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

java 复制代码

@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;
    }
}
}

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

导入依赖：

XML 复制代码

<!‐‐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>

/**：访问当前项目的任何资，都去(静态资源文件夹)找映射

XML 复制代码

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

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

JSP、Velocity、Freemarker、Thymeleaf：

SpringBoot 推荐的 Thymeleaf：语法更简单，功能更强大

引入 thymeleaf：

XML 复制代码

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

从 Spring 父文件中能看到 SpringBoot 2.0.1 所使用的 thymeleaf 版本是 3.0.9
SpringBoot 启动的时候会自动配置：
1. org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration

从 ThymeleafAutoConfiguration 的源代码中我们可以得知 ThymelaefProperties 中配置了 Thymeleaf 的规则：

java 复制代码

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;
}

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

示例：

在 templates 下创建一个 success.html
在 html 中引入 thymeleaf 的命名空间
java 复制代码
```
<html lang="en" xmlns:th="http://www.thymeleaf.org">
```

创建一个 Controller 提供一个访问的方法：

java 复制代码

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

在 thymeleaf 模板中取值：

java 复制代码

<!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>