RestTemplate OR Spring Cloud Feign 上传文件

SpringBoot，通过RestTemplate 或者 Spring Cloud Feign，上传文件（支持多文件上传），服务端接口是MultipartFile接收。

将文件的字节流，放入ByteArrayResource中，并重写getFilename方法。

然后将ByteArrayResource放入MultiValueMap中（如果是Feign调用，方法里传参就是MultiValueMap），

然后进行上传时，Spring会自动识别到Map中的文件数据，然后通过FormHttpMessageConverter，将数据转成form表单型的multipart/formdata请求。

这里有个坑！

Spring web 4里面的FormHttpMessageConverter在将文件转成formdata时，会将文件名转成Byte[]，但是使用的编码却是写死 US-ASCII，该编码不支持中文，使用该编码转换后，中文变成？号，是无法转回来的。

我想到的解决方法：

1.将spring版本升到5，Spring5里面，该编码是可以传入修改的。Springboot，默认UTF8

2.客户端进行一次编码，比如URLEncoder。然后服务端进行Decoder。

贴部分代码：

Feign

 调用方，使用Spring 的MultiValueMap类，将文件File 转成 Resource，如果多个文件，则可以循环 用 add 方法，放入一个key下。

MultiValueMap是允许一key多值的。

或者，将多个Resource放入list，然后将list  put 进 map中。

 接收方

接收，可以用

（MultiValueMap map）

如果有其他的 值。

则是（MultiValueMap map，String XXX，String  AAA）

多文件，则是

（MultiValueMap[] map，String XXX，String  AAA）

或者用对象接收，也可以，不需要 @RequestBody 注解，这个注解是接收 http body里的json的。

（Bean bean），bean对象里，则是  MultiValueMap[] map，String XXX，String  AAA

======================  分割线  =================================

我在查询Feign上传文件时，还查到了另一种方式，就是专门给Feign方式提供的feign form相关Jar包，

引入Jar包后，然后进行相关配置，便可以在Feign方法中，参数直接传递MultipartFile。

该方法，或许也可以解决Spring4的编码问题。

===================     分隔线：2018-11-8补充 关于 feign form用法      ====================

先引入相关jar：

<dependency>
			<groupId>io.github.openfeign.form</groupId>
			<artifactId>feign-form</artifactId>
			<version>3.2.2</version>
		</dependency>
		<dependency>
			<groupId>io.github.openfeign.form</groupId>
			<artifactId>feign-form-spring</artifactId>
			<version>3.2.2</version>
		</dependency>

　　

@Bean
	public Logger.Level feignLoggerLevel() {
		return Logger.Level.FULL;
	}

	@Bean
	public Encoder feignFormEncoder() {
		return new SpringFormEncoder();
	}

　　

feign 调用方法 写法 ： 

save(@RequestPart MultipartFile file,@RequestParam("khbh") String khbh)

但是如果，参数多时，一个一个写较为麻烦，可以用

save(Map<String,?> param)

但是，经过测试，发现如果 map中value是null，会出现异常。（原因好像是因为，在将 值写入 formdata时，没有null判断）

========== 上面的用的 feign form

下面 有从网络上查到的，是类似于  feign form的解决方式：
http://b-l-east.iteye.com/blog/2373462

糞坑-SpringCloud中使用Feign的坑
示例如下：
@FeignClient("service-resource")
//@RequestMapping("/api/test")
public interface TestResourceItg {

   @RequestMapping(value = "/api/test/raw", method = RequestMethod.POST, consumes = "application/x-www-form-urlencoded")
   public String raw1(@PathVariable("subject") String subject, // 标题
                  @RequestParam("content") String content); // 内容

}
 
 
说明：
*使用RequestMapping中的consumes指定生成的请求的Content-Type
*RequestParam指定的参数会拼接在URL之后，如: ?name=xxx&age=18
*PathVariable指定的参数会放到一个LinkedHashMap<String, ?>传入到feign的Encoder中进行处理，而在Spring中实现了该接口的Encoder为SpringEncoder，而该实现又会使用Spring中的HttpMessageConverter进行请求体的写入。
 
 
坑：
*不要在接口类名上使用RequestMapping，虽然可以使用，但同时SpringMVC会把该接口的实例当作Controller开放出去，这个可以在启动的Mapping日志中查看到
*使用默认的SpringEncoder，在不指定consumes时，PathVariable中的参数会生成JSON字符串发送，且默认情况下不支持Form表单的生成方式，原因为:FormHttpMessageConverter只能处理MultiValueMap，而使用PathVariable参数被放在了HashMap中。默认更不支持文件上传。其实已经有支持处理各种情况的HttpMessageConverter存在。
 
填坑：
*支持Form表单提交：只需要编写一个支持Map的FormHttpMessageConverter即可，内部可调用FormHttpMessageConverter的方法简化操作。
*支持文件上传：只需要把要上传的文件封装成一个Resource(该Resource一定要实现filename接口，这个是把请求参数解析成文件的标识)，使用默认的ResourceHttpMessageConverter处理即可。
*支持处理MultipartFile参数：编写一个支持MultipartFile的MultipartFileHttpMessageConverter即可，内部可调用ResourceHttpMessageConverter实现，同时注意需要将其添加至FormHttpMessageConverter的Parts中，并重写FormHttpMessageConverter的getFilename方法支持从MultipartFile中获取filename
*所有的HttpMessageConverter直接以@Bean的方式生成即可，spring会自动识别添加
 
完美支持表单和文件上传：
方案一：
使用附件中的MapFormHttpMessageConverter.java和MultipartFileHttpMessageConverter.java
在Spring中进行如下配置即可
@Bean
public MapFormHttpMessageConverter mapFormHttpMessageConverter(MultipartFileHttpMessageConverter multipartFileHttpMessageConverter) {
   MapFormHttpMessageConverter mapFormHttpMessageConverter = new MapFormHttpMessageConverter();
   mapFormHttpMessageConverter.addPartConverter(multipartFileHttpMessageConverter);
   return mapFormHttpMessageConverter;
}

@Bean
public MultipartFileHttpMessageConverter multipartFileHttpMessageConverter() {
   return new MultipartFileHttpMessageConverter();
}
方案二：
使用FeignSpringFormEncoder.java
在Spring中配置如下：
@Bean
public Encoder feignEncoder(ObjectFactory<HttpMessageConverters> messageConverters) {
   return new FeignSpringFormEncoder(messageConverters);
}
 
推荐使用方案一
方案二为参考https://github.com/pcan/feign-client-test而来，未测
 

　　

上面方案中所用代码，贴在下面：

package com.access.service.saas.cmpt.utl;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.springframework.core.io.InputStreamResource;
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.http.converter.ResourceHttpMessageConverter;
import org.springframework.web.multipart.MultipartFile;

/**
 * @author elvis.xu
 * @since 2017-05-09 11:17
 */
public class MultipartFileHttpMessageConverter implements HttpMessageConverter<MultipartFile> {
	protected List<MediaType> supportedMediaTypes = new ArrayList<MediaType>();
	protected ResourceHttpMessageConverter resourceHttpMessageConverter;

	public MultipartFileHttpMessageConverter() {
		supportedMediaTypes.add(MediaType.APPLICATION_OCTET_STREAM);
		resourceHttpMessageConverter = new ResourceHttpMessageConverter();
	}

	public void setSupportedMediaTypes(List<MediaType> supportedMediaTypes) {
		this.supportedMediaTypes = supportedMediaTypes;
	}

	@Override
	public List<MediaType> getSupportedMediaTypes() {
		return Collections.unmodifiableList(this.supportedMediaTypes);
	}

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

	@Override
	public boolean canWrite(Class<?> clazz, MediaType mediaType) {
		if (!MultipartFile.class.isAssignableFrom(clazz)) {
			return false;
		}
		if (mediaType == null || MediaType.ALL.equals(mediaType)) {
			return true;
		}
		for (MediaType supportedMT : getSupportedMediaTypes()) {
			if (supportedMT.isCompatibleWith(mediaType)) {
				return true;
			}
		}
		return false;
	}

	@Override
	public MultipartFile read(Class<? extends MultipartFile> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
		return null;
	}

	@Override
	public void write(MultipartFile file, MediaType contentType, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
		MultipartFileResource multipartFileResource = new MultipartFileResource(file);
		resourceHttpMessageConverter.write(multipartFileResource, contentType, outputMessage);
	}

	public static class MultipartFileResource extends InputStreamResource {

		private final String filename;
		private final long size;

		public MultipartFileResource(MultipartFile multipartFile) throws IOException {
			this(multipartFile.getOriginalFilename(), multipartFile.getSize(), multipartFile.getInputStream());
		}

		public MultipartFileResource(String filename, long size, InputStream inputStream) {
			super(inputStream);
			this.size = size;
			this.filename = filename;
		}

		@Override
		public String getFilename() {
			return this.filename;
		}

		@Override
		public InputStream getInputStream() throws IOException, IllegalStateException {
			return super.getInputStream(); //To change body of generated methods, choose Tools | Templates.
		}

		@Override
		public long contentLength() throws IOException {
			return size;
		}

	}
}

　　

package com.access.service.saas.cmpt.utl;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Type;
import java.nio.charset.Charset;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

import feign.RequestTemplate;
import feign.codec.EncodeException;

import org.springframework.beans.factory.ObjectFactory;
import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
import org.springframework.cloud.netflix.feign.support.SpringEncoder;
import org.springframework.core.io.InputStreamResource;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.web.multipart.MultipartFile;

/**
 * @author elvis.xu
 * @since 2017-04-11 15:33
 */
public class FeignSpringFormEncoder extends SpringEncoder {

	protected ObjectFactory<HttpMessageConverters> messageConverters;
	protected HttpHeaders multipartHeaders = new HttpHeaders();
	public static final Charset UTF_8 = Charset.forName("UTF-8");

	public FeignSpringFormEncoder(ObjectFactory<HttpMessageConverters> messageConverters) {
		super(messageConverters);
		this.messageConverters = messageConverters;
		multipartHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);
	}

	protected static boolean isFormRequest(Type type) {
		return MAP_STRING_WILDCARD.equals(type);
	}

	protected static boolean isMultipart(Object body, Type bodyType) {
		if (isFormRequest(bodyType)) {
			Map<String, ?> map = (Map<String, ?>) body;
			for (Map.Entry<String, ?> entry : map.entrySet()) {
				Object value = entry.getValue();
				if (isMultipartFile(value) || isMultipartFileArray(value)) {
					return true;
				}
			}
		}
		return false;
	}

	protected static boolean isMultipartFile(Object obj) {
		return obj instanceof MultipartFile;
	}

	protected static boolean isMultipartFileArray(Object o) {
		return o != null && o.getClass().isArray() && MultipartFile.class.isAssignableFrom(o.getClass().getComponentType());
	}

	@Override
	public void encode(Object requestBody, Type bodyType, RequestTemplate request) throws EncodeException {
		if (isMultipart(requestBody, bodyType)) {
			encodeMultipartFormRequest((Map<String, ?>) requestBody, request);
		} else {
			super.encode(requestBody, bodyType, request);
		}
	}

	/**
	 * Encodes the request as a multipart form. It can detect a single {@link MultipartFile}, an
	 * array of {@link MultipartFile}s, or POJOs (that are converted to JSON).
	 *
	 * @param formMap
	 * @param template
	 * @throws EncodeException
	 */
	private void encodeMultipartFormRequest(Map<String, ?> formMap, RequestTemplate template) throws EncodeException {
		if (formMap == null) {
			throw new EncodeException("Cannot encode request with null form.");
		}
		LinkedMultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
		for (Map.Entry<String, ?> entry : formMap.entrySet()) {
			Object value = entry.getValue();
			if (isMultipartFile(value)) {
				map.add(entry.getKey(), encodeMultipartFile((MultipartFile) value));
			} else if (isMultipartFileArray(value)) {
				encodeMultipartFiles(map, entry.getKey(), Arrays.asList((MultipartFile[]) value));
			} else {
				map.add(entry.getKey(), encodeJsonObject(value));
			}
		}
		encodeRequest(map, multipartHeaders, template);
	}

	/**
	 * Wraps a single {@link MultipartFile} into a {@link HttpEntity} and sets the
	 * {@code Content-type} header to {@code application/octet-stream}
	 *
	 * @param file
	 * @return
	 */
	private HttpEntity<?> encodeMultipartFile(MultipartFile file) {
		HttpHeaders filePartHeaders = new HttpHeaders();
		filePartHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);
		try {
			Resource multipartFileResource = new MultipartFileResource(file.getOriginalFilename(), file.getSize(), file.getInputStream());
			return new HttpEntity<>(multipartFileResource, filePartHeaders);
		} catch (IOException ex) {
			throw new EncodeException("Cannot encode request.", ex);
		}
	}

	/**
	 * Fills the request map with {@link HttpEntity}s containing the given {@link MultipartFile}s.
	 * Sets the {@code Content-type} header to {@code application/octet-stream} for each file.
	 *
	 * @param map the current request map.
	 * @param name the name of the array field in the multipart form.
	 * @param files
	 */
	private void encodeMultipartFiles(LinkedMultiValueMap<String, Object> map, String name, List<? extends MultipartFile> files) {
		HttpHeaders filePartHeaders = new HttpHeaders();
		filePartHeaders.setContentType(MediaType.APPLICATION_OCTET_STREAM);
		try {
			for (MultipartFile file : files) {
				Resource multipartFileResource = new MultipartFileResource(file.getOriginalFilename(), file.getSize(), file.getInputStream());
				map.add(name, new HttpEntity<>(multipartFileResource, filePartHeaders));
			}
		} catch (IOException ex) {
			throw new EncodeException("Cannot encode request.", ex);
		}
	}

	/**
	 * Wraps an object into a {@link HttpEntity} and sets the {@code Content-type} header to
	 * {@code application/json}
	 *
	 * @param o
	 * @return
	 */
	private HttpEntity<?> encodeJsonObject(Object o) {
		HttpHeaders jsonPartHeaders = new HttpHeaders();
		jsonPartHeaders.setContentType(MediaType.APPLICATION_JSON);
		return new HttpEntity<>(o, jsonPartHeaders);
	}

	/**
	 * Calls the conversion chain actually used by
	 * {@link org.springframework.web.client.RestTemplate}, filling the body of the request
	 * template.
	 *
	 * @param value
	 * @param requestHeaders
	 * @param template
	 * @throws EncodeException
	 */
	private void encodeRequest(Object value, HttpHeaders requestHeaders, RequestTemplate template) throws EncodeException {
		ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
		HttpOutputMessage dummyRequest = new HttpOutputMessageImpl(outputStream, requestHeaders);
		try {
			Class<?> requestType = value.getClass();
			MediaType requestContentType = requestHeaders.getContentType();
			for (HttpMessageConverter<?> messageConverter : messageConverters.getObject().getConverters()) {
				if (messageConverter.canWrite(requestType, requestContentType)) {
					((HttpMessageConverter<Object>) messageConverter).write(value, requestContentType, dummyRequest);
					break;
				}
			}
		} catch (IOException ex) {
			throw new EncodeException("Cannot encode request.", ex);
		}
		HttpHeaders headers = dummyRequest.getHeaders();
		if (headers != null) {
			for (Map.Entry<String, List<String>> entry : headers.entrySet()) {
				template.header(entry.getKey(), entry.getValue());
			}
		}
        /*
        we should use a template output stream... this will cause issues if files are too big,
        since the whole request will be in memory.
         */
		template.body(outputStream.toByteArray(), UTF_8);
	}

	/**
	 * Dummy resource class. Wraps file content and its original name.
	 */
	static class MultipartFileResource extends InputStreamResource {

		private final String filename;
		private final long size;

		public MultipartFileResource(String filename, long size, InputStream inputStream) {
			super(inputStream);
			this.size = size;
			this.filename = filename;
		}

		@Override
		public String getFilename() {
			return this.filename;
		}

		@Override
		public InputStream getInputStream() throws IOException, IllegalStateException {
			return super.getInputStream(); //To change body of generated methods, choose Tools | Templates.
		}

		@Override
		public long contentLength() throws IOException {
			return size;
		}

	}

	/**
	 * Minimal implementation of {@link org.springframework.http.HttpOutputMessage}. It's needed to
	 * provide the request body output stream to
	 * {@link org.springframework.http.converter.HttpMessageConverter}s
	 */
	private class HttpOutputMessageImpl implements HttpOutputMessage {

		private final OutputStream body;
		private final HttpHeaders headers;

		public HttpOutputMessageImpl(OutputStream body, HttpHeaders headers) {
			this.body = body;
			this.headers = headers;
		}

		@Override
		public OutputStream getBody() throws IOException {
			return body;
		}

		@Override
		public HttpHeaders getHeaders() {
			return headers;
		}

	}
}

　　

package com.access.service.saas.cmpt.utl;

import java.io.IOException;
import java.util.List;
import java.util.Map;

import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.FormHttpMessageConverter;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.multipart.MultipartFile;

/**
 * @author elvis.xu
 * @since 2017-05-09 10:58
 */
public class MapFormHttpMessageConverter implements HttpMessageConverter<Map<String, ?>> {

	protected FormHttpMessageConverter formHttpMessageConverter;

	public MapFormHttpMessageConverter() {
		this.formHttpMessageConverter = new MultipartFormHttpMessageConverter();
	}


	public void addPartConverter(HttpMessageConverter<?> partConverter) {
		this.formHttpMessageConverter.addPartConverter(partConverter);
	}

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

	@Override
	public List<MediaType> getSupportedMediaTypes() {
		return formHttpMessageConverter.getSupportedMediaTypes();
	}

	@Override
	public boolean canWrite(Class<?> clazz, MediaType mediaType) {
		if (!Map.class.isAssignableFrom(clazz)) {
			return false;
		}
		if (mediaType == null || MediaType.ALL.equals(mediaType)) {
			return true;
		}
		for (MediaType supportedMediaType : getSupportedMediaTypes()) {
			if (supportedMediaType.isCompatibleWith(mediaType)) {
				return true;
			}
		}
		return false;
	}

	@Override
	public Map<String, ?> read(Class<? extends Map<String, ?>> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
		 return formHttpMessageConverter.read(null, inputMessage);
	}

	public void write(Map<String, ?> map, MediaType contentType, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
		MultiValueMap<String, Object> multiMap = null;
		if (map != null) {
			if (map instanceof MultiValueMap) {
				multiMap = (MultiValueMap<String, Object>) map;
			} else {
				multiMap = new LinkedMultiValueMap<>();
				for (Map.Entry<String, ?> entry : map.entrySet()) {
					multiMap.add(entry.getKey(), entry.getValue());
				}
			}
		}
		formHttpMessageConverter.write(multiMap, contentType, outputMessage);
	}

	public static class MultipartFormHttpMessageConverter extends FormHttpMessageConverter {
		@Override
		protected String getFilename(Object part) {
			String rt = super.getFilename(part);
			if (rt == null && part instanceof MultipartFile) {
				return ((MultipartFile) part).getOriginalFilename();
			}
			return null;
		}
	}
}