工作中一直使用的是SpringCloud，其中的多个组件的使用也已经有一段时间了，包括对组件的配置文件的编写，今天要讲的是SpringCloud中的一个远程服务调用的组件，使用Feign之后，我们调用Eureka注册的其他服务，在代码中就像各个service之间相互调用那么简单。那至于为什么要调用其他服务的接口，就是微服务架构的内容了，今天我讲的是我们项目中独立出来的文件上传模块，我们在项目中将其做成一个通用的接口，使得其他服务中有相同需求时，可以直接调用该服务的接口进行文件上传以及文件管理。
Feign简介
Feign是Netflix开发的声明式，模板化的HTTP客户端，其灵感来自Retrofit，JAXRS-2.0以及WebSocket。
- Feign可帮助我们更加便捷，优雅的调用HTTP API。
- 在SpringCloud中，使用Feign非常简单——创建一个接口，并在接口上添加一些注解，代码就完成了。
- Feign支持多种注解，例如Feign自带的注解或者JAX-RS注解等。
- SpringCloud对Feign进行了增强，使Feign支持了SpringMVC注解，并整合了Ribbon和Eureka，从而让Feign的使用更加方便。
文件上传服务
文件上传我们在项目中将其单独作为一个服务使用，这是考虑到系统中有其他不同的模块需要使用到文件上传，因此独立出来，能够避免在各个子模块中重复编写文件上传的代码，也提高了文件上传接口的使用率。创建文件上传服务的过程就不再介绍了，文件上传想必大家做的都非常多了，我们将主要接口暴露出来。
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@Controller
@RequestMapping("/UploadAppendixCommonController")
public class UploadAppendixCommonController extends BaseController {
private Logger logger = LoggerFactory.getLogger(UploadAppendixCommonController.class);
@Autowired
HttpServletRequest request;
@Autowired
HttpServletResponse response;
@Autowired
private SessionUtils sessionUtils;
@Autowired
private UploadAppendixCommonService uploadAppendixCommonService;
@Autowired
private UploadAppendixCommonConf uploadAppendixCommonConf;
@RequestMapping("/uploadAppendixToServer4Feign")
@ResponseBody
public String uploadAppendixToServer4Feign(@RequestPart("file") MultipartFile file) throws Exception{
List<String> fileNames = new ArrayList<String>();
String fileName = null;
try {
String uuid = UUID.randomUUID().toString().replaceAll("-", "");
SimpleDateFormat df = new SimpleDateFormat("yyyyMMdd");
String time = df.format(new Date());
File uploadfile = new File(uploadAppendixCommonConf.getPath()+time);
if (!uploadfile.exists()) {
uploadfile.mkdirs();
}
if (file != null) {
fileName = file.getOriginalFilename();
String path = uploadAppendixCommonConf.getPath() + time + "/"
+ uuid + fileName.substring(fileName.length()-5,fileName.length());
File localFile = new File(path);
file.transferTo(localFile);
fileNames.add(fileName);
}
String appendixPath = uploadAppendixCommonConf.getPath()+time+"/";
uploadAppendixCommonService.uploadAppendixToServer(uuid,fileNames,null,appendixPath);
return uuid;
}catch (Exception e){
logger.error("UploadAppendixCommonController.uploadAppendixToServer抛出了异常: ", e.getMessage() + e);
throw new Exception(e);
}
}
@RequestMapping("/downloadFileByUUID4Feign")
@ResponseBody
public void downloadFileByUUID4Feign(@RequestParam("UUID") String uuid) throws Exception{
Writer out = null;
try {
response.setHeader("Connection", "close");
response.setContentType("multipart/form-data");
DataModel dataModel = uploadAppendixCommonService.getFileName(uuid);
String fileName = dataModel.get("APPENDIX_NAME").toString();
String filePath = dataModel.get("APPENDIX_PATH").toString();
String tempFileName = "";
try {
tempFileName = ExportUtil2.encodeFileName(request, fileName);
}catch (Exception e){
logger.error("UploadAppendixCommonController.downloadFileByUUID抛出了异常: ", e.getMessage() + e);
}
response.setHeader("Content-Disposition", "attachment;filename=" + tempFileName);
File file = new File(filePath);
if (file.exists()){
byte[] buffer = new byte[1024];
FileInputStream fis = null;
BufferedInputStream bis = null;
try {
fis = new FileInputStream(file);
bis = new BufferedInputStream(fis);
OutputStream os = response.getOutputStream();
int i = bis.read(buffer);
while (i != -1) {
os.write(buffer, 0, i);
i = bis.read(buffer);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (bis != null) {
try {
bis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (fis != null) {
try {
fis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}catch (Exception e){
logger.error("UploadAppendixCommonController.downloadFileByUUID抛出了异常: ", e.getMessage() + e);
throw new Exception(e);
}
}
@RequestMapping("/deleteFileByUUID")
@ResponseBody
public String deleteFileByUUID(@RequestParam("UUID")String uuid) throws Exception{
try {
return uploadAppendixCommonService.deleteFileByUUID(uuid);
}catch (Exception e){
logger.error("UploadAppendixCommonController.deleteFileByUUID抛出了异常: ", e.getMessage() + e);
throw new Exception(e);
}
}
}
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值得注意的一点是，需要在SpringCloud的启动程序中加入Feign的注解。
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| @SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
@EnableSwagger2
public class BusinessFileManageSystemApplication {
public static void main(String[] args) {
SpringApplication.run(BusinessFileManageSystemApplication.class, args);
}
}
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对文件上传服务的调用
文件上传服务配置完成之后，我们进行该服务的调用，首先需要在项目中配置接口，用作在整个项目中进行调用。
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@FeignClient(name = "business-file-manage-system",configuration = FeignMultipartSupportConfig.class)
public interface UploaderServiceFeignClient {
@RequestMapping(value="/UploadAppendixCommonController/uploadAppendixToServer4Feign", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
public String uploadAppendixToServer(@RequestPart("file") MultipartFile file);
@RequestMapping(value="/UploadAppendixCommonController/downloadFileByUUID4Feign")
public Response downloadFileByUUID4Feign(@RequestParam("UUID") String uuid);
@RequestMapping(value = "/UploadAppendixCommonController/downloadFileByUUID",method = RequestMethod.GET)
Response downloadFileByUUID(@RequestParam("UUID")String uuid);
@RequestMapping(value = "/UploadAppendixCommonController/deleteFileByUUID")
String deleteFileByUUID(@RequestParam("UUID")String uuid);
public class UploaderServiceFallback implements UploaderServiceFeignClient{
public String uploadAppendixToServer(MultipartFile file) {
return ResponseEntity.error("上传服务断线，请稍后重试！");
}
public Response downloadFileByUUID4Feign(String uuid) {
throw new RuntimeException("上传服务断线，请稍后重试！");
}
@Override
public Response downloadFileByUUID(String uuid) {
throw new RuntimeException("上传服务断线，请稍后重试！");
}
@Override
public String deleteFileByUUID(String uuid) {
return ResponseEntity.error("上传服务断线，请稍后重试！");
}
}
}
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编写完interface后，在调用处需要将接口实例注入，然后通过接口实例调用接口中的方法，我们以调用文件上传为例，下面提供代码。
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@RequestMapping("/uploadAppendixToServer")
@ResponseBody
public String uploadAppendixToServer(HttpServletRequest request, HttpServletResponse response) throws Exception{
Writer out = null;
List<String> fileNames = new ArrayList<String>();
String fileName = null;
String id = request.getParameter("id");
String uuid = null;
try {
CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(
request.getSession().getServletContext());
if (multipartResolver.isMultipart(request)) {
MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request;
Iterator<String> iter = multiRequest.getFileNames();
while (iter.hasNext()) {
MultipartFile file = multiRequest.getFile(iter.next());
if (file != null) {
uuid = uploaderServiceFeignClient.uploadAppendixToServer(file);
}
}
}
uploadAppendixCommonService.updateAppendixNameListId(id,uuid);
return ResponseEntity.success(uuid,"success");
}catch (Exception e){
logger.error("UploadAppendixCommonController.uploadAppendixToServer抛出了异常: ", e.getMessage() + e);
throw new Exception(e);
}
}
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其实整个过程并不复杂，可以看到我们在配置完Feign之后，调用接口就像调用普通的service一样，同时通过Feign将模块与模块之间联系起来，后续SpringCloud其他组件我们还会再做介绍.
