org.springframework.batch.item.data

Class Neo4jItemReader<T>

java.lang.Object

org.springframework.batch.item.ItemStreamSupport

org.springframework.batch.item.support.AbstractItemStreamItemReader<T>

org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader<T>

org.springframework.batch.item.data.AbstractPaginatedDataItemReader<T>

org.springframework.batch.item.data.Neo4jItemReader<T>

All Implemented Interfaces:

ItemReader<T>, ItemStream, org.springframework.beans.factory.InitializingBean

public class Neo4jItemReader<T>
extends AbstractPaginatedDataItemReader<T>
implements org.springframework.beans.factory.InitializingBean

Restartable ItemReader that reads objects from the graph database Neo4j via a paging technique.

It executes cypher queries built from the statement fragments provided to retrieve the requested data. The query is executed using paged requests of a size specified in AbstractPaginatedDataItemReader.setPageSize(int). Additional pages are requested as needed when the AbstractItemCountingItemStreamItemReader.read() method is called. On restart, the reader will begin again at the same number item it left off at.

Performance is dependent on your Neo4J configuration (embedded or remote) as well as page size. Setting a fairly large page size and using a commit interval that matches the page size should provide better performance.

This implementation is thread-safe between calls to AbstractItemCountingItemStreamItemReader.open(org.springframework.batch.item.ExecutionContext), however you should set saveState=false if used in a multi-threaded environment (no restart available).

Author:

Michael Minella

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.commons.logging.Log	logger

Fields inherited from class org.springframework.batch.item.data.AbstractPaginatedDataItemReader

page, pageSize, results

Constructor Summary

Constructors

Constructor and Description
Neo4jItemReader()

Method Summary

Methods

Modifier and Type	Method and Description
void	afterPropertiesSet() Checks mandatory properties
protected Iterator<T>	doPageRead() Method this ItemStreamReader delegates to for the actual work of reading a page.
void	setMatchStatement(String matchStatement) An optional match fragment of the cypher query.
void	setOrderByStatement(String orderByStatement) A list of properties to order the results by.
void	setResultConverter(org.springframework.data.neo4j.conversion.ResultConverter resultConverter) Set the converter used to convert node to the targetType.
void	setReturnStatement(String returnStatement) The return statement of the cypher query.
void	setStartStatement(String startStatement) The start segment of the cypher query.
void	setTargetType(Class targetType) The object type to be returned from each call to AbstractItemCountingItemStreamItemReader.read()
void	setTemplate(org.springframework.data.neo4j.template.Neo4jOperations template) Used to perform operations against the Neo4J database.
void	setWhereStatement(String whereStatement) An optional where fragement of the cypher query.

Methods inherited from class org.springframework.batch.item.data.AbstractPaginatedDataItemReader

doClose, doOpen, doRead, jumpToItem, setPageSize

Methods inherited from class org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader

close, getCurrentItemCount, isSaveState, open, read, setCurrentItemCount, setMaxItemCount, setSaveState, update

Methods inherited from class org.springframework.batch.item.ItemStreamSupport

getExecutionContextKey, setExecutionContextName, setName

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected org.apache.commons.logging.Log logger

Constructor Detail

Neo4jItemReader

public Neo4jItemReader()

Method Detail

setStartStatement

public void setStartStatement(String startStatement)

The start segment of the cypher query. START is prepended to the statement provided and should not be included.

Parameters:

startStatement - the start fragment of the cypher query.

setReturnStatement

public void setReturnStatement(String returnStatement)

The return statement of the cypher query. RETURN is prepended to the statement provided and should not be included

Parameters:

returnStatement - the return fragment of the cypher query.

setMatchStatement

public void setMatchStatement(String matchStatement)

An optional match fragment of the cypher query. MATCH is prepended to the statement provided and should not be included.

Parameters:

matchStatement - the match fragment of the cypher query

setWhereStatement

public void setWhereStatement(String whereStatement)

An optional where fragement of the cypher query. WHERE is prepended to the statement provided and should not be included.

Parameters:

whereStatement - where fragment of the cypher query

setOrderByStatement

public void setOrderByStatement(String orderByStatement)

A list of properties to order the results by. This is required so that subsequent page requests pull back the segment of results correctly. ORDER BY is prepended to the statement provided and should not be included.

Parameters:

orderByStatement - order by fragment of the cypher query.

setTemplate

public void setTemplate(org.springframework.data.neo4j.template.Neo4jOperations template)

Used to perform operations against the Neo4J database.

Parameters:

template - the Neo4jOperations instance to use

See Also:

Neo4jOperations

setTargetType

public void setTargetType(Class targetType)

The object type to be returned from each call to AbstractItemCountingItemStreamItemReader.read()

Parameters:

targetType - the type of object to return.

setResultConverter

public void setResultConverter(org.springframework.data.neo4j.conversion.ResultConverter resultConverter)

Set the converter used to convert node to the targetType. By default, DefaultConverter is used.

Parameters:

resultConverter - the converter to use.

doPageRead

protected Iterator<T> doPageRead()

Description copied from class: AbstractPaginatedDataItemReader

Method this ItemStreamReader delegates to for the actual work of reading a page. Each time this method is called, the resulting Iterator should contain the items read within the next page.

If the Iterator is empty or null when it is returned, this ItemReader will assume that the input has been exhausted.

Specified by:

doPageRead in class AbstractPaginatedDataItemReader<T>

Returns:

an Iterator containing the items within a page.

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Checks mandatory properties

Specified by:

afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean

Throws:

Exception

See Also:

InitializingBean.afterPropertiesSet()