這篇文章主要爲大家詳細介紹了Spring Cloud中FeignClient實現文件上傳功能,具有一定的參考價值,感興趣的小夥伴們可以參考一下
項目概況:Spring Cloud搭的微服務,使用了eureka,FeignClient,現在遇到FeignClient調用接口時不支持上傳文件,
百度到兩種方案,一種是使用feign-form和feign-form-spring庫來做,源碼地址。
具體的使用方法是加入maven依賴
<dependency> <groupId>io.github.openfeign.form</groupId> <artifactId>feign-form-spring</artifactId> <version>3.2.2</version> </dependency> <dependency> <groupId>io.github.openfeign.form</groupId> <artifactId>feign-form</artifactId> <version>3.2.2</version> </dependency>
注入SpringFormEncoder類
@Bean @Primary @Scope("prototype") public Encoder multipartFormEncoder() { return new SpringFormEncoder(); }
FeignClient接口裏方法參數是文件類型的要用@RequestPart註解,且要設置ContentType爲multipart/form-data
@ResponseBody @RequestMapping(value = "/ctstestcase/updateTestCase", method = {RequestMethod.POST}, consumes = MediaType.MULTIPART_FORM_DATA_VALUE) Map<String, Object> updateTestCase(@RequestParam("testcaseId") String testcaseId, @RequestParam("name") String name, @RequestParam("assignId") String assignId, @RequestParam("areaId") String areaId, @RequestParam("state") Integer state, @RequestParam("iterationId") String iterationId,@RequestParam("priority") Integer priority, @RequestParam("moduleId") String moduleId, @RequestParam("executionType") Integer executionType, @RequestParam("summary") String summary, @RequestParam("tcsteps") String tcsteps, @RequestParam("relations") String relations,@RequestParam("attachments") String attachments, @RequestPart("files") MultipartFile[] files);
但遇到一個問題,就是不支持文件數組類型,我看了源碼,發現源碼裏底層是有對MultipartFile[]類型的支持的,源碼中有個類叫SpringManyMultipartFilesWriter,是專門針對文件數組類型進行操作的,但是配置到項目裏的SpringFormEncoder類裏卻沒有對文件數組類型的判斷,以致不能支持文件數組的上傳.。
SpringManyMultipartFilesWriter源碼:
@FieldDefaults(level = PRIVATE, makeFinal = true) public class SpringManyMultipartFilesWriter extends AbstractWriter { SpringSingleMultipartFileWriter fileWriter = new SpringSingleMultipartFileWriter(); @Override public void write (Output output, String boundary, String key, Object value) throws Exception { if (value instanceof MultipartFile[]) { val files = (MultipartFile[]) value; for (val file : files) { fileWriter.write(output, boundary, key, file); } } else if (value instanceof Iterable) { val iterable = (Iterable<?>) value; for (val file : iterable) { fileWriter.write(output, boundary, key, file); } } } @Override public boolean isApplicable (Object value) { if (value == null) { return false; } if (value instanceof MultipartFile[]) { return true; } if (value instanceof Iterable) { val iterable = (Iterable<?>) value; val iterator = iterable.iterator(); if (iterator.hasNext() && iterator.next() instanceof MultipartFile) { return true; } } return false; }
SpringFormEncoder源碼:
public class SpringFormEncoder extends FormEncoder { /** * Constructor with the default Feign's encoder as a delegate. */ public SpringFormEncoder () { this(new Encoder.Default()); } /** * Constructor with specified delegate encoder. * * @param delegate delegate encoder, if this encoder couldn't encode object. */ public SpringFormEncoder (Encoder delegate) { super(delegate); val processor = (MultipartFormContentProcessor) getContentProcessor(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)) { super.encode(object, bodyType, template); return; } val file = (MultipartFile) object; val data = singletonMap(file.getName(), object); super.encode(data, MAP_STRING_WILDCARD, template); } }
從上面SpringFormEncoder的源碼上可以看到SpringFormEncoder類構造時把SpringManyMultipartFilesWriter實例添加到了處理器列表裏了,但是在encode方法裏又只判斷了MultipartFile類型,沒有判斷數組類型,這就比較奇怪了,底層有對數組的支持但上層卻缺少了相應判斷,而且在源碼裏的test包裏也沒有對文件數組類型的測試,難道只是encode方法裏漏掉了?還是說那個文件數組的支持有問題?所以encode方法裏纔沒有加入對其的判斷?
於是我先試着對encode方法進行擴展加入對文件數組的判斷,應該就可以支持文件數組的上傳了,於是把SpringFormEncoder類源碼複製出來重命名爲FeignSpringFormEncoder,源碼如下:
public class FeignSpringFormEncoder extends FormEncoder { /** * Constructor with the default Feign's encoder as a delegate. */ public FeignSpringFormEncoder() { this(new Encoder.Default()); } /** * Constructor with specified delegate encoder. * * @param delegate delegate encoder, if this encoder couldn't encode object. */ public FeignSpringFormEncoder(Encoder delegate) { super(delegate); val processor = (MultipartFormContentProcessor) getContentProcessor(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)) { val file = (MultipartFile) object; val data = singletonMap(file.getName(), object); super.encode(data, MAP_STRING_WILDCARD, template); return; } else if (bodyType.equals(MultipartFile[].class)) { val file = (MultipartFile[]) object; if(file != null) { val data = singletonMap(file.length == 0 ? "" : file[0].getName(), object); super.encode(data, MAP_STRING_WILDCARD, template); return; } } super.encode(object, bodyType, template); } }
經過測試,已經可以支持文件數組了,完美解決。
這裏再順便說一下當時還百度到另一個解決文件上傳的方案,這個方案就不細說了,直接上我用到的那個開源代碼的地址
這個我試過也是可以解決文件上傳問題的,但問題是FeignClient不能用SpringMVC的註解,得用Feign自帶的註解,也因此我才擴展了第一種方法來做的文件上傳功能。
以上就是本文的全部內容,希望對大家的學習有所幫助,也希望大家多多支持神馬文庫。