7.SpringBoot 之 Web

添加资源处理

package org.springframework.boot.autoconfigure.web.servlet.
public class WebMvcAutoConfiguration {

　　private final ResourceProperties resourceProperties;

　　public void addResourceHandlers(ResourceHandlerRegistry registry) {
            if (!this.resourceProperties.isAddMappings()) {
                logger.debug("Default resource handling disabled");
            } else {
                Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
                CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
                if (!registry.hasMappingForPattern("/webjars/**")) {
                    this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{"/webjars/**"})//解析此路径下的静态资源文件
　　　　　　　　　　　　　　.addResourceLocations(new String[]{"classpath:/META-INF/resources/webjars/"})　　　　　　　　　　//解析此路径下的静态资源文件
　　　　　　　　　　　　　　.setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
                }
 
                String staticPathPattern = this.mvcProperties.getStaticPathPattern();
                if (!registry.hasMappingForPattern(staticPathPattern)) {
                    this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{staticPathPattern})
　　　　　　　　　　　　　　.addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations()))
　　　　　　　　　　　　　　.setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
                }
            }
        }
　　}

欢迎页：

 　　　　@Bean
        public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext) {
            return new WelcomePageHandlerMapping(new TemplateAvailabilityProviders(applicationContext),
　　　　　　　　　　　applicationContext, this.getWelcomePage(), this.mvcProperties.getStaticPathPattern());//1.欢迎页所在的静态资源访问根路径：/**
        }
 
        static String[] getResourceLocations(String[] staticLocations) {
            String[] locations = new String[staticLocations.length + WebMvcAutoConfiguration.SERVLET_LOCATIONS.length];
            System.arraycopy(staticLocations, 0, locations, 0, staticLocations.length);
            System.arraycopy(WebMvcAutoConfiguration.SERVLET_LOCATIONS, 0, locations, staticLocations.length, WebMvcAutoConfiguration.SERVLET_LOCATIONS.length);
            return locations;
        }
 
        private Optional<Resource> getWelcomePage() {
            String[] locations = getResourceLocations(this.resourceProperties.getStaticLocations());//2.静态页所在的根路径下的路径
            return Arrays.stream(locations).map(this::getIndexHtml).filter(this::isReadable).findFirst();
        }
 
        private Resource getIndexHtml(String location) {
            return this.resourceLoader.getResource(location + "index.html");//3.欢迎页的默认文件名叫index.html
        }

//1.欢迎页所在的静态资源访问根路径：/** 

//2.静态页所在的根路径下的路径

@ConfigurationProperties(
    prefix = "spring.resources",
    ignoreUnknownFields = false
)
public class ResourceProperties {
    private static final String[] CLASSPATH_RESOURCE_LOCATIONS = 
　　　　　　　　　　　　 new String[]{"classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"};//静态页路径
    private String[] staticLocations;
    private boolean addMappings;
    private final ResourceProperties.Chain chain;
    private final ResourceProperties.Cache cache;
 
    public ResourceProperties() {
        this.staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
        this.addMappings = true;
        this.chain = new ResourceProperties.Chain();
        this.cache = new ResourceProperties.Cache();
    }
 
    public String[] getStaticLocations() {
        return this.staticLocations;
    }

　　

   

欢迎页

                   

1、WebJars介绍

Web前端使用了越来越多的JS或CSS，如jQuery，Backbone.js和Bootstrap。一般情况下，我们是将这些Web资源拷贝到Java Web项目的webapp相应目录下进行管理。这种通过人工方式管理可能会产生版本误差，拷贝版本错误，漏拷等现象，导致前端页面无法正确展示，版本不一致，文件混乱等，导致出现一些莫名其妙的错误等。

WebJars是将web前端资源（js，css等）打成jar包文件，然后借助Maven工具，以jar包形式对web前端资源进行统一依赖管理，保证这些Web资源版本唯一性。WebJars的jar包部署在Maven中央仓库上。

WebJars官网：https://www.webjars.org/

2、SpringBoot使用WebJars

 
页面图标

public class WebMvcAutoConfiguration {
　　　　 @Configuration
        @ConditionalOnProperty(
            value = {"spring.mvc.favicon.enabled"},
            matchIfMissing = true
        )
        public static class FaviconConfiguration implements ResourceLoaderAware {
            private final ResourceProperties resourceProperties;
            private ResourceLoader resourceLoader;
 
            public FaviconConfiguration(ResourceProperties resourceProperties) {
                this.resourceProperties = resourceProperties;
            }
 
            public void setResourceLoader(ResourceLoader resourceLoader) {
                this.resourceLoader = resourceLoader;
            }
 
            @Bean
            public SimpleUrlHandlerMapping faviconHandlerMapping() {
                SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
                mapping.setOrder(-2147483647);
                mapping.setUrlMap(Collections.singletonMap("**/favicon.ico", this.faviconRequestHandler()));
                return mapping;
            }
 
            @Bean
            public ResourceHttpRequestHandler faviconRequestHandler() {
                ResourceHttpRequestHandler requestHandler = new ResourceHttpRequestHandler();
                requestHandler.setLocations(this.resolveFaviconLocations());
                return requestHandler;
            }
 
            private List<Resource> resolveFaviconLocations() {、
　　　　　　　　　　//"classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"
　　　　　　　　　　 String[] staticLocations = WebMvcAutoConfiguration.WebMvcAutoConfigurationAdapter.getResourceLocations(this.resourceProperties.getStaticLocations());
                List<Resource> locations = new ArrayList(staticLocations.length + 1);
                Stream var10000 = Arrays.stream(staticLocations);
                ResourceLoader var10001 = this.resourceLoader;
                this.resourceLoader.getClass();
                var10000.map(var10001::getResource).forEach(locations::add);
                locations.add(new ClassPathResource("/"));
                return Collections.unmodifiableList(locations);
            }
        }
}

自定义静态资源路径

<link href="asserts/css/bootstrap.min.css" th:href="@{/webjars/bootstrap/4.1.3/css/bootstrap.css}" rel="stylesheet">
<link href="asserts/css/dashboard.css" th:href="@{/asserts/css/dashboard.css}" rel="stylesheet">
<script type="text/javascript" src="asserts/js/jquery-3.2.1.slim.min.js" th:src="@{/webjars/jquery/3.3.1-1/jquery.js}"></script>
<script type="text/javascript" src="asserts/js/popper.min.js" th:src="@{/webjars/popper.js/1.14.4/popper.js}"></script>
<script type="text/javascript" src="asserts/js/bootstrap.min.js" th:src="@{/webjars/bootstrap/4.1.3/js/bootstrap.js}"></script>
<script type="text/javascript" src="asserts/js/feather.min.js" th:src="@{/asserts/js/feather.min.js}"></script>
<script type="text/javascript" src="asserts/js/Chart.min.js" th:src="@{/asserts/js/Chart.min.js}"></script>

如果不写th：src  或者th:href 去连接获取，若URL请求路径是多级的，eg:http://localhost:8080/emp/add
那么资源文件就会去/emp/asserts/js/下去寻找。寻找不到就会报错了。