/*
* 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 javax.persistence.EntityManagerFactory;
import org.springframework.batch.item.database.JpaPagingItemReader;
import org.springframework.batch.item.database.orm.JpaQueryProvider;
import org.springframework.util.Assert;
/**
* Creates a fully qualified JpaPagingItemReader.
*
* @author Michael Minella
*
* @since 4.0
*/
public class JpaPagingItemReaderBuilder<T> {
private String name;
private int currentItem = 0;
private int maxItemCount = Integer.MAX_VALUE;
private boolean saveState = true;
private int pageSize = 10;
private EntityManagerFactory entityManagerFactory;
private Map<String, Object> parameterValues;
private boolean transacted = true;
private String queryString;
private JpaQueryProvider queryProvider;
/**
* 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 JpaPagingItemReader#setName(String)
*/
public JpaPagingItemReaderBuilder<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 JpaPagingItemReader#setCurrentItemCount(int)
*/
public JpaPagingItemReaderBuilder<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 JpaPagingItemReader#setMaxItemCount(int)
*/
public JpaPagingItemReaderBuilder<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 JpaPagingItemReader#setSaveState(boolean)
*/
public JpaPagingItemReaderBuilder<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 JpaPagingItemReader#setPageSize(int)
*/
public JpaPagingItemReaderBuilder<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 JpaPagingItemReader#setParameterValues(Map)
*/
public JpaPagingItemReaderBuilder<T> parameterValues(Map<String, Object> parameterValues) {
this.parameterValues = parameterValues;
return this;
}
/**
* A query provider. This should be set only if {@link #queryString(String)} have not
* been set.
*
* @param queryProvider the query provider
* @return this instance for method chaining
* @see JpaPagingItemReader#setQueryProvider(JpaQueryProvider)
*/
public JpaPagingItemReaderBuilder<T> queryProvider(JpaQueryProvider queryProvider) {
this.queryProvider = queryProvider;
return this;
}
/**
* The HQL query string to execute. This should only be set if
* {@link #queryProvider(JpaQueryProvider)} has not been set.
*
* @param queryString the HQL query
* @return this instance for method chaining
* @see JpaPagingItemReader#setQueryString(String)
*/
public JpaPagingItemReaderBuilder<T> queryString(String queryString) {
this.queryString = queryString;
return this;
}
/**
* Indicates if a transaction should be created around the read (true by default).
* Can be set to false in cases where JPA implementation doesn't support a particular
* transaction, however this may cause object inconsistency in the EntityManagerFactory.
*
* @param transacted defaults to true
* @return this instance for method chaining
* @see JpaPagingItemReader#setTransacted(boolean)
*/
public JpaPagingItemReaderBuilder<T> transacted(boolean transacted) {
this.transacted = transacted;
return this;
}
/**
* The {@link EntityManagerFactory} to be used for executing the configured
* {@link #queryString}.
*
* @param entityManagerFactory
* @return
*/
public JpaPagingItemReaderBuilder<T> entityManagerFactory(EntityManagerFactory entityManagerFactory) {
this.entityManagerFactory = entityManagerFactory;
return this;
}
/**
* Returns a fully constructed {@link JpaPagingItemReader}.
*
* @return a new {@link JpaPagingItemReader}
*/
public JpaPagingItemReader<T> build() {
Assert.isTrue(this.pageSize > 0, "pageSize must be greater than zero");
Assert.notNull(this.entityManagerFactory, "An EntityManagerFactory is required");
if(this.saveState) {
Assert.hasText(this.name,
"A name is required when saveState is set to true");
}
if(this.queryProvider == null) {
Assert.hasLength(this.queryString, "Query string is required when queryProvider is null");
}
JpaPagingItemReader<T> reader = new JpaPagingItemReader<>();
reader.setQueryString(this.queryString);
reader.setPageSize(this.pageSize);
reader.setParameterValues(this.parameterValues);
reader.setEntityManagerFactory(this.entityManagerFactory);
reader.setQueryProvider(this.queryProvider);
reader.setTransacted(this.transacted);
reader.setCurrentItemCount(this.currentItem);
reader.setMaxItemCount(this.maxItemCount);
reader.setSaveState(this.saveState);
reader.setName(this.name);
return reader;
}
}