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SQLInputImpl (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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javax.sql.rowset.serial
Class SQLInputImpl

java.lang.Object
  extended by javax.sql.rowset.serial.SQLInputImpl
All Implemented Interfaces:
SQLInput
public class SQLInputImpl
extends Object
implements SQLInput

An input stream used for custom mapping user-defined types (UDTs). An SQLInputImpl object is an input stream that contains a stream of values that are the attributes of a UDT.

This class is used by the driver behind the scenes when the method getObject is called on an SQL structured or distinct type that has a custom mapping; a programmer never invokes SQLInputImpl methods directly. They are provided here as a convenience for those who write RowSet implementations.

The SQLInputImpl class provides a set of reader methods analogous to the ResultSet getter methods. These methods make it possible to read the values in an SQLInputImpl object.

The method wasNull is used to determine whether the the last value read was SQL NULL.

When the method getObject is called with an object of a class implementing the interface SQLData, the JDBC driver calls the method SQLData.getSQLType to determine the SQL type of the UDT being custom mapped. The driver creates an instance of SQLInputImpl, populating it with the attributes of the UDT. The driver then passes the input stream to the method SQLData.readSQL, which in turn calls the SQLInputImpl reader methods to read the attributes from the input stream.

See Also:
SQLData

Constructor Summary
SQLInputImpl(Object[] attributes, Map<String,Class<?>> map)
          Creates an SQLInputImpl object initialized with the given array of attributes and the given type map.
 
Method Summary
 Array readArray()
          Reads an SQL ARRAY value from the stream and returns it as an Array object in the Java programming language.
 InputStream readAsciiStream()
          Returns the next attribute in this SQLInputImpl object as a stream of ASCII characters.
 BigDecimal readBigDecimal()
          Retrieves the next attribute in this SQLInputImpl object as a java.math.BigDecimal.
 InputStream readBinaryStream()
          Returns the next attribute in this SQLInputImpl object as a stream of uninterpreted bytes.
 Blob readBlob()
          Retrieves the BLOB value at the head of this SQLInputImpl object as a Blob object in the Java programming language.
 boolean readBoolean()
          Retrieves the next attribute in this SQLInputImpl object as a boolean in the Java programming language.
 byte readByte()
          Retrieves the next attribute in this SQLInputImpl object as a byte in the Java programming language.
 byte[] readBytes()
          Retrieves the next attribute in this SQLInputImpl object as an array of bytes.
 Reader readCharacterStream()
          Retrieves the next attribute in this SQLInputImpl object as a stream of Unicode characters.
 Clob readClob()
          Retrieves the CLOB value at the head of this SQLInputImpl object as a Clob object in the Java programming language.
 Date readDate()
          Retrieves the next attribute in this SQLInputImpl as a java.sql.Date object.
 double readDouble()
          Retrieves the next attribute in this SQLInputImpl object as a double in the Java programming language.
 float readFloat()
          Retrieves the next attribute in this SQLInputImpl object as a float in the Java programming language.
 int readInt()
          Retrieves the next attribute in this SQLInputImpl object as an int in the Java programming language.
 long readLong()
          Retrieves the next attribute in this SQLInputImpl object as a long in the Java programming language.
 NClob readNClob()
          Reads an SQL NCLOB value from the stream and returns it as a Clob object in the Java programming language.
 String readNString()
          Reads the next attribute in the stream and returns it as a String in the Java programming language.
 Object readObject()
          Retrieves the value at the head of this SQLInputImpl object as an Object in the Java programming language.
 Ref readRef()
          Retrieves the value at the head of this SQLInputImpl object as a Ref object in the Java programming language.
 RowId readRowId()
          Reads an SQL ROWID value from the stream and returns it as a RowId object in the Java programming language.
 short readShort()
          Retrieves the next attribute in this SQLInputImpl object as a short in the Java programming language.
 SQLXML readSQLXML()
          Reads an SQL XML value from the stream and returns it as a SQLXML object in the Java programming language.
 String readString()
          Retrieves the next attribute in this SQLInputImpl object as a String in the Java programming language.
 Time readTime()
          Retrieves the next attribute in this SQLInputImpl object as a java.sql.Time object.
 Timestamp readTimestamp()
          Retrieves the next attribute in this SQLInputImpl object as a java.sql.Timestamp object.
 URL readURL()
          Reads an SQL DATALINK value from the stream and returns it as an URL object in the Java programming language.
 boolean wasNull()
          Ascertains whether the last value read from this SQLInputImpl object was null.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

SQLInputImpl

public SQLInputImpl(Object[] attributes,
                    Map<String,Class<?>> map)
             throws SQLException
Creates an SQLInputImpl object initialized with the given array of attributes and the given type map. If any of the attributes is a UDT whose name is in an entry in the type map, the attribute will be mapped according to the corresponding SQLData implementation.

Parameters:
attributes - an array of Object instances in which each element is an attribute of a UDT. The order of the attributes in the array is the same order in which the attributes were defined in the UDT definition.
map - a java.util.Map object containing zero or more entries, with each entry consisting of 1) a String giving the fully qualified name of the UDT and 2) the Class object for the SQLData implementation that defines how the UDT is to be mapped
Throws:
SQLException - if the attributes or the map is a null value
Method Detail

readString

public String readString()
                  throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a String in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readString in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no further values in the stream.

readBoolean

public boolean readBoolean()
                    throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a boolean in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readBoolean in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no further values in the stream.

readByte

public byte readByte()
              throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a byte in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readByte in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no further values in the stream

readShort

public short readShort()
                throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a short in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readShort in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no more values in the stream

readInt

public int readInt()
            throws SQLException
Retrieves the next attribute in this SQLInputImpl object as an int in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readInt in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no more values in the stream

readLong

public long readLong()
              throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a long in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readLong in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no more values in the stream

readFloat

public float readFloat()
                throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a float in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readFloat in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no more values in the stream

readDouble

public double readDouble()
                  throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a double in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readDouble in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no more values in the stream

readBigDecimal

public BigDecimal readBigDecimal()
                          throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a java.math.BigDecimal.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readBigDecimal in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no more values in the stream

readBytes

public byte[] readBytes()
                 throws SQLException
Retrieves the next attribute in this SQLInputImpl object as an array of bytes.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readBytes in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no more values in the stream

readDate

public Date readDate()
              throws SQLException
Retrieves the next attribute in this SQLInputImpl as a java.sql.Date object.

This method does not perform type-safe checking to determine if the returned type is the expected type; this responsibility is delegated to the UDT mapping as defined by a SQLData implementation.

Specified by:
readDate in interface SQLInput
Returns:
the next attribute in this SQLInputImpl object; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position or if there are no more values in the stream

readTime

public Time readTime()
              throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a java.sql.Time object.

This method does not perform type-safe checking to determine if the returned type is the expected type as this responsibility is delegated to the UDT mapping as implemented by a SQLData implementation.

Specified by:
readTime in interface SQLInput
Returns:
the attribute; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readTimestamp

public Timestamp readTimestamp()
                        throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a java.sql.Timestamp object.

Specified by:
readTimestamp in interface SQLInput
Returns:
the attribute; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readCharacterStream

public Reader readCharacterStream()
                           throws SQLException
Retrieves the next attribute in this SQLInputImpl object as a stream of Unicode characters.

This method does not perform type-safe checking to determine if the returned type is the expected type as this responsibility is delegated to the UDT mapping as implemented by a SQLData implementation.

Specified by:
readCharacterStream in interface SQLInput
Returns:
the attribute; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readAsciiStream

public InputStream readAsciiStream()
                            throws SQLException
Returns the next attribute in this SQLInputImpl object as a stream of ASCII characters.

This method does not perform type-safe checking to determine if the returned type is the expected type as this responsibility is delegated to the UDT mapping as implemented by a SQLData implementation.

Specified by:
readAsciiStream in interface SQLInput
Returns:
the attribute; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readBinaryStream

public InputStream readBinaryStream()
                             throws SQLException
Returns the next attribute in this SQLInputImpl object as a stream of uninterpreted bytes.

This method does not perform type-safe checking to determine if the returned type is the expected type as this responsibility is delegated to the UDT mapping as implemented by a SQLData implementation.

Specified by:
readBinaryStream in interface SQLInput
Returns:
the attribute; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readObject

public Object readObject()
                  throws SQLException
Retrieves the value at the head of this SQLInputImpl object as an Object in the Java programming language. The actual type of the object returned is determined by the default mapping of SQL types to types in the Java programming language unless there is a custom mapping, in which case the type of the object returned is determined by this stream's type map.

The JDBC technology-enabled driver registers a type map with the stream before passing the stream to the application.

When the datum at the head of the stream is an SQL NULL, this method returns null. If the datum is an SQL structured or distinct type with a custom mapping, this method determines the SQL type of the datum at the head of the stream, constructs an object of the appropriate class, and calls the method SQLData.readSQL on that object. The readSQL method then calls the appropriate SQLInputImpl.readXXX methods to retrieve the attribute values from the stream.

Specified by:
readObject in interface SQLInput
Returns:
the value at the head of the stream as an Object in the Java programming language; null if the value is SQL NULL
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readRef

public Ref readRef()
            throws SQLException
Retrieves the value at the head of this SQLInputImpl object as a Ref object in the Java programming language.

Specified by:
readRef in interface SQLInput
Returns:
a Ref object representing the SQL REF value at the head of the stream; if the value is SQL NULL return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readBlob

public Blob readBlob()
              throws SQLException
Retrieves the BLOB value at the head of this SQLInputImpl object as a Blob object in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type as this responsibility is delegated to the UDT mapping as implemented by a SQLData implementation.

Specified by:
readBlob in interface SQLInput
Returns:
a Blob object representing the SQL BLOB value at the head of this stream; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readClob

public Clob readClob()
              throws SQLException
Retrieves the CLOB value at the head of this SQLInputImpl object as a Clob object in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type as this responsibility is delegated to the UDT mapping as implemented by a SQLData implementation.

Specified by:
readClob in interface SQLInput
Returns:
a Clob object representing the SQL CLOB value at the head of the stream; if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readArray

public Array readArray()
                throws SQLException
Reads an SQL ARRAY value from the stream and returns it as an Array object in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type as this responsibility is delegated to the UDT mapping as implemented by a SQLData implementation.

Specified by:
readArray in interface SQLInput
Returns:
an Array object representing the SQL ARRAY value at the head of the stream; * if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

wasNull

public boolean wasNull()
                throws SQLException
Ascertains whether the last value read from this SQLInputImpl object was null.

Specified by:
wasNull in interface SQLInput
Returns:
true if the SQL value read most recently was null; otherwise, false; by default it will return false
Throws:
SQLException - if an error occurs determining the last value read was a null value or not;

readURL

public URL readURL()
            throws SQLException
Reads an SQL DATALINK value from the stream and returns it as an URL object in the Java programming language.

This method does not perform type-safe checking to determine if the returned type is the expected type as this responsibility is delegated to the UDT mapping as implemented by a SQLData implementation.

Specified by:
readURL in interface SQLInput
Returns:
an URL object representing the SQL DATALINK value at the head of the stream; * if the value is SQL NULL, return null
Throws:
SQLException - if the read position is located at an invalid position; or if there are no further values in the stream.

readNClob

public NClob readNClob()
                throws SQLException
Reads an SQL NCLOB value from the stream and returns it as a Clob object in the Java programming language.

Specified by:
readNClob in interface SQLInput
Returns:
a NClob object representing data of the SQL NCLOB value at the head of the stream; null if the value read is SQL NULL
Throws:
SQLException - if a database access error occurs

readNString

public String readNString()
                   throws SQLException
Reads the next attribute in the stream and returns it as a String in the Java programming language. It is intended for use when accessing NCHAR,NVARCHAR and LONGNVARCHAR columns.

Specified by:
readNString in interface SQLInput
Returns:
the attribute; if the value is SQL NULL, returns null
Throws:
SQLException - if a database access error occurs

readSQLXML

public SQLXML readSQLXML()
                  throws SQLException
Reads an SQL XML value from the stream and returns it as a SQLXML object in the Java programming language.

Specified by:
readSQLXML in interface SQLInput
Returns:
a SQLXML object representing data of the SQL XML value at the head of the stream; null if the value read is SQL NULL
Throws:
SQLException - if a database access error occurs

readRowId

public RowId readRowId()
                throws SQLException
Reads an SQL ROWID value from the stream and returns it as a RowId object in the Java programming language.

Specified by:
readRowId in interface SQLInput
Returns:
a RowId object representing data of the SQL ROWID value at the head of the stream; null if the value read is SQL NULL
Throws:
SQLException - if a database access error occurs
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For further API reference and developer documentation, see Java SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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