Java tutorial
/* * Copyright (C) 2012 Facebook, Inc. * * 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.facebook.swift.codec.internal.reflection; import com.facebook.swift.codec.ThriftCodec; import com.facebook.swift.codec.ThriftCodecManager; import com.facebook.swift.codec.internal.TProtocolReader; import com.facebook.swift.codec.internal.TProtocolWriter; import com.facebook.swift.codec.metadata.FieldKind; import com.facebook.swift.codec.metadata.ThriftConstructorInjection; import com.facebook.swift.codec.metadata.ThriftFieldInjection; import com.facebook.swift.codec.metadata.ThriftFieldMetadata; import com.facebook.swift.codec.metadata.ThriftInjection; import com.facebook.swift.codec.metadata.ThriftMethodInjection; import com.facebook.swift.codec.metadata.ThriftStructMetadata; import com.google.common.base.Throwables; import com.google.common.collect.Maps; import org.apache.thrift.protocol.TProtocol; import javax.annotation.concurrent.Immutable; import java.lang.reflect.InvocationTargetException; import java.util.Map; import static com.facebook.swift.codec.metadata.FieldKind.THRIFT_FIELD; import static com.google.common.base.Preconditions.checkNotNull; import static com.google.common.base.Preconditions.checkState; import static com.google.common.collect.Iterables.getOnlyElement; import static java.lang.String.format; @Immutable public class ReflectionThriftUnionCodec<T> extends AbstractReflectionThriftCodec<T> { private final Map<Short, ThriftFieldMetadata> metadataMap; private final Map.Entry<ThriftFieldMetadata, ThriftCodec<?>> idField; public ReflectionThriftUnionCodec(ThriftCodecManager manager, ThriftStructMetadata metadata) { super(manager, metadata); ThriftFieldMetadata idField = getOnlyElement(metadata.getFields(FieldKind.THRIFT_UNION_ID)); this.idField = Maps.<ThriftFieldMetadata, ThriftCodec<?>>immutableEntry(idField, manager.getCodec(idField.getThriftType())); checkNotNull(this.idField.getValue(), "No codec for id field %s found", idField); this.metadataMap = Maps.uniqueIndex(metadata.getFields(), ThriftFieldMetadata.getIdGetter()); } @Override public T read(TProtocol protocol) throws Exception { TProtocolReader reader = new TProtocolReader(protocol); reader.readStructBegin(); Map.Entry<Short, Object> data = null; Short fieldId = null; while (reader.nextField()) { checkState(fieldId == null, "Received Union with more than one value (seen id %s, now id %s)", fieldId, reader.getFieldId()); fieldId = reader.getFieldId(); // do we have a codec for this field ThriftCodec<?> codec = fields.get(fieldId); if (codec == null) { reader.skipFieldData(); } else { // is this field readable ThriftFieldMetadata field = metadata.getField(fieldId); if (field.isWriteOnly() || field.getType() != THRIFT_FIELD) { reader.skipFieldData(); continue; } // read the value Object value = reader.readField(codec); if (value == null) { continue; } data = Maps.immutableEntry(fieldId, value); } } reader.readStructEnd(); // build the struct return constructStruct(data); } @Override public void write(T instance, TProtocol protocol) throws Exception { TProtocolWriter writer = new TProtocolWriter(protocol); Short idValue = (Short) getFieldValue(instance, idField.getKey()); writer.writeStructBegin(metadata.getStructName()); if (metadataMap.containsKey(idValue)) { ThriftFieldMetadata fieldMetadata = metadataMap.get(idValue); if (fieldMetadata.isReadOnly() || fieldMetadata.getType() != THRIFT_FIELD) { throw new IllegalStateException(format("Field %s is not readable", fieldMetadata.getName())); } Object fieldValue = getFieldValue(instance, fieldMetadata); // write the field if (fieldValue != null) { @SuppressWarnings("unchecked") ThriftCodec<Object> codec = (ThriftCodec<Object>) fields.get(fieldMetadata.getId()); writer.writeField(fieldMetadata.getName(), fieldMetadata.getId(), codec, fieldValue); } } writer.writeStructEnd(); } @SuppressWarnings("unchecked") private T constructStruct(Map.Entry<Short, Object> data) throws Exception { // construct instance Object instance = null; ThriftFieldMetadata fieldMetadata = null; if (data != null) { fieldMetadata = metadataMap.get(data.getKey()); if (fieldMetadata != null && fieldMetadata.getConstructorInjection().isPresent()) { ThriftConstructorInjection constructor = fieldMetadata.getConstructorInjection().get(); Object[] parametersValues = new Object[] { data.getValue() }; try { instance = constructor.getConstructor().newInstance(parametersValues); } catch (InvocationTargetException e) { if (e.getTargetException() != null) { Throwables.propagateIfInstanceOf(e.getTargetException(), Exception.class); } throw e; } } } if (instance == null && metadata.getConstructorInjection().isPresent()) { ThriftConstructorInjection constructor = metadata.getConstructorInjection().get(); // must be no-args Object[] parametersValues = new Object[0]; try { instance = constructor.getConstructor().newInstance(parametersValues); } catch (InvocationTargetException e) { if (e.getTargetException() != null) { Throwables.propagateIfInstanceOf(e.getTargetException(), Exception.class); } throw e; } } if (fieldMetadata != null) { // inject fields for (ThriftInjection injection : fieldMetadata.getInjections()) { if (injection instanceof ThriftFieldInjection) { ThriftFieldInjection fieldInjection = (ThriftFieldInjection) injection; if (data.getValue() != null) { fieldInjection.getField().set(instance, data.getValue()); } } } if (fieldMetadata.getMethodInjection().isPresent()) { Object[] parametersValues = new Object[] { data.getValue() }; if (data.getValue() != null) { try { fieldMetadata.getMethodInjection().get().getMethod().invoke(instance, parametersValues); } catch (InvocationTargetException e) { if (e.getTargetException() != null) { Throwables.propagateIfInstanceOf(e.getTargetException(), Exception.class); } throw e; } } } } if (data != null) { // inject id value for (ThriftInjection injection : idField.getKey().getInjections()) { if (injection instanceof ThriftFieldInjection) { ThriftFieldInjection fieldInjection = (ThriftFieldInjection) injection; fieldInjection.getField().set(instance, data.getKey()); } } // builder method if (metadata.getBuilderMethod().isPresent()) { ThriftMethodInjection builderMethod = metadata.getBuilderMethod().get(); Object[] parametersValues = new Object[] { data.getValue() }; try { instance = builderMethod.getMethod().invoke(instance, parametersValues); checkState(instance != null, "Builder method returned a null instance"); checkState(metadata.getStructClass().isInstance(instance), "Builder method returned instance of type %s, but an instance of %s is required", instance.getClass().getName(), metadata.getStructClass().getName()); } catch (InvocationTargetException e) { if (e.getTargetException() != null) { Throwables.propagateIfInstanceOf(e.getTargetException(), Exception.class); } throw e; } } } return (T) instance; } }