org.springframework.data.rest.webmvc.convert.UriListHttpMessageConverter.java Source code

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Here is the source code for org.springframework.data.rest.webmvc.convert.UriListHttpMessageConverter.java

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/*
 * Copyright 2012-2019 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
 *
 *      https://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.data.rest.webmvc.convert;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

import org.springframework.core.convert.converter.Converter;
import org.springframework.hateoas.Link;
import org.springframework.hateoas.RepresentationModel;
import org.springframework.hateoas.CollectionModel;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.util.StringUtils;

/**
 * {@link Converter} to render all {@link Link}s contained in a {@link ResourceSupport} as {@code text/uri-list} and
 * parse a request of that media type back into a {@link ResourceSupport} instance.
 *
 * @author Jon Brisbin
 * @author Greg Turnquist
 * @author Oliver Gierke
 */
public class UriListHttpMessageConverter implements HttpMessageConverter<RepresentationModel> {

    private static final List<MediaType> MEDIA_TYPES = new ArrayList<MediaType>();

    static {
        MEDIA_TYPES.add(MediaType.parseMediaType("text/uri-list"));
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.http.converter.HttpMessageConverter#canRead(java.lang.Class, org.springframework.http.MediaType)
     */
    @Override
    public boolean canRead(Class<?> clazz, MediaType mediaType) {
        if (null == mediaType) {
            return false;
        }
        return RepresentationModel.class.isAssignableFrom(clazz) && mediaType.getSubtype().contains("uri-list");
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.http.converter.HttpMessageConverter#canWrite(java.lang.Class, org.springframework.http.MediaType)
     */
    @Override
    public boolean canWrite(Class<?> clazz, MediaType mediaType) {
        return canRead(clazz, mediaType);
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.http.converter.HttpMessageConverter#getSupportedMediaTypes()
     */
    @Override
    public List<MediaType> getSupportedMediaTypes() {
        return MEDIA_TYPES;
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.http.converter.HttpMessageConverter#read(java.lang.Class, org.springframework.http.HttpInputMessage)
     */
    @Override
    public RepresentationModel read(Class<? extends RepresentationModel> clazz, HttpInputMessage inputMessage)
            throws IOException, HttpMessageNotReadableException {

        List<Link> links = new ArrayList<Link>();

        Scanner scanner = new Scanner(inputMessage.getBody());

        try {

            while (scanner.hasNextLine()) {

                String line = scanner.nextLine();
                if (StringUtils.hasText(line)) {
                    links.add(new Link(line));
                }
            }

        } finally {
            scanner.close();
        }

        return new CollectionModel<Object>(Collections.emptyList(), links);
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.http.converter.HttpMessageConverter#write(java.lang.Object, org.springframework.http.MediaType, org.springframework.http.HttpOutputMessage)
     */
    @Override
    public void write(RepresentationModel resource, MediaType contentType, HttpOutputMessage outputMessage)
            throws IOException, HttpMessageNotWritableException {

        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputMessage.getBody()));

        for (Link link : resource.getLinks()) {
            writer.write(link.getHref());
            writer.newLine();
        }

        writer.flush();
    }
}