com.jenkov.mrpersister.impl.mapping
Class Key

java.lang.Object
  com.jenkov.mrpersister.impl.mapping.Key

All Implemented Interfaces:

IKey

public class Key
extends java.lang.Object
implements IKey

Represents a key, either primary or foreign key, in a database table. The key consists of one or more columns. To create key values for a compound primary or foreign key, use the IKeyValue interface and the KeyValue implementation.

Author:

Jakob Jenkov - Copyright 2005 Jenkov Development

See Also:

IKeyValue, KeyValue

Field Summary

protected java.util.Collection	columns
protected IObjectMapping	objectMapping
protected java.lang.String	table

Constructor Summary

Key()
Creates an empty key instance.

Key(java.util.Collection columns)
Creates a key consisting of the given columns.

Key(java.lang.String column)
Creates a key consisting of a single column.

Key(java.lang.String[] columns)
Creates a key consisting of the given columns.

Method Summary

void	addColumn(java.lang.String column) Adds a column to this key mapping.
boolean	equals(java.lang.Object obj)
java.lang.String	getColumn() If this key only consists of one column, this method will return that column.
java.util.Collection	getColumns() Returns the collection of columns used in this key mapping.
java.lang.String	getTable() Returns the table this key mapping points to.
boolean	isValid(IKeyValue keyValue) Validates an IKeyValue instance against this key.
void	removeColumn(java.lang.String column) Removes a column from this key mapping
void	setColumns(java.util.Collection columns) Sets the collection of columns to use in this key mapping.
void	setTable(java.lang.String table) Sets the table this key points to.
int	size() Returns the number of columns in this key.
IKeyValue	toKeyValue(java.lang.Object keyValueObject) Wraps the given key value object in a IKeyValue instance.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

objectMapping

protected IObjectMapping objectMapping

table

protected java.lang.String table

columns

protected java.util.Collection columns

Constructor Detail

Key

public Key()

Creates an empty key instance. You can add columns to the key after creation.

Key

public Key(java.util.Collection columns)

Creates a key consisting of the given columns. You can add more columns to the key after creation.

Parameters:

columns - The names of the columns in the key.

Key

public Key(java.lang.String column)

Creates a key consisting of a single column. You can add more columns to the key after creation.

Parameters:

column - The name of the key column.

Key

public Key(java.lang.String[] columns)

Creates a key consisting of the given columns. You can add more columns to the key after creation.

Parameters:

columns - The names of the columns in the key.

Method Detail

getTable

public java.lang.String getTable()

Description copied from interface: IKey

Returns the table this key mapping points to. For a primary key this is the same table as the key exists in. For a foreign key this is the table the primary key the foreign key points to exists in.

Specified by:

getTable in interface IKey

Returns:

The table this key mapping points to.

setTable

public void setTable(java.lang.String table)

Description copied from interface: IKey

Sets the table this key points to. For a primary key this is the same table as the key exists in. For a foreign key this is the table the primary key the foreign key points to exists in.

Specified by:

setTable in interface IKey

Parameters:

table - The table this key mapping is to point to.

getColumns

public java.util.Collection getColumns()

Description copied from interface: IKey

Returns the collection of columns used in this key mapping.

Specified by:

getColumns in interface IKey

Returns:

The collection of columns used in this key mapping.

setColumns

public void setColumns(java.util.Collection columns)

Description copied from interface: IKey

Sets the collection of columns to use in this key mapping.

Specified by:

setColumns in interface IKey

Parameters:

columns - The collection of columns to use in this key mapping.

size

public int size()

Description copied from interface: IKey

Returns the number of columns in this key.

Specified by:

size in interface IKey

Returns:

The number of columns in this key.

addColumn

public void addColumn(java.lang.String column)

Description copied from interface: IKey

Adds a column to this key mapping.

Specified by:

addColumn in interface IKey

Parameters:

column - The column to add to this key mapping.

removeColumn

public void removeColumn(java.lang.String column)

Description copied from interface: IKey

Removes a column from this key mapping

Specified by:

removeColumn in interface IKey

Parameters:

column - The column to remove

isValid

public boolean isValid(IKeyValue keyValue)

Description copied from interface: IKey

Validates an IKeyValue instance against this key. If the key value contains values for all columns in this key, this method returns true. False if not.

If the key value contains values for columns that are not part of this key, these column values are ignored.

Specified by:

isValid in interface IKey

Parameters:

keyValue - The key value to validate.

Returns:

True if the key is valid. False if not.

getColumn

public java.lang.String getColumn()
                           throws PersistenceException

Description copied from interface: IKey

If this key only consists of one column, this method will return that column. Otherwise a PersistenceException is thrown.

Specified by:

getColumn in interface IKey

Returns:

The column of this key, if it consists of only one column.

Throws:

PersistenceException - If this key contains zero, or more than one column.

toKeyValue

public IKeyValue toKeyValue(java.lang.Object keyValueObject)
                     throws PersistenceException

Description copied from interface: IKey

Wraps the given key value object in a IKeyValue instance. If the object to be wrapped is already a IKeyValue instance it will be returned unchanged. This will only work if this IKey instance only consists of a single column.

Specified by:

toKeyValue in interface IKey

Parameters:

keyValueObject - The object to wrap in a IKeyValue instance.

Returns:

An IKeyValue instance wrapping the given object.

Throws:

PersistenceException - if this IKey instance is a compound key (multi column key), or if empty.

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object