Ligthweight generation of protobuf <-> bean mapper classes. Based on annotation processing. It depends directly on the generated Java code from:
- google [protoc compiler] (https://code.google.com/p/protobuf/downloads/list) (tested on versions 2.4.1 and 2.5.0)
- square [wire compiler] (https://github.com/square/wire) (tested on version 1.3.3)
To get generated mapper of java bean <-> protobuf message/enum you have to annotate your java bean class with @Mapper(protoClass = CorrespondingProtobuf.class) annonation. Also you have to annonate required for mapping fields with @Field annotation. Optionally you could provide name value if a field name declared in a java bean differs from such in the protocol definition. Also add optional value if a field is optional in the protocol.
For example, suppose we generated Services.java with protoc (or Result.java, Entry.java and Map.java with wire) in package com.model.protobuf.dto from the following protobuf protocol:
enum Result {
OK = 1;
WRONG_CREDENTIALS = 2;
BLOCKED_ACCOUNT = 3;
}
message Entry {
required string key = 1;
optional string value = 2;
}
message Map {
repeated Entry entries = 1;
}
Also we defined three Java bean classes. Now add @Mapper and @Field annotations to them:
//@Mapper(protoClass = com.model.protobuf.dto.Result.class) - for wire
@Mapper(protoClass = com.model.protobuf.dto.Services.Result.class)
public enum Result {
OK(1),
WRONG_CREDENTIALS(2),
BLOCKED_ACCOUNT(3);
@Field
public final int code;
private Result(int code) {
this.code = code;
}
}
Note: enum must have one public or package field with @Field annotation. Values of that field must corresponds to values from protocol.
For Map and Entry:
//@Mapper(protoClass = com.model.protobuf.dto.Entry.class) - for wire
@Mapper(protoClass = com.model.protobuf.dto.Services.Entry.class)
public class Entry {
private @Field String key;
private @Field String value;
public String getKey() {
return key;
}
public void setKey(String key) {
this.key = key;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
//@Mapper(protoClass = com.model.protobuf.dto.Map.class) - for wire
@Mapper(protoClass = com.model.protobuf.dto.Services.Map.class)
public class Map {
private @Field List<Entry> entries;
public List<Entry> getEntries() {
return entries;
}
public void setEntries(List<Entry> entries) {
this.entries = entries;
}
}
After processing this classes Proto-Mapper will generate for ResultMapper.java:
public class ResultMapper
implements com.shaubert.protomapper.protoc.ProtoMappers.Mapper<Result, Services.Result> {
@Override
public Result mapFromProto(InputStream stream) throws IOException {
throw new UnsupportedOperationException("Can not parse enum class from InputStream");
}
@Override
public Result mapFromProto(Services.Result protoClass) {
for (Result result : Result.values()) {
if (result.code == protoClass.getNumber()) {
return result;
}
}
throw new IllegalArgumentException("Unable to parse Result from: "
+ protoClass);
}
@Override
public Services.Result mapToProto(Result modelClass) {
for (Services.Result result : Services.Result.values()) {
if (result.getNumber() == modelClass.code) {
return result;
}
}
throw new IllegalArgumentException("Unable to convert " + modelClass
+ " to " + Services.Result.class);
}
@Override
public Class<Result> getDataClass() {
return Result.class;
}
@Override
public Class<Services.Result> getProtoClass() {
return Services.Result.class;
}
}
EntryMapper.java:
public class EntryMapper
implements com.shaubert.protomapper.protoc.ProtoMappers.Mapper<Entry, Services.Entry> {
@Override
public Entry mapFromProto(InputStream stream) throws IOException {
Services.Entry protoClass =
Services.Entry.parseFrom(stream);
return mapFromProto(protoClass);
}
@Override
public Entry mapFromProto(Services.Entry protoClass) {
Entry result = new Entry();
result.setKey(protoClass.getKey());
result.setValue(protoClass.getValue());
return result;
}
@Override
public Services.Entry mapToProto(Entry modelClass) {
Services.Entry.Builder result =
Services.Entry.newBuilder();
result.setKey(modelClass.getKey());
result.setValue(modelClass.getValue());
return result.build();
}
@Override
public Class<Entry> getDataClass() {
return Entry.class;
}
@Override
public Class<Services.Entry> getProtoClass() {
return Services.Entry.class;
}
}
And MapMapper.java:
public class MapMapper
implements com.shaubert.protomapper.protoc.ProtoMappers.Mapper<Map, Services.Map> {
@Override
public Map mapFromProto(InputStream stream) throws IOException {
Services.Map protoClass =
Services.Map.parseFrom(stream);
return mapFromProto(protoClass);
}
@Override
public Map mapFromProto(Services.Map protoClass) {
Map result = new Map();
List<Entry> entries = new ArrayList<Entry>();
{
EntryMapper mapper = new EntryMapper();
for (Services.Entry el : protoClass.getEntriesList()) {
entries.add(mapper.mapFromProto(el));
}
}
result.setEntries(entries);
return result;
}
@Override
public Services.Map mapToProto(Map modelClass) {
Services.Map.Builder result =
Services.Map.newBuilder();
{
EntryMapper mapper = new EntryMapper();
for (Entry el : modelClass.getEntries()) {
result.addEntries(mapper.mapToProto(el));
}
}
return result.build();
}
@Override
public Class<Map> getDataClass() {
return Map.class;
}
@Override
public Class<Services.Map> getProtoClass() {
return Services.Map.class;
}
}
Also you will get com.shaubert.protomapper.protoc.ProtoMappers:
public class ProtoMappers {
public interface Mapper<DataClass, ProtoClass> {
DataClass mapFromProto(InputStream inputStream) throws IOException;
DataClass mapFromProto(ProtoClass protoClass);
ProtoClass mapToProto(DataClass dataClass);
Class<DataClass> getDataClass();
Class<ProtoClass> getProtoClass();
}
protected List<Mapper<?, ?>> mappers = new ArrayList<Mapper<?, ?>>();
private static ProtoMappers instance;
public static ProtoMappers getInstance() {
if (instance == null) {
instance = new ProtoMappers();
}
return instance;
}
public ProtoMappers() {
mappers.add(new com.shaubert.protomapper.ResultMapper());
mappers.add(new com.shaubert.protomapper.EntryMapper());
mappers.add(new com.shaubert.protomapper.MapMapper());
}
@SuppressWarnings("unchecked")
public <DataClass, ProtoClass> Mapper<DataClass, ProtoClass> getMapper(
Class<DataClass> dataClass, Class<ProtoClass> protoClass) {
for (Mapper<?, ?> mapper : mappers) {
if (mapper.getDataClass().equals(dataClass)
&& mapper.getProtoClass().equals(protoClass)) {
return (Mapper<DataClass, ProtoClass>) mapper;
}
}
return null;
}
@SuppressWarnings("unchecked")
public <DataClass, ProtoClass> Mapper<DataClass, ProtoClass> getFirstFromData(Class<DataClass> dataClass) {
for (Mapper<?, ?> mapper : mappers) {
if (mapper.getDataClass().equals(dataClass)) {
return (Mapper<DataClass, ProtoClass>) mapper;
}
}
return null;
}
@SuppressWarnings("unchecked")
public <DataClass, ProtoClass> Mapper<DataClass, ProtoClass> getFirstFromProto(Class<ProtoClass> protoClass) {
for (Mapper<?, ?> mapper : mappers) {
if (mapper.getProtoClass().equals(protoClass)) {
return (Mapper<DataClass, ProtoClass>) mapper;
}
}
return null;
}
@SuppressWarnings("unchecked")
public static AbstractMessageLite mapToMessage(Object data) {
ProtoMappers mappers = getInstance();
Mapper mapper = mappers.getFirstFromData(data.getClass());
throwIfMapperNotFound(mapper, data.getClass());
return (AbstractMessageLite) mapper.mapToProto(data);
}
@SuppressWarnings("unchecked")
public static <T> T mapFromProto(Object proto) {
ProtoMappers mappers = getInstance();
Mapper mapper = mappers.getFirstFromProto(proto.getClass());
throwIfMapperNotFound(mapper, proto.getClass());
return (T) mapper.mapFromProto(proto);
}
@SuppressWarnings("unchecked")
public static <T> T mapFromProtoByProtoClass(InputStream inputStream, Class<?> protoClass) throws IOException {
ProtoMappers mappers = getInstance();
Mapper mapper = mappers.getFirstFromProto(protoClass);
throwIfMapperNotFound(mapper, protoClass);
return (T) mapper.mapFromProto(inputStream);
}
@SuppressWarnings("unchecked")
public static <T> T mapFromProtoByDataClass(InputStream inputStream, Class<?> dataClass) throws IOException {
ProtoMappers mappers = getInstance();
Mapper mapper = mappers.getFirstFromData(dataClass);
throwIfMapperNotFound(mapper, dataClass);
return (T) mapper.mapFromProto(inputStream);
}
private static void throwIfMapperNotFound(Object mapper, Class<?> forClass) {
if (mapper == null) {
throw new NullPointerException("mapper for " + forClass + " not found");
}
}
}
ResultMapper.java:
public class ResultMapper
implements ProtoMappers.Mapper<Result, com.model.protobuf.dto.Result> {
@Override
public Result mapFromProto(InputStream stream) throws IOException {
throw new UnsupportedOperationException("Can not parse enum class from InputStream, "
+ "call mapFromProto(protoClass) instead");
}
@Override
public Result mapFromProto(com.model.protobuf.dto.Result protoClass) {
for (LoginResultTest result :
LoginResultTest.values()) {
if (result.code == protoClass.getValue()) {
return result;
}
}
throw new IllegalArgumentException("Unable to parse LoginResultTest from: "
+ protoClass);
}
@Override
public com.model.protobuf.dto.Result mapToProto(LoginResultTest modelClass) {
for (com.model.protobuf.dto.Result result :
com.model.protobuf.dto.Result.values()) {
if (result.getValue() == modelClass.code) {
return result;
}
}
throw new IllegalArgumentException("Unable to convert " + modelClass
+ " to " + com.model.protobuf.dto.Result.class);
}
@Override
public Class<Result> getDataClass() {
return Result.class;
}
@Override
public Class<com.model.protobuf.dto.Result> getProtoClass() {
return com.model.protobuf.dto.Result.class;
}
}
EntryMapper.java:
public class EntryMapper
implements ProtoMappers.Mapper<Entry, com.model.protobuf.dto.Entry> {
@Override
public Entry mapFromProto(InputStream stream) throws IOException {
Wire wire = ProtoMappers.get().getWire();
com.model.protobuf.dto.Entry protoClass =
wire.parseFrom(stream, com.model.protobuf.dto.Entry.class);
return mapFromProto(protoClass);
}
@Override
public Entry mapFromProto(com.model.protobuf.dto.Entry protoClass) {
Entry result = new Entry();
result.setKey(protoClass.key);
result.setValue(protoClass.value);
return result;
}
@Override
public com.model.protobuf.dto.Entry mapToProto(Entry modelClass) {
com.model.protobuf.dto.Entry.Builder result =
new com.model.protobuf.dto.Entry.Builder();
result.key(modelClass.getKey());
result.value(modelClass.getValue());
return result.build();
}
@Override
public Class<Entry> getDataClass() {
return Entry.class;
}
@Override
public Class<com.model.protobuf.dto.Entry> getProtoClass() {
return com.model.protobuf.dto.Entry.class;
}
}
And MapMapper.java:
public class MapMapper
implements ProtoMappers.Mapper<Map, com.model.protobuf.dto.Map> {
@Override
public Map mapFromProto(InputStream stream) throws IOException {
Wire wire = ProtoMappers.get().getWire();
com.model.protobuf.dto.Map protoClass =
wire.parseFrom(stream, com.model.protobuf.dto.Map.class);
return mapFromProto(protoClass);
}
@Override
public Map mapFromProto(com.model.protobuf.dto.Map protoClass) {
Map result = new Map();
java.util.List<com.shaubert.protomapper.wire.sample.EntryTest> entries = new java.util.ArrayList<com.shaubert.protomapper.wire.sample.EntryTest>();
{
com.shaubert.protomapper.wire.sample.EntryTestMapper mapper = new com.shaubert.protomapper.wire.sample.EntryTestMapper();
for (com.model.protobuf.dto.Entry el : protoClass.entries) {
entries.add(mapper.mapFromProto(el));
}
}
result.setEntries(entries);
return result;
}
@Override
public com.model.protobuf.dto.Map mapToProto(Map modelClass) {
com.model.protobuf.dto.Map.Builder result =
new com.model.protobuf.dto.Map.Builder();
{
java.util.List<com.model.protobuf.dto.Entry> entries =
new java.util.ArrayList<com.model.protobuf.dto.Entry>(modelClass.getEntries().size());
com.shaubert.protomapper.wire.sample.EntryTestMapper mapper = new com.shaubert.protomapper.wire.sample.EntryTestMapper();
for (com.shaubert.protomapper.wire.sample.EntryTest el : modelClass.getEntries()) {
entries.add(mapper.mapToProto(el));
}
result.entries(entries);
}
return result.build();
}
@Override
public Class<Map> getDataClass() {
return Map.class;
}
@Override
public Class<com.model.protobuf.dto.Map> getProtoClass() {
return com.model.protobuf.dto.Map.class;
}
}
Also you will get com.shaubert.protomapper.wire.ProtoMappers:
public class ProtoMappers {
public interface Mapper<DataClass, ProtoClass> {
DataClass mapFromProto(InputStream inputStream) throws IOException;
DataClass mapFromProto(ProtoClass protoClass);
ProtoClass mapToProto(DataClass dataClass);
Class<DataClass> getDataClass();
Class<ProtoClass> getProtoClass();
}
protected List<Mapper<?, ?>> mappers = new ArrayList<Mapper<?, ?>>();
private Wire wire;
private static ProtoMappers instance;
public static synchronized ProtoMappers get() {
if (instance == null) {
instance = new ProtoMappers();
}
return instance;
}
public ProtoMappers() {
wire = new Wire();
mappers.add(new com.shaubert.protomapper.wire.sample.ResultMapper());
mappers.add(new com.shaubert.protomapper.wire.sample.EntryMapper());
mappers.add(new com.shaubert.protomapper.wire.sample.MapMapper());
}
public Wire getWire() {
return wire;
}
@SuppressWarnings("unchecked")
public <DataClass, ProtoClass> Mapper<DataClass, ProtoClass> getMapper(
Class<DataClass> dataClass, Class<ProtoClass> protoClass) {
for (Mapper<?, ?> mapper : mappers) {
if (mapper.getDataClass().equals(dataClass)
&& mapper.getProtoClass().equals(protoClass)) {
return (Mapper<DataClass, ProtoClass>) mapper;
}
}
return null;
}
@SuppressWarnings("unchecked")
public <DataClass, ProtoClass> Mapper<DataClass, ProtoClass> getFirstFromData(Class<DataClass> dataClass) {
for (Mapper<?, ?> mapper : mappers) {
if (mapper.getDataClass().equals(dataClass)) {
return (Mapper<DataClass, ProtoClass>) mapper;
}
}
return null;
}
@SuppressWarnings("unchecked")
public <DataClass, ProtoClass> Mapper<DataClass, ProtoClass> getFirstFromProto(Class<ProtoClass> protoClass) {
for (Mapper<?, ?> mapper : mappers) {
if (mapper.getProtoClass().equals(protoClass)) {
return (Mapper<DataClass, ProtoClass>) mapper;
}
}
return null;
}
@SuppressWarnings("unchecked")
public static Message mapToMessage(Object data) {
ProtoMappers mappers = get();
Mapper mapper = mappers.getFirstFromData(data.getClass());
throwIfMapperNotFound(mapper, data.getClass());
return (Message) mapper.mapToProto(data);
}
@SuppressWarnings("unchecked")
public static <T> T mapFromProto(Object proto) {
ProtoMappers mappers = get();
Mapper mapper = mappers.getFirstFromProto(proto.getClass());
throwIfMapperNotFound(mapper, proto.getClass());
return (T) mapper.mapFromProto(proto);
}
@SuppressWarnings("unchecked")
public static <T> T mapFromProtoByProtoClass(InputStream inputStream, Class<?> protoClass) throws IOException {
ProtoMappers mappers = get();
Mapper mapper = mappers.getFirstFromProto(protoClass);
throwIfMapperNotFound(mapper, protoClass);
return (T) mapper.mapFromProto(inputStream);
}
@SuppressWarnings("unchecked")
public static <T> T mapFromProtoByDataClass(InputStream inputStream, Class<?> dataClass) throws IOException {
ProtoMappers mappers = get();
Mapper mapper = mappers.getFirstFromData(dataClass);
throwIfMapperNotFound(mapper, dataClass);
return (T) mapper.mapFromProto(inputStream);
}
private static void throwIfMapperNotFound(Object mapper, Class<?> forClass) {
if (mapper == null) {
throw new NullPointerException("mapper for " + forClass + " not found");
}
}
}
Copyright 2013 iDa Mobile.
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.
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