Java example source code file (StreamingTypeAdaptersTest.java)

This example Java source code file (StreamingTypeAdaptersTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

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Java - Java tags/keywords

double, gson, ioexception, jesse, jodie, jsonobject, jsonprimitive, node, override, person, string, truck, typeadapter, typetoken, util

The StreamingTypeAdaptersTest.java Java example source code

/*
 * Copyright (C) 2011 Google 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.google.gson.functional;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSyntaxException;
import com.google.gson.TypeAdapter;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import junit.framework.TestCase;

public final class StreamingTypeAdaptersTest extends TestCase {
  private Gson miniGson = new GsonBuilder().create();
  private TypeAdapter<Truck> truckAdapter = miniGson.getAdapter(Truck.class);
  private TypeAdapter<Map mapAdapter
      = miniGson.getAdapter(new TypeToken<Map() {});

  public void testSerialize() throws IOException {
    Truck truck = new Truck();
    truck.passengers = Arrays.asList(new Person("Jesse", 29), new Person("Jodie", 29));
    truck.horsePower = 300;

    assertEquals("{'horsePower':300.0,"
        + "'passengers':[{'age':29,'name':'Jesse'},{'age':29,'name':'Jodie'}]}",
        toJson(truckAdapter, truck).replace('\"', '\''));
  }

  public void testDeserialize() throws IOException {
    String json = "{'horsePower':300.0,"
        + "'passengers':[{'age':29,'name':'Jesse'},{'age':29,'name':'Jodie'}]}";
    Truck truck = fromJson(truckAdapter, json);
    assertEquals(300.0, truck.horsePower);
    assertEquals(Arrays.asList(new Person("Jesse", 29), new Person("Jodie", 29)), truck.passengers);
  }

  public void testSerializeNullField() throws IOException {
    Truck truck = new Truck();
    truck.passengers = null;
    assertEquals("{'horsePower':0.0,'passengers':null}",
        toJson(truckAdapter, truck).replace('\"', '\''));
  }

  public void testDeserializeNullField() throws IOException {
    Truck truck = fromJson(truckAdapter, "{'horsePower':0.0,'passengers':null}");
    assertNull(truck.passengers);
  }

  public void testSerializeNullObject() throws IOException {
    Truck truck = new Truck();
    truck.passengers = Arrays.asList((Person) null);
    assertEquals("{'horsePower':0.0,'passengers':[null]}",
        toJson(truckAdapter, truck).replace('\"', '\''));
  }

  public void testDeserializeNullObject() throws IOException {
    Truck truck = fromJson(truckAdapter, "{'horsePower':0.0,'passengers':[null]}");
    assertEquals(Arrays.asList((Person) null), truck.passengers);
  }

  public void testSerializeWithCustomTypeAdapter() throws IOException {
    usePersonNameAdapter();
    Truck truck = new Truck();
    truck.passengers = Arrays.asList(new Person("Jesse", 29), new Person("Jodie", 29));
    assertEquals("{'horsePower':0.0,'passengers':['Jesse','Jodie']}",
        toJson(truckAdapter, truck).replace('\"', '\''));
  }

  public void testDeserializeWithCustomTypeAdapter() throws IOException {
    usePersonNameAdapter();
    Truck truck = fromJson(truckAdapter, "{'horsePower':0.0,'passengers':['Jesse','Jodie']}");
    assertEquals(Arrays.asList(new Person("Jesse", -1), new Person("Jodie", -1)), truck.passengers);
  }

  private void usePersonNameAdapter() {
    TypeAdapter<Person> personNameAdapter = new TypeAdapter() {
      @Override public Person read(JsonReader in) throws IOException {
        String name = in.nextString();
        return new Person(name, -1);
      }
      @Override public void write(JsonWriter out, Person value) throws IOException {
        out.value(value.name);
      }
    };
    miniGson = new GsonBuilder().registerTypeAdapter(Person.class, personNameAdapter).create();
    truckAdapter = miniGson.getAdapter(Truck.class);
  }

  public void testSerializeMap() throws IOException {
    Map<String, Double> map = new LinkedHashMap();
    map.put("a", 5.0);
    map.put("b", 10.0);
    assertEquals("{'a':5.0,'b':10.0}", toJson(mapAdapter, map).replace('"', '\''));
  }

  public void testDeserializeMap() throws IOException {
    Map<String, Double> map = new LinkedHashMap();
    map.put("a", 5.0);
    map.put("b", 10.0);
    assertEquals(map, fromJson(mapAdapter, "{'a':5.0,'b':10.0}"));
  }

  public void testSerialize1dArray() throws IOException {
    TypeAdapter<double[]> arrayAdapter = miniGson.getAdapter(new TypeToken() {});
    assertEquals("[1.0,2.0,3.0]", toJson(arrayAdapter, new double[]{1.0, 2.0, 3.0}));
  }

  public void testDeserialize1dArray() throws IOException {
    TypeAdapter<double[]> arrayAdapter = miniGson.getAdapter(new TypeToken() {});
    double[] array = fromJson(arrayAdapter, "[1.0,2.0,3.0]");
    assertTrue(Arrays.toString(array), Arrays.equals(new double[]{1.0, 2.0, 3.0}, array));
  }

  public void testSerialize2dArray() throws IOException {
    TypeAdapter<double[][]> arrayAdapter = miniGson.getAdapter(new TypeToken() {});
    double[][] array = { {1.0, 2.0 }, { 3.0 } };
    assertEquals("[[1.0,2.0],[3.0]]", toJson(arrayAdapter, array));
  }

  public void testDeserialize2dArray() throws IOException {
    TypeAdapter<double[][]> arrayAdapter = miniGson.getAdapter(new TypeToken() {});
    double[][] array = fromJson(arrayAdapter, "[[1.0,2.0],[3.0]]");
    double[][] expected = { {1.0, 2.0 }, { 3.0 } };
    assertTrue(Arrays.toString(array), Arrays.deepEquals(expected, array));
  }

  public void testNullSafe() {
    TypeAdapter<Person> typeAdapter = new TypeAdapter() {
      @Override public Person read(JsonReader in) throws IOException {
        String[] values = in.nextString().split(",");
        return new Person(values[0], Integer.parseInt(values[1]));
      }
      public void write(JsonWriter out, Person person) throws IOException {
        out.value(person.name + "," + person.age);
      }
    };
    Gson gson = new GsonBuilder().registerTypeAdapter(
        Person.class, typeAdapter).create();
    Truck truck = new Truck();
    truck.horsePower = 1.0D;
    truck.passengers = new ArrayList<Person>();
    truck.passengers.add(null);
    truck.passengers.add(new Person("jesse", 30));
    try {
      gson.toJson(truck, Truck.class);
      fail();
    } catch (NullPointerException expected) {}
    String json = "{horsePower:1.0,passengers:[null,'jesse,30']}";
    try {
      gson.fromJson(json, Truck.class);
      fail();
    } catch (JsonSyntaxException expected) {}
    gson = new GsonBuilder().registerTypeAdapter(Person.class, typeAdapter.nullSafe()).create();
    assertEquals("{\"horsePower\":1.0,\"passengers\":[null,\"jesse,30\"]}",
        gson.toJson(truck, Truck.class));
    truck = gson.fromJson(json, Truck.class);
    assertEquals(1.0D, truck.horsePower);
    assertNull(truck.passengers.get(0));
    assertEquals("jesse", truck.passengers.get(1).name);
  }

  public void testSerializeRecursive() throws IOException {
    TypeAdapter<Node> nodeAdapter = miniGson.getAdapter(Node.class);
    Node root = new Node("root");
    root.left = new Node("left");
    root.right = new Node("right");
    assertEquals("{'label':'root',"
        + "'left':{'label':'left','left':null,'right':null},"
        + "'right':{'label':'right','left':null,'right':null}}",
        toJson(nodeAdapter, root).replace('"', '\''));
  }
  
  public void testFromJsonTree() {
    JsonObject truckObject = new JsonObject();
    truckObject.add("horsePower", new JsonPrimitive(300));
    JsonArray passengersArray = new JsonArray();
    JsonObject jesseObject = new JsonObject();
    jesseObject.add("age", new JsonPrimitive(30));
    jesseObject.add("name", new JsonPrimitive("Jesse"));
    passengersArray.add(jesseObject);
    truckObject.add("passengers", passengersArray);

    Truck truck = truckAdapter.fromJsonTree(truckObject);
    assertEquals(300.0, truck.horsePower);
    assertEquals(Arrays.asList(new Person("Jesse", 30)), truck.passengers);
  }

  static class Truck {
    double horsePower;
    List<Person> passengers = Collections.emptyList();
  }

  static class Person {
    int age;
    String name;
    Person(String name, int age) {
      this.name = name;
      this.age = age;
    }

    @Override public boolean equals(Object o) {
      return o instanceof Person
          && ((Person) o).name.equals(name)
          && ((Person) o).age == age;
    }
    @Override public int hashCode() {
      return name.hashCode() ^ age;
    }
  }

  static class Node {
    String label;
    Node left;
    Node right;
    Node(String label) {
      this.label = label;
    }
  }

  // TODO: remove this when TypeAdapter.toJson() is public
  private static <T> String toJson(TypeAdapter typeAdapter, T value) throws IOException {
    StringWriter stringWriter = new StringWriter();
    JsonWriter writer = new JsonWriter(stringWriter);
    typeAdapter.write(writer, value);
    return stringWriter.toString();
  }

  // TODO: remove this when TypeAdapter.fromJson() is public
  private <T> T fromJson(TypeAdapter typeAdapter, String json) throws IOException {
    JsonReader reader = new JsonReader(new StringReader(json));
    reader.setLenient(true); // TODO: non-lenient?
    return typeAdapter.read(reader);
  }
}