prajna.io

Class DbLookup

java.lang.Object

prajna.io.DbLookup

public class DbLookup
extends java.lang.Object

This class is designed as a utility class for creating lookup tables for database keys. Since relational databases frequently have tables of values with keys for normalization or compression, this class retrieves the values from such tables and provides a lookup facility without having to query the database each time.

Author:

Edward Swing

Constructor Summary

Constructors

Constructor and Description
DbLookup(java.sql.Connection connection) Creates a new lookup utility with the given connection

Method Summary

Methods

Modifier and Type	Method and Description
java.util.Map<java.lang.Integer,java.lang.String>	addLookup(java.lang.String tableName, java.lang.String keyColumn, java.lang.String labelColumn) Add the lookup table.
java.util.Map<java.lang.Integer,java.lang.String>	addLookup(java.lang.String lookupName, java.lang.String tableName, java.lang.String keyColumn, java.lang.String labelColumn) Adds the lookup table.
int	findKey(java.lang.String lookupName, java.lang.String label) Find the key value.
java.lang.String	getLabel(java.lang.String lookupName, int key) Gets the label for the specified key.
void	setConnection(java.sql.Connection connection) Sets the connection to the JDBC database

Methods inherited from class java.lang.Object

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

Constructor Detail

DbLookup

public DbLookup(java.sql.Connection connection)

Creates a new lookup utility with the given connection

Parameters:

connection - the connection to the database

Method Detail

addLookup

public java.util.Map<java.lang.Integer,java.lang.String> addLookup(java.lang.String tableName,
                                                          java.lang.String keyColumn,
                                                          java.lang.String labelColumn)

Add the lookup table. This uses the table name as the lookup name.

Parameters:

tableName - the table name

keyColumn - the key column

labelColumn - the label column

Returns:

a copy of the lookup table

addLookup

public java.util.Map<java.lang.Integer,java.lang.String> addLookup(java.lang.String lookupName,
                                                          java.lang.String tableName,
                                                          java.lang.String keyColumn,
                                                          java.lang.String labelColumn)

Adds the lookup table. The method returns a copy of the lookup table, preventing changes to the underlying table. If the lookup table has already been added, this method will reread the table to retrieve any updates.

Parameters:

lookupName - the lookup name, used to access the lookup table

tableName - the table name within the database

keyColumn - the key column within the table

labelColumn - the label column within the table

Returns:

a copy of the lookup table

findKey

public int findKey(java.lang.String lookupName,
          java.lang.String label)

Find the key value. This is the index of the associated value.

Parameters:

lookupName - the lookup name, which refers to the table

label - the label. This is the string value within the table.

Returns:

the key value, or -1 if the label is not found.

getLabel

public java.lang.String getLabel(java.lang.String lookupName,
                        int key)

Gets the label for the specified key.

Parameters:

lookupName - the lookup name, which refers to the table

key - the key

Returns:

the label, which is the string value within the table.

setConnection

public void setConnection(java.sql.Connection connection)

Sets the connection to the JDBC database

Parameters:

connection - the new connection