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org.apache.derby.iapi.types
Class XML

java.lang.Object
  org.apache.derby.iapi.types.DataType
      org.apache.derby.iapi.types.XML

All Implemented Interfaces:: CloneableObject, DataValueDescriptor, java.io.Externalizable, org.apache.derby.iapi.services.io.Formatable, Orderable, java.io.Serializable, org.apache.derby.iapi.services.io.Storable, org.apache.derby.iapi.services.io.StreamStorable, org.apache.derby.iapi.services.io.TypedFormat, XMLDataValue

public class XML
extends DataType
implements XMLDataValue, org.apache.derby.iapi.services.io.StreamStorable

This type implements the XMLDataValue interface and thus is the type on which all XML related operations are executed. The first and simplest XML store implementation is a UTF-8 based one--all XML data is stored on disk as a UTF-8 string, just like the other Derby string types. In order to make it possible for smarter XML implementations to exist in the future, this class always writes an "XML implementation id" to disk before writing the rest of its data. When reading the data, the impl id is read first and serves as an indicator of how the rest of the data should be read. So long as there's only one implementation (UTF-8) the impl id can be ignored; but when smarter implementations are written, the impl id will be the key to figuring out how an XML value should be read, written, and processed.

Nested Class Summary

private class XML.ExistsHandler


private class XML.XMLErrorHandler


Field Summary

private static int BASE_MEMORY_USAGE


private static java.lang.String QUERY_MATCH_STRING


protected org.xml.sax.XMLReader saxReader


private org.apache.xalan.processor.TransformerFactoryImpl saxTFactory


protected static short UTF8_IMPL_ID


protected static java.lang.String XML_PARSER_CLASS


private SQLChar xmlStringValue


private static java.lang.String XPATH_PLACEHOLDER


private org.xml.sax.XMLReader xsltReader


private static java.lang.String xsltStylesheet


Fields inherited from interface org.apache.derby.iapi.types.Orderable

ORDER_OP_EQUALS, ORDER_OP_GREATEROREQUALS, ORDER_OP_GREATERTHAN, ORDER_OP_LESSOREQUALS, ORDER_OP_LESSTHAN

Constructor Summary

XML()
          Default constructor.

private XML(SQLChar val)
          Private constructor used for the getClone() method.

Method Summary

int compare(DataValueDescriptor other)
          Compare two XML DataValueDescriptors.

int estimateMemoryUsage()
          Estimate the memory usage in bytes of the data value and the overhead of the class.

boolean exists(java.lang.String xExpr)
          Helper method for XMLExists.

DataValueDescriptor getClone()
          Clone this DataValueDescriptor.

int getLength()
          Gets the length of the data value.

DataValueDescriptor getNewNull()
          Get a new null value of the same type as this data value.

java.lang.String getString()
          Gets the value in the data value descriptor as a String.

int getTypeFormatId()
          Get a universally unique identifier for the type of this object.

java.lang.String getTypeName()
          Get the SQL name of the datatype

boolean isNull()
          Return whether the value is null or not.

protected void loadSAXReader()
          Load an XMLReader for SAX events that can be used for parsing XML data.

void loadStream()
          sets the stream state for the object.

private void loadXSLTObjects()
          Prepare for an XSLT query by loading the objects required for such a query.

void parseAndLoadXML(java.lang.String text, boolean preserveWS)
          Method to parse an XML string and, if it's valid, store the _parsed_ version for subsequent use.

void readExternal(java.io.ObjectInput in)
          Read an XML value from an input stream.

void readExternalFromArray(org.apache.derby.iapi.services.io.ArrayInputStream in)
          Read the DataValueDescriptor from the stream.

private java.lang.String replaceDoubleQuotes(java.lang.String queryText)
          Takes a string (which is an XPath query specified by the user) and replaces any double quotes with single quotes.

void restoreToNull()
          Restore this object to its (SQL)null value.

java.io.InputStream returnStream()
          Return the stream state of the object.

protected void setFrom(DataValueDescriptor theValue)


void setStream(java.io.InputStream newStream)
          sets the stream state for the object.

void setValueFromResultSet(java.sql.ResultSet resultSet, int colNumber, boolean isNullable)
          Set the value based on the value for the specified DataValueDescriptor from the specified ResultSet.

int typePrecedence()
          Each built-in type in JSQL has a precedence.

void writeExternal(java.io.ObjectOutput out)
          Write an XML value.

BooleanDataValue XMLExists(StringDataValue xExpr, XMLDataValue xml)
          The SQL/XML XMLExists operator.

StringDataValue XMLSerialize(StringDataValue result, int targetType, int targetWidth)
          The SQL/XML XMLSerialize operator.

Methods inherited from class org.apache.derby.iapi.types.DataType

checkHostVariable, cloneObject, coalesce, compare, dataTypeConversion, equals, equals, flip, genericSetObject, getBoolean, getByte, getBytes, getDate, getDouble, getFloat, getInt, getLong, getNationalString, getObject, getShort, getStream, getTime, getTimestamp, greaterOrEquals, greaterThan, in, invalidFormat, isNotNull, isNullOp, lessOrEquals, lessThan, normalize, notEquals, outOfRange, setBigDecimal, setInto, setInto, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, throwLangSetMismatch, throwLangSetMismatch, typeToBigDecimal

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.derby.iapi.types.DataValueDescriptor

checkHostVariable, coalesce, compare, equals, getBoolean, getByte, getBytes, getDate, getDouble, getFloat, getInt, getLong, getObject, getShort, getStream, getTime, getTimestamp, greaterOrEquals, greaterThan, in, isNotNull, isNullOp, lessOrEquals, lessThan, normalize, notEquals, setBigDecimal, setInto, setInto, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, typeToBigDecimal

Field Detail

UTF8_IMPL_ID

protected static final short UTF8_IMPL_ID

See Also:: Constant Field Values

XML_PARSER_CLASS

protected static final java.lang.String XML_PARSER_CLASS

See Also:: Constant Field Values

BASE_MEMORY_USAGE

private static final int BASE_MEMORY_USAGE

xmlStringValue

private SQLChar xmlStringValue

saxReader

protected org.xml.sax.XMLReader saxReader

XPATH_PLACEHOLDER

private static final java.lang.String XPATH_PLACEHOLDER

See Also:: Constant Field Values

QUERY_MATCH_STRING

private static final java.lang.String QUERY_MATCH_STRING

See Also:: Constant Field Values

xsltStylesheet

private static java.lang.String xsltStylesheet

xsltReader

private org.xml.sax.XMLReader xsltReader

saxTFactory

private org.apache.xalan.processor.TransformerFactoryImpl saxTFactory

Constructor Detail

XML

public XML()

Default constructor.

XML

private XML(SQLChar val)

Private constructor used for the getClone() method. Takes a SQLChar and clones it.

Method Detail

getClone

public DataValueDescriptor getClone()

Description copied from interface: DataValueDescriptor

Clone this DataValueDescriptor. Results in a new object that has the same value as this but can be modified independently.

Specified by:: getClone in interface DataValueDescriptor

getNewNull

public DataValueDescriptor getNewNull()

Description copied from interface: DataValueDescriptor

Get a new null value of the same type as this data value.

Specified by:: getNewNull in interface DataValueDescriptor

getTypeName

public java.lang.String getTypeName()

Description copied from interface: DataValueDescriptor

Get the SQL name of the datatype

Specified by:: getTypeName in interface DataValueDescriptor

typePrecedence

public int typePrecedence()

Description copied from interface: DataValueDescriptor

Each built-in type in JSQL has a precedence. This precedence determines how to do type promotion when using binary operators. For example, float has a higher precedence than int, so when adding an int to a float, the result type is float. The precedence for some types is arbitrary. For example, it doesn't matter what the precedence of the boolean type is, since it can't be mixed with other types. But the precedence for the number types is critical. The SQL standard requires that exact numeric types be promoted to approximate numeric when one operator uses both. Also, the precedence is arranged so that one will not lose precision when promoting a type.

Specified by:: typePrecedence in interface DataValueDescriptor
Overrides:: typePrecedence in class DataType

getString

public java.lang.String getString()
                           throws org.apache.derby.iapi.error.StandardException

Description copied from interface: DataValueDescriptor

Gets the value in the data value descriptor as a String. Throws an exception if the data value is not a string.

Specified by:: getString in interface DataValueDescriptor

getLength

public int getLength()
              throws org.apache.derby.iapi.error.StandardException

Description copied from interface: DataValueDescriptor

Gets the length of the data value. The meaning of this is implementation-dependent. For string types, it is the number of characters in the string. For numeric types, it is the number of bytes used to store the number. This is the actual length of this value, not the length of the type it was defined as. For example, a VARCHAR value may be shorter than the declared VARCHAR (maximum) length.

Specified by:: getLength in interface DataValueDescriptor

estimateMemoryUsage

public int estimateMemoryUsage()

Description copied from interface: DataValueDescriptor

Estimate the memory usage in bytes of the data value and the overhead of the class.

Specified by:: estimateMemoryUsage in interface DataValueDescriptor

readExternalFromArray

public void readExternalFromArray(org.apache.derby.iapi.services.io.ArrayInputStream in)
                           throws java.io.IOException

Description copied from interface: DataValueDescriptor

Read the DataValueDescriptor from the stream.

Initialize the data value by reading it's values from the ArrayInputStream. This interface is provided as a way to achieve possible performance enhancement when reading an array can be optimized over reading from a generic stream from readExternal().

Specified by:: readExternalFromArray in interface DataValueDescriptor

setFrom

protected void setFrom(DataValueDescriptor theValue)
                throws org.apache.derby.iapi.error.StandardException

Overrides:: setFrom in class DataType

setValueFromResultSet

public final void setValueFromResultSet(java.sql.ResultSet resultSet,
                                        int colNumber,
                                        boolean isNullable)
                                 throws java.sql.SQLException

Description copied from interface: DataValueDescriptor

Set the value based on the value for the specified DataValueDescriptor from the specified ResultSet.

Specified by:: setValueFromResultSet in interface DataValueDescriptor

compare

public int compare(DataValueDescriptor other)
            throws org.apache.derby.iapi.error.StandardException

Compare two XML DataValueDescriptors. NOTE: This method should only be used by the database store for the purpose of index positioning--comparisons of XML type are not allowed from the language side of things. That said, all store wants to do is order the NULLs, so we don't actually have to do a full comparison. Just return an order value based on whether or not this XML value and the other XML value are null. As mentioned in the "compare" method of DataValueDescriptor, nulls are considered equal to other nulls and less than all other values. An example of when this method might be used is if the user executed a query like: select i from x_table where x_col is not null

Specified by:: compare in interface DataValueDescriptor

getTypeFormatId

public int getTypeFormatId()

Description copied from interface: org.apache.derby.iapi.services.io.TypedFormat

Get a universally unique identifier for the type of this object.

Specified by:: getTypeFormatId in interface org.apache.derby.iapi.services.io.TypedFormat

isNull

public boolean isNull()

Description copied from interface: org.apache.derby.iapi.services.io.Storable

Return whether the value is null or not.

Specified by:: isNull in interface org.apache.derby.iapi.services.io.Storable

restoreToNull

public void restoreToNull()

Description copied from interface: org.apache.derby.iapi.services.io.Storable

Restore this object to its (SQL)null value.

Specified by:: restoreToNull in interface org.apache.derby.iapi.services.io.Storable

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException

Read an XML value from an input stream.

Specified by:: readExternal in interface java.io.Externalizable

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Write an XML value.

Specified by:: writeExternal in interface java.io.Externalizable

returnStream

public java.io.InputStream returnStream()

Description copied from interface: org.apache.derby.iapi.services.io.StreamStorable

Return the stream state of the object.

Specified by:: returnStream in interface org.apache.derby.iapi.services.io.StreamStorable

setStream

public void setStream(java.io.InputStream newStream)

Description copied from interface: org.apache.derby.iapi.services.io.StreamStorable

sets the stream state for the object.

Specified by:: setStream in interface org.apache.derby.iapi.services.io.StreamStorable

loadStream

public void loadStream()
                throws org.apache.derby.iapi.error.StandardException

Description copied from interface: org.apache.derby.iapi.services.io.StreamStorable

sets the stream state for the object.

Specified by:: loadStream in interface org.apache.derby.iapi.services.io.StreamStorable

parseAndLoadXML

public void parseAndLoadXML(java.lang.String text,
                            boolean preserveWS)
                     throws org.apache.derby.iapi.error.StandardException

Method to parse an XML string and, if it's valid, store the _parsed_ version for subsequent use.

Specified by:: parseAndLoadXML in interface XMLDataValue

XMLSerialize

public StringDataValue XMLSerialize(StringDataValue result,
                                    int targetType,
                                    int targetWidth)
                             throws org.apache.derby.iapi.error.StandardException

The SQL/XML XMLSerialize operator. Converts this XML value into a string with a user-specified type, and returns that string via the received StringDataValue (if the received StringDataValue is non-null; else a new StringDataValue is returned).

Specified by:: XMLSerialize in interface XMLDataValue

XMLExists

public BooleanDataValue XMLExists(StringDataValue xExpr,
                                  XMLDataValue xml)
                           throws org.apache.derby.iapi.error.StandardException

The SQL/XML XMLExists operator. Takes an XML query expression (as a string) and an XML value and checks if at least one node in the XML value matches the query expression. NOTE: For now, the query expression must be XPath only (XQuery not supported).

Specified by:: XMLExists in interface XMLDataValue

exists

public boolean exists(java.lang.String xExpr)
               throws org.apache.derby.iapi.error.StandardException

Helper method for XMLExists. See if the received XPath expression returns at least one node when evaluated against _this_ XML value.

Specified by:: exists in interface XMLDataValue

loadSAXReader

protected void loadSAXReader()
                      throws java.lang.Exception

Load an XMLReader for SAX events that can be used for parsing XML data. This method is currently only used for XMLPARSE, and the SQL/XML[2003] spec says that XMLPARSE should NOT perform validation -- Seciont 6.11: "Perform a non-validating parse of a character string to produce an XML value." Thus, we make sure to disable validation on the XMLReader loaded here. At some point in the future we will probably want to add support for the XMLVALIDATE function--but until then, user is unable to validate the XML values s/he inserts. Note that, even with validation turned off, XMLPARSE _will_ still check the well-formedness of the values, and it _will_ still process DTDs to get default values, etc--but that's it; no validation errors will be thrown. For future reference: the features needed to perform validation (with Xerces) are: http://apache.org/xml/features/validation/schema http://apache.org/xml/features/validation/dynamic

loadXSLTObjects

private void loadXSLTObjects()
                      throws org.xml.sax.SAXException

Prepare for an XSLT query by loading the objects required for such a query. We should only have to do this once per XML object.

replaceDoubleQuotes

private java.lang.String replaceDoubleQuotes(java.lang.String queryText)

Takes a string (which is an XPath query specified by the user) and replaces any double quotes with single quotes. We have to do this because a double quote in the XSLT stylesheet (which is where the user's query ends up) will be parsed as a query terminator thus will cause XSLT execution errors.

Overview

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Class

Use

Deprecated

Index

Home >> All >> org >> apache >> derby >> iapi >> [ types overview ]

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Nested Class Summary
`private class`	`XML.ExistsHandler`
`private class`	`XML.XMLErrorHandler`

Field Summary
`private static int`	`BASE_MEMORY_USAGE`
`private static java.lang.String`	`QUERY_MATCH_STRING`
`protected org.xml.sax.XMLReader`	`saxReader`
`private org.apache.xalan.processor.TransformerFactoryImpl`	`saxTFactory`
`protected static short`	`UTF8_IMPL_ID`
`protected static java.lang.String`	`XML_PARSER_CLASS`
`private SQLChar`	`xmlStringValue`
`private static java.lang.String`	`XPATH_PLACEHOLDER`
`private org.xml.sax.XMLReader`	`xsltReader`
`private static java.lang.String`	`xsltStylesheet`

Constructor Summary
	`XML()` Default constructor.
`private`	`XML(SQLChar val)` Private constructor used for the getClone() method.

Method Summary
`int`	`compare(DataValueDescriptor other)` Compare two XML DataValueDescriptors.
`int`	`estimateMemoryUsage()` Estimate the memory usage in bytes of the data value and the overhead of the class.
`boolean`	`exists(java.lang.String xExpr)` Helper method for XMLExists.
`DataValueDescriptor`	`getClone()` Clone this DataValueDescriptor.
`int`	`getLength()` Gets the length of the data value.
`DataValueDescriptor`	`getNewNull()` Get a new null value of the same type as this data value.
`java.lang.String`	`getString()` Gets the value in the data value descriptor as a String.
`int`	`getTypeFormatId()` Get a universally unique identifier for the type of this object.
`java.lang.String`	`getTypeName()` Get the SQL name of the datatype
`boolean`	`isNull()` Return whether the value is null or not.
`protected void`	`loadSAXReader()` Load an XMLReader for SAX events that can be used for parsing XML data.
`void`	`loadStream()` sets the stream state for the object.
`private void`	`loadXSLTObjects()` Prepare for an XSLT query by loading the objects required for such a query.
`void`	`parseAndLoadXML(java.lang.String text, boolean preserveWS)` Method to parse an XML string and, if it's valid, store the _parsed_ version for subsequent use.
`void`	`readExternal(java.io.ObjectInput in)` Read an XML value from an input stream.
`void`	`readExternalFromArray(org.apache.derby.iapi.services.io.ArrayInputStream in)` Read the DataValueDescriptor from the stream.
`private java.lang.String`	`replaceDoubleQuotes(java.lang.String queryText)` Takes a string (which is an XPath query specified by the user) and replaces any double quotes with single quotes.
`void`	`restoreToNull()` Restore this object to its (SQL)null value.
`java.io.InputStream`	`returnStream()` Return the stream state of the object.
`protected void`	`setFrom(DataValueDescriptor theValue)`
`void`	`setStream(java.io.InputStream newStream)` sets the stream state for the object.
`void`	`setValueFromResultSet(java.sql.ResultSet resultSet, int colNumber, boolean isNullable)` Set the value based on the value for the specified DataValueDescriptor from the specified ResultSet.
`int`	`typePrecedence()` Each built-in type in JSQL has a precedence.
`void`	`writeExternal(java.io.ObjectOutput out)` Write an XML value.
`BooleanDataValue`	`XMLExists(StringDataValue xExpr, XMLDataValue xml)` The SQL/XML XMLExists operator.
`StringDataValue`	`XMLSerialize(StringDataValue result, int targetType, int targetWidth)` The SQL/XML XMLSerialize operator.

org.apache.derby.iapi.types Class XML

UTF8_IMPL_ID

XML_PARSER_CLASS

BASE_MEMORY_USAGE

xmlStringValue

saxReader

XPATH_PLACEHOLDER

QUERY_MATCH_STRING

xsltStylesheet

xsltReader

saxTFactory

XML

XML

getClone

getNewNull

getTypeName

typePrecedence

getString

getLength

estimateMemoryUsage

readExternalFromArray

setFrom

setValueFromResultSet

compare

getTypeFormatId

isNull

restoreToNull

readExternal

writeExternal

returnStream

setStream

loadStream

parseAndLoadXML

XMLSerialize

XMLExists

exists

loadSAXReader

loadXSLTObjects

replaceDoubleQuotes

org.apache.derby.iapi.types
Class XML