spring ResourceRegionHttpMessageConverter 源码

spring ResourceRegionHttpMessageConverter 代码

文件路径：/spring-web/src/main/java/org/springframework/http/converter/ResourceRegionHttpMessageConverter.java

/*
 * Copyright 2002-2022 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.http.converter;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.nio.charset.StandardCharsets;
import java.util.Collection;

import org.springframework.core.io.Resource;
import org.springframework.core.io.support.ResourceRegion;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.MediaTypeFactory;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.MimeTypeUtils;
import org.springframework.util.StreamUtils;

/**
 * Implementation of {@link HttpMessageConverter} that can write a single
 * {@link ResourceRegion} or Collections of {@link ResourceRegion ResourceRegions}.
 *
 * @author Brian Clozel
 * @author Juergen Hoeller
 * @author Sam Brannen
 * @since 4.3
 */
public class ResourceRegionHttpMessageConverter extends AbstractGenericHttpMessageConverter<Object> {

	public ResourceRegionHttpMessageConverter() {
		super(MediaType.ALL);
	}


	@Override
	@SuppressWarnings("unchecked")
	protected MediaType getDefaultContentType(Object object) {
		Resource resource = null;
		if (object instanceof ResourceRegion resourceRegion) {
			resource = resourceRegion.getResource();
		}
		else {
			Collection<ResourceRegion> regions = (Collection<ResourceRegion>) object;
			if (!regions.isEmpty()) {
				resource = regions.iterator().next().getResource();
			}
		}
		return MediaTypeFactory.getMediaType(resource).orElse(MediaType.APPLICATION_OCTET_STREAM);
	}

	@Override
	public boolean canRead(Class<?> clazz, @Nullable MediaType mediaType) {
		return false;
	}

	@Override
	public boolean canRead(Type type, @Nullable Class<?> contextClass, @Nullable MediaType mediaType) {
		return false;
	}

	@Override
	public Object read(Type type, @Nullable Class<?> contextClass, HttpInputMessage inputMessage)
			throws IOException, HttpMessageNotReadableException {

		throw new UnsupportedOperationException();
	}

	@Override
	protected ResourceRegion readInternal(Class<?> clazz, HttpInputMessage inputMessage)
			throws IOException, HttpMessageNotReadableException {

		throw new UnsupportedOperationException();
	}

	@Override
	public boolean canWrite(Class<?> clazz, @Nullable MediaType mediaType) {
		return canWrite(clazz, null, mediaType);
	}

	@Override
	public boolean canWrite(@Nullable Type type, @Nullable Class<?> clazz, @Nullable MediaType mediaType) {
		if (!(type instanceof ParameterizedType parameterizedType)) {
			return (type instanceof Class<?> c && ResourceRegion.class.isAssignableFrom(c));
		}
		if (!(parameterizedType.getRawType() instanceof Class<?> rawType)) {
			return false;
		}
		if (!(Collection.class.isAssignableFrom(rawType))) {
			return false;
		}
		if (parameterizedType.getActualTypeArguments().length != 1) {
			return false;
		}
		Type typeArgument = parameterizedType.getActualTypeArguments()[0];
		if (!(typeArgument instanceof Class<?> typeArgumentClass)) {
			return false;
		}
		return ResourceRegion.class.isAssignableFrom(typeArgumentClass);
	}

	@Override
	@SuppressWarnings("unchecked")
	protected void writeInternal(Object object, @Nullable Type type, HttpOutputMessage outputMessage)
			throws IOException, HttpMessageNotWritableException {

		if (object instanceof ResourceRegion resourceRegion) {
			writeResourceRegion(resourceRegion, outputMessage);
		}
		else {
			Collection<ResourceRegion> regions = (Collection<ResourceRegion>) object;
			if (regions.size() == 1) {
				writeResourceRegion(regions.iterator().next(), outputMessage);
			}
			else {
				writeResourceRegionCollection(regions, outputMessage);
			}
		}
	}


	protected void writeResourceRegion(ResourceRegion region, HttpOutputMessage outputMessage) throws IOException {
		Assert.notNull(region, "ResourceRegion must not be null");
		HttpHeaders responseHeaders = outputMessage.getHeaders();

		long start = region.getPosition();
		long end = start + region.getCount() - 1;
		long resourceLength = region.getResource().contentLength();
		end = Math.min(end, resourceLength - 1);
		long rangeLength = end - start + 1;
		responseHeaders.add("Content-Range", "bytes " + start + '-' + end + '/' + resourceLength);
		responseHeaders.setContentLength(rangeLength);

		InputStream in = region.getResource().getInputStream();
		// We cannot use try-with-resources here for the InputStream, since we have
		// custom handling of the close() method in a finally-block.
		try {
			StreamUtils.copyRange(in, outputMessage.getBody(), start, end);
		}
		finally {
			try {
				in.close();
			}
			catch (IOException ex) {
				// ignore
			}
		}
	}

	private void writeResourceRegionCollection(Collection<ResourceRegion> resourceRegions,
			HttpOutputMessage outputMessage) throws IOException {

		Assert.notNull(resourceRegions, "Collection of ResourceRegion should not be null");
		HttpHeaders responseHeaders = outputMessage.getHeaders();

		MediaType contentType = responseHeaders.getContentType();
		String boundaryString = MimeTypeUtils.generateMultipartBoundaryString();
		responseHeaders.set(HttpHeaders.CONTENT_TYPE, "multipart/byteranges; boundary=" + boundaryString);
		OutputStream out = outputMessage.getBody();

		Resource resource = null;
		InputStream in = null;
		long inputStreamPosition = 0;

		try {
			for (ResourceRegion region : resourceRegions) {
				long start = region.getPosition() - inputStreamPosition;
				if (start < 0 || resource != region.getResource()) {
					if (in != null) {
						in.close();
					}
					resource = region.getResource();
					in = resource.getInputStream();
					inputStreamPosition = 0;
					start = region.getPosition();
				}
				long end = start + region.getCount() - 1;
				// Writing MIME header.
				println(out);
				print(out, "--" + boundaryString);
				println(out);
				if (contentType != null) {
					print(out, "Content-Type: " + contentType);
					println(out);
				}
				long resourceLength = region.getResource().contentLength();
				end = Math.min(end, resourceLength - inputStreamPosition - 1);
				print(out, "Content-Range: bytes " +
						region.getPosition() + '-' + (region.getPosition() + region.getCount() - 1) +
						'/' + resourceLength);
				println(out);
				println(out);
				// Printing content
				StreamUtils.copyRange(in, out, start, end);
				inputStreamPosition += (end + 1);
			}
		}
		finally {
			try {
				if (in != null) {
					in.close();
				}
			}
			catch (IOException ex) {
				// ignore
			}
		}

		println(out);
		print(out, "--" + boundaryString + "--");
	}

	private static void println(OutputStream os) throws IOException {
		os.write('\r');
		os.write('\n');
	}

	private static void print(OutputStream os, String buf) throws IOException {
		os.write(buf.getBytes(StandardCharsets.US_ASCII));
	}

}

相关信息

spring 源码目录

相关文章

spring AbstractGenericHttpMessageConverter 源码

spring AbstractHttpMessageConverter 源码

spring BufferedImageHttpMessageConverter 源码

spring ByteArrayHttpMessageConverter 源码

spring FormHttpMessageConverter 源码

spring GenericHttpMessageConverter 源码

spring HttpMessageConversionException 源码

spring HttpMessageConverter 源码

spring HttpMessageNotReadableException 源码

spring HttpMessageNotWritableException 源码