基本概念
使用Spring Boot
1、创建Spring Boot应用，选中需要的模块
2、Spring Boot默认将这些场景配置好了，只需要在配置文件中指定少量配置就可运行
3、编写业务代码
自动配置原理？
这个场景Spring Boot帮助我们配置了什么？能不能修改？能修改哪些配置？能不能扩展？…
xxxxAutoConfiguration：帮我们给容器中自动配置组件
xxxxProperties：配置类来封装配置文件的内容
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Spring Boot对静态资源的映射规则
Spring Boot中添加资源映射的源码：
@ConfigurationProperties(
prefix = "spring.resources",
ignoreUnknownFields = false
)
public class ResourceProperties {
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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));
}
}
}
@Bean
public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext) {
return new WelcomePageHandlerMapping(new TemplateAvailabilityProviders(applicationContext), applicationContext, this.getWelcomePage(), this.mvcProperties.getStaticPathPattern());
}
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分析：
1、所有/webjars/**下的请求，都去classpath:/META-INF/resources/webjars/下找资源。
webjars：以jar包的方式引入静态资源。相关网址
以jquery为例，其结构目录如下：
在pom.xml中引入如下依赖：
<dependency>
<groupId>org.webjars</groupId>
<artifactId>jquery</artifactId>
<version>3.3.1-1</version>
</dependency>
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在访问时只需要写webjars下面资源的名称即可
比如通过localhost:8080/webjars/jquery/3.3.1-1/jquery.js即可访问下面jquery.js文件
2、/**访问当前项目的任何资源（静态资源的文件夹）
"classpath:/META-INF/resources/", 类路径下的/META-INF/resources
"classpath:/resources/", 类路径下的/resources
"classpath:/static/", 类路径下的/static
"classpath:/public/" 类路径下的/public
"/"：当前项目的根路径
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/java/和/resources/是类路径(classpath)的根路径。
访问规则：localhost:8080/abc === 到静态资源文件夹里找abc
3、欢迎页，静态资源文件夹下的所有index.html页面，被/**映射
localhost:8080/ 找index页面
private Resource getIndexHtml(String location) {
return this.resourceLoader.getResource(location + "index.html");
}
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4、所有的**/favicon.ico都是在静态资源文件下找
@Configuration
@ConditionalOnProperty(
value = {"spring.mvc.favicon.enabled"},
matchIfMissing = true
)
public static class FaviconConfiguration implements ResourceLoaderAware {
... ...
@Bean
public SimpleUrlHandlerMapping faviconHandlerMapping() {
SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
mapping.setOrder(-2147483647);
mapping.setUrlMap(Collections.singletonMap("**/favicon.ico", this.faviconRequestHandler()));
return mapping;
}
... ...
}
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模板引擎
工作原理
Spring Boot推荐使用Thymeleaf，语法简单，功能强大
使用方法
1、引入thymeleaf
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<properties>
<thymeleaf.version>3.0.9.RELEASE</thymeleaf.version>
<thymeleaf-layout-dialect.version>2.2.2</thymeleaf-layout-dialect.version>
</properties>
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2、Thymeleaf使用&语法
@ConfigurationProperties(
prefix = "spring.thymeleaf"
)
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";
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说明：只要将HTML页面放在classpath:/templates/，thymeleaf就能自动渲染
1、导入thymeleaf的名称空间
<html lang="en" xmlns:th="http://www.thymeleaf.org">
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2、使用thymeleaf语法
<div th:text="${hello}"></div>
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语法规则
th:text 改变当前元素里面的文本内容
th：任意html属性，来替换原生属性的值
表达式
Simple expressions:（表达式语法）
Variable Expressions: ${...} #获取变量值，OGNL
说明：
1）获取对象的属性、调用方法
2）使用内置的基本对象：
#ctx: the context object.
#vars: the context variables.
#locale: the context locale.
#request: (only in Web Contexts) the HttpServletRequest object.
#response: (only in Web Contexts) the HttpServletResponse object.
#session: (only in Web Contexts) the HttpSession object.
#servletContext: (only in Web Contexts) the ServletContext object.
3）内置的一些工具对象
Selection Variable Expressions: *{...} #选择表达式，和${}在功能上是一样的
说明：配合th:object="${session.user}"
Message Expressions: #{...} #获取国际化内容
Link URL Expressions: @{...} #定义URL
举例：@{/order/process(execId=${execId},execType='FAST')}
Fragment Expressions: ~{...} #片段引用表达式
举例：<div th:insert="~{commons :: main}">...</div>
Literals: （字面量）
Text literals: 'one text', 'Another one!',…
Number literals: 0, 34, 3.0, 12.3,…
Boolean literals: true, false
Null literal: null
Literal tokens: one, sometext, main,…
Text operations: （文本操作）
String concatenation: +
Literal substitutions: |The name is ${name}|
Arithmetic operations: (数学运算)
Binary operators: +, -, *, /, %
Minus sign (unary operator): -
Boolean operations: （布尔运算）
Binary operators: and, or
Boolean negation (unary operator): !, not
Comparisons and equality: （比较运算）
Comparators: >, <, >=, <= (gt, lt, ge, le)
Equality operators: ==, != (eq, ne)
Conditional operators: （条件运算）
If-then: (if) ? (then)
If-then-else: (if) ? (then) : (else)
Default: (value) ?: (defaultvalue)
Special tokens:
No-Operation: _
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