gson/com/google/gson/internal/bind/DateTypeAdapter.java

   1 /*
   2  * Copyright (C) 2011 Google Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 package com.google.gson.internal.bind;
  18
  19 import com.google.gson.Gson;
  20 import com.google.gson.JsonSyntaxException;
  21 import com.google.gson.TypeAdapter;
  22 import com.google.gson.TypeAdapterFactory;
  23 import com.google.gson.reflect.TypeToken;
  24 import com.google.gson.stream.JsonReader;
  25 import com.google.gson.stream.JsonToken;
  26 import com.google.gson.stream.JsonWriter;
  27 import java.io.IOException;
  28 import java.text.DateFormat;
  29 import java.text.ParseException;
  30 import java.text.SimpleDateFormat;
  31 import java.util.Date;
  32 import java.util.Locale;
  33 import java.util.TimeZone;
  34
  35 /**
  36  * Adapter for Date. Although this class appears stateless, it is not.
  37  * DateFormat captures its time zone and locale when it is created, which gives
  38  * this class state. DateFormat isn't thread safe either, so this class has
  39  * to synchronize its read and write methods.
  40  */
  41 public final class DateTypeAdapter extends TypeAdapter<Date> {
  42   public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
  43     @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
  44     public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
  45       return typeToken.getRawType() == Date.class ? (TypeAdapter<T>) new DateTypeAdapter() : null;
  46     }
  47   };
  48
  49   private final DateFormat enUsFormat
  50       = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.US);
  51   private final DateFormat localFormat
  52       = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT);
  53   private final DateFormat iso8601Format = buildIso8601Format();
  54
  55   private static DateFormat buildIso8601Format() {
  56     DateFormat iso8601Format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US);
  57     iso8601Format.setTimeZone(TimeZone.getTimeZone("UTC"));
  58     return iso8601Format;
  59   }
  60
  61   @Override public Date read(JsonReader in) throws IOException {
  62     if (in.peek() == JsonToken.NULL) {
  63       in.nextNull();
  64       return null;
  65     }
  66     return deserializeToDate(in.nextString());
  67   }
  68
  69   private synchronized Date deserializeToDate(String json) {
  70     try {
  71       return localFormat.parse(json);
  72     } catch (ParseException ignored) {
  73     }
  74     try {
  75       return enUsFormat.parse(json);
  76     } catch (ParseException ignored) {
  77     }
  78     try {
  79       return iso8601Format.parse(json);
  80     } catch (ParseException e) {
  81       throw new JsonSyntaxException(json, e);
  82     }
  83   }
  84
  85   @Override public synchronized void write(JsonWriter out, Date value) throws IOException {
  86     if (value == null) {
  87       out.nullValue();
  88       return;
  89     }
  90     String dateFormatAsString = enUsFormat.format(value);
  91     out.value(dateFormatAsString);
  92   }
  93 }