/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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 org.springframework.http.converter.xml;

import javax.xml.transform.Result;
import javax.xml.transform.Source;

import org.springframework.beans.TypeMismatchException;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.lang.Nullable;
import org.springframework.oxm.Marshaller;
import org.springframework.oxm.Unmarshaller;
import org.springframework.util.Assert;

Implementation of HttpMessageConverter that can read and write XML using Spring's Marshaller and Unmarshaller abstractions. 
This converter requires a Marshaller and Unmarshaller before it can be used. These can be injected by the constructor or bean properties. 
By default, this converter supports text/xml and application/xml. This can be overridden by setting the supportedMediaTypes property. 
Author:
Arjen Poutsma
Since:
3.0/**
 * Implementation of {@link org.springframework.http.converter.HttpMessageConverter HttpMessageConverter}
 * that can read and write XML using Spring's {@link Marshaller} and {@link Unmarshaller} abstractions.
 *
 * <p>This converter requires a {@code Marshaller} and {@code Unmarshaller} before it can be used.
 * These can be injected by the {@linkplain #MarshallingHttpMessageConverter(Marshaller) constructor}
 * or {@linkplain #setMarshaller(Marshaller) bean properties}.
 *
 * <p>By default, this converter supports {@code text/xml} and {@code application/xml}. This can be
 * overridden by setting the {@link #setSupportedMediaTypes(java.util.List) supportedMediaTypes} property.
 *
 * @author Arjen Poutsma
 * @since 3.0
 */
public class MarshallingHttpMessageConverter extends AbstractXmlHttpMessageConverter<Object> {

	@Nullable
	private Marshaller marshaller;

	@Nullable
	private Unmarshaller unmarshaller;


	
Construct a new MarshallingHttpMessageConverter with no Marshaller or Unmarshaller set. The Marshaller and Unmarshaller must be set after construction by invoking setMarshaller(Marshaller) and setUnmarshaller(Unmarshaller). /**
	 * Construct a new {@code MarshallingHttpMessageConverter} with no {@link Marshaller} or
	 * {@link Unmarshaller} set. The Marshaller and Unmarshaller must be set after construction
	 * by invoking {@link #setMarshaller(Marshaller)} and {@link #setUnmarshaller(Unmarshaller)}.
	 */
	public MarshallingHttpMessageConverter() {
	}

	
Construct a new MarshallingMessageConverter with the given Marshaller set. 
If the given Marshaller also implements the Unmarshaller interface, it is used for both marshalling and unmarshalling. Otherwise, an exception is thrown. 
Note that all Marshaller implementations in Spring also implement the Unmarshaller interface, so that you can safely use this constructor. 
Params:
marshaller – object used as marshaller and unmarshaller/**
	 * Construct a new {@code MarshallingMessageConverter} with the given {@link Marshaller} set.
	 * <p>If the given {@link Marshaller} also implements the {@link Unmarshaller} interface,
	 * it is used for both marshalling and unmarshalling. Otherwise, an exception is thrown.
	 * <p>Note that all {@code Marshaller} implementations in Spring also implement the
	 * {@code Unmarshaller} interface, so that you can safely use this constructor.
	 * @param marshaller object used as marshaller and unmarshaller
	 */
	public MarshallingHttpMessageConverter(Marshaller marshaller) {
		Assert.notNull(marshaller, "Marshaller must not be null");
		this.marshaller = marshaller;
		if (marshaller instanceof Unmarshaller) {
			this.unmarshaller = (Unmarshaller) marshaller;
		}
	}

	
Construct a new MarshallingMessageConverter with the given Marshaller and Unmarshaller. 
Params:
marshaller – the Marshaller to use
unmarshaller – the Unmarshaller to use/**
	 * Construct a new {@code MarshallingMessageConverter} with the given
	 * {@code Marshaller} and {@code Unmarshaller}.
	 * @param marshaller the Marshaller to use
	 * @param unmarshaller the Unmarshaller to use
	 */
	public MarshallingHttpMessageConverter(Marshaller marshaller, Unmarshaller unmarshaller) {
		Assert.notNull(marshaller, "Marshaller must not be null");
		Assert.notNull(unmarshaller, "Unmarshaller must not be null");
		this.marshaller = marshaller;
		this.unmarshaller = unmarshaller;
	}


	
Set the Marshaller to be used by this message converter. /**
	 * Set the {@link Marshaller} to be used by this message converter.
	 */
	public void setMarshaller(Marshaller marshaller) {
		this.marshaller = marshaller;
	}

	
Set the Unmarshaller to be used by this message converter. /**
	 * Set the {@link Unmarshaller} to be used by this message converter.
	 */
	public void setUnmarshaller(Unmarshaller unmarshaller) {
		this.unmarshaller = unmarshaller;
	}


	@Override
	public boolean canRead(Class<?> clazz, @Nullable MediaType mediaType) {
		return (canRead(mediaType) && this.unmarshaller != null && this.unmarshaller.supports(clazz));
	}

	@Override
	public boolean canWrite(Class<?> clazz, @Nullable MediaType mediaType) {
		return (canWrite(mediaType) && this.marshaller != null && this.marshaller.supports(clazz));
	}

	@Override
	protected boolean supports(Class<?> clazz) {
		// should not be called, since we override canRead()/canWrite()
		throw new UnsupportedOperationException();
	}

	@Override
	protected Object readFromSource(Class<?> clazz, HttpHeaders headers, Source source) throws Exception {
		Assert.notNull(this.unmarshaller, "Property 'unmarshaller' is required");
		Object result = this.unmarshaller.unmarshal(source);
		if (!clazz.isInstance(result)) {
			throw new TypeMismatchException(result, clazz);
		}
		return result;
	}

	@Override
	protected void writeToResult(Object o, HttpHeaders headers, Result result) throws Exception {
		Assert.notNull(this.marshaller, "Property 'marshaller' is required");
		this.marshaller.marshal(o, result);
	}

}