04.spring-boot与web开发

spring-boot与web开发

1. 创建应用，选择想要创建的场景
2. 在配置文件中指定少量配置
3. 编写业务代码

- xxxAutoConfigration给容器中配置主件
- xxxProperties封装配置的内容

静态资源映射规则

WebMvcAutoConfiguration类

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/**"}).addResourceLocations(new String[]{"classpath:/META-INF/resources/webjars/"}).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));
        }

    }
}

/webjars/**：所有这种类型的请求都去"classpath:/META-INF/resources/webjars/"这个路径下找资源。(以jar包的方式引入静态资源)

https://www.webjars.org/(一般以maven的方式引入前端框架)

http://localhost:8080/webjars/jquery/3.3.1-1/jquery.js 利用webjars访问公共资源

ResourceProperties配置类

//和静态资源相关的配置
@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/"};
    private String[] staticLocations;
    private boolean addMappings;
    private final ResourceProperties.Chain chain;
    private final ResourceProperties.Cache cache;
}

staticPathPattern = "/**"：如果访问的路径没人处理，会默认去CLASSPATH_RESOURCE_LOCATIONS = new String[]{"classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"};这些个资源下面找。

classpath:/META-INF/resources/
classpath:/resources/
classpath:/static/
classpath:/public/

spring-boot初始化的时候只默认建了static，我们就不麻烦建其它的文件夹了，默认静态文件就放在static。

欢迎页映射(找所有静态资源文件下的index.html页面)，由"/**"映射

WelcomePageHandlerMapping(TemplateAvailabilityProviders templateAvailabilityProviders, ApplicationContext applicationContext, Optional<Resource> welcomePage, String staticPathPattern) {
    if (welcomePage.isPresent() && "/**".equals(staticPathPattern)) {
        logger.info("Adding welcome page: " + welcomePage.get());
        this.setRootViewName("forward:index.html");
    } else if (this.welcomeTemplateExists(templateAvailabilityProviders, applicationContext)) {
        logger.info("Adding welcome page template: index");
        this.setRootViewName("index");
    }
}

http://localhost:8080/ 就会找index.html页面

FaviconConfiguration 图标配置

@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() {
        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);
    }
}

页面访问的时候左上角的图片"**/favicon.ico"也是在静态资源文件夹下找

模版引擎 Thymeleaf(用于页面与后端数据交互)

//把html页面放在templates下面就可以自动渲染了
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";

Thymeleaf常用语法

//更改div的文本值，id，class等，即可以用th的任意属性替换原生的属性。
//其中传入变量的方式大多数情况下使用"${...}"
<div th:text="${hello}" th:id="" th:class=""></div>

//"*{...}"基本和$一样，在如下情况下，比"${...}"用着方便些
<div th:object="${session.user}">
    //等同于${session.user.firstName}
    <p>Name: <span th:text="*{firstName}">Sebastian</span>.</p> 
    <p>Surname: <span th:text="*{lastName}">Pepper</span>.</p> 
    <p>Nationality: <span th:text="*{nationality}">Saturn</span>.</p>
</div>

//"#{...}"用于国际化

//"@{...}"用于定义url链接，传入多个变量，用","分割即可
<a href="details.html" th:href="@{/order/{orderId}/details(orderId=${o.id})}">view</a>

//对象遍历，集合遍历
List<User> users = new ArrayList<>();
map.put("users", users);

<table>
    <tr th:each="user: ${users}">
        <td th:text="${user.name}"></td>
        <td th:text="${user.age}"></td>
    </tr>
</table>