Package org.springframework.batch.item.database

Class HibernateCursorItemReader<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.database.HibernateCursorItemReader<T>
All Implemented Interfaces:
ItemReader<T>, ItemStream, ItemStreamReader<T>, org.springframework.beans.factory.InitializingBean
public class HibernateCursorItemReader<T> extends AbstractItemCountingItemStreamItemReader<T> implements org.springframework.beans.factory.InitializingBean
ItemStreamReader for reading database records built on top of Hibernate. It executes the HQL query when initialized iterates over the result set as AbstractItemCountingItemStreamItemReader.read() method is called, returning an object corresponding to current row. The query can be set directly using setQueryString(String), a named query can be used by setQueryName(String), or a query provider strategy can be supplied via setQueryProvider(HibernateQueryProvider).

The reader can be configured to use either StatelessSession sufficient for simple mappings without the need to cascade to associated objects or standard hibernate Session for more advanced mappings or when caching is desired. When stateful session is used it will be cleared in the update(ExecutionContext) method without being flushed (no data modifications are expected).

The implementation is not thread-safe.
Author:
Robert Kasanicky, Dave Syer

  • Constructor Details

    • HibernateCursorItemReader

      public HibernateCursorItemReader()

  • Method Details

    • afterPropertiesSet

      public void afterPropertiesSet() throws Exception
      Specified by:
      afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean
      Throws:
      Exception

    • setParameterValues

      public void setParameterValues(Map<String,Object> parameterValues)
      The parameter values to apply to a query (map of name:value).
      Parameters:
      parameterValues - the parameter values to set

    • setQueryName

      public void setQueryName(String queryName)
      A query name for an externalized query. Either this or the { query string or the { query provider should be set.
      Parameters:
      queryName - name of a hibernate named query

    • setFetchSize

      public void setFetchSize(int fetchSize)
      Fetch size used internally by Hibernate to limit amount of data fetched from database per round trip.
      Parameters:
      fetchSize - the fetch size to pass down to Hibernate

    • setQueryProvider

      public void setQueryProvider(HibernateQueryProvider<T> queryProvider)
      A query provider. Either this or the {query string or the {query name should be set.
      Parameters:
      queryProvider - Hibernate query provider

    • setQueryString

      public void setQueryString(String queryString)
      A query string in HQL. Either this or the { query provider or the { query name should be set.
      Parameters:
      queryString - HQL query string

    • setSessionFactory

      public void setSessionFactory(org.hibernate.SessionFactory sessionFactory)
      The Hibernate SessionFactory to use the create a session.
      Parameters:
      sessionFactory - the SessionFactory to set

    • setUseStatelessSession

      public void setUseStatelessSession(boolean useStatelessSession)
      Can be set only in uninitialized state.
      Parameters:
      useStatelessSession - true to use StatelessSession false to use standard hibernate Session

    • doRead

      @Nullable protected T doRead() throws Exception
      Description copied from class: AbstractItemCountingItemStreamItemReader
      Read next item from input.
      Specified by:
      doRead in class AbstractItemCountingItemStreamItemReader<T>
      Returns:
      an item or null if the data source is exhausted
      Throws:
      Exception - Allows subclasses to throw checked exceptions for interpretation by the framework

    • doOpen

      protected void doOpen() throws Exception
      Open hibernate session and create a forward-only cursor for the query.
      Specified by:
      doOpen in class AbstractItemCountingItemStreamItemReader<T>
      Throws:
      Exception - Allows subclasses to throw checked exceptions for interpretation by the framework

    • update

      public void update(ExecutionContext executionContext) throws ItemStreamException
      Update the context and clear the session if stateful.
      Specified by:
      update in interface ItemStream
      Overrides:
      update in class AbstractItemCountingItemStreamItemReader<T>
      Parameters:
      executionContext - the current ExecutionContext
      Throws:
      ItemStreamException - if there is a problem
      See Also:

    • jumpToItem

      protected void jumpToItem(int itemIndex) throws Exception
      Wind forward through the result set to the item requested. Also clears the session every now and then (if stateful) to avoid memory problems. The frequency of session clearing is the larger of the fetch size (if set) and 100.
      Overrides:
      jumpToItem in class AbstractItemCountingItemStreamItemReader<T>
      Parameters:
      itemIndex - the first item to read
      Throws:
      Exception - if there is a problem
      See Also:

    • doClose

      protected void doClose() throws Exception
      Close the cursor and hibernate session.
      Specified by:
      doClose in class AbstractItemCountingItemStreamItemReader<T>
      Throws:
      Exception - Allows subclasses to throw checked exceptions for interpretation by the framework