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package eu.dnetlib.dhp.common.utils;
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import java.lang.reflect.Field;
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import org.apache.avro.Schema;
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/**
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*
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* @author Mateusz Kobos
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*
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*/
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public final class AvroUtils {
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public final static String primitiveTypePrefix = "org.apache.avro.Schema.Type.";
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//------------------------ CONSTRUCTORS -------------------
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private AvroUtils() {}
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//------------------------ LOGIC --------------------------
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/**
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* For a given name of a class generated from Avro schema return
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* a JSON schema.
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*
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* Apart from a name of a class you can also give a name of one of enums
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* defined in {@link org.apache.avro.Schema.Type}; in such case an
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* appropriate primitive type will be returned.
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*
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* @param typeName fully qualified name of a class generated from Avro schema,
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* e.g. {@code eu.dnetlib.dhp.common.avro.Person},
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* or a fully qualified name of enum defined by
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* {@link org.apache.avro.Schema.Type},
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* e.g. {@link org.apache.avro.Schema.Type.STRING}.
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* @return JSON string
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*/
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public static Schema toSchema(String typeName) {
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Schema schema = null;
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if(typeName.startsWith(primitiveTypePrefix)){
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String shortName = typeName.substring(
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primitiveTypePrefix.length(), typeName.length());
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schema = getPrimitiveTypeSchema(shortName);
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} else {
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schema = getAvroClassSchema(typeName);
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}
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return schema;
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}
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private static Schema getPrimitiveTypeSchema(String shortName){
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Schema.Type type = Schema.Type.valueOf(shortName);
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return Schema.create(type);
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}
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private static Schema getAvroClassSchema(String className){
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try {
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Class<?> avroClass = Class.forName(className);
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Field f = avroClass.getDeclaredField("SCHEMA$");
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return (Schema) f.get(null);
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} catch (ClassNotFoundException e) {
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throw new RuntimeException(
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"Class \""+className+"\" does not exist", e);
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} catch (SecurityException e) {
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throw new RuntimeException(e);
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} catch (NoSuchFieldException e) {
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throw new RuntimeException(e);
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} catch (IllegalArgumentException e) {
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throw new RuntimeException(e);
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} catch (IllegalAccessException e) {
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throw new RuntimeException(e);
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}
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}
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}
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