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A StreamMessage
object is used to send a stream of primitive
types in the Java programming language. It is filled and read sequentially.
It inherits from the Message
interface
and adds a stream message body. Its methods are based largely on those
found in java.io.DataInputStream
and
java.io.DataOutputStream
.
The primitive types can be read or written explicitly using methods
for each type. They may also be read or written generically as objects.
For instance, a call to StreamMessage.writeInt(6)
is
equivalent to StreamMessage.writeObject(new Integer(6))
.
Both forms are provided, because the explicit form is convenient for
static programming, and the object form is needed when types are not known
at compile time.
When the message is first created, and when clearBody
is called, the body of the message is in write-only mode. After the
first call to reset
has been made, the message body is in
read-only mode.
After a message has been sent, the client that sent it can retain and
modify it without affecting the message that has been sent. The same message
object can be sent multiple times.
When a message has been received, the provider has called
reset
so that the message body is in read-only mode for the client.
If clearBody
is called on a message in read-only mode,
the message body is cleared and the message body is in write-only mode.
If a client attempts to read a message in write-only mode, a
MessageNotReadableException
is thrown.
If a client attempts to write a message in read-only mode, a
MessageNotWriteableException
is thrown.
StreamMessage
objects support the following conversion
table. The marked cases must be supported. The unmarked cases must throw a
JMSException
. The String
-to-primitive conversions
may throw a runtime exception if the primitive's valueOf()
method does not accept it as a valid String
representation of
the primitive.
A value written as the row type can be read as the column type.
| | boolean byte short char int long float double String byte[] |---------------------------------------------------------------------- |boolean | X X |byte | X X X X X |short | X X X X |char | X X |int | X X X |long | X X |float | X X X |double | X X |String | X X X X X X X X |byte[] | X |----------------------------------------------------------------------
Attempting to read a null value as a primitive type must be treated
as calling the primitive's corresponding valueOf(String)
conversion method with a null value. Since char
does not
support a String
conversion, attempting to read a null value
as a char
must throw a NullPointerException
.
Session.createStreamMessage()
,
BytesMessage
,
MapMessage
,
Message
,
ObjectMessage
,
TextMessage
Field Summary |
Fields inherited from interface javax.jms.Message |
DEFAULT_DELIVERY_MODE, DEFAULT_PRIORITY, DEFAULT_TIME_TO_LIVE |
Method Summary | |
boolean |
readBoolean()
Reads a boolean from the stream message. |
byte |
readByte()
Reads a byte value from the stream message. |
int |
readBytes(byte[] value)
Reads a byte array field from the stream message into the specified byte[] object (the read buffer). |
char |
readChar()
Reads a Unicode character value from the stream message. |
double |
readDouble()
Reads a double from the stream message. |
float |
readFloat()
Reads a float from the stream message. |
int |
readInt()
Reads a 32-bit integer from the stream message. |
long |
readLong()
Reads a 64-bit integer from the stream message. |
Object |
readObject()
Reads an object from the stream message. |
short |
readShort()
Reads a 16-bit integer from the stream message. |
String |
readString()
Reads a String from the stream message. |
void |
reset()
Puts the message body in read-only mode and repositions the stream to the beginning. |
void |
writeBoolean(boolean value)
Writes a boolean to the stream message. |
void |
writeByte(byte value)
Writes a byte to the stream message. |
void |
writeBytes(byte[] value)
Writes a byte array field to the stream message. |
void |
writeBytes(byte[] value,
int offset,
int length)
Writes a portion of a byte array as a byte array field to the stream message. |
void |
writeChar(char value)
Writes a char to the stream message. |
void |
writeDouble(double value)
Writes a double to the stream message. |
void |
writeFloat(float value)
Writes a float to the stream message. |
void |
writeInt(int value)
Writes an int to the stream message. |
void |
writeLong(long value)
Writes a long to the stream message. |
void |
writeObject(Object value)
Writes an object to the stream message. |
void |
writeShort(short value)
Writes a short to the stream message. |
void |
writeString(String value)
Writes a String to the stream message. |
Method Detail |
public boolean readBoolean() throws JMSException
boolean
from the stream message.
boolean
value read
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.public byte readByte() throws JMSException
byte
value from the stream message.
byte
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.public short readShort() throws JMSException
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.public char readChar() throws JMSException
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid
MessageNotReadableException
- if the message is in write-only
mode.public int readInt() throws JMSException
int
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.public long readLong() throws JMSException
long
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.public float readFloat() throws JMSException
float
from the stream message.
float
value from the stream message
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.public double readDouble() throws JMSException
double
from the stream message.
double
value from the stream message
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.public String readString() throws JMSException
String
from the stream message.
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.public int readBytes(byte[] value) throws JMSException
byte[]
object (the read buffer).
To read the field value, readBytes
should be
successively called
until it returns a value less than the length of the read buffer.
The value of the bytes in the buffer following the last byte
read is undefined.
If readBytes
returns a value equal to the length of the
buffer, a subsequent readBytes
call must be made. If there
are no more bytes to be read, this call returns -1.
If the byte array field value is null, readBytes
returns -1.
If the byte array field value is empty, readBytes
returns 0.
Once the first readBytes
call on a byte[]
field value has been made,
the full value of the field must be read before it is valid to read
the next field. An attempt to read the next field before that has
been done will throw a MessageFormatException
.
To read the byte field value into a new byte[]
object,
use the readObject
method.
value
- the buffer into which the data is read
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.readObject()
public Object readObject() throws JMSException
This method can be used to return, in objectified format,
an object in the Java programming language ("Java object") that has
been written to the stream with the equivalent
writeObject
method call, or its equivalent primitive
writetype
method.
Note that byte values are returned as byte[]
, not
Byte[]
.
An attempt to call readObject
to read a byte field
value into a new byte[]
object before the full value of the
byte field has been read will throw a
MessageFormatException
.
int
,
an Integer
is returned)
JMSException
- if the JMS provider fails to read the message
due to some internal error.
MessageEOFException
- if unexpected end of message stream has
been reached.
MessageFormatException
- if this type conversion is invalid.
MessageNotReadableException
- if the message is in write-only
mode.readBytes(byte[] value)
public void writeBoolean(boolean value) throws JMSException
boolean
to the stream message.
The value true
is written as the value
(byte)1
; the value false
is written as
the value (byte)0
.
value
- the boolean
value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeByte(byte value) throws JMSException
byte
to the stream message.
value
- the byte
value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeShort(short value) throws JMSException
short
to the stream message.
value
- the short
value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeChar(char value) throws JMSException
char
to the stream message.
value
- the char
value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeInt(int value) throws JMSException
int
to the stream message.
value
- the int
value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeLong(long value) throws JMSException
long
to the stream message.
value
- the long
value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeFloat(float value) throws JMSException
float
to the stream message.
value
- the float
value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeDouble(double value) throws JMSException
double
to the stream message.
value
- the double
value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeString(String value) throws JMSException
String
to the stream message.
value
- the String
value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeBytes(byte[] value) throws JMSException
The byte array value
is written to the message
as a byte array field. Consecutively written byte array fields are
treated as two distinct fields when the fields are read.
value
- the byte array value to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeBytes(byte[] value, int offset, int length) throws JMSException
The a portion of the byte array value
is written to the
message as a byte array field. Consecutively written byte
array fields are treated as two distinct fields when the fields are
read.
value
- the byte array value to be writtenoffset
- the initial offset within the byte arraylength
- the number of bytes to use
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageNotWriteableException
- if the message is in read-only
mode.public void writeObject(Object value) throws JMSException
This method works only for the objectified primitive
object types (Integer
, Double
,
Long
...), String
objects, and byte
arrays.
value
- the Java object to be written
JMSException
- if the JMS provider fails to write the message
due to some internal error.
MessageFormatException
- if the object is invalid.
MessageNotWriteableException
- if the message is in read-only
mode.public void reset() throws JMSException
JMSException
- if the JMS provider fails to reset the message
due to some internal error.
MessageFormatException
- if the message has an invalid
format.
|
Novell exteNd Messaging Platform 5.1 | |||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |