自定义资源映射addResourceHandlers：
在springboot中，我们可以通过重写addResourceHandlers方法来映射静态资源目录；
具体做法：编写类继承WebMvcConfigurerAdapter类，重写该类的addResourceHandlers方法；其中addResourceHandler指向映射路径，addResourceLocations指向资源文件路径；资源文件路径地址必须以/结尾，指向文件目录上一层；
比如：

package com.bootdo.common.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Component
class WebConfigurer extends WebMvcConfigurerAdapter {
	@Autowired
	BootdoConfig bootdoConfig;
	@Override
	public void addResourceHandlers(ResourceHandlerRegistry registry) {
		registry.addResourceHandler("/files/**").addResourceLocations("file:///"+"/Users/fanzhen/Documents/ideaworkspaces/bootdo/bootdo/uploaded_files/");
	}

}

我们还可以在addResourceHandlers方法中写多套映射策略：
比如：

package com.bootdo.common.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Component
class WebConfigurer extends WebMvcConfigurerAdapter {
	@Autowired
	BootdoConfig bootdoConfig;
	@Override
	public void addResourceHandlers(ResourceHandlerRegistry registry) {
		//图片资源
		registry.addResourceHandler("/files/**").addResourceLocations("file:///"+"/Users/fanzhen/Documents/ideaworkspaces/bootdo/bootdo/uploaded_files/");
		//文档资源
		registry.addResourceHandler("/docs/**").addResourceLocations("file:///"+"/Users/fanzhen/Documents/ideaworkspaces/bootdo/bootdo/uploaded_files/docs/");
		super.addResourceHandlers(registry);
	}

}