org.springframework.batch.item.database.support

Class AbstractSqlPagingQueryProvider

java.lang.Object

org.springframework.batch.item.database.support.AbstractSqlPagingQueryProvider

All Implemented Interfaces:

PagingQueryProvider

Direct Known Subclasses:

H2PagingQueryProvider, HsqlPagingQueryProvider, MySqlPagingQueryProvider, OraclePagingQueryProvider, PostgresPagingQueryProvider, SqlitePagingQueryProvider, SqlWindowingPagingQueryProvider

public abstract class AbstractSqlPagingQueryProvider
extends java.lang.Object
implements PagingQueryProvider

Abstract SQL Paging Query Provider to serve as a base class for all provided SQL paging query providers. Any implementation must provide a way to specify the select clause, from clause and optionally a where clause. In addition a way to specify a single column sort key must also be provided. This sort key will be used to provide the paging functionality. It is recommended that there should be an index for the sort key to provide better performance. Provides properties and preparation for the mandatory "selectClause" and "fromClause" as well as for the optional "whereClause". Also provides property for the mandatory "sortKeys". Note: The columns that make up the sort key must be a true key and not just a column to order by. It is important to have a unique key constraint on the sort key to guarantee that no data is lost between executions.

Since:

2.0

Author:

Thomas Risberg, Dave Syer, Michael Minella, Mahmoud Ben Hassine, Benjamin Hetz

Constructor Summary

Constructors

Constructor and Description
AbstractSqlPagingQueryProvider()

Method Summary

Modifier and Type	Method and Description
abstract java.lang.String	generateFirstPageQuery(int pageSize) Method generating the query string to be used for retrieving the first page.
abstract java.lang.String	generateJumpToItemQuery(int itemIndex, int pageSize) Method generating the query string to be used for jumping to a specific item position.
abstract java.lang.String	generateRemainingPagesQuery(int pageSize) Method generating the query string to be used for retrieving the pages following the first page.
protected java.lang.String	getFromClause()
java.lang.String	getGroupClause() The getter for the group by clause
int	getParameterCount() The number of parameters that are declared in the query
protected java.lang.String	getSelectClause()
java.lang.String	getSortKeyPlaceHolder(java.lang.String keyName) The sort key placeholder will vary depending on whether named parameters or traditional placeholders are used in query strings.
java.util.Map<java.lang.String,Order>	getSortKeys() A Map<String, Boolean> of sort columns as the key and boolean for ascending/descending (ascending = true).
java.util.Map<java.lang.String,Order>	getSortKeysWithoutAliases() The sort key (unique single column name) without alias.
protected java.lang.String	getWhereClause()
void	init(javax.sql.DataSource dataSource) Check mandatory properties.
boolean	isUsingNamedParameters() Indicate whether the generated queries use named parameter syntax.
void	setFromClause(java.lang.String fromClause)
void	setGroupClause(java.lang.String groupClause) The setter for the group by clause
void	setSelectClause(java.lang.String selectClause)
void	setSortKeys(java.util.Map<java.lang.String,Order> sortKeys)
void	setWhereClause(java.lang.String whereClause)

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractSqlPagingQueryProvider

public AbstractSqlPagingQueryProvider()

Method Detail

setGroupClause

public void setGroupClause(java.lang.String groupClause)

The setter for the group by clause

Parameters:

groupClause - SQL GROUP BY clause part of the SQL query string

getGroupClause

public java.lang.String getGroupClause()

The getter for the group by clause

Returns:

SQL GROUP BY clause part of the SQL query string

setSelectClause

public void setSelectClause(java.lang.String selectClause)

Parameters:

selectClause - SELECT clause part of SQL query string

getSelectClause

protected java.lang.String getSelectClause()

Returns:

SQL SELECT clause part of SQL query string

setFromClause

public void setFromClause(java.lang.String fromClause)

Parameters:

fromClause - FROM clause part of SQL query string

getFromClause

protected java.lang.String getFromClause()

Returns:

SQL FROM clause part of SQL query string

setWhereClause

public void setWhereClause(java.lang.String whereClause)

Parameters:

whereClause - WHERE clause part of SQL query string

getWhereClause

protected java.lang.String getWhereClause()

Returns:

SQL WHERE clause part of SQL query string

setSortKeys

public void setSortKeys(java.util.Map<java.lang.String,Order> sortKeys)

Parameters:

sortKeys - key to use to sort and limit page content

getSortKeys

public java.util.Map<java.lang.String,Order> getSortKeys()

A Map<String, Boolean> of sort columns as the key and boolean for ascending/descending (ascending = true).

Specified by:

getSortKeys in interface PagingQueryProvider

Returns:

sortKey key to use to sort and limit page content

getParameterCount

public int getParameterCount()

Description copied from interface: PagingQueryProvider

The number of parameters that are declared in the query

Specified by:

getParameterCount in interface PagingQueryProvider

Returns:

number of parameters

isUsingNamedParameters

public boolean isUsingNamedParameters()

Description copied from interface: PagingQueryProvider

Indicate whether the generated queries use named parameter syntax.

Specified by:

isUsingNamedParameters in interface PagingQueryProvider

Returns:

true if named parameter syntax is used

getSortKeyPlaceHolder

public java.lang.String getSortKeyPlaceHolder(java.lang.String keyName)

The sort key placeholder will vary depending on whether named parameters or traditional placeholders are used in query strings.

Specified by:

getSortKeyPlaceHolder in interface PagingQueryProvider

Parameters:

keyName - The sort key name

Returns:

place holder for sortKey.

init

public void init(javax.sql.DataSource dataSource)
          throws java.lang.Exception

Check mandatory properties.

Specified by:

init in interface PagingQueryProvider

Parameters:

dataSource - DataSource to use for any initialization

Throws:

java.lang.Exception - for errors when initializing

See Also:

InitializingBean.afterPropertiesSet()

generateFirstPageQuery

public abstract java.lang.String generateFirstPageQuery(int pageSize)

Method generating the query string to be used for retrieving the first page. This method must be implemented in sub classes.

Specified by:

generateFirstPageQuery in interface PagingQueryProvider

Parameters:

pageSize - number of rows to read per page

Returns:

query string

generateRemainingPagesQuery

public abstract java.lang.String generateRemainingPagesQuery(int pageSize)

Method generating the query string to be used for retrieving the pages following the first page. This method must be implemented in sub classes.

Specified by:

generateRemainingPagesQuery in interface PagingQueryProvider

Parameters:

pageSize - number of rows to read per page

Returns:

query string

generateJumpToItemQuery

public abstract java.lang.String generateJumpToItemQuery(int itemIndex,
                                                         int pageSize)

Method generating the query string to be used for jumping to a specific item position. This method must be implemented in sub classes.

Specified by:

generateJumpToItemQuery in interface PagingQueryProvider

Parameters:

itemIndex - the index of the item to jump to

pageSize - number of rows to read per page

Returns:

query string

getSortKeysWithoutAliases

public java.util.Map<java.lang.String,Order> getSortKeysWithoutAliases()

Description copied from interface: PagingQueryProvider

The sort key (unique single column name) without alias.

Specified by:

getSortKeysWithoutAliases in interface PagingQueryProvider

Returns:

sortKey key to use to sort and limit page content (without alias)