Java tutorial
/** * Copyright 2014 Groupon.com * * 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 com.arpnetworking.configuration.jackson; import com.arpnetworking.commons.builder.OvalBuilder; import com.arpnetworking.commons.jackson.databind.ObjectMapperFactory; import com.arpnetworking.configuration.Configuration; import com.arpnetworking.logback.annotations.LogValue; import com.arpnetworking.steno.LogValueMapFactory; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.type.TypeFactory; import net.sf.oval.constraint.NotNull; import java.io.IOException; import java.lang.reflect.Type; import java.util.Optional; import java.util.function.Function; /** * Common base class for <code>Configuration</code> implementations based on * Jackson's <code>ObjectMapper</code>. * * @author Ville Koskela (ville dot koskela at inscopemetrics dot com) */ public abstract class BaseJacksonConfiguration extends com.arpnetworking.configuration.BaseConfiguration { /** * {@inheritDoc} */ @Override public Optional<String> getProperty(final String name) { final Optional<JsonNode> jsonNode = getJsonSource().getValue(name.split("\\.")); if (jsonNode.isPresent()) { return Optional.ofNullable(jsonNode.get().asText()); } return Optional.empty(); } /** * {@inheritDoc} */ @Override public <T> Optional<T> getPropertyAs(final String name, final Class<? extends T> clazz) throws IllegalArgumentException { final Optional<String> property = getProperty(name); if (!property.isPresent()) { return Optional.empty(); } try { return Optional.ofNullable(_objectMapper.readValue(property.get(), clazz)); } catch (final IOException e) { throw new IllegalArgumentException( String.format("Unable to construct object from configuration; name=%s, class=%s, property=%s", name, clazz, property), e); } } /** * {@inheritDoc} */ @Override public <T> Optional<T> getAs(final Class<? extends T> clazz) throws IllegalArgumentException { final Optional<JsonNode> property = getJsonSource().getValue(); if (!property.isPresent()) { return Optional.empty(); } try { return Optional.ofNullable(_objectMapper.treeToValue(property.get(), clazz)); } catch (final JsonProcessingException e) { throw new IllegalArgumentException(String.format( "Unable to construct object from configuration; class=%s, property=%s", clazz, property), e); } } /** * {@inheritDoc} */ @Override public <T> Optional<T> getPropertyAs(final String name, final Type type) throws IllegalArgumentException { final Optional<String> property = getProperty(name); if (!property.isPresent()) { return Optional.empty(); } try { final TypeFactory typeFactory = _objectMapper.getTypeFactory(); @SuppressWarnings("unchecked") final Optional<T> value = Optional .ofNullable((T) _objectMapper.readValue(property.get(), typeFactory.constructType(type))); return value; } catch (final IOException e) { throw new IllegalArgumentException( String.format("Unable to construct object from configuration; name=%s, type=%s, property=%s", name, type, property), e); } } /** * {@inheritDoc} */ @Override public <T> Optional<T> getAs(final Type type) throws IllegalArgumentException { final Optional<JsonNode> property = getJsonSource().getValue(); if (!property.isPresent()) { return Optional.empty(); } try { final TypeFactory typeFactory = _objectMapper.getTypeFactory(); @SuppressWarnings("unchecked") final Optional<T> value = Optional.ofNullable((T) _objectMapper .readValue(_objectMapper.treeAsTokens(property.get()), typeFactory.constructType(type))); return value; } catch (final IOException e) { throw new IllegalArgumentException(String.format( "Unable to construct object from configuration; type=%s, property=%s", type, property), e); } } /** * {@inheritDoc} */ @LogValue @Override public Object toLogValue() { return LogValueMapFactory.builder(this).put("super", super.toLogValue()).put("ObjectMapper", _objectMapper) .build(); } /** * Accessor for active root <code>JsonSource</code> instance. * * @return Instance of <code>JsonSource</code>. */ protected abstract JsonNodeSource getJsonSource(); /** * Protected constructor. * * @param builder The <code>Builder</code> instance to construct from. */ protected BaseJacksonConfiguration(final Builder<?, ?> builder) { _objectMapper = builder._objectMapper; } protected final ObjectMapper _objectMapper; /** * Builder for <code>BaseObjectMapperConfiguration</code>. * * @param <T> type of the builder * @param <S> type of the object to be built */ protected abstract static class Builder<T extends Builder<?, ?>, S extends Configuration> extends OvalBuilder<S> { /** * Protected constructor for subclasses. * * @param targetConstructor The constructor for the concrete type to be created by this builder. */ @SuppressWarnings(value = { "rawtypes", "unchecked" }) protected Builder(final Function<T, S> targetConstructor) { super((Function<? extends Builder, S>) targetConstructor); } /** * Set the <code>ObjectMapper</code> instance. Optional. Default is * created by <code>ObjectMapperFactory</code>. Cannot be null. * * @param value The <code>ObjectMapper</code> instance. * @return This <code>Builder</code> instance. */ public T setObjectMapper(final ObjectMapper value) { _objectMapper = value; return self(); } /** * Called by setters to always return appropriate subclass of * <code>Builder</code>, even from setters of base class. * * @return instance with correct <code>Builder</code> class type. */ protected abstract T self(); @NotNull private ObjectMapper _objectMapper = ObjectMapperFactory.getInstance(); } }