Spring Boot 静态资源映射与上传文件路由配置

默认静态资源映射目录

默认映射路径

在平常的 web 开发中，避免不了需要访问静态资源，如常规的样式,JS,图片，上传文件等;Spring Boot 默认配置对静态资源映射提供了如下路径的映射 /static (or /public or /resources or /META-INF/resources) ,如下:

/META-INF/resources/
classpath:/resources/
classpath:/static/
classpath:/public/

可以在源码中可以查看到

private static final String[] CLASSPATH_RESOURCE_LOCATIONS = { "classpath:/META-INF/resources/", "classpath:/resources/",  "classpath:/static/", "classpath:/public/" };

当然可以通过配置的方式自定义静态资源的路径,但是会覆盖默认约定的映射目录(默认的配置不可用)

# Locations of static resources.
spring.resources.static-locations=classpath:/META-INF/resources/,classpath:/resources/,classpath:/static/,classpath:/public/

一般情况没有特殊需求不建议自定义配置，使用默认的就好，约定大于配置嘛。也就是在 resources 目录下 public、resources、static(新建项目自带) 三个目录。

默认访问路由

静态资源的默认路由匹配 /** , 路由会从这三个目录中寻找静态资源，如果有则返回,当然可以配置改变默认的路由,如下:

spring.mvc.static-path-pattern=/resources/**

OK，我新建了一个项目，结构目录如下:

比如在 static 目录下新增一个 MP_verify_46Daxcm7OmhjBcYa.txt 文本文件,浏览器访问 http://localhost:8080/MP_verify_46Daxcm7OmhjBcYa.txt 即可,引用 css，js ，图片等资源也不需要再加 static 目录了。

自定义静态资源映射目录

自定义静态资源映射目录可以通过上述配置的方式配置,当然也可以通过编码的方式实现

WebConfig

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        //将访问/static/** 的路由映射到classpath:/static/ 目录下
        registry.addResourceHandler("/static/**").addResourceLocations("classpath:/static/");
    }
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
        registry.addViewController("/groovy").setViewName("hello");
        registry.addViewController("/app").setViewName("app");
    }
}

上传文件映射路径配置

默认 Spring Boot 是内置了 Tomcat 以单个 Jar 包的运行(当然也可以使用 war 包的方式运行在容器里),Spring Boot 项目启动的时候会跟根据约定把静态文件加载到 classpath 目录下,如果要上传文件或写文件日志的话,必须把访问的路由映射到服务器的文件目录。

FileUploadController
    private final ResourceLoader resourceLoader;  
  
    @Autowired  
    public UploadController(ResourceLoader resourceLoader) {  
        this.resourceLoader = resourceLoader;  
    }  

    /**
     * 上传文件
     * @param file
     * @param model
     * @param request
     * @return
     */
    @RequestMapping(method = RequestMethod.POST, value = "/")  
    public String upload(@RequestParam("file") MultipartFile file, Model model, HttpServletRequest request) {  
        if (!file.isEmpty()) {  
            try {  
                Files.copy(file.getInputStream(), Paths.get("/upload", file.getOriginalFilename()));  
                model.addAttribute("message",  "You successfully uploaded " + file.getOriginalFilename() + "!");  
                } catch (IOException|RuntimeException e) {  
                    model.addAttribute("message", "Failued to upload " + file.getOriginalFilename() + " => " + e.getMessage());  
                }  
            } else {  
                model.addAttribute("message", "Failed to upload " + file.getOriginalFilename() + " because it was empty");  
            }  
            return "redirect:/";  
        }  
  }  
    /**
     * 绑定微信用户 （头像图片编码base64）
     * @param weixinBindRequest
     * @param session
     * @return
     */
    @ResponseBody
    @RequestMapping(value = "/uploadImgbase64",method= RequestMethod.POST)
    public WeixinBindResponse uploadImgbase64(@RequestBody WeixinBindRequest weixinBindRequest, HttpSession session) {
        //logger.info("weixinbind req: " + JSON.toJSONString(weixinBindRequest));
        WeixinBindResponse response= new WeixinBindResponse();
        logger.info("weixinbind  openId: "+weixinBindRequest.getOpenid());
        //保存用户头像
        for (int i=0;i<weixinBindRequest.getImgs().length;i++){
            String dataPrix = "";
            String data = "";
            String suffix = "";
            String [] d = weixinBindRequest.getImgs()[i].split("base64,");
            if(d != null && d.length == 2){
                dataPrix = d[0];
                data = d[1];
            }
            if("data:image/jpeg;".equalsIgnoreCase(dataPrix)){//data:image/jpeg;base64,base64编码的jpeg图片数据
                suffix = ".jpg";
            } else if("data:image/x-icon;".equalsIgnoreCase(dataPrix)){//data:image/x-icon;base64,base64编码的icon图片数据
                suffix = ".ico";
            } else if("data:image/gif;".equalsIgnoreCase(dataPrix)){//data:image/gif;base64,base64编码的gif图片数据
                suffix = ".gif";
            } else if("data:image/png;".equalsIgnoreCase(dataPrix)){//data:image/png;base64,base64编码的png图片数据
                suffix = ".png";
            }
            String fileName = weixinBindRequest.getOpenid() +"_"+i + suffix;
            try{
                //  request.getSession().getServletContext().getRealPath("upload");
                //  String path = String.valueOf(Paths.get("upload", weixinBindRequest.getOpenid()));
                FileUtils.writeByteArrayToFile(new File("upload", fileName), Base64Utils.decodeFromString(data));
            }catch(Exception ee){

            }
        }
        //微信绑定用户信息
         boolean flag =  this.userSerice.bindWeixinUser(weixinBindRequest);
        if(!flag){
            response.setIsError(true);
            response.setErrorCode(500);
            response.setErrorMsg("微信绑定用户信息失败！！！");
            return response;
        }
        response.setIsError(false);
        response.setErrorCode(200);
        response.setErrorMsg("微信绑定用户信息成功！！！");
        return response;
    }

    /**
     * 显示图片
     * @param filename
     * @return
     */
    @RequestMapping(method = RequestMethod.GET, value = "/{filename:.+}")
    @ResponseBody
    public ResponseEntity<?> getFile(@PathVariable String filename) {
        try {
            return ResponseEntity.ok(resourceLoader.getResource("file:" + Paths.get("upload", filename).toString()));
        } catch (Exception e) {
            return ResponseEntity.notFound().build();
        }
    }

上传文件的路径会项目根目录上创建，所以不能被直接访问到 ，Spring 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,具体看官方的列子吧: 

https://spring.io/guides/gs/uploading-files/
https://github.com/spring-guides/gs-uploading-files.git

上传文件大小限制

最后别忘了配置文件大小的限制

spring.http.multipart.max-file-size=128KB
spring.http.multipart.max-request-size=128KB

遇到的问题:

如果使用了 nginx 代理提示如下错误：

Troubleshooting “Request Entity Too Large” (HTTP 413) error message returned to browser

nginx 中配置 client_max_body_size 允许的大小 

client_max_body_size       100m; 
client_body_buffer_size    128k;

配置附录:

# SPRING RESOURCES HANDLING (ResourceProperties)
spring.resources.add-mappings=true # Enable default resource handling.
spring.resources.cache-period= # Cache period for the resources served by the resource handler, in seconds.
spring.resources.chain.cache=true # Enable caching in the Resource chain.
spring.resources.chain.enabled= # Enable the Spring Resource Handling chain. Disabled by default unless at least one strategy has been enabled.
spring.resources.chain.gzipped=false # Enable resolution of already gzipped resources.
spring.resources.chain.html-application-cache=false # Enable HTML5 application cache manifest rewriting.
spring.resources.chain.strategy.content.enabled=false # Enable the content Version Strategy.
spring.resources.chain.strategy.content.paths=/** # Comma-separated list of patterns to apply to the Version Strategy.
spring.resources.chain.strategy.fixed.enabled=false # Enable the fixed Version Strategy.
spring.resources.chain.strategy.fixed.paths=/** # Comma-separated list of patterns to apply to the Version Strategy.
spring.resources.chain.strategy.fixed.version= # Version string to use for the Version Strategy.
spring.resources.static-locations=classpath:/META-INF/resources/,classpath:/resources/,classpath:/static/,classpath:/public/ # Locations of static resources.

REFER:
https://spring.io/blog/2014/07/24/spring-framework-4-1-handling-static-web-resources
https://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/#boot-features-spring-mvc-static-content