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Java 2 Platform SE v1.3.1: Interface SQLInput - JDK 5 Documentation v1.3.1, Java 2 SDK 英文文档

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java.sql
Interface SQLInput

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public interface SQLInput

An input stream that contains a stream of values representing an instance of an SQL structured or distinct type. This interface, used only for custom mapping, is used by the driver behind the scenes, and a programmer never directly invokes SQLInput methods. The readXXX methods provide a way to read the values in an SQLInput 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 user-defined type (UDT) being custom mapped. The driver creates an instance of SQLInput, 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 SQLInput.readXXX methods in its implementation for reading the attributes from the input stream.

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

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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 the stream as a stream of ASCII characters.
BigDecimal	readBigDecimal()           Reads the next attribute in the stream as a java.math.BigDecimal object in the Java programming language.
InputStream	readBinaryStream()           Returns the next attribute in the stream as a stream of uninterpreted bytes.
Blob	readBlob()           Reads an SQL BLOB value from the stream and returns it as a Blob object in the Java programming language.
boolean	readBoolean()           Reads the next attribute in the stream as a boolean in the Java programming language.
byte	readByte()           Reads the next attribute in the stream as a byte in the Java programming language.
byte[]	readBytes()           Reads the next attribute in the stream as an array of bytes in the Java programming language.
Reader	readCharacterStream()           Returns the next attribute in the stream as a stream of Unicode characters.
Clob	readClob()           Reads an SQL CLOB value from the stream and returns it as a Clob object in the Java programming language.
Date	readDate()           Reads the next attribute in the stream as a java.sql.Date object.
double	readDouble()           Reads the next attribute in the stream as a double in the Java programming language.
float	readFloat()           Reads the next attribute in the stream as a float in the Java programming language.
int	readInt()           Reads the next attribute in the stream as an int in the Java programming language.
long	readLong()           Reads the next attribute in the stream as a long in the Java programming language.
Object	readObject()           Returns the datum at the head of the stream as an Object in the Java programming language.
Ref	readRef()           Reads an SQL REF value from the stream and returns it as a Ref object in the Java programming language.
short	readShort()           Reads the next attribute in the stream as a short in the Java programming language.
String	readString()           Reads the next attribute in the stream as a String in the Java programming language.
Time	readTime()           Reads the next attribute in the stream as a java.sql.Time object.
Timestamp	readTimestamp()           Reads the next attribute in the stream as a java.sql.Timestamp object.
boolean	wasNull()           Determines whether the last value read was SQL NULL.

 

Method Detail

readString

public String readString()
                  throws SQLException

Reads the next attribute in the stream as a String in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns null

Throws:

SQLException - if a database access error occurs

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readBoolean

public boolean readBoolean()
                    throws SQLException

Reads the next attribute in the stream as a boolean in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns false

Throws:

SQLException - if a database access error occurs

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readByte

public byte readByte()
              throws SQLException

Reads the next attribute in the stream as a byte in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns 0

Throws:

SQLException - if a database access error occurs

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readShort

public short readShort()
                throws SQLException

Reads the next attribute in the stream as a short in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns 0

Throws:

SQLException - if a database access error occurs

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readInt

public int readInt()
            throws SQLException

Reads the next attribute in the stream as an int in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns 0

Throws:

SQLException - if a database access error occurs

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readLong

public long readLong()
              throws SQLException

Reads the next attribute in the stream as a long in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns 0

Throws:

SQLException - if a database access error occurs

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readFloat

public float readFloat()
                throws SQLException

Reads the next attribute in the stream as a float in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns 0

Throws:

SQLException - if a database access error occurs

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readDouble

public double readDouble()
                  throws SQLException

Reads the next attribute in the stream as a double in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns 0

Throws:

SQLException - if a database access error occurs

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readBigDecimal

public BigDecimal readBigDecimal()
                          throws SQLException

Reads the next attribute in the stream as a java.math.BigDecimal object in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns null

Throws:

SQLException - if a database access error occurs

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readBytes

public byte[] readBytes()
                 throws SQLException

Reads the next attribute in the stream as an array of bytes in the Java programming language.

Returns:

the attribute; if the value is SQL NULL, returns null

Throws:

SQLException - if a database access error occurs

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readDate

public Date readDate()
              throws SQLException

Reads the next attribute in the stream as a java.sql.Date object.

Returns:

the attribute; if the value is SQL NULL, returns null

Throws:

SQLException - if a database access error occurs

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readTime

public Time readTime()
              throws SQLException

Reads the next attribute in the stream as a java.sql.Time object.

Returns:

the attribute; if the value is SQL NULL, returns null

Throws:

SQLException - if a database access error occurs

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readTimestamp

public Timestamp readTimestamp()
                        throws SQLException

Reads the next attribute in the stream as a java.sql.Timestamp object.

Returns:

the attribute; if the value is SQL NULL, returns null

Throws:

SQLException - if a database access error occurs

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readCharacterStream

public Reader readCharacterStream()
                           throws SQLException

Returns the next attribute in the stream as a stream of Unicode characters.

Returns:

the attribute; if the value is SQL NULL, returns null

Throws:

SQLException - if a database access error occurs

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readAsciiStream

public InputStream readAsciiStream()
                            throws SQLException

Returns the next attribute in the stream as a stream of ASCII characters.

Returns:

the attribute; if the value is SQL NULL, returns null

Throws:

SQLException - if a database access error occurs

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readBinaryStream

public InputStream readBinaryStream()
                             throws SQLException

Returns the next attribute in the stream as a stream of uninterpreted bytes.

Returns:

the attribute; if the value is SQL NULL, returns null

Throws:

SQLException - if a database access error occurs

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readObject

public Object readObject()
                  throws SQLException

Returns the datum at the head of the stream as an Object in the Java programming language. The actual type of the object returned is determined by the default type mapping, and any customizations present in this stream's type map.

A type map is registered with the stream by the JDBC driver before the stream is passed to the application.

When the datum at the head of the stream is an SQL NULL, the method returns null. If the datum is an SQL structured or distinct type, it determines the SQL type of the datum at the head of the stream. If the stream's type map has an entry for that SQL type, the driver constructs an object of the appropriate class and calls the method SQLData.readSQL on that object, which reads additional data from the stream, using the protocol described for that method.

Returns:

the datum at the head of the stream as an Object in the Java programming language;null if the datum is SQL NULL

Throws:

SQLException - if a database access error occurs

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readRef

public Ref readRef()
            throws SQLException

Reads an SQL REF value from the stream and returns it as a Ref object in the Java programming language.

Returns:

a Ref object representing the SQL REF 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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readBlob

public Blob readBlob()
              throws SQLException

Reads an SQL BLOB value from the stream and returns it as a Blob object in the Java programming language.

Returns:

a Blob object representing data of the SQL BLOB 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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readClob

public Clob readClob()
              throws SQLException

Reads an SQL CLOB value from the stream and returns it as a Clob object in the Java programming language.

Returns:

a Clob object representing data of the SQL CLOB 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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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.

Returns:

an Array object representing data of the SQL ARRAY 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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wasNull

public boolean wasNull()
                throws SQLException

Determines whether the last value read was SQL NULL.

Returns:

true if the most recently read SQL value was SQL NULL; otherwise, false

Throws:

SQLException - if a database access error occurs

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