spring boot 图片上传与显示功能实例详解
spring boot 图片上传与显示功能实例详解
发布时间:2017-04-13 来源:查字典编辑
摘要:首先描述一下问题,springboot使用的是内嵌的tomcat,所以不清楚文件上传到哪里去了,而且springboot把静态的文件全部在启...

  首先描述一下问题,spring boot 使用的是内嵌的tomcat, 所以不清楚文件上传到哪里去了, 而且spring boot 把静态的文件全部在启动的时候都会加载到classpath的目录下的,所以上传的文件不知相对于应用目录在哪,也不知怎么写访问路径合适,对于新手的自己真的一头雾水。

  后面想起了官方的例子,没想到一开始被自己找到的官方例子,后面太依赖百度谷歌了,结果发现只有官方的例子能帮上忙,而且帮上大忙,直接上密码的代码

  package hello;

  import static org.springframework.hateoas.mvc.ControllerLinkBuilder.linkTo;

  import static org.springframework.hateoas.mvc.ControllerLinkBuilder.methodOn;

  import java.io.IOException;

  import java.nio.file.Files;

  import java.nio.file.Paths;

  import java.util.stream.Collectors;

  import javax.servlet.http.HttpServletRequest;

  import org.slf4j.Logger;

  import org.slf4j.LoggerFactory;

  import org.springframework.beans.factory.annotation.Autowired;

  import org.springframework.core.io.ResourceLoader;

  import org.springframework.http.ResponseEntity;

  import org.springframework.stereotype.Controller;

  import org.springframework.ui.Model;

  import org.springframework.web.bind.annotation.PathVariable;

  import org.springframework.web.bind.annotation.RequestMapping;

  import org.springframework.web.bind.annotation.RequestMethod;

  import org.springframework.web.bind.annotation.RequestParam;

  import org.springframework.web.bind.annotation.ResponseBody;

  import org.springframework.web.multipart.MultipartFile;

  import org.springframework.web.servlet.mvc.support.RedirectAttributes;

  @Controller

  public class FileUploadController {

  private static final Logger log = LoggerFactory.getLogger(FileUploadController.class);

  public static final String ROOT = "upload-dir";

  private final ResourceLoader resourceLoader;

  @Autowired

  public FileUploadController(ResourceLoader resourceLoader) {

  this.resourceLoader = resourceLoader;

  }

  @RequestMapping(method = RequestMethod.GET, value = "/")

  public String provideUploadInfo(Model model) throws IOException {

  model.addAttribute("files", Files.walk(Paths.get(ROOT))

  .filter(path -> !path.equals(Paths.get(ROOT)))

  .map(path -> Paths.get(ROOT).relativize(path))

  .map(path -> linkTo(methodOn(FileUploadController.class).getFile(path.toString())).withRel(path.toString()))

  .collect(Collectors.toList()));

  return "uploadForm";

  }

  //显示图片的方法关键 匹配路径像 localhost:8080/b7c76eb3-5a67-4d41-ae5c-1642af3f8746.png

  @RequestMapping(method = RequestMethod.GET, value = "/{filename:.+}")

  @ResponseBody

  public ResponseEntity getFile(@PathVariable String filename) {

  try {

  return ResponseEntity.ok(resourceLoader.getResource("file:" + Paths.get(ROOT, filename).toString()));

  } catch (Exception e) {

  return ResponseEntity.notFound().build();

  }

  }

  //上传的方法

  @RequestMapping(method = RequestMethod.POST, value = "/")

  public String handleFileUpload(@RequestParam("file") MultipartFile file,

  RedirectAttributes redirectAttributes, HttpServletRequest request) {

  System.out.println(request.getParameter("member"));

  if (!file.isEmpty()) {

  try {

  Files.copy(file.getInputStream(), Paths.get(ROOT, file.getOriginalFilename()));

  redirectAttributes.addFlashAttribute("message",

  "You successfully uploaded " + file.getOriginalFilename() + "!");

  } catch (IOException|RuntimeException e) {

  redirectAttributes.addFlashAttribute("message", "Failued to upload " + file.getOriginalFilename() + " => " + e.getMessage());

  }

  } else {

  redirectAttributes.addFlashAttribute("message", "Failed to upload " + file.getOriginalFilename() + " because it was empty");

  }

  return "redirect:/";

  }

  }

  看完上面的代码可以理解到spring boot 的存取文件思路了,存的时候的路径为

  Paths.get(ROOT, filename).toString()))

  这个路径会在本地的工程根目录上创建,不应用部署里的目录,所以一般的访问http访问不可能 ,所以它提供了ResourceLoader,利于这个类可以加载非应用目录的里文件然后返回

  所以就可以读取文件,所以就要写getFIle方法来显示图片

spring boot 图片上传与显示功能实例详解 查字典教程网

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