parameters are considered.
dataFlavor
- the DataFlavor
to be comparedMimeType
s are equal, otherwise falsepublic boolean isMimeTypeSerializedObject()
Does the DataFlavor
represent a serialized object?
public final Class<?> getDefaultRepresentationClass()
public final String getDefaultRepresentationClassAsString()
public boolean isRepresentationClassInputStream()
Does the DataFlavor
represent a java.io.InputStream
?
public boolean isRepresentationClassReader()
Returns whether the representation class for this DataFlavor
is java.io.Reader
or a subclass thereof.
public boolean isRepresentationClassCharBuffer()
Returns whether the representation class for this DataFlavor
is java.nio.CharBuffer
or a subclass thereof.
public boolean isRepresentationClassByteBuffer()
Returns whether the representation class for this DataFlavor
is java.nio.ByteBuffer
or a subclass thereof.
public boolean isRepresentationClassSerializable()
Returns true if the representation class can be serialized.
public boolean isRepresentationClassRemote()
Returns true if the representation class is Remote
.
Remote
public boolean isFlavorSerializedObjectType()
Returns true if the DataFlavor
specified represents a serialized object.
DataFlavor
specified represents a Serialized Objectpublic boolean isFlavorRemoteObjectType()
Returns true if the DataFlavor
specified represents a remote object.
DataFlavor
specified represents a Remote Objectpublic boolean isFlavorJavaFileListType()
Returns true if the DataFlavor
specified represents a list of file objects.
DataFlavor
specified represents a List of File objectspublic boolean isFlavorTextType()
Returns whether this DataFlavor
is a valid text flavor for this implementation of the Java platform. Only flavors equivalent to DataFlavor.stringFlavor
and DataFlavor
s with a primary MIME type of "text" can be valid text flavors.
If this flavor supports the charset parameter, it must be equivalent to DataFlavor.stringFlavor
, or its representation must be java.io.Reader
, java.lang.String
, java.nio.CharBuffer
, [C
, java.io.InputStream
, java.nio.ByteBuffer
, or [B
. If the representation is java.io.InputStream
, java.nio.ByteBuffer
, or [B
, then this flavor's charset
parameter must be supported by this implementation of the Java platform. If a charset is not specified, then the platform default charset, which is always supported, is assumed.
If this flavor does not support the charset parameter, its representation must be java.io.InputStream
, java.nio.ByteBuffer
, or [B
.
See selectBestTextFlavor
for a list of text flavors which support the charset parameter.
true
if this DataFlavor
is a valid text flavor as described above; false
otherwiseselectBestTextFlavor(java.awt.datatransfer.DataFlavor[])
public void writeExternal(ObjectOutput os) throws IOException
Serializes this DataFlavor
.
writeExternal
in interface Externalizable
os
- the stream to write the object toIOException
- Includes any I/O exceptions that may occurpublic void readExternal(ObjectInput is) throws IOException, ClassNotFoundException
Restores this DataFlavor
from a Serialized state.
readExternal
in interface Externalizable
is
- the stream to read data from in order to restore the objectIOException
- if I/O errors occurClassNotFoundException
- If the class for an object being restored cannot be found.public Object clone() throws CloneNotSupportedException
Returns a clone of this DataFlavor
.
clone
in class Object
DataFlavor
CloneNotSupportedException
- if the object's class does not support the Cloneable
interface. Subclasses that override the clone
method can also throw this exception to indicate that an instance cannot be cloned.Cloneable
@Deprecated protected String normalizeMimeTypeParameter(String parameterName, String parameterValue)
Deprecated.
Called on DataFlavor
for every MIME Type parameter to allow DataFlavor
subclasses to handle special parameters like the text/plain charset
parameters, whose values are case insensitive. (MIME type parameter values are supposed to be case sensitive.
This method is called for each parameter name/value pair and should return the normalized representation of the parameterValue
. This method is never invoked by this implementation from 1.1 onwards.
@Deprecated protected String normalizeMimeType(String mimeType)
Deprecated.
Called for each MIME type string to give DataFlavor
subtypes the opportunity to change how the normalization of MIME types is accomplished. One possible use would be to add default parameter/value pairs in cases where none are present in the MIME type string passed in. This method is never invoked by this implementation from 1.1 onwards.
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Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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