/*
* 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.file.builder;
import java.util.Comparator;
import org.springframework.batch.item.ExecutionContext;
import org.springframework.batch.item.ItemStream;
import org.springframework.batch.item.file.MultiResourceItemReader;
import org.springframework.batch.item.file.ResourceAwareItemReaderItemStream;
import org.springframework.core.io.Resource;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* A builder implementation for the {@link MultiResourceItemReader}.
*
* @author Glenn Renfro
* @since 4.0
* @see MultiResourceItemReader
*/
public class MultiResourceItemReaderBuilder<T> {
private ResourceAwareItemReaderItemStream<? extends T> delegate;
private Resource[] resources;
private boolean saveState = true;
private boolean strict = false;
private String name;
private Comparator<Resource> comparator;
/**
* The array of resources that the {@link MultiResourceItemReader} will use to
* retrieve items.
*
* @param resources the array of resources to use.
* @return this instance for method chaining.
*
* @see MultiResourceItemReader#setResources(Resource[])
*/
public MultiResourceItemReaderBuilder<T> resources(Resource[] resources) {
this.resources = resources;
return this;
}
/**
* Establishes the delegate to use for reading the resources provided.
*
* @param delegate reads items from single {@link Resource}.
* @return this instance for method chaining.
*
* @see MultiResourceItemReader#setDelegate(ResourceAwareItemReaderItemStream)
*/
public MultiResourceItemReaderBuilder<T> delegate(ResourceAwareItemReaderItemStream<? extends T> delegate) {
this.delegate = delegate;
return this;
}
/**
* Set the boolean indicating whether or not state should be saved in the provided
* {@link ExecutionContext} during the {@link ItemStream} call to update.
*
* @param saveState true to update ExecutionContext. False do not update
* ExecutionContext.
* @return this instance for method chaining.
* @see MultiResourceItemReader#setSaveState(boolean)
*
*/
public MultiResourceItemReaderBuilder<T> saveState(boolean saveState) {
this.saveState = saveState;
return this;
}
/**
* In strict mode the reader will throw an exception on
* {@link MultiResourceItemReader#open(org.springframework.batch.item.ExecutionContext)}
* if there are no resources to read.
*
* @param strict false by default.
* @return this instance for method chaining.
* @see MultiResourceItemReader#setStrict(boolean)
*/
public MultiResourceItemReaderBuilder<T> setStrict(boolean strict) {
this.strict = strict;
return this;
}
/**
* The name of the component which will be used as a stem for keys in the
* {@link ExecutionContext}. Subclasses should provide a default value, e.g. the short
* form of the class name.
*
* @param name the name for the component.
* @return this instance for method chaining.
* @see MultiResourceItemReader#setName(String)
*/
public MultiResourceItemReaderBuilder<T> name(String name) {
this.name = name;
return this;
}
/**
* Used to order the injected resources, by default compares
* {@link Resource#getFilename()} values.
*
* @param comparator the comparator to use for ordering resources.
* @return this instance for method chaining.
* @see MultiResourceItemReader#setComparator(Comparator)
*/
public MultiResourceItemReaderBuilder<T> comparator(Comparator<Resource> comparator) {
this.comparator = comparator;
return this;
}
/**
* Builds the {@link MultiResourceItemReader}.
*
* @return a {@link MultiResourceItemReader}
*/
public MultiResourceItemReader<T> build() {
Assert.notNull(this.resources, "resources array is required.");
Assert.notNull(this.delegate, "delegate is required.");
if (this.saveState) {
Assert.state(StringUtils.hasText(this.name), "A name is required when saveState is set to true.");
}
MultiResourceItemReader<T> reader = new MultiResourceItemReader<>();
reader.setResources(this.resources);
reader.setDelegate(this.delegate);
reader.setSaveState(this.saveState);
reader.setStrict(this.strict);
if (comparator != null) {
reader.setComparator(this.comparator);
}
if (StringUtils.hasText(this.name)) {
reader.setName(this.name);
}
return reader;
}
}