com.ibm.mq.headers

Class MQHeaderList

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList

com.ibm.mq.headers.MQHeaderList

All Implemented Interfaces:

java.lang.Iterable, java.util.Collection, java.util.List

public class MQHeaderList
extends java.util.AbstractList

An MQHeaderList represents an ordered list of header instances. Like an MQHeaderIterator, an MQHeaderList can read and decode header content from a message. The contents of the list can be written out to another message, having first been modified if desired. Possible modifications include removing headers, updating their field contents, and adding or inserting new headers.

Constructor Summary

Constructors

Constructor and Description
MQHeaderList() Default constructor
MQHeaderList(java.io.DataInput message) Initializes an MQHeaderList from the contents of a message or byte stream using the initial format, encoding and CCSID given by the MQMD fields in the message.
MQHeaderList(java.io.DataInput message, boolean readBody) Initializes an MQHeaderList from the contents of a message or byte stream using the initial format, encoding and CCSID given by the MQMD fields in the message.
MQHeaderList(java.io.DataInput message, java.lang.String format, int encoding, int characterSet) Initializes an MQHeaderList from the contents of a message or byte stream using the given initial format, encoding and CCSID.
MQHeaderList(MQHeader[] headers) Constructs an MQHeaderList from an array of headers.
MQHeaderList(java.lang.String format) Initializes an MQHeaderList for reading a byte stream starting with the specified initial format.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(int index, java.lang.Object header) Inserts a new MQHeader instance before the given position in the list.
boolean	add(java.lang.Object header) Adds a new MQHeader instance to the end of the list.
MQData	asMQData() Returns an MQData adapter for this MQHeaderList.
java.lang.Object	get(int index) Returns the header object at the given position in the list.
java.lang.Object	getBody() Returns the body object obtained during the last read operation if the readBody argument was specified.
java.lang.String	getFormat() Returns the format for the first item in the header list.
int	indexOf(java.lang.String type) Returns the index of the first header in the list of the specified header type, or -1 if not found.
int	read(java.io.DataInput message) Populates an MQHeaderList from the contents of a message or byte stream using the initial format, encoding and CCSID given by the MQMD fields in the message.
int	read(java.io.DataInput message, boolean readBody) Populates an MQHeaderList from the contents of a message or byte stream and reads the message body if the readBody argument is true.
int	read(java.io.DataInput message, int encoding, int characterSet) Populates an MQHeaderList from the contents of a message or byte stream using the given initial format, encoding and CCSID.
int	read(java.io.DataInput message, int encoding, int characterSet, boolean readBody) Populates an MQHeaderList from the contents of a message or byte stream and reads the message body if the readBody argument is true.
java.lang.Object	remove(int index) Removes the MQHeader at the specified position in this list.
java.lang.Object	set(int index, java.lang.Object header) Replaces the MQHeader instance at the given position in the list with the specified value.
int	size() Returns the number of headers in the list.
java.lang.String	toString() Returns the string representation of the class instance
java.lang.String	updateHeaderChaining() Traverses the headers in the list, updating the format field of each Chainable header and returning the format of the first header for setting into the message descriptor.
java.lang.String	updateHeaderChaining(boolean useBodyFormat) Deprecated. No longer required
java.lang.String	updateHeaderChaining(java.lang.String bodyFormat) Updates the format of headers in the list, setting the last one to the given body format.
int	write(java.io.DataOutput message) Writes the headers in this MQHeaderList to the target message.
int	write(java.io.DataOutput message, boolean writeBody) Writes the headers in this MQHeaderList to the target message, and writes the body if the writeBody argument is true and a body has previously been read.
int	write(java.io.DataOutput message, int encoding, int characterSet) Writes the headers in this MQHeaderList to the target message using the given encoding and CCSID.
int	write(java.io.DataOutput message, int encoding, int characterSet, boolean writeBody) Writes the headers in this MQHeaderList to the target message using the given encoding and CCSID, and writes the body if the writeBody argument is true and a body has previously been read.

Methods inherited from class java.util.AbstractList

addAll, clear, equals, hashCode, indexOf, iterator, lastIndexOf, listIterator, listIterator, subList

Methods inherited from class java.util.AbstractCollection

addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.List

addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray

Constructor Detail

MQHeaderList

public MQHeaderList()

Default constructor

MQHeaderList

public MQHeaderList(java.lang.String format)

Initializes an MQHeaderList for reading a byte stream starting with the specified initial format. This format is used in subsequent read operations to identify the first header.

Parameters:

format - The format to intialise

MQHeaderList

public MQHeaderList(MQHeader[] headers)

Constructs an MQHeaderList from an array of headers.

Parameters:

headers - The array of headers

MQHeaderList

public MQHeaderList(java.io.DataInput message)
             throws MQDataException,
                    java.io.IOException

Initializes an MQHeaderList from the contents of a message or byte stream using the initial format, encoding and CCSID given by the MQMD fields in the message. All headers visible from the current position in the message are consumed into the list and the message is left positioned at the start of the body data.

Parameters:

message - the message.

Throws:

MQDataException - If the call fails

java.io.IOException - If there is an IO error

MQHeaderList

public MQHeaderList(java.io.DataInput message,
            boolean readBody)
             throws MQDataException,
                    java.io.IOException

Initializes an MQHeaderList from the contents of a message or byte stream using the initial format, encoding and CCSID given by the MQMD fields in the message. All headers visible from the current position in the message are consumed into the list, and the body is read. The body object can be retrieved using the getBody method.

Parameters:

message - the message.

readBody - a flag to indicate whether message body is to be read

Throws:

MQDataException - If the call fails

java.io.IOException - If there is an IO error

MQHeaderList

public MQHeaderList(java.io.DataInput message,
            java.lang.String format,
            int encoding,
            int characterSet)
             throws MQDataException,
                    java.io.IOException

Initializes an MQHeaderList from the contents of a message or byte stream using the given initial format, encoding and CCSID. All headers visible from the current position in the message are consumed into the list and the message is left positioned at the start of the body data.

Parameters:

message - the message.

format - the message format (see CMQC.MQFMT_* for values)

encoding - the numeric encoding. see (CMQC.MQENC_* for values).

characterSet - the Coded Character Set Identifier.

Throws:

MQDataException - If the call fails

java.io.IOException - If there is an IO error

Method Detail

updateHeaderChaining

public java.lang.String updateHeaderChaining()

Traverses the headers in the list, updating the format field of each Chainable header and returning the format of the first header for setting into the message descriptor. The encoding and CCSID fields in the headers are not updated. If written to a message or byte stream using the write method, the header contents will be written in a uniform encoding and CCSID. The encoding and CCSID values come from the DataInput or the arguments to the write method, and the header content is converted to this encoding and CCSID during the write process. The effective encoding and CCSID settings are not disrupted or corrupted when headers are added, removed or re-ordered in the list.

Returns:

The updated header chain

updateHeaderChaining

public java.lang.String updateHeaderChaining(boolean useBodyFormat)

Deprecated. No longer required

Updates the format of headers in the list, setting the last one to the format of the existing body object, if any. A body object will only be present if the header list was constructed or read with the readBody option.

Parameters:

useBodyFormat - Indicates if bodyFormat has to be used

Returns:

The updated body format

See Also:

updateHeaderChaining()

updateHeaderChaining

public java.lang.String updateHeaderChaining(java.lang.String bodyFormat)

Updates the format of headers in the list, setting the last one to the given body format.

Parameters:

bodyFormat - the header format (see CMQC.MQFMT_* for values)

Returns:

The updated header chain

See Also:

updateHeaderChaining()

read

public int read(java.io.DataInput message)
         throws MQDataException,
                java.io.IOException

Populates an MQHeaderList from the contents of a message or byte stream using the initial format, encoding and CCSID given by the MQMD fields in the message. All headers visible from the current position in the message are consumed into the list and the message is left positioned at the start of the body data. The current contents of the list (if any) are discarded before the read begins.

Parameters:

message - the message.

Returns:

The number of bytes read

Throws:

MQDataException - If the call fails

java.io.IOException - If there is an IO error

read

public int read(java.io.DataInput message,
       boolean readBody)
         throws MQDataException,
                java.io.IOException

Populates an MQHeaderList from the contents of a message or byte stream and reads the message body if the readBody argument is true. The body object can be retrieved using the getBody method.

Parameters:

message - the message.

readBody - a flag to indicate whether message body is to be read

Returns:

The number of bytes read

Throws:

MQDataException - If the call fails

java.io.IOException - If there is an IO error

read

public int read(java.io.DataInput message,
       int encoding,
       int characterSet)
         throws MQDataException,
                java.io.IOException

Populates an MQHeaderList from the contents of a message or byte stream using the given initial format, encoding and CCSID. All headers visible from the current position in the message are consumed into the list and the message is left positioned at the start of the body data. The current contents of the list (if any) are discarded before the read begins. The initial format used is the value originally passed in the constructor of this MQHeaderList, if applicable.

Parameters:

message - the message.

encoding - the numeric encoding. see (CMQC.MQENC_* for values).

characterSet - the Coded Character Set Identifier.

Returns:

The number of bytes read

Throws:

MQDataException - If the call fails

java.io.IOException - If there is an IO error

read

public int read(java.io.DataInput message,
       int encoding,
       int characterSet,
       boolean readBody)
         throws MQDataException,
                java.io.IOException

Populates an MQHeaderList from the contents of a message or byte stream and reads the message body if the readBody argument is true. The body object can be retrieved using the getBody method.

Parameters:

message - the message.

encoding - the numeric encoding. see (CMQC.MQENC_* for values).

characterSet - the Coded Character Set Identifier.

readBody - Indicates if message body has to be read also

Returns:

The number of bytes read

Throws:

MQDataException - If the call fails

java.io.IOException - If there is an IO error

write

public int write(java.io.DataOutput message)
          throws java.io.IOException

Writes the headers in this MQHeaderList to the target message. The content is written using the encoding and characterSet values from the message descriptor.

Parameters:

message - the message.

Returns:

The number of bytes written

Throws:

java.io.IOException - If there is an IO error

write

public int write(java.io.DataOutput message,
        boolean writeBody)
          throws java.io.IOException

Writes the headers in this MQHeaderList to the target message, and writes the body if the writeBody argument is true and a body has previously been read. The content is written using the encoding and characterSet values from the message descriptor.

Parameters:

message - the message.

writeBody - whether or not the body should be written to the message

Returns:

The number of bytes written

Throws:

java.io.IOException - If there is an IO error

write

public int write(java.io.DataOutput message,
        int encoding,
        int characterSet)
          throws java.io.IOException

Writes the headers in this MQHeaderList to the target message using the given encoding and CCSID.

Parameters:

message - the message.

encoding - the numeric encoding. see (CMQC.MQENC_* for values).

characterSet - the Coded Character Set Identifier.

Returns:

The number of bytes written

Throws:

java.io.IOException - If there is an IO error

write

public int write(java.io.DataOutput message,
        int encoding,
        int characterSet,
        boolean writeBody)
          throws java.io.IOException

Writes the headers in this MQHeaderList to the target message using the given encoding and CCSID, and writes the body if the writeBody argument is true and a body has previously been read.

Parameters:

message - the message.

encoding - the numeric encoding. see (CMQC.MQENC_* for values).

characterSet - the Coded Character Set Identifier.

writeBody - whether or not the body should be written to the message

Returns:

The number of bytes written

Throws:

java.io.IOException - If there is an IO error

indexOf

public int indexOf(java.lang.String type)

Returns the index of the first header in the list of the specified header type, or -1 if not found.

Parameters:

type - identifies the header type required

Returns:

Index of the first header of the specified type

getFormat

public java.lang.String getFormat()

Returns the format for the first item in the header list. This value can be set into the MQMD or the preceding header if the contents of the header list are written into a message. The format value returned is the initial format passed as an argument to the MQHeaderIterator(java.lang.String) constructor (if applicable), or the value resulting from updateHeaderChaining having been invoked. The value may be null.

Returns:

The format

getBody

public java.lang.Object getBody()

Returns the body object obtained during the last read operation if the readBody argument was specified.

Returns:

The body object

get

public java.lang.Object get(int index)

Returns the header object at the given position in the list.

Specified by:

get in interface java.util.List

Specified by:

get in class java.util.AbstractList

Parameters:

index - the position required

Returns:

The object at the specified position

size

public int size()

Returns the number of headers in the list.

Specified by:

size in interface java.util.Collection

Specified by:

size in interface java.util.List

Specified by:

size in class java.util.AbstractCollection

Returns:

The number of headers in the list

add

public void add(int index,
       java.lang.Object header)

Inserts a new MQHeader instance before the given position in the list.

Specified by:

add in interface java.util.List

Overrides:

add in class java.util.AbstractList

Parameters:

index - the position at which to insert

header - the MQHeader to insert

add

public boolean add(java.lang.Object header)

Adds a new MQHeader instance to the end of the list.

Specified by:

add in interface java.util.Collection

Specified by:

add in interface java.util.List

Overrides:

add in class java.util.AbstractList

Parameters:

header - the MQHeader to add

Returns:

true

remove

public java.lang.Object remove(int index)

Removes the MQHeader at the specified position in this list.

Specified by:

remove in interface java.util.List

Overrides:

remove in class java.util.AbstractList

Parameters:

index - the index of the element to removed.

Returns:

the element previously at the specified position.

set

public java.lang.Object set(int index,
                   java.lang.Object header)

Replaces the MQHeader instance at the given position in the list with the specified value.

Specified by:

set in interface java.util.List

Overrides:

set in class java.util.AbstractList

Parameters:

index - the position at which to replace

header - the MQHeader to replace with

Returns:

The element previously at the specified position

asMQData

public MQData asMQData()

Returns an MQData adapter for this MQHeaderList. The MQHeaderList class does not directly implement the com.ibm.mq.headers.MQData interface because its size method conflicts with the size method from java.util.List. The size returned by the MQData adapter includes the size of the body object, if present. A body object will be present if the MQHeaderList was constructed or read with the readBody option.

Returns:

The MQData adapter

toString

public java.lang.String toString()

Returns the string representation of the class instance

Overrides:

toString in class java.util.AbstractCollection

Returns:

The string representation

See Also:

Object.toString()