Spring Boot Web项目全解析：从前端请求到后端处理

第一章：对静态资源的整合

@ConfigurationProperties(prefix
= "spring.resources", ignoreUnknownFields
= false)public
class ResourceProperties implements
ResourceLoaderAware
{//可以设置和静态资源有关的参数，缓存时间等
    WebMvcAuotConfiguration：
    @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));
        }
        String staticPathPattern = this.mvcProperties.getStaticPathPattern();
    //静态资源文件夹映射
        if (!registry.hasMappingForPattern(staticPathPattern)) {
            customizeResourceHandlerRegistration(registry.
                    addResourceHandler(staticPathPattern).addResourceLocations(this.resourceProperties.getStaticLocations()).setCachePeriod(cachePeriod));
        }
} /
        /配置欢迎页映射
@Bean
public WelcomePageHandlerMapping welcomePageHandlerMapping(
        ResourceProperties resourceProperties) {
    return new WelcomePageHandlerMapping(resourceProperties.getWelcomePage(),
            this.mvcProperties.getStaticPathPattern());
}
//配置喜欢的图标
@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);
        //所有 **/favicon.ico
        mapping.setUrlMap(Collections.singletonMap("**/favicon.ico",
                faviconRequestHandler());
        return mapping;
    }
    @Bean
    public ResourceHttpRequestHandler faviconRequestHandler() {
        ResourceHttpRequestHandler requestHandler = new ResourceHttpRequestHandler();
        requestHandler.setLocations(this.resourceProperties.getFaviconLocations());
        return requestHandler;
    }
}
}

1. 所有 /webjars/**，都去 classpath：/META-INF/resources/webjars/ 中找资源
2. webjars：以 jar 包方式引入静态资源WebJars - Web Libraries in Jars
3. 导入依赖：

   <!‐‐引入jquery‐webjar‐‐>在访问的时候只需要写webjars下面资源的名称即可
   <dependency>
       <groupId>org.webjars</groupId>
       <artifactId>jquery</artifactId>
       <version>3.3.1</version>
   </dependency>

4. /**：访问当前项目的任何资，都去(静态资源文件夹)找映射

   "classpath:/META‐INF/resources/",
   "classpath:/resources/",
   "classpath:/static/",
   "classpath:/public/"
   "/"：当前项目的根路径

5. 首页：静态资源文件夹下的所有 index.html 页面，被 /** 映射
   1. localhost:端口号/index页面

第二章：模板引擎

1. JSP、Velocity、Freemarker、Thymeleaf：

   1. SpringBoot 推荐的 Thymeleaf：语法更简单，功能更强大

2. 引入 thymeleaf：

   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-thymeleaf</artifactId>
   </dependency>

   1. 从 Spring 父文件中能看到 SpringBoot 2.0.1 所使用的 thymeleaf 版本是 3.0.9
   2. SpringBoot 启动的时候会自动配置：
      1. org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration
   3. 从 ThymeleafAutoConfiguration 的源代码中我们可以得知 ThymelaefProperties 中配置了 Thymeleaf 的规则：

      public class ThymeleafProperties {
          private static final Charset DEFAULT_ENCODING;
          public static final String DEFAULT_PREFIX = "classpath:/templates/";
          public static final String DEFAULT_SUFFIX = ".html";
          private boolean checkTemplate = true;
          private boolean checkTemplateLocation = true;
          private String prefix = "classpath:/templates/";
          private String suffix = ".html";
          private String mode = "HTML";
          private Charset encoding;
          private boolean cache;
      }

   4. 使用 html 作为模板，而且默认的前缀是放在 classpath:/templates/ 下，后缀是 .html
   5. 这些属性可以通过 application.properties 来修改

3. 示例：

   1. 在 templates 下创建一个 success.html
   2. 在 html 中引入 thymeleaf 的命名空间

      <html lang="en" xmlns:th="http://www.thymeleaf.org">

   3. 创建一个 Controller 提供一个访问的方法：

      @RequestMapping("/success")public String hello(Model model){    model.addAttribute("hello","<h1>zhangsan</h1>");  
        return "success";
        }

   4. 在 thymeleaf 模板中取值：

      <!DOCTYPE
      HTML PUBLIC "-//W3C//DTD HTML 4.01       "http://www.w3.org/TR/html4/loose.dtd"
      Transitional//EN">
      html lang="en" xmlns:th="http://www.thymeleaf.org">
      head>
      title>Title</title>
      head>
      body>
      div  th:text="${hello}"> </div>
      body>
      html>