org.springframework.batch.item.json.JsonItemReader Maven / Gradle / Ivy
/*
* Copyright 2018 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
*
* https://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.json;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.batch.item.ItemStreamReader;
import org.springframework.batch.item.file.ResourceAwareItemReaderItemStream;
import org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader;
import org.springframework.core.io.Resource;
import org.springframework.util.Assert;
/**
* {@link ItemStreamReader} implementation that reads Json objects from a
* {@link Resource} having the following format:
*
*
* [
* {
* // JSON object
* },
* {
* // JSON object
* }
* ]
*
*
*
* The implementation is not thread-safe.
*
* @param the type of json objects to read
*
* @author Mahmoud Ben Hassine
* @since 4.1
*/
public class JsonItemReader extends AbstractItemCountingItemStreamItemReader implements
ResourceAwareItemReaderItemStream {
private static final Log LOGGER = LogFactory.getLog(JsonItemReader.class);
private Resource resource;
private JsonObjectReader jsonObjectReader;
private boolean strict = true;
/**
* Create a new {@link JsonItemReader} instance.
* @param resource the input json resource
* @param jsonObjectReader the json object reader to use
*/
public JsonItemReader(Resource resource, JsonObjectReader jsonObjectReader) {
Assert.notNull(resource, "The resource must not be null.");
Assert.notNull(jsonObjectReader, "The json object reader must not be null.");
this.resource = resource;
this.jsonObjectReader = jsonObjectReader;
}
/**
* Set the {@link JsonObjectReader} to use to read and map Json fragments to domain objects.
* @param jsonObjectReader the json object reader to use
*/
public void setJsonObjectReader(JsonObjectReader jsonObjectReader) {
this.jsonObjectReader = jsonObjectReader;
}
/**
* In strict mode the reader will throw an exception on
* {@link #open(org.springframework.batch.item.ExecutionContext)} if the
* input resource does not exist.
* @param strict true by default
*/
public void setStrict(boolean strict) {
this.strict = strict;
}
@Override
public void setResource(Resource resource) {
this.resource = resource;
}
@Override
protected T doRead() throws Exception {
return jsonObjectReader.read();
}
@Override
protected void doOpen() throws Exception {
if (!this.resource.exists()) {
if (this.strict) {
throw new IllegalStateException("Input resource must exist (reader is in 'strict' mode)");
}
LOGGER.warn("Input resource does not exist " + this.resource.getDescription());
return;
}
if (!this.resource.isReadable()) {
if (this.strict) {
throw new IllegalStateException("Input resource must be readable (reader is in 'strict' mode)");
}
LOGGER.warn("Input resource is not readable " + this.resource.getDescription());
return;
}
this.jsonObjectReader.open(this.resource);
}
@Override
protected void doClose() throws Exception {
this.jsonObjectReader.close();
}
}