hadoop JsonObjectMapperWriter 源码
haddop JsonObjectMapperWriter 代码
文件路径：/hadoop-tools/hadoop-rumen/src/main/java/org/apache/hadoop/tools/rumen/JsonObjectMapperWriter.java
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.hadoop.tools.rumen;
import java.io.Closeable;
import java.io.IOException;
import java.io.OutputStream;
import com.fasterxml.jackson.core.JsonEncoding;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.Version;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import org.apache.hadoop.mapreduce.ID;
import org.apache.hadoop.tools.rumen.datatypes.DataType;
import org.apache.hadoop.tools.rumen.serializers.DefaultRumenSerializer;
import org.apache.hadoop.tools.rumen.serializers.ObjectStringSerializer;
/**
* Simple wrapper around {@link JsonGenerator} to write objects in JSON format.
* @param <T> The type of the objects to be written.
*/
public class JsonObjectMapperWriter<T> implements Closeable {
private JsonGenerator writer;
public JsonObjectMapperWriter(OutputStream output, boolean prettyPrint) throws IOException {
ObjectMapper mapper = new ObjectMapper();
// define a module
SimpleModule module = new SimpleModule(
"Default Serializer", new Version(0, 1, 1, "FINAL", "", ""));
// add various serializers to the module
// add default (all-pass) serializer for all rumen specific data types
module.addSerializer(DataType.class, new DefaultRumenSerializer());
// add a serializer to use object.toString() while serializing
module.addSerializer(ID.class, new ObjectStringSerializer<ID>());
// register the module with the object-mapper
mapper.registerModule(module);
writer = mapper.getFactory().createGenerator(output, JsonEncoding.UTF8);
if (prettyPrint) {
writer.useDefaultPrettyPrinter();
}
}
public void write(T object) throws IOException {
writer.writeObject(object);
}
@Override
public void close() throws IOException {
writer.close();
}
}
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