org.htmlparser
Class Attribute

java.lang.Object
  org.htmlparser.Attribute

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

PageAttribute

public class Attribute
extends Object
implements Serializable

An attribute within a tag. Holds the name, assignment string, value and quote character.

This class was made deliberately simple. Except for RawValue, the properties are completely orthogonal, that is: each property is independant of the others. This means you have enough rope here to hang yourself, and it's very easy to create malformed HTML. Where it's obvious, warnings and notes have been provided in the setters javadocs, but it is up to you -- the programmer -- to ensure that the contents of the four fields will yield valid HTML (if that's what you want).

Be especially mindful of quotes and assignment strings. These are handled by the constructors where it's obvious, but in general, you need to set them explicitly when building an attribute. For example to construct the attribute label="A multi word value." you could use:

     attribute = new Attribute ();
     attribute.setName ("label");
     attribute.setAssignment ("=");
     attribute.setValue ("A multi word value.");
     attribute.setQuote ('"');
 

or

     attribute = new Attribute ();
     attribute.setName ("label");
     attribute.setAssignment ("=");
     attribute.setRawValue ("A multi word value.");
 

or

     attribute = new Attribute ("label", "A multi word value.");
 

Note that the assignment value and quoting need to be set separately when building the attribute from scratch using the properties.

Valid States for Attributes.

Description	toString()	Name	Assignment	Value	Quote
whitespace attribute	value	null	null	"value"	0
standalone attribute	name	"name"	null	null	0
empty attribute	name=	"name"	"="	null	0
empty single quoted attribute	name=''	"name"	"="	null	'
empty double quoted attribute	name=""	"name"	"="	null	"
naked attribute	name=value	"name"	"="	"value"	0
single quoted attribute	name='value'	"name"	"="	"value"	'
double quoted attribute	name="value"	"name"	"="	"value"	"

In words:
If Name is null, and Assignment is null, and Quote is zero, it's whitepace and Value has the whitespace text -- value
If Name is not null, and both Assignment and Value are null it's a standalone attribute -- name
If Name is not null, and Assignment is an equals sign, and Quote is zero it's an empty attribute -- name=
If Name is not null, and Assignment is an equals sign, and Value is "" or null, and Quote is ' it's an empty single quoted attribute -- name=''
If Name is not null, and Assignment is an equals sign, and Value is "" or null, and Quote is " it's an empty double quoted attribute -- name=""
If Name is not null, and Assignment is an equals sign, and Value is something, and Quote is zero it's a naked attribute -- name=value
If Name is not null, and Assignment is an equals sign, and Value is something, and Quote is ' it's a single quoted attribute -- name='value'
If Name is not null, and Assignment is an equals sign, and Value is something, and Quote is " it's a double quoted attribute -- name="value"
All other states are invalid HTML.

From the HTML 4.01 Specification, W3C Recommendation 24 December 1999 http://www.w3.org/TR/html4/intro/sgmltut.html#h-3.2.2:

3.2.2 Attributes

Elements may have associated properties, called attributes, which may have values (by default, or set by authors or scripts). Attribute/value pairs appear before the final ">" of an element's start tag. Any number of (legal) attribute value pairs, separated by spaces, may appear in an element's start tag. They may appear in any order.

In this example, the id attribute is set for an H1 element:

 
 <H1 id="section1">

  This is an identified heading thanks to the id attribute

  </H1>
 
 

By default, SGML requires that all attribute values be delimited using either double quotation marks (ASCII decimal 34) or single quotation marks (ASCII decimal 39). Single quote marks can be included within the attribute value when the value is delimited by double quote marks, and vice versa. Authors may also use numeric character references to represent double quotes (") and single quotes ('). For doublequotes authors can also use the character entity reference ".

In certain cases, authors may specify the value of an attribute without any quotation marks. The attribute value may only contain letters (a-z and A-Z), digits (0-9), hyphens (ASCII decimal 45), periods (ASCII decimal 46), underscores (ASCII decimal 95), and colons (ASCII decimal 58). We recommend using quotation marks even when it is possible to eliminate them.

Attribute names are always case-insensitive.

Attribute values are generally case-insensitive. The definition of each attribute in the reference manual indicates whether its value is case-insensitive.

All the attributes defined by this specification are listed in the attribute index.

See Also:

Serialized Form

Field Summary

protected String	mAssignment The assignment string of the attribute.
protected String	mName The name of this attribute.
protected char	mQuote The quote, if any, surrounding the value of the attribute, if any.
protected String	mValue The value of the attribute.

Constructor Summary

Attribute()
Create an empty attribute.

Attribute(String value)
Create a whitespace attribute with the value given.

Attribute(String name, String value)
Create an attribute with the name and value given.

Attribute(String name, String value, char quote)
Create an attribute with the name, value and quote given.

Attribute(String name, String assignment, String value)
Create an attribute with the name, assignment string and value given.

Attribute(String name, String assignment, String value, char quote)
Create an attribute with the name, assignment, value and quote given.

Method Summary

String	getAssignment() Get the assignment string of this attribute.
void	getAssignment(StringBuffer buffer) Get the assignment string of this attribute.
int	getLength() Get the length of the string value of this attribute.
String	getName() Get the name of this attribute.
void	getName(StringBuffer buffer) Get the name of this attribute.
char	getQuote() Get the quote, if any, surrounding the value of the attribute, if any.
void	getQuote(StringBuffer buffer) Get the quote, if any, surrounding the value of the attribute, if any.
String	getRawValue() Get the raw value of the attribute.
void	getRawValue(StringBuffer buffer) Get the raw value of the attribute.
String	getValue() Get the value of the attribute.
void	getValue(StringBuffer buffer) Get the value of the attribute.
boolean	isEmpty() Predicate to determine if this attribute has an equals sign but no value.
boolean	isStandAlone() Predicate to determine if this attribute has no equals sign (or value).
boolean	isValued() Predicate to determine if this attribute has a value.
boolean	isWhitespace() Predicate to determine if this attribute is whitespace.
void	setAssignment(String assignment) Set the assignment string of this attribute.
void	setName(String name) Set the name of this attribute.
void	setQuote(char quote) Set the quote surrounding the value of the attribute.
void	setRawValue(String value) Set the value of the attribute and the quote character.
void	setValue(String value) Set the value of the attribute.
String	toString() Get a text representation of this attribute.
void	toString(StringBuffer buffer) Get a text representation of this attribute.

Methods inherited from class java.lang.Object

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

Field Detail

mName

protected String mName

The name of this attribute. The part before the equals sign, or the stand-alone attribute. This will be null if the attribute is whitespace.

mAssignment

protected String mAssignment

The assignment string of the attribute. The equals sign. This will be null if the attribute is a stand-alone attribute.

mValue

protected String mValue

The value of the attribute. The part after the equals sign. This will be null if the attribute is an empty or stand-alone attribute.

mQuote

protected char mQuote

The quote, if any, surrounding the value of the attribute, if any. This will be zero if there are no quotes around the value.

Constructor Detail

Attribute

public Attribute(String name,
                 String assignment,
                 String value,
                 char quote)

Create an attribute with the name, assignment, value and quote given. If the quote value is zero, assigns the value using setRawValue(java.lang.String) which sets the quote character to a proper value if necessary.

Parameters:

name - The name of this attribute.

assignment - The assignment string of this attribute.

value - The value of this attribute.

quote - The quote around the value of this attribute.

Attribute

public Attribute(String name,
                 String value,
                 char quote)

Create an attribute with the name, value and quote given. Uses an equals sign as the assignment string if the value is not null, and calls setRawValue(java.lang.String) to get the correct quoting if quote is zero.

Parameters:

name - The name of this attribute.

value - The value of this attribute.

quote - The quote around the value of this attribute.

Attribute

public Attribute(String value)
          throws IllegalArgumentException

Create a whitespace attribute with the value given.

Parameters:

value - The value of this attribute.

Throws:

IllegalArgumentException - if the value contains other than whitespace. To set a real value use Attribute(String,String).

Attribute

public Attribute(String name,
                 String value)

Create an attribute with the name and value given. Uses an equals sign as the assignment string if the value is not null, and calls setRawValue(java.lang.String) to get the correct quoting.

Parameters:

name - The name of this attribute.

value - The value of this attribute.

Attribute

public Attribute(String name,
                 String assignment,
                 String value)

Create an attribute with the name, assignment string and value given. Calls setRawValue(java.lang.String) to get the correct quoting.

Parameters:

name - The name of this attribute.

assignment - The assignment string of this attribute.

value - The value of this attribute.

Attribute

public Attribute()

Create an empty attribute. This will provide "" from the toString() and toString(StringBuffer) methods.

Method Detail

getName

public String getName()

Get the name of this attribute. The part before the equals sign, or the contents of the stand-alone attribute.

Returns:

The name, or null if it's just a whitepace 'attribute'.

See Also:

setName(java.lang.String)

getName

public void getName(StringBuffer buffer)

Get the name of this attribute.

Parameters:

buffer - The buffer to place the name in.

See Also:

getName(), setName(java.lang.String)

setName

public void setName(String name)

Set the name of this attribute. Set the part before the equals sign, or the contents of the stand-alone attribute. WARNING: Setting this to null can result in malformed HTML if the assignment string is not null.

Parameters:

name - The new name.

See Also:

getName(), getName(StringBuffer)

getAssignment

public String getAssignment()

Get the assignment string of this attribute. This is usually just an equals sign, but in poorly formed attributes it can include whitespace on either or both sides of an equals sign.

Returns:

The assignment string.

See Also:

setAssignment(java.lang.String)

getAssignment

public void getAssignment(StringBuffer buffer)

Get the assignment string of this attribute.

Parameters:

buffer - The buffer to place the assignment string in.

See Also:

getAssignment(), setAssignment(java.lang.String)

setAssignment

public void setAssignment(String assignment)

Set the assignment string of this attribute. WARNING: Setting this property to other than an equals sign or null will result in malformed HTML. In the case of a null, the value should also be set to null.

Parameters:

assignment - The new assignment string.

See Also:

getAssignment(), getAssignment(StringBuffer)

getValue

public String getValue()

Get the value of the attribute. The part after the equals sign, or the text if it's just a whitepace 'attribute'. NOTE: This does not include any quotes that may have enclosed the value when it was read. To get the un-stripped value use getRawValue().

Returns:

The value, or null if it's a stand-alone or empty attribute, or the text if it's just a whitepace 'attribute'.

See Also:

setValue(java.lang.String)

getValue

public void getValue(StringBuffer buffer)

Get the value of the attribute.

Parameters:

buffer - The buffer to place the value in.

See Also:

getValue(), setValue(java.lang.String)

setValue

public void setValue(String value)

Set the value of the attribute. The part after the equals sign, or the text if it's a whitepace 'attribute'. WARNING: Setting this property to a value that needs to be quoted without also setting the quote character will result in malformed HTML.

Parameters:

value - The new value.

See Also:

getValue(), getValue(StringBuffer)

getQuote

public char getQuote()

Get the quote, if any, surrounding the value of the attribute, if any.

Returns:

Either ' or " if the attribute value was quoted, or zero if there are no quotes around it.

See Also:

setQuote(char)

getQuote

public void getQuote(StringBuffer buffer)

Get the quote, if any, surrounding the value of the attribute, if any.

Parameters:

buffer - The buffer to place the quote in.

See Also:

getQuote(), setQuote(char)

setQuote

public void setQuote(char quote)

Set the quote surrounding the value of the attribute. WARNING: Setting this property to zero will result in malformed HTML if the value needs to be quoted (i.e. contains whitespace).

Parameters:

quote - The new quote value.

See Also:

getQuote(), getQuote(StringBuffer)

getRawValue

public String getRawValue()

Get the raw value of the attribute. The part after the equals sign, or the text if it's just a whitepace 'attribute'. This includes the quotes around the value if any.

Returns:

The value, or null if it's a stand-alone attribute, or the text if it's just a whitepace 'attribute'.

See Also:

setRawValue(java.lang.String)

getRawValue

public void getRawValue(StringBuffer buffer)

Get the raw value of the attribute. The part after the equals sign, or the text if it's just a whitepace 'attribute'. This includes the quotes around the value if any.

Parameters:

buffer - The string buffer to append the attribute value to.

See Also:

getRawValue(), setRawValue(java.lang.String)

setRawValue

public void setRawValue(String value)

Set the value of the attribute and the quote character. If the value is pure whitespace, assign it 'as is' and reset the quote character. If not, check for leading and trailing double or single quotes, and if found use this as the quote character and the inner contents of value as the real value. Otherwise, examine the string to determine if quotes are needed and an appropriate quote character if so. This may involve changing double quotes within the string to character references.

Parameters:

value - The new value.

See Also:

getRawValue(), getRawValue(StringBuffer)

isWhitespace

public boolean isWhitespace()

Predicate to determine if this attribute is whitespace.

Returns:

true if this attribute is whitespace, false if it is a real attribute.

isStandAlone

public boolean isStandAlone()

Predicate to determine if this attribute has no equals sign (or value).

Returns:

true if this attribute is a standalone attribute. false if has an equals sign.

isEmpty

public boolean isEmpty()

Predicate to determine if this attribute has an equals sign but no value.

Returns:

true if this attribute is an empty attribute. false if has an equals sign and a value.

isValued

public boolean isValued()

Predicate to determine if this attribute has a value.

Returns:

true if this attribute has a value. false if it is empty or standalone.

getLength

public int getLength()

Get the length of the string value of this attribute.

Returns:

The number of characters required to express this attribute.

toString

public String toString()

Get a text representation of this attribute. Suitable for insertion into a tag, the output is one of the forms:

 value
 name
 name=
 name=value
 name='value'
 name="value"
 

Overrides:

toString in class Object

Returns:

A string that can be used within a tag.

toString

public void toString(StringBuffer buffer)

Get a text representation of this attribute.

Parameters:

buffer - The accumulator for placing the text into.

See Also:

toString()