/*
* Copyright 2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.batch.item.database.builder;
import java.util.Map;
import org.hibernate.SessionFactory;
import org.springframework.batch.item.database.HibernatePagingItemReader;
import org.springframework.batch.item.database.orm.HibernateQueryProvider;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* A builder for the {@link HibernatePagingItemReader}. When configuring, only one of the
* following should be provided:
* <ul>
* <li>{@link #queryString(String)}</li>
* <li>{@link #queryName(String)}</li>
* <li>{@link #queryProvider(HibernateQueryProvider)}</li>
* </ul>
*
* @author Michael Minella
* @since 4.0
* @see HibernatePagingItemReader
*/
public class HibernatePagingItemReaderBuilder<T> {
private String name;
private int currentItem = 0;
private int maxItemCount = Integer.MAX_VALUE;
private boolean saveState = true;
private int pageSize = 10;
private Map<String, Object> parameterValues;
private String queryName;
private int fetchSize;
private HibernateQueryProvider<? extends T> queryProvider;
private String queryString;
private SessionFactory sessionFactory;
private boolean statelessSession = true;
/**
* A name used to prevent key collisions while saving the state in the
* {@link org.springframework.batch.item.ExecutionContext}
*
* @param name unique name for this reader instance
* @return this instance for method chaining
* @see HibernatePagingItemReader#setName(String)
*/
public HibernatePagingItemReaderBuilder<T> name(String name) {
this.name = name;
return this;
}
/**
* Index for the current item. Used on restarts to indicate where to start from.
*
* @param currentItem current index
* @return this instance for method chaining
* @see HibernatePagingItemReader#setCurrentItemCount(int)
*/
public HibernatePagingItemReaderBuilder<T> currentItem(int currentItem) {
this.currentItem = currentItem;
return this;
}
/**
* The index of the max item to be read.
*
* @param maxItemCount max index
* @return this instance for method chaining
* @see HibernatePagingItemReader#setMaxItemCount(int)
*/
public HibernatePagingItemReaderBuilder<T> maxItemCount(int maxItemCount) {
this.maxItemCount = maxItemCount;
return this;
}
/**
* Indicates if the state should be saved. If set to false, restarts will begin at
* the beginning of the dataset. Defaults to true
*
* @param saveState indicator
* @return this instance for method chaining
* @see HibernatePagingItemReader#setSaveState(boolean)
*/
public HibernatePagingItemReaderBuilder<T> saveState(boolean saveState) {
this.saveState = saveState;
return this;
}
/**
* The number of records to request per page/query. Defaults to 10. Must be greater
* than zero.
*
* @param pageSize number of items
* @return this instance for method chaining
* @see HibernatePagingItemReader#setPageSize(int)
*/
public HibernatePagingItemReaderBuilder<T> pageSize(int pageSize) {
this.pageSize = pageSize;
return this;
}
/**
* A map of parameter values to be set on the query. The key of the map is the name
* of the parameter to be set with the value being the value to be set.
*
* @param parameterValues map of values
* @return this instance for method chaining
* @see HibernatePagingItemReader#setParameterValues(Map)
*/
public HibernatePagingItemReaderBuilder<T> parameterValues(Map<String, Object> parameterValues) {
this.parameterValues = parameterValues;
return this;
}
/**
* The name of the Hibernate named query to be executed for this reader.
*
* @param queryName name of the query to execute
* @return this instance for method chaining
* @see HibernatePagingItemReader#setQueryName(String)
*/
public HibernatePagingItemReaderBuilder<T> queryName(String queryName) {
this.queryName = queryName;
return this;
}
/**
* Fetch size used internally by Hibernate to limit amount of data fetched
* from database per round trip.
*
* @param fetchSize number of records
* @return this instance for method chaining
* @see HibernatePagingItemReader#setFetchSize(int)
*/
public HibernatePagingItemReaderBuilder<T> fetchSize(int fetchSize) {
this.fetchSize = fetchSize;
return this;
}
/**
* A query provider. This should be set only if {@link #queryString(String)} and
* {@link #queryName(String)} have not been set.
*
* @param queryProvider the query provider
* @return this instance for method chaining
* @see HibernatePagingItemReader#setQueryProvider(HibernateQueryProvider)
*/
public HibernatePagingItemReaderBuilder<T> queryProvider(HibernateQueryProvider queryProvider) {
this.queryProvider = queryProvider;
return this;
}
/**
* The HQL query string to execute. This should only be set if
* {@link #queryProvider(HibernateQueryProvider)} and {@link #queryName(String)} have
* not been set.
*
* @param queryString the HQL query
* @return this instance for method chaining
* @see HibernatePagingItemReader#setQueryString(String)
*/
public HibernatePagingItemReaderBuilder<T> queryString(String queryString) {
this.queryString = queryString;
return this;
}
/**
* The Hibernate {@link SessionFactory} to execute the query against.
*
* @param sessionFactory the session factory
* @return this instance for method chaining
* @see HibernatePagingItemReader#setSessionFactory(SessionFactory)
*/
public HibernatePagingItemReaderBuilder<T> sessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
return this;
}
/**
* Indicator for whether to use a {@link org.hibernate.StatelessSession}
* (<code>true</code>) or a {@link org.hibernate.Session} (<code>false</code>).
*
* @param useStatelessSession Defaults to false
* @return this instance for method chaining
* @see HibernatePagingItemReader#setUseStatelessSession(boolean)
*/
public HibernatePagingItemReaderBuilder<T> useSatelessSession(boolean useStatelessSession) {
this.statelessSession = useStatelessSession;
return this;
}
/**
* Returns a fully constructed {@link HibernatePagingItemReader}.
*
* @return a new {@link HibernatePagingItemReader}
*/
public HibernatePagingItemReader<T> build() {
Assert.notNull(this.sessionFactory, "A SessionFactory must be provided");
Assert.state(this.fetchSize >= 0, "fetchSize must not be negative");
if(this.saveState) {
Assert.hasText(this.name,
"A name is required when saveState is set to true");
}
if(this.queryProvider == null) {
Assert.state(StringUtils.hasText(queryString) ^ StringUtils.hasText(queryName),
"queryString or queryName must be set");
}
HibernatePagingItemReader<T> reader = new HibernatePagingItemReader<>();
reader.setSessionFactory(this.sessionFactory);
reader.setSaveState(this.saveState);
reader.setMaxItemCount(this.maxItemCount);
reader.setCurrentItemCount(this.currentItem);
reader.setName(this.name);
reader.setFetchSize(this.fetchSize);
reader.setParameterValues(this.parameterValues);
reader.setQueryName(this.queryName);
reader.setQueryProvider(this.queryProvider);
reader.setQueryString(this.queryString);
reader.setPageSize(this.pageSize);
reader.setUseStatelessSession(this.statelessSession);
return reader;
}
}