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Java example source code file (DefaultDateTypeAdapter.java)

This example Java source code file (DefaultDateTypeAdapter.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.

Learn more about this Java project at its project page.

Java - Java tags/keywords

dateformat, defaultdatetypeadapter, illegalargumentexception, jdbc, jsondeserializationcontext, jsonparseexception, jsonprimitive, jsonserializationcontext, override, parseexception, parseposition, reflection, simpledateformat, sql, string, stringbuilder, text, the, util

The DefaultDateTypeAdapter.java Java example source code

/*
 * Copyright (C) 2008 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;

import java.lang.reflect.Type;
import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import com.google.gson.internal.bind.util.ISO8601Utils;

/**
 * This type adapter supports three subclasses of date: Date, Timestamp, and
 * java.sql.Date.
 *
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
final class DefaultDateTypeAdapter implements JsonSerializer<Date>, JsonDeserializer {

  // TODO: migrate to streaming adapter

  private final DateFormat enUsFormat;
  private final DateFormat localFormat;

  DefaultDateTypeAdapter() {
    this(DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.US),
        DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT));
  }

  DefaultDateTypeAdapter(String datePattern) {
    this(new SimpleDateFormat(datePattern, Locale.US), new SimpleDateFormat(datePattern));
  }

  DefaultDateTypeAdapter(int style) {
    this(DateFormat.getDateInstance(style, Locale.US), DateFormat.getDateInstance(style));
  }

  public DefaultDateTypeAdapter(int dateStyle, int timeStyle) {
    this(DateFormat.getDateTimeInstance(dateStyle, timeStyle, Locale.US),
        DateFormat.getDateTimeInstance(dateStyle, timeStyle));
  }

  DefaultDateTypeAdapter(DateFormat enUsFormat, DateFormat localFormat) {
    this.enUsFormat = enUsFormat;
    this.localFormat = localFormat;
  }

  // These methods need to be synchronized since JDK DateFormat classes are not thread-safe
  // See issue 162
  @Override
  public JsonElement serialize(Date src, Type typeOfSrc, JsonSerializationContext context) {
    synchronized (localFormat) {
      String dateFormatAsString = enUsFormat.format(src);
      return new JsonPrimitive(dateFormatAsString);
    }
  }

  @Override
  public Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
      throws JsonParseException {
    if (!(json instanceof JsonPrimitive)) {
      throw new JsonParseException("The date should be a string value");
    }
    Date date = deserializeToDate(json);
    if (typeOfT == Date.class) {
      return date;
    } else if (typeOfT == Timestamp.class) {
      return new Timestamp(date.getTime());
    } else if (typeOfT == java.sql.Date.class) {
      return new java.sql.Date(date.getTime());
    } else {
      throw new IllegalArgumentException(getClass() + " cannot deserialize to " + typeOfT);
    }
  }

  private Date deserializeToDate(JsonElement json) {
    synchronized (localFormat) {
      try {
      	return localFormat.parse(json.getAsString());
      } catch (ParseException ignored) {}
      try {
        return enUsFormat.parse(json.getAsString());
      } catch (ParseException ignored) {}
      try {
        return ISO8601Utils.parse(json.getAsString(), new ParsePosition(0));
      } catch (ParseException e) {
        throw new JsonSyntaxException(json.getAsString(), e);
      }
    }
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append(DefaultDateTypeAdapter.class.getSimpleName());
    sb.append('(').append(localFormat.getClass().getSimpleName()).append(')');
    return sb.toString();
  }
}

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