spring boot隨筆三
阿新 • • 發佈：2020-10-29
Web開發
1、使用SpringBoot：
1）建立SpringBoot應用，選中需要的模組
2）SpringBoot已經預設將這些場景配置好了，只需要在配置檔案中指定少量配置就可以執行起來
3）自己編寫業務程式碼
自動配置原理
xxxAutoConfiguration：幫我們給容器中自動配置元件
xxxProperties：配置類來封裝配置檔案的內容
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2、SpringBoot對靜態資源的對映規則
@ConfigurationProperties(
prefix = "spring.resources",
ignoreUnknownFields = false
)
public class ResourceProperties {
//可以設定和靜態資源有關的引數，快取時間等
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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(WebMvcAutoConfiguration.getResourceLocations(this.resourceProperties.getStaticLocations())).setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
}
}
}
//配置歡迎頁對映
@Bean
public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext, FormattingConversionService mvcConversionService, ResourceUrlProvider mvcResourceUrlProvider) {
WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(new TemplateAvailabilityProviders(applicationContext), applicationContext, this.getWelcomePage(), this.mvcProperties.getStaticPathPattern());
welcomePageHandlerMapping.setInterceptors(this.getInterceptors(mvcConversionService, mvcResourceUrlProvider));
return welcomePageHandlerMapping;
}
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1）所有/webjars/**，都去classpath:/META-INF/resources//webjars/找資源
webjars：以jar包的方式引入靜態資源；
https://www.webjars.org/
<dependency>
<groupId>org.webjars</groupId>
<artifactId>jquery</artifactId>
<version>3.4.1</version>
</dependency>
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2）“/**”訪問當前專案的任何資源（靜態資源的資料夾）
"classpath:/META-INF/resources/",
"classpath:/resources/",
"classpath:/static/",
"classpath:/public/"
"/":當前專案的根路徑
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3）歡迎頁：靜態資原始檔夾下的所有index.html頁面，被"/"對映
4）所有的/favicon.ico 都是在靜態資原始檔下找
3、模板引擎
SpringBoot推薦的Thymeleaf：語法更簡單，功能更強大
3.1 引入Thymeleaf
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
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3.2 Thymeleaf使用&語法
@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";
//只要把html頁面放在classpath:/templates/，thymeleaf就能自動渲染
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使用：
3.2.1 匯入thymeleaf的名稱空間
<html lang="en" xmlns:th="http://www/thymeleaf.org">
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3.2.2 使用thymeleaf語法
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www/thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h1>success</h1>
<!--th:text 將div裡面的文字內容設定為-->
<div th:text="${hello}">這裡顯示歡迎資訊</div>
</body>
</html>
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1）th:text：改變當前元素裡面的文字內容th：任意html屬性，來替換原生屬性的值
2）表示式語法
Simple expressions:
Variable Expressions: ${...}
Selection Variable Expressions: *{...}
Message Expressions: #{...}
Link URL Expressions: @{...}
Fragment Expressions: ~{...}
Literals
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:
String concatenation: +
Literal substitutions: |The name is ${name}|
Arithmetic operations:
Binary operators: +, -, *, /, %
Minus sign (unary operator): -
Boolean operations:
Binary operators: and, or
Boolean negation (unary operator): !, not
Comparisons and equality:
Comparators: >, <, >=, <= (gt, lt, ge, le)
Equality operators: ==, != (eq, ne)
Conditional operators:If-then: (if) ? (then)
If-then-else: (if) ? (then) : (else)
Default: (value) ?: (defaultvalue)
Special tokens:
No-Operation: _