org.gwt.dynamic.common.client.util.JsonHelper.java Source code

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Here is the source code for org.gwt.dynamic.common.client.util.JsonHelper.java

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/*
 * Copyright 2014 Maxim Dominichenko
 * 
 * Licensed under The MIT License (MIT) (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * https://github.com/domax/gwt-dynamic-plugins/blob/master/LICENSE
 * 
 * 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 org.gwt.dynamic.common.client.util;

import java.util.HashMap;
import java.util.List;
import java.util.logging.Logger;

import name.pehl.piriti.json.client.JsonReader;
import name.pehl.piriti.json.client.JsonWriter;

import com.google.gwt.json.client.JSONParser;
import com.google.gwt.json.client.JSONValue;

public final class JsonHelper {

    private static final Logger LOG = Logger.getLogger(JsonHelper.class.getName());
    private static final HashMap<String, JsonWriter<?>> JSON_WRITERS = new HashMap<String, JsonWriter<?>>();
    private static final HashMap<String, JsonReader<?>> JSON_READERS = new HashMap<String, JsonReader<?>>();

    public static void registerJsonBeanReaderWriter(Class<?> clazz, JsonReader<?> jsonReader,
            JsonWriter<?> jsonWriter) {
        if (clazz == null)
            return;
        if (jsonReader != null) {
            JSON_READERS.put(clazz.getName(), jsonReader);
            LOG.info("registerJsonBeanReaderWriter: registered new reader for class " + clazz.getName());
        }
        if (jsonWriter != null) {
            JSON_WRITERS.put(clazz.getName(), jsonWriter);
            LOG.info("registerJsonBeanReaderWriter: registered new writer for class " + clazz.getName());
        }
    }

    public static boolean isJsonReaderRegisteredFor(Class<?> clazz) {
        if (clazz == null)
            return false;
        return JSON_READERS.containsKey(clazz.getName());
    }

    public static boolean isJsonWriterRegisteredFor(Class<?> clazz) {
        if (clazz == null)
            return false;
        return JSON_WRITERS.containsKey(clazz.getName());
    }

    @SuppressWarnings("unchecked")
    private static <T> JsonWriter<T> getWriterForBean(T bean) {
        if (bean == null)
            throw new IllegalArgumentException("Bean to be serialized cannot be a null");
        JsonWriter<T> writer = (JsonWriter<T>) JSON_WRITERS.get(bean.getClass().getName());
        LOG.info("getWriterForBean: bean.class.name=" + bean.getClass().getName() + "; writer=" + writer);
        if (writer == null)
            throw new IllegalArgumentException("JsonWriter for specified bean isn't registered");
        return writer;
    }

    @SuppressWarnings("unchecked")
    private static <T> JsonReader<T> getReaderForBean(Class<T> beanClass) {
        if (beanClass == null)
            throw new IllegalArgumentException("Bean class to be deserialized cannot be a null");
        JsonReader<T> reader = (JsonReader<T>) JSON_READERS.get(beanClass.getName());
        LOG.info("getReaderForBean: beanClass.name=" + beanClass.getName() + "; reader=" + reader);
        if (reader == null)
            throw new IllegalArgumentException("JsonReader for specified bean class isn't registered");
        return reader;
    }

    public static <T> String toJson(T bean) {
        return getWriterForBean(bean).toJson(bean);
    }

    public static <T> String toJson(List<T> list) {
        if (list == null)
            throw new IllegalArgumentException("Bean list to be serialized cannot be a null");
        if (list.isEmpty())
            return "[]";
        return getWriterForBean(list.get(0)).toJson(list, "items").replaceFirst("^\\{\"items\":", "")
                .replaceFirst("\\}$", "");
    }

    public static <T> T fromJsonBean(Class<T> beanClass, String json) {
        JSONValue value = JSONParser.parseStrict(json);
        return getReaderForBean(beanClass).read(value.isObject());
    }

    public static <T> List<T> fromJsonList(Class<T> beanClass, String json) {
        JSONValue value = JSONParser.parseStrict(json);
        return getReaderForBean(beanClass).readList(value.isArray());
    }

    public static <T> T fromJsonBean(Class<T> beanClass, JSONValue json) {
        if (json == null)
            throw new NullPointerException();
        return getReaderForBean(beanClass).read(json.isObject());
    }

    public static <T> List<T> fromJsonList(Class<T> beanClass, JSONValue json) {
        if (json == null)
            throw new NullPointerException();
        return getReaderForBean(beanClass).readList(json.isArray());
    }

    private JsonHelper() {
    }
}