上一篇博文说明了SpringBoot对WebJars的支持，那么项目中还有其他静态资源文件，如自定义CSS、JS、image等，SpringBoot同样提供了映射支持。
【1】静态资源文件映射规则
同样查看WebMVCAutoConfiguration源码如下：
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
if (!this.resourceProperties.isAddMappings()) {
logger.debug("Default resource handling disabled");
return;
}
Integer cachePeriod = this.resourceProperties.getCachePeriod();
if (!registry.hasMappingForPattern("/webjars/**")) {
customizeResourceHandlerRegistration(
registry.addResourceHandler("/webjars/**")
.addResourceLocations(
"classpath:/META-INF/resources/webjars/")
.setCachePeriod(cachePeriod));
}
// 对静态资源文件映射支持
String staticPathPattern = this.mvcProperties.getStaticPathPattern();
if (!registry.hasMappingForPattern(staticPathPattern)) {
customizeResourceHandlerRegistration(
registry.addResourceHandler(staticPathPattern)
.addResourceLocations(
this.resourceProperties.getStaticLocations())
.setCachePeriod(cachePeriod));
}
}具体支持代码如下：
String staticPathPattern = this.mvcProperties.getStaticPathPattern();
if (!registry.hasMappingForPattern(staticPathPattern)) {
customizeResourceHandlerRegistration(
registry.addResourceHandler(staticPathPattern)
.addResourceLocations(
this.resourceProperties.getStaticLocations())
.setCachePeriod(cachePeriod));
}第一步拿到staticPathPattern；
/**
* Path pattern used for static resources.
*/
private String staticPathPattern = "/**";第二步如果资源请求没有对应映射，就添加资源处理器及资源找寻位置并设置缓存
if (!registry.hasMappingForPattern(staticPathPattern)) {
customizeResourceHandlerRegistration(
registry.addResourceHandler(staticPathPattern)
.addResourceLocations(
this.resourceProperties.getStaticLocations())
.setCachePeriod(cachePeriod));
}其中 staticLocations在ResourceProperties类中，源码如下：
/**
* Properties used to configure resource handling.
*
* @author Phillip Webb
* @author Brian Clozel
* @author Dave Syer
* @author Venil Noronha
* @since 1.1.0
*/
@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties implements ResourceLoaderAware {
private static final String[] SERVLET_RESOURCE_LOCATIONS = { "/" };
private static final String[] CLASSPATH_RESOURCE_LOCATIONS = {
"classpath:/META-INF/resources/", "classpath:/resources/",
"classpath:/static/", "classpath:/public/" };
private static final String[] RESOURCE_LOCATIONS;
static {
RESOURCE_LOCATIONS = new String[CLASSPATH_RESOURCE_LOCATIONS.length
+ SERVLET_RESOURCE_LOCATIONS.length];
System.arraycopy(SERVLET_RESOURCE_LOCATIONS, 0, RESOURCE_LOCATIONS, 0,
SERVLET_RESOURCE_LOCATIONS.length);
System.arraycopy(CLASSPATH_RESOURCE_LOCATIONS, 0, RESOURCE_LOCATIONS,
SERVLET_RESOURCE_LOCATIONS.length, CLASSPATH_RESOURCE_LOCATIONS.length);
}
/**
* Locations of static resources. Defaults to classpath:[/META-INF/resources/,
* /resources/, /static/, /public/] plus context:/ (the root of the servlet context).
*/
private String[] staticLocations = RESOURCE_LOCATIONS;即："/**"访问当前项目的任何资源，只要没有匹配的处理映射，则都去静态资源的文件夹找映射
"classpath:/META‐INF/resources/",
"classpath:/resources/",
"classpath:/static/",
"classpath:/public/"
"/"：当前项目的根路径
如下图，访问static/asserts/img/bootstrap-solid.svg：
URL ： http://localhost:8083/asserts/img/bootstrap-solid.svg；
这里注意URL上面不要添加静态资源文件夹(路径)的名字，如static、public等等。
【2】默认欢迎页的映射
代码如下：
@Bean
public WelcomePageHandlerMapping welcomePageHandlerMapping(
ResourceProperties resourceProperties) {
return new WelcomePageHandlerMapping(resourceProperties.getWelcomePage(),
this.mvcProperties.getStaticPathPattern());
}注册了WelcomePageHandlerMappingBean来处理项目的默认欢迎页面,构造器有两个参数，第一个是项目中存在的欢迎页资源，第二个是静态资源路径映射规则。
① 获取欢迎页资源
其中跟踪resourceProperties.getWelcomePage()源码：
public Resource getWelcomePage() {
for (String location : getStaticWelcomePageLocations()) {
Resource resource = this.resourceLoader.getResource(location);
try {
if (resource.exists()) {
resource.getURL();
return resource;
}
}
catch (Exception ex) {
// Ignore
}
}
return null;
}即找到存在的欢迎页的资源，继续跟getStaticWelcomePageLocations()源码：
private String[] getStaticWelcomePageLocations() {
String[] result = new String[this.staticLocations.length];
for (int i = 0; i < result.length; i++) {
String location = this.staticLocations[i];
if (!location.endsWith("/")) {
location = location + "/";
}
result[i] = location + "index.html";
}
return result;
}即 欢迎页的位置为第【1】部分中静态资源文件路径下的index.html。
如下所示：
"classpath:/META‐INF/resources/index.html",
"classpath:/resources/index.html",
"classpath:/static/index.html",
"classpath:/public/index.html"
"/"：/index.html② 静态路径映射规则
/**
* Path pattern used for static resources.
*/
private String staticPathPattern = "/**";③ WelcomePageHandlerMapping类
static final class WelcomePageHandlerMapping extends AbstractUrlHandlerMapping {
private static final Log logger = LogFactory
.getLog(WelcomePageHandlerMapping.class);
private WelcomePageHandlerMapping(Resource welcomePage,
String staticPathPattern) {
if (welcomePage != null && "/**".equals(staticPathPattern)) {
logger.info("Adding welcome page: " + welcomePage);
ParameterizableViewController controller = new ParameterizableViewController();
controller.setViewName("forward:index.html");
setRootHandler(controller);
setOrder(0);
}
}
@Override
public Object getHandlerInternal(HttpServletRequest request) throws Exception {
for (MediaType mediaType : getAcceptedMediaTypes(request)) {
if (mediaType.includes(MediaType.TEXT_HTML)) {
return super.getHandlerInternal(request);
}
}
return null;
}
private List<MediaType> getAcceptedMediaTypes(HttpServletRequest request) {
String acceptHeader = request.getHeader(HttpHeaders.ACCEPT);
return MediaType.parseMediaTypes(
StringUtils.hasText(acceptHeader) ? acceptHeader : "*/*");
}
}总结：项目访问时，请求如http://localhost:8083/，则SpringBoot会从静态资源文件路径下找index.html，如果存在一个这样的资源，就转发请求到该页面。
【3】项目浏览器图标的映射
SpringBoot同样对项目浏览器图标请求映射做了默认配置。浏览器图片即项目访问时，浏览器页面上呈现的图标，如CSDN图标如下
代码如下：
@Configuration
@ConditionalOnProperty(value = "spring.mvc.favicon.enabled", matchIfMissing = true)
public static class FaviconConfiguration {
private final ResourceProperties resourceProperties;
public FaviconConfiguration(ResourceProperties resourceProperties) {
this.resourceProperties = resourceProperties;
}
@Bean
public SimpleUrlHandlerMapping faviconHandlerMapping() {
SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
mapping.setOrder(Ordered.HIGHEST_PRECEDENCE + 1);
mapping.setUrlMap(Collections.singletonMap("**/favicon.ico",
faviconRequestHandler()));
return mapping;
}
@Bean
public ResourceHttpRequestHandler faviconRequestHandler() {
ResourceHttpRequestHandler requestHandler = new ResourceHttpRequestHandler();
requestHandler
.setLocations(this.resourceProperties.getFaviconLocations());
return requestHandler;
}
}跟踪源码this.resourceProperties.getFaviconLocations()如下：
List<Resource> getFaviconLocations() {
List<Resource> locations = new ArrayList<Resource>(
this.staticLocations.length + 1);
if (this.resourceLoader != null) {
for (String location : this.staticLocations) {
locations.add(this.resourceLoader.getResource(location));
}
}
locations.add(new ClassPathResource("/"));
return Collections.unmodifiableList(locations);
}即在静态资源文件下找所有的favicon.ico ！