Introduce factory for converter concept.

This is still highly-inefficient in its internal use and there are no tests proving that we now fail earlier in configuring a service method. Both of those will come in follow up commits

Author: JakeWharton

retrofit-adapters/rxjava/src/test/java/retrofit/ObservableCallAdapterFactoryTest.java

@@ -49,7 +49,7 @@ interface Service {
   @Before public void setUp() {
     Retrofit retrofit = new Retrofit.Builder()
         .endpoint(server.getUrl("/").toString())
-        .converter(new StringConverter())
+        .converterFactory(new StringConverterFactory())
         .callAdapterFactory(ObservableCallAdapterFactory.create())
         .build();
     service = retrofit.create(Service.class);
@@ -195,13 +195,17 @@ interface Service {
     }
   }
 
-  static class StringConverter implements Converter {
-    @Override public Object fromBody(ResponseBody body, Type type) throws IOException {
-      return body.string();
-    }
+  static class StringConverterFactory implements Converter.Factory {
+    @Override public Converter<?> get(Type type) {
+      return new Converter<String>() {
+        @Override public String fromBody(ResponseBody body) throws IOException {
+          return body.string();
+        }
 
-    @Override public RequestBody toBody(Object object, Type type) {
-      return RequestBody.create(MediaType.parse("text/plain"), String.valueOf(object));
+        @Override public RequestBody toBody(String value) {
+          return RequestBody.create(MediaType.parse("text/plain"), value);
+        }
+      };
     }
   }
 }

retrofit-converters/gson/src/main/java/retrofit/GsonConverter.java

@@ -15,71 +15,48 @@
  */
 package retrofit;
 
-import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
 import com.squareup.okhttp.MediaType;
 import com.squareup.okhttp.RequestBody;
 import com.squareup.okhttp.ResponseBody;
 import java.io.IOException;
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.lang.reflect.Type;
+import java.io.OutputStreamWriter;
+import java.io.Reader;
+import java.io.Writer;
 import java.nio.charset.Charset;
+import okio.Buffer;
 
-/**
- * A {@link Converter} which uses GSON for serialization and deserialization of entities.
- */
-public class GsonConverter implements Converter {
-  private final Gson gson;
-  private final Charset charset;
-  private final MediaType mediaType;
-
-  /**
-   * Create an instance using a default {@link Gson} instance for conversion. Encoding to JSON and
-   * decoding from JSON (when no charset is specified by a header) will use UTF-8.
-   */
-  public GsonConverter() {
-    this(new Gson());
-  }
+final class GsonConverter<T> implements Converter<T> {
+  private static final MediaType MEDIA_TYPE = MediaType.parse("application/json; charset=UTF-8");
+  private static final Charset UTF_8 = Charset.forName("UTF-8");
 
-  /**
-   * Create an instance using the supplied {@link Gson} object for conversion. Encoding to JSON and
-   * decoding from JSON (when no charset is specified by a header) will use UTF-8.
-   */
-  public GsonConverter(Gson gson) {
-    this(gson, Charset.forName("UTF-8"));
-  }
+  private final TypeAdapter<T> typeAdapter;
 
-  /**
-   * Create an instance using the supplied {@link Gson} object for conversion. Encoding to JSON and
-   * decoding from JSON (when no charset is specified by a header) will use the specified charset.
-   */
-  public GsonConverter(Gson gson, Charset charset) {
-    if (gson == null) throw new NullPointerException("gson == null");
-    if (charset == null) throw new NullPointerException("charset == null");
-    this.gson = gson;
-    this.charset = charset;
-    this.mediaType = MediaType.parse("application/json; charset=" + charset.name());
+  GsonConverter(TypeAdapter<T> typeAdapter) {
+    this.typeAdapter = typeAdapter;
   }
 
-  @Override public Object fromBody(ResponseBody body, Type type) throws IOException {
-    Charset charset = this.charset;
-    if (body.contentType() != null) {
-      charset = body.contentType().charset(charset);
-    }
-
-    InputStream is = body.byteStream();
+  @Override public T fromBody(ResponseBody body) throws IOException {
+    Reader in = body.charStream();
     try {
-      return gson.fromJson(new InputStreamReader(is, charset), type);
+      return typeAdapter.fromJson(in);
     } finally {
       try {
-        is.close();
+        in.close();
       } catch (IOException ignored) {
       }
     }
   }
 
-  @Override public RequestBody toBody(Object object, Type type) {
-    String json = gson.toJson(object, type);
-    return RequestBody.create(mediaType, json);
+  @Override public RequestBody toBody(T value) {
+    Buffer buffer = new Buffer();
+    Writer writer = new OutputStreamWriter(buffer.outputStream(), UTF_8);
+    try {
+      typeAdapter.toJson(writer, value);
+      writer.flush();
+    } catch (IOException e) {
+      throw new AssertionError(e); // Writing to Buffer does no I/O.
+    }
+    return RequestBody.create(MEDIA_TYPE, buffer.readByteString());
   }
 }

retrofit-converters/gson/src/main/java/retrofit/GsonConverterFactory.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 Square, 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 retrofit;
+
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.reflect.TypeToken;
+import java.lang.reflect.Type;
+
+/** A {@linkplain Converter.Factory converter} which uses Gson for JSON. */
+public final class GsonConverterFactory implements Converter.Factory {
+  /**
+   * Create an instance using a default {@link Gson} instance for conversion. Encoding to JSON and
+   * decoding from JSON (when no charset is specified by a header) will use UTF-8.
+   */
+  public static GsonConverterFactory create() {
+    return create(new Gson());
+  }
+
+  /**
+   * Create an instance using {@code gson} for conversion. Encoding to JSON and
+   * decoding from JSON (when no charset is specified by a header) will use UTF-8.
+   */
+  public static GsonConverterFactory create(Gson gson) {
+    return new GsonConverterFactory(gson);
+  }
+
+  private final Gson gson;
+
+  private GsonConverterFactory(Gson gson) {
+    if (gson == null) throw new NullPointerException("gson == null");
+    this.gson = gson;
+  }
+
+  @Override public Converter<?> get(Type type) {
+    TypeAdapter<?> adapter = gson.getAdapter(TypeToken.get(type));
+    return new GsonConverter<>(adapter);
+  }
+}

retrofit-converters/gson/src/test/java/retrofit/GsonConverterTest.java retrofit-converters/gson/src/test/java/retrofit/GsonConverterFactoryTest.java

@@ -33,7 +33,7 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-public final class GsonConverterTest {
+public final class GsonConverterFactoryTest {
   interface AnInterface {
     String getName();
   }
@@ -87,10 +87,9 @@ interface Service {
     Gson gson = new GsonBuilder()
         .registerTypeAdapter(AnInterface.class, new AnInterfaceAdapter())
         .create();
-    Converter converter = new GsonConverter(gson);
     Retrofit retrofit = new Retrofit.Builder()
         .endpoint(server.getUrl("/").toString())
-        .converter(converter)
+        .converterFactory(GsonConverterFactory.create(gson))
         .build();
     service = retrofit.create(Service.class);
   }

retrofit-converters/jackson/src/main/java/retrofit/JacksonConverter.java

@@ -1,39 +1,45 @@
+/*
+ * Copyright (C) 2015 Square, 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 retrofit;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.JavaType;
-import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectReader;
+import com.fasterxml.jackson.databind.ObjectWriter;
 import com.squareup.okhttp.MediaType;
 import com.squareup.okhttp.RequestBody;
 import com.squareup.okhttp.ResponseBody;
 import java.io.IOException;
 import java.io.InputStream;
-import java.lang.reflect.Type;
 
-/**
- * A {@link Converter} which uses Jackson for reading and writing entities.
- *
- * @author Kai Waldron ([email protected])
- */
-public class JacksonConverter implements Converter {
+final class JacksonConverter<T> implements Converter<T> {
   private static final MediaType MEDIA_TYPE = MediaType.parse("application/json; charset=UTF-8");
 
-  private final ObjectMapper objectMapper;
+  private final ObjectWriter writer;
+  private final ObjectReader reader;
 
-  public JacksonConverter() {
-    this(new ObjectMapper());
+  JacksonConverter(ObjectWriter writer, ObjectReader reader) {
+    this.writer = writer;
+    this.reader = reader;
   }
 
-  public JacksonConverter(ObjectMapper objectMapper) {
-    if (objectMapper == null) throw new NullPointerException("objectMapper == null");
-    this.objectMapper = objectMapper;
-  }
 
-  @Override public Object fromBody(ResponseBody body, Type type) throws IOException {
+  @Override public T fromBody(ResponseBody body) throws IOException {
     InputStream is = body.byteStream();
     try {
-      JavaType javaType = objectMapper.getTypeFactory().constructType(type);
-      return objectMapper.readValue(is, javaType);
+      return reader.readValue(is);
     } finally {
       try {
         is.close();
@@ -42,11 +48,10 @@ public JacksonConverter(ObjectMapper objectMapper) {
     }
   }
 
-  @Override public RequestBody toBody(Object object, Type type) {
+  @Override public RequestBody toBody(T value) {
     try {
-      JavaType javaType = objectMapper.getTypeFactory().constructType(type);
-      String json = objectMapper.writerWithType(javaType).writeValueAsString(object);
-      return RequestBody.create(MEDIA_TYPE, json);
+      byte[] bytes = writer.writeValueAsBytes(value);
+      return RequestBody.create(MEDIA_TYPE, bytes);
     } catch (JsonProcessingException e) {
       throw new RuntimeException(e);
     }

retrofit-converters/jackson/src/main/java/retrofit/JacksonConverterFactory.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2015 Square, 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 retrofit;
+
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectReader;
+import com.fasterxml.jackson.databind.ObjectWriter;
+import java.lang.reflect.Type;
+
+/** A {@linkplain Converter.Factory converter} which uses Jackson. */
+public final class JacksonConverterFactory implements Converter.Factory {
+  /** Create an instance using a default {@link ObjectMapper} instance for conversion. */
+  public static JacksonConverterFactory create() {
+    return create(new ObjectMapper());
+  }
+
+  /** Create an instance using {@code mapper} for conversion. */
+  public static JacksonConverterFactory create(ObjectMapper mapper) {
+    return new JacksonConverterFactory(mapper);
+  }
+
+  private final ObjectMapper mapper;
+
+  private JacksonConverterFactory(ObjectMapper mapper) {
+    if (mapper == null) throw new NullPointerException("mapper == null");
+    this.mapper = mapper;
+  }
+
+  @Override public Converter<?> get(Type type) {
+    JavaType javaType = mapper.getTypeFactory().constructType(type);
+    ObjectWriter writer = mapper.writerWithType(javaType);
+    ObjectReader reader = mapper.reader(javaType);
+    return new JacksonConverter<>(writer, reader);
+  }
+}

retrofit-converters/jackson/src/test/java/retrofit/JacksonConverterTest.java

@@ -119,10 +119,9 @@ interface Service {
         .getDefaultVisibilityChecker()
         .withFieldVisibility(JsonAutoDetect.Visibility.ANY));
 
-    Converter converter = new JacksonConverter(mapper);
     Retrofit retrofit = new Retrofit.Builder()
         .endpoint(server.getUrl("/").toString())
-        .converter(converter)
+        .converterFactory(JacksonConverterFactory.create(mapper))
         .build();
     service = retrofit.create(Service.class);
   }