/**
* 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.avro.data;
import java.io.IOException;
import java.util.Iterator;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.node.JsonNodeFactory;
import org.codehaus.jackson.node.LongNode;
import org.codehaus.jackson.node.DoubleNode;
import org.codehaus.jackson.node.TextNode;
import org.codehaus.jackson.node.BooleanNode;
import org.codehaus.jackson.node.NullNode;
import org.codehaus.jackson.node.ArrayNode;
import org.codehaus.jackson.node.ObjectNode;
import org.apache.avro.Schema;
import org.apache.avro.AvroRuntimeException;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.io.Encoder;
import org.apache.avro.io.Decoder;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.io.ResolvingDecoder;
/** Utilities for reading and writing arbitrary Json data in Avro format. */
public class Json {
private Json() {} // singleton: no public ctor
/** The schema for Json data. */
public static final Schema SCHEMA;
static {
try {
SCHEMA = Schema.parse
(Json.class.getResourceAsStream("/org/apache/avro/data/Json.avsc"));
} catch (IOException e) {
throw new AvroRuntimeException(e);
}
}
/** {@link DatumWriter} for arbitrary Json data. */
public static class Writer implements DatumWriter<JsonNode> {
@Override public void setSchema(Schema schema) {
if (!SCHEMA.equals(schema))
throw new RuntimeException("Not the Json schema: "+schema);
}
@Override
public void write(JsonNode datum, Encoder out) throws IOException {
Json.write(datum, out);
}
}
/** {@link DatumReader} for arbitrary Json data. */
public static class Reader implements DatumReader<JsonNode> {
private Schema written;
private ResolvingDecoder resolver;
@Override public void setSchema(Schema schema) {
this.written = SCHEMA.equals(written) ? null : schema;
}
@Override
public JsonNode read(JsonNode reuse, Decoder in) throws IOException {
if (written == null) // same schema
return Json.read(in);
// use a resolver to adapt alternate version of Json schema
if (resolver == null)
resolver = DecoderFactory.get().resolvingDecoder(written, SCHEMA, null);
resolver.configure(in);
JsonNode result = Json.read(resolver);
resolver.drain();
return result;
}
}
/** Note: this enum must be kept aligned with the union in Json.avsc. */
private enum JsonType { LONG, DOUBLE, STRING, BOOLEAN, NULL, ARRAY, OBJECT }
/** Write Json data as Avro data. */
public static void write(JsonNode node, Encoder out) throws IOException {
switch(node.asToken()) {
case VALUE_NUMBER_INT:
out.writeIndex(JsonType.LONG.ordinal());
out.writeLong(node.getLongValue());
break;
case VALUE_NUMBER_FLOAT:
out.writeIndex(JsonType.DOUBLE.ordinal());
out.writeDouble(node.getDoubleValue());
break;
case VALUE_STRING:
out.writeIndex(JsonType.STRING.ordinal());
out.writeString(node.getTextValue());
break;
case VALUE_TRUE:
out.writeIndex(JsonType.BOOLEAN.ordinal());
out.writeBoolean(true);
break;
case VALUE_FALSE:
out.writeIndex(JsonType.BOOLEAN.ordinal());
out.writeBoolean(false);
break;
case VALUE_NULL:
out.writeIndex(JsonType.NULL.ordinal());
out.writeNull();
break;
case START_ARRAY:
out.writeIndex(JsonType.ARRAY.ordinal());
out.writeArrayStart();
out.setItemCount(node.size());
for (JsonNode element : node) {
out.startItem();
write(element, out);
}
out.writeArrayEnd();
break;
case START_OBJECT:
out.writeIndex(JsonType.OBJECT.ordinal());
out.writeMapStart();
out.setItemCount(node.size());
Iterator<String> i = node.getFieldNames();
while (i.hasNext()) {
out.startItem();
String name = i.next();
out.writeString(name);
write(node.get(name), out);
}
out.writeMapEnd();
break;
default:
throw new AvroRuntimeException(node.asToken()+" unexpected: "+node);
}
}
/** Read Json data from Avro data. */
public static JsonNode read(Decoder in) throws IOException {
switch (JsonType.values()[in.readIndex()]) {
case LONG:
return new LongNode(in.readLong());
case DOUBLE:
return new DoubleNode(in.readDouble());
case STRING:
return new TextNode(in.readString());
case BOOLEAN:
return in.readBoolean() ? BooleanNode.TRUE : BooleanNode.FALSE;
case NULL:
in.readNull();
return NullNode.getInstance();
case ARRAY:
ArrayNode array = JsonNodeFactory.instance.arrayNode();
for (long l = in.readArrayStart(); l > 0; l = in.arrayNext())
for (long i = 0; i < l; i++)
array.add(read(in));
return array;
case OBJECT:
ObjectNode object = JsonNodeFactory.instance.objectNode();
for (long l = in.readMapStart(); l > 0; l = in.mapNext())
for (long i = 0; i < l; i++)
object.put(in.readString(), read(in));
return object;
default:
throw new AvroRuntimeException("Unexpected Json node type");
}
}
}