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 )
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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;
}
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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 ){
}
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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 );
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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
服务名 | 端口号 | 角色 |
---|---|---|
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);
}
}
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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 >
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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();
}
}
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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);
}
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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);
}
}
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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);
}
}
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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);
}
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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);
}
}
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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 ;
}
}
}
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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);
}
}
}
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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);
}
}
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注册配置类
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@Configuration
public class FeignSupportConfig {
@Bean
public Encoder feignFormEncoder() {
return new FeignSpringFormEncoder();
}
}
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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服务器之家。
原文链接:https://blog.csdn.net/lhz121/article/details/116715273