具体需求：
我们的项目是基于springboot框架的springcloud微服务搭建的，后端服务技术层面整体上分为business服务和core服务，business服务用于作为应用层，直接连接客户端，通常用于聚合数据，core服务用来客户端具体操作不同需求来控制数据库，文件上传是通过客户端上传接口，通过business服务，由服务端调用feign接口，也是第一次做这种文件中转，遇到各种问题，下面是我自己的解决方案，不喜勿喷，代码小白一枚;
一、core服务层接口@requestmapping
属性加上consumes=MediaType.MULTIPART_FORM_DATA_VALUE如下代码
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@PostMapping (value = "/upload" ,consumes = MediaType.MULTIPART_FORM_DATA_VALUE) @ResponseBody public Result<TbFile> upload( @RequestPart (value = "file" ,required = true ) MultipartFile file, @RequestParam (name = "id" ,required = true ) Integer id, @RequestParam (name = "desc" ,required = false ) String desc, @RequestParam (name = "fileId" ,required = false ) Integer fileId ) |
解释：@RequestMapping存在以下两个属性：
1.String[] consumes() default {};
2.String[] produces() default {};
两个属性的解释及参考例子：
① 属性produces：指定返回值类型，并且可以设置返回值类型和返回值的字符编码；代码例子参考如下：
属性produces="application/json"时，返回json数据
属性produces="MediaType.APPLICATION_JSON_VALUE;charset=utf-8"时，设置返回数据的字符编码为utf-8
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@Controller @RequestMapping (value = "/getperson" , method = RequestMethod.GET, produces= "application/json" ) public Object getPerson( int id) { //实现自己的逻辑调用 Person p= new person();
return p; } |
特别说明：produces="application/json"和注解@ResponseBody是一样的效果，使用了注解其实可以不使用该属性了
② 属性consumes： 指定处理请求当中的提交内容类型（Content-Type）：application/json, text/html等;
代码例子参考如下：
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@PostMapping (value = "/upload" ,consumes = MediaType.MULTIPART_FORM_DATA_VALUE) @ResponseBody public Result<TbFile> upload( @RequestPart (value = "file" ,required = true ) MultipartFile file, @RequestParam (name = "id" ,required = true ) Integer id, @RequestParam (name = "desc" ,required = false ) String desc, @RequestParam (name = "fileId" ,required = false ) Integer fileId ){ } |
解释： MediaType.MULTIPART_FORM_DATA_VALUE 代表的值为multipart/form-data它会将表单的数据处理为一条消息，以标签为单元，用分隔符分开。既可以上传键值对，也可以上传文件。当上传的字段是文件时，会有Content-Type来表名文件类型；content-disposition，用来说明字段的一些信息；
二、business客户层接口@requestmapping
属性加上consumes=MediaType.MULTIPART_FORM_DATA_VALUE如下代码
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@PostMapping (value = "/upload" ,produces = MediaType.APPLICATION_JSON_UTF8_VALUE, consumes = MediaType.MULTIPART_FORM_DATA_VALUE) @ResponseBody Result<TbFile> upload( @RequestPart (value = "file" ,required = true ) MultipartFile file, @RequestParam (name = "id" ,required = true ) Integer id, @RequestParam (name = "desc" ,required = false ) String desc, @RequestParam (name = "fileId" ,required = false ) Integer fileId ); |
具体大概就这么多。能力有限，多多指教!!!
feign微服务间文件上传（Finchley版本）
在Spring Cloud 的Feign组件中并不支持文件的传输，会出现这样的错误提示：
feign.codec.EncodeException: class [Lorg.springframework.web.multipart.MultipartFile; is not a type supported by this encoder.
at feign.codec.Encoder$Default.encode(Encoder.java:90) ~[feign-core-9.5.1.jar:na]
at feign.form.FormEncoder.encode(FormEncoder.java:87) ~[feign-form-3.3.0.jar:3.3.0]
at feign.form.spring.SpringFormEncoder.encode(SpringFormEncoder.java:64) ~[feign-form-spring-3.3.0.jar:3.3.0]
但是我们可以通过使用Feign的扩展包实现这个功能。
一. 示例介绍
| feign_upload_first | 8100 | feign服务提供者 |
| feign_upload_second | 8101 | feign服务消费者 |
我们调用feign_upload_second的上传文件接口上传文件，feign_upload_second内部使用feign调用feign_upload_first实现文件上传。
二 、单文件上传
2.1 feign_upload_first服务提供者
文件上传的服务提供者接口比较简单，如下所示：
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@SpringBootApplication public class FeignUploadFirstApplication { @RestController public class UploadController { @RequestMapping (value = "/uploadFile" ,method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE) public String handleFileUpload( @RequestPart (value = "file" ) MultipartFile file) { return file.getOriginalFilename(); } } public static void main(String[] args) { SpringApplication.run(FeignUploadFirstApplication. class , args); } } |
2.2 feign_upload_second服务消费者
增加扩展包依赖
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< dependency > < groupId >io.github.openfeign.form</ groupId > < artifactId >feign-form</ artifactId > < version >3.3.0</ version > </ dependency > < dependency > < groupId >io.github.openfeign.form</ groupId > < artifactId >feign-form-spring</ artifactId > < version >3.3.0</ version > </ dependency > < dependency > < groupId >commons-fileupload</ groupId > < artifactId >commons-fileupload</ artifactId > < version >1.3.3</ version > </ dependency > |
新增feign实现文件上传的配置类
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@Configuration public class FeignSupportConfig { @Bean public Encoder feignFormEncoder() { return new SpringFormEncoder(); } } |
feign远程调用接口
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@FeignClient (name = "file" ,url = "http://localhost:8100" ,configuration = FeignSupportConfig. class ) public interface UploadService { @RequestMapping (value = "/uploadFile" , consumes = MediaType.MULTIPART_FORM_DATA_VALUE) String handleFileUpload( @RequestPart (value = "file" ) MultipartFile file); } |
上传文件接口
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@RestController public class UploadController { @Autowired UploadService uploadService;
@RequestMapping (value = "/uploadFile" ,method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE) public String handleFileUpload( @RequestPart (value = "file" ) MultipartFile file) { return uploadService.handleFileUpload(file); } } |
2.3 测试
使用postman进行测试，可以正常上传文件
三、多文件上传
既然单个文件可以上传，那么多文件应该也没问题吧，我们对上面的代码进行修改
3.1 feign_upload_first服务提供者
文件上传的服务提供者接口比较简单，如下所示：
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@SpringBootApplication public class FeignUploadFirstApplication { @RestController public class UploadController {
@RequestMapping (value = "/uploadFile" ,method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE) public String handleFileUpload( @RequestPart (value = "file" ) MultipartFile file) { return file.getOriginalFilename(); }
@RequestMapping (value = "/uploadFile2" ,method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE) public String handleFileUpload( @RequestPart (value = "file" ) MultipartFile[] file) { String fileName = "" ; for (MultipartFile f : file){ fileName += f.getOriginalFilename()+ "---" ; } return fileName; } } public static void main(String[] args) { SpringApplication.run(FeignUploadFirstApplication. class , args); } } |
3.2 feign_upload_second服务消费者
feign远程调用接口
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@FeignClient (name = "file" ,url = "http://localhost:8100" ,configuration = FeignSupportConfig. class ) public interface UploadService { @RequestMapping (value = "/uploadFile" , consumes = MediaType.MULTIPART_FORM_DATA_VALUE) String handleFileUpload( @RequestPart (value = "file" ) MultipartFile file);
@RequestMapping (value = "/uploadFile2" , consumes = MediaType.MULTIPART_FORM_DATA_VALUE) String handleFileUpload( @RequestPart (value = "file" ) MultipartFile[] file); } |
上传文件接口
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@RestController public class UploadController { @Autowired UploadService uploadService;
@RequestMapping (value = "/uploadFile" ,method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE) public String handleFileUpload( @RequestPart (value = "file" ) MultipartFile file) { return uploadService.handleFileUpload(file); }
@RequestMapping (value = "/uploadFile2" ,method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE) public String handleFileUpload2( @RequestPart (value = "file" ) MultipartFile[] file) { return uploadService.handleFileUpload(file); } } |
3.3 测试
经过测试发现，无法上传多个文件。经过检查，发现源码里底层是有对MultipartFile[]类型的支持的，源码中有个类叫SpringManyMultipartFilesWriter，是专门针对文件数组类型进行操作的，但是配置到项目里的SpringFormEncoder类里却没有对文件数组类型的判断，以致不能支持文件数组的上传
SpringManyMultipartFilesWriter源码
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public class SpringManyMultipartFilesWriter extends AbstractWriter { private final SpringSingleMultipartFileWriter fileWriter = new SpringSingleMultipartFileWriter(); public SpringManyMultipartFilesWriter() { } public void write(Output output, String boundary, String key, Object value) throws Exception { if (value instanceof MultipartFile[]) { MultipartFile[] files = (MultipartFile[])((MultipartFile[])value); MultipartFile[] var6 = files; int var7 = files.length; for ( int var8 = 0 ; var8 < var7; ++var8) { MultipartFile file = var6[var8]; this .fileWriter.write(output, boundary, key, file); } } else if (value instanceof Iterable) { Iterable<?> iterable = (Iterable)value; Iterator var11 = iterable.iterator(); while (var11.hasNext()) { Object file = var11.next(); this .fileWriter.write(output, boundary, key, file); } } } public boolean isApplicable(Object value) { if (value == null ) { return false ; } else if (value instanceof MultipartFile[]) { return true ; } else { if (value instanceof Iterable) { Iterable<?> iterable = (Iterable)value; Iterator<?> iterator = iterable.iterator(); if (iterator.hasNext() && iterator.next() instanceof MultipartFile) { return true ; } } return false ; } } } |
SpringFormEncoder源码
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public class SpringFormEncoder extends FormEncoder { public SpringFormEncoder() { this ( new Default()); } public SpringFormEncoder(Encoder delegate) { super (delegate); MultipartFormContentProcessor processor = (MultipartFormContentProcessor) this .getContentProcessor(ContentType.MULTIPART); processor.addWriter( new SpringSingleMultipartFileWriter()); processor.addWriter( new SpringManyMultipartFilesWriter()); } public void encode(Object object, Type bodyType, RequestTemplate template) throws EncodeException { if (!bodyType.equals(MultipartFile. class )) { super .encode(object, bodyType, template); } else { MultipartFile file = (MultipartFile)object; Map<String, Object> data = Collections.singletonMap(file.getName(), object); super .encode(data, MAP_STRING_WILDCARD, template); } } } |
从上面SpringFormEncoder的源码上可以看到SpringFormEncoder类构造时把SpringManyMultipartFilesWriter实例添加到了处理器列表里了，但是在encode方法里又只判断了MultipartFile类型，没有判断数组类型，底层有对数组的支持但上层却缺少了相应判断。那么我们可以自己去扩展FormEncoder，仿照SpringFormEncoder源码，只修改encode方法。
3.3 扩展FormEncoder支持多文件上传
扩展FormEncoder,命名为FeignSpringFormEncoder
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public class FeignSpringFormEncoder extends FormEncoder { /** * Constructor with the default Feign's encoder as a delegate. */ public FeignSpringFormEncoder() { this ( new Default()); }
/** * Constructor with specified delegate encoder. * * @param delegate delegate encoder, if this encoder couldn't encode object. */ public FeignSpringFormEncoder(Encoder delegate) { super (delegate);
MultipartFormContentProcessor processor = (MultipartFormContentProcessor) getContentProcessor(ContentType.MULTIPART); processor.addWriter( new SpringSingleMultipartFileWriter()); processor.addWriter( new SpringManyMultipartFilesWriter()); }
@Override public void encode(Object object, Type bodyType, RequestTemplate template) throws EncodeException { if (bodyType.equals(MultipartFile. class )) { MultipartFile file = (MultipartFile) object; Map data = Collections.singletonMap(file.getName(), object); super .encode(data, MAP_STRING_WILDCARD, template); return ; } else if (bodyType.equals(MultipartFile[]. class )) { MultipartFile[] file = (MultipartFile[]) object; if (file != null ) { Map data = Collections.singletonMap(file.length == 0 ? "" : file[ 0 ].getName(), object); super .encode(data, MAP_STRING_WILDCARD, template); return ; } } super .encode(object, bodyType, template); } } |
注册配置类
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@Configuration public class FeignSupportConfig { @Bean public Encoder feignFormEncoder() { return new FeignSpringFormEncoder(); } } |
经过测试可以上传多个文件。
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。
原文链接：https://blog.csdn.net/lhz121/article/details/116715273
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