springBoot——Web開發簡介【七】

前言

今天咱們終於進入到web學習的階段啦,下面就開始學習吧。

步驟

簡介

如何使springBoot

1. 建立SpringBoot應用，選中咱們須要的模塊；

2. SpringBoot已經默認將這些場景配置好了，只須要在配置文件中指定少許配置就能夠運行起來

3. 編寫業務代碼；

自動配置原理
這個場景SpringBoot幫咱們配置了什麼？能不能修改？能修改哪些配置？能不能擴展？
xxxxAutoConfiguration：幫咱們給容器中自動配置組件；
xxxxProperties:配置類來封裝配置文件的內容；

CURD初試

使用spingboot初始化器，建立一個項目，選擇web模塊便可。

1. 查看項目中的pom.xml文件，查看引入的模塊
2. 建立controller文件夾並建立相應的HelloController類文件

SpringBoot對靜態資源的映射規則

@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties implements ResourceLoaderAware {
  //能夠設置和靜態資源有關的參數，緩存時間等

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();
          	//靜態資源文件夾映射
			if (!registry.hasMappingForPattern(staticPathPattern)) {
				customizeResourceHandlerRegistration(
						registry.addResourceHandler(staticPathPattern)
								.addResourceLocations(
										this.resourceProperties.getStaticLocations())
						.setCachePeriod(cachePeriod));
			}
		}

        //配置歡迎頁映射
		@Bean
		public WelcomePageHandlerMapping welcomePageHandlerMapping(
				ResourceProperties resourceProperties) {
			return new WelcomePageHandlerMapping(resourceProperties.getWelcomePage(),
					this.mvcProperties.getStaticPathPattern());
		}

       //配置喜歡的圖標
		@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);
              	//全部  **/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. 全部 /webjars/ ，都去 classpath:/META-INF/resources/webjars/ 找資源**
webjars：以jar包的方式引入靜態資源 http://www.webjars.org/

<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>jquery</artifactId>
    <version>3.3.1</version>
</dependency>

訪問 | localhost:8080/webjars/jquery/3.3.1/jquery.js

2."/" 訪問當前項目的任何資源，都去（靜態資源的文件夾）找映射**

"classpath:/META-INF/resources/", 
"classpath:/resources/",
"classpath:/static/", 
"classpath:/public/" 
"/"：當前項目的根路徑

訪問 | localhost:8080/abc ===> 去資源文件下找abc

3.歡迎頁,靜態資源文件夾下的全部index.html頁面；被"/"映射**

訪問 | localhost:8080/ ===> 找index頁面

4. 全部的/favicon.ico 都是在靜態資源文件下找

模板引擎

JSP、Velocity、Freemarker、Thymeleaf

pringBoot推薦的Thymeleaf===>語法簡單功能強大

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>
    <!-- 佈局功能的支持程序  thymeleaf3主程序  layout2以上版本 -->
    <!-- thymeleaf2   layout1-->
    <thymeleaf-layout-dialect.version>2.2.2</thymeleaf-layout-dialect.version>
  </properties>

2. 使用thymeleaf

@ConfigurationProperties(prefix = "spring.thymeleaf")
public class ThymeleafProperties {

	private static final Charset DEFAULT_ENCODING = Charset.forName("UTF-8");

	private static final MimeType DEFAULT_CONTENT_TYPE = MimeType.valueOf("text/html");

	public static final String DEFAULT_PREFIX = "classpath:/templates/";

	public static final String DEFAULT_SUFFIX = ".html";

只要咱們把HTML頁面放在classpath:/templates/，thymeleaf就能自動渲染；

使用：

一、導入thymeleaf的名稱空間

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

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>成功！</h1>
    <!--th:text 將div裏面的文本內容設置爲 -->
    <div th:text="${hello}">這是顯示歡迎信息</div>
</body>
</html>

3. 語法規則

1. th:text；改變當前元素裏面的文本內容；
   th：任意html屬性；來替換原生屬性的值
   

2. 表達式

Simple expressions:（表達式語法）
    Variable Expressions: ${...}：獲取變量值；OGNL；
    		1）、獲取對象的屬性、調用方法
    		2）、使用內置的基本對象：
    			#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.
                
                ${session.foo}
            3）、內置的一些工具對象：
#execInfo : information about the template being processed.
#messages : methods for obtaining externalized messages inside variables expressions, in the same way as they would be obtained using #{…} syntax.
#uris : methods for escaping parts of URLs/URIs
#conversions : methods for executing the configured conversion service (if any).
#dates : methods for java.util.Date objects: formatting, component extraction, etc.
#calendars : analogous to #dates , but for java.util.Calendar objects.
#numbers : methods for formatting numeric objects.
#strings : methods for String objects: contains, startsWith, prepending/appending, etc.
#objects : methods for objects in general.
#bools : methods for boolean evaluation.
#arrays : methods for arrays.
#lists : methods for lists.
#sets : methods for sets.
#maps : methods for maps.
#aggregates : methods for creating aggregates on arrays or collections.
#ids : methods for dealing with id attributes that might be repeated (for example, as a result of an iteration).

    Selection Variable Expressions: *{...}：選擇表達式：和${}在功能上是同樣；
    	補充：配合 th:object="${session.user}：
   <div th:object="${session.user}">
    <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>
    
    Message Expressions: #{...}：獲取國際化內容
    Link URL Expressions: @{...}：定義URL；
    		@{/order/process(execId=${execId},execType='FAST')}
    Fragment Expressions: ~{...}：片斷引用表達式
    		<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:（文本操做）
    String concatenation: +
    Literal substitutions: |The name is ${name}|
Arithmetic operations:（數學運算）
    Binary operators: + , - , * , / , %
    Minus sign (unary operator): -
Boolean operations:（布爾運算）
    Binary operators: and , or
    Boolean negation (unary operator): ! , not
Comparisons and equality:（比較運算）
    Comparators: > , < , >= , <= ( gt , lt , ge , le )
    Equality operators: == , != ( eq , ne )
Conditional operators:條件運算（三元運算符）
    If-then: (if) ? (then)
    If-then-else: (if) ? (then) : (else)
    Default: (value) ?: (defaultvalue)
Special tokens:
    No-Operation: _

SpringMVC自動配置

Spring MVC auto-configuration

1. Spring MVC auto-configuration
Spring Boot 自動配置好了SpringMVC
如下是SpringBoot對SpringMVC的默認配置:（WebMvcAutoConfiguration）
Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.
自動配置了ViewResolver（視圖解析器：根據方法的返回值獲得視圖對象（View），視圖對象決定如何
渲染（轉發？重定向？））
ContentNegotiatingViewResolver：組合全部的視圖解析器的；
如何定製：咱們能夠本身給容器中添加一個視圖解析器；自動的將其組合進來；
Support for serving static resources, including support for WebJars (see below).靜態資源文件夾路
徑,webjars
Static index.html support. 靜態首頁訪問
Custom Favicon support (see below). favicon.ico
自動註冊了 of Converter , GenericConverter , Formatter beans.
Converter：轉換器； public String hello(User user)：類型轉換使用Converter
Formatter 格式化器； 2017.12.17===Date；

@Bean
@ConditionalOnProperty(prefix = "spring.mvc", name = "date‐format")//在文件中配置日期格
式化的規則
public Formatter<Date> dateFormatter() {
return new DateFormatter(this.mvcProperties.getDateFormat());//日期格式化組件
}

本身添加的格式化器轉換器，咱們只須要放在容器中便可
Support for HttpMessageConverters (see below).
HttpMessageConverter：SpringMVC用來轉換Http請求和響應的；User---Json；
HttpMessageConverters 是從容器中肯定；獲取全部的HttpMessageConverter；
本身給容器中添加HttpMessageConverter，只須要將本身的組件註冊容器中
（@Bean,@Component）
Automatic registration of MessageCodesResolver (see below).定義錯誤代碼生成規則
Automatic use of a ConfigurableWebBindingInitializer bean (see below).
咱們能夠配置一個ConfigurableWebBindingInitializer來替換默認的；（添加到容器）

初始化WebDataBinder；
請求數據=====JavaBean；

org.springframework.boot.autoconfigure.web：web的全部自動場景；
If you want to keep Spring Boot MVC features, and you just want to add additional MVC configuration
(interceptors, formatters, view controllers etc.) you can add your own @Configuration class of type
WebMvcConfigurerAdapter , but without @EnableWebMvc . If you wish to provide custom instances of
RequestMappingHandlerMapping , RequestMappingHandlerAdapter or ExceptionHandlerExceptionResolver
you can declare a WebMvcRegistrationsAdapter instance providing such components.
If you want to take complete control of Spring MVC, you can add your own @Configuration annotated with
@EnableWebMvc .

2. 擴展SpringMVC

<mvc:view‐controller path="/hello" view‐name="success"/>
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/hello"/>
<bean></bean>
</mvc:interceptor>
</mvc:interceptors>

編寫一個配置類（@Configuration），是WebMvcConfigurerAdapter類型；不能標註@EnableWebMvc;
既保留了全部的自動配置，也能用咱們擴展的配置；

//使用WebMvcConfigurerAdapter能夠來擴展SpringMVC的功能
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
// super.addViewControllers(registry);
//瀏覽器發送 /atguigu 請求來到 success
registry.addViewController("/atguigu").setViewName("success");
}
}

原理：
1）WebMvcAutoConfiguration是SpringMVC的自動配置類
2）在作其餘自動配置時會導入；@Import(EnableWebMvcConfiguration.class)

@Configuration
public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {
private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();
//從容器中獲取全部的WebMvcConfigurer
@Autowired(required = false)
public void setConfigurers(List<WebMvcConfigurer> configurers) {
if (!CollectionUtils.isEmpty(configurers)) {
this.configurers.addWebMvcConfigurers(configurers);
//一個參考實現；將全部的WebMvcConfigurer相關配置都來一塊兒調用；
@Override
// public void addViewControllers(ViewControllerRegistry registry) {
//
//
//
}
}
}

3）容器中全部的WebMvcConfigurer都會一塊兒起做用；
4）咱們的配置類也會被調用；

效果：SpringMVC的自動配置和咱們的擴展配置都會起做用；

3. 全面接管SpringMVC
SpringBoot對SpringMVC的自動配置不須要了，全部都是咱們本身配置；全部的SpringMVC的自動配置都失效了
咱們須要在配置類中添加@EnableWebMvc便可；

//使用WebMvcConfigurerAdapter能夠來擴展SpringMVC的功能
@EnableWebMvc
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
// super.addViewControllers(registry);
//瀏覽器發送 /atguigu 請求來到 success
registry.addViewController("/atguigu").setViewName("success");
}
}

原理：
爲何@EnableWebMvc自動配置就失效了；

1）@EnableWebMvc的核心

@Import(DelegatingWebMvcConfiguration.class)
public @interface EnableWebMvc {

@Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {

@Configuration
@ConditionalOnWebApplication
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class,
WebMvcConfigurerAdapter.class })
//容器中沒有這個組件的時候，這個自動配置類才生效
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,
ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {

4）@EnableWebMvc將WebMvcConfigurationSupport組件導入進來；
5）導入的WebMvcConfigurationSupport只是SpringMVC最基本的功能；

5. 如何修改SpringBoot的默認配置
模式：
1）SpringBoot在自動配置不少組件的時候，先看容器中有沒有用戶本身配置的（@Bean、@Component）如
果有就用用戶配置的，若是沒有，才自動配置；若是有些組件能夠有多個（ViewResolver）將用戶配置的和本身默
認的組合起來；
2）在SpringBoot中會有很是多的xxxConfigurer幫助咱們進行擴展配置
3）在SpringBoot中會有不少的xxxCustomizer幫助咱們進行定製配置

6. RestfulCRUD

1. 默認訪問首頁

//使用WebMvcConfigurerAdapter能夠來擴展SpringMVC的功能
//@EnableWebMvc 不要接管SpringMVC
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
// super.addViewControllers(registry);
//瀏覽器發送 /atguigu 請求來到 success
registry.addViewController("/atguigu").setViewName("success");
}
//全部的WebMvcConfigurerAdapter組件都會一塊兒起做用
@Bean //將組件註冊在容器
public WebMvcConfigurerAdapter webMvcConfigurerAdapter(){
WebMvcConfigurerAdapter adapter = new WebMvcConfigurerAdapter() {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/").setViewName("login");
registry.addViewController("/index.html").setViewName("login");
}
};
return adapter;
}
｝

2）國際化
編寫國際化配置文件；使用ResourceBundleMessageSource管理國際化資源文件；在頁面使用fmt:message取出國際化內容；
步驟：
1️⃣編寫國際化配置文件，抽取頁面須要顯示的國際化消息

2️⃣SpringBoot自動配置好了管理國際化資源文件的組件；

@ConfigurationProperties(prefix = "spring.messages")
public class MessageSourceAutoConfiguration {
/**
* Comma‐separated list of basenames (essentially a fully‐qualified classpath
* location), each following the ResourceBundle convention with relaxed support for
* slash based locations. If it doesn't contain a package qualifier (such as
* "org.mypackage"), it will be resolved from the classpath root.
*/
private String basename = "messages";
//咱們的配置文件能夠直接放在類路徑下叫messages.properties；
@Bean
public MessageSource messageSource() {
ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
if (StringUtils.hasText(this.basename)) {
//設置國際化資源文件的基礎名（去掉語言國家代碼的）
messageSource.setBasenames(StringUtils.commaDelimitedListToStringArray(
StringUtils.trimAllWhitespace(this.basename)));
}
if (this.encoding != null) {
messageSource.setDefaultEncoding(this.encoding.name());
}
messageSource.setFallbackToSystemLocale(this.fallbackToSystemLocale);
messageSource.setCacheSeconds(this.cacheSeconds);
messageSource.setAlwaysUseMessageFormat(this.alwaysUseMessageFormat);
return messageSource;
}

3️⃣去頁面獲取國際化的值；

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta http‐equiv="Content‐Type" content="text/html; charset=UTF‐8">
<meta name="viewport" content="width=device‐width, initial‐scale=1, shrink‐to‐
fit=no">
<meta name="description" content="">
<meta name="author" content="">
<title>Signin Template for Bootstrap</title>
<!‐‐ Bootstrap core CSS ‐‐>
<link href="asserts/css/bootstrap.min.css"
th:href="@{/webjars/bootstrap/4.0.0/css/bootstrap.css}" rel="stylesheet">
<!‐‐ Custom styles for this template ‐‐>
<link href="asserts/css/signin.css" th:href="@{/asserts/css/signin.css}"
rel="stylesheet">
</head>
<body class="text‐center">
<form class="form‐signin" action="dashboard.html">
<img class="mb‐4" th:src="@{/asserts/img/bootstrap‐solid.svg}"
src="asserts/img/bootstrap‐solid.svg" alt="" width="72" height="72">
<h1 class="h3 mb‐3 font‐weight‐normal" th:text="#{login.tip}">Please sign
in</h1>
<label class="sr‐only" th:text="#{login.username}">Username</label>
<input type="text" class="form‐control" placeholder="Username" th:placeholder="#
{login.username}" required="" autofocus="">
<label class="sr‐only" th:text="#{login.password}">Password</label>
<input type="password" class="form‐control" placeholder="Password"
th:placeholder="#{login.password}" required="">
<div class="checkbox mb‐3">
<label>
<input type="checkbox" value="remember‐me"/> [[#{login.remember}]]
</label>
</div>
<button class="btn btn‐lg btn‐primary btn‐block" type="submit" th:text="#
{login.btn}">Sign in</button>
<p class="mt‐5 mb‐3 text‐muted">© 2017‐2018</p>
<a class="btn btn‐sm">中文</a>
<a class="btn btn‐sm">English</a>
</form>
</body>
</html>

根據瀏覽器語言設置信息切換國際化

原理:
國際化Locale（區域信息對象）；LocaleResolver（獲取區域信息對象）；

@Bean
@ConditionalOnMissingBean
@ConditionalOnProperty(prefix = "spring.mvc", name = "locale")
public LocaleResolver localeResolver() {
if (this.mvcProperties
.getLocaleResolver() == WebMvcProperties.LocaleResolver.FIXED) {
return new FixedLocaleResolver(this.mvcProperties.getLocale());
}
AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
localeResolver.setDefaultLocale(this.mvcProperties.getLocale());
return localeResolver;
}
默認的就是根據請求頭帶來的區域信息獲取Locale進行國際化

4️⃣ 點擊連接切換國際化

/**
* 能夠在鏈接上攜帶區域信息
*/
public class MyLocaleResolver implements LocaleResolver {
@Override
public Locale resolveLocale(HttpServletRequest request) {
String l = request.getParameter("l");
Locale locale = Locale.getDefault();
if(!StringUtils.isEmpty(l)){
String[] split = l.split("_");
locale = new Locale(split[0],split[1]);
}
return locale;
}
@Override
public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale
locale) {
}
}
@Bean
public LocaleResolver localeResolver(){
return new MyLocaleResolver();
}
}

3. 登錄

開發期間模板引擎頁面修改之後，要實時生效

1️⃣ 禁用模板引擎頁面修改之後，實時生效

# 禁用緩存
spring.thymeleaf.cache=false

2️⃣ 頁面修改完成ctrl+f9,從新編譯

登錄錯誤信息的顯示

<p style="color: red" th:text="${msg}" th:if="${not #strings.isEmpty(msg)}"></p>

4. 攔截器進行登錄檢查

攔截器

/**
* 登錄檢查，
*/
public class LoginHandlerInterceptor implements HandlerInterceptor {
//目標方法執行以前
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
Object handler) throws Exception {
Object user = request.getSession().getAttribute("loginUser");
if(user == null){
//未登錄，返回登錄頁面
request.setAttribute("msg","沒有權限請先登錄");
request.getRequestDispatcher("/index.html").forward(request,response);
return false;
}else{
//已登錄，放行請求
return true;
}
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object
handler, ModelAndView modelAndView) throws Exception {
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
Object handler, Exception ex) throws Exception {
}
}

註冊攔截器

//全部的WebMvcConfigurerAdapter組件都會一塊兒起做用
@Bean //將組件註冊在容器
public WebMvcConfigurerAdapter webMvcConfigurerAdapter(){
WebMvcConfigurerAdapter adapter = new WebMvcConfigurerAdapter() {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/").setViewName("login");
registry.addViewController("/index.html").setViewName("login");
registry.addViewController("/main.html").setViewName("dashboard");
}
//註冊攔截器
@Override
public void addInterceptors(InterceptorRegistry registry) {
//super.addInterceptors(registry);
//靜態資源； *.css , *.js
//SpringBoot已經作好了靜態資源映射
registry.addInterceptor(new
LoginHandlerInterceptor()).addPathPatterns("/**")
.excludePathPatterns("/index.html","/","/user/login");
}
};
return adapter;
}

5. CURD-員工列表

實驗要求：

1️⃣ RestfulCRUD：CRUD知足Rest風格；
URI： /資源名稱/資源標識 HTTP請求方式區分對資源CRUD操做

2️⃣ 實驗的請求架構

3️⃣ 員工列表

thymeleaf公共頁面元素抽取

一、抽取公共片斷
<div th:fragment="copy">
&copy; 2011 The Good Thymes Virtual Grocery
</div>
二、引入公共片斷
<div th:insert="~{footer :: copy}"></div>
~{templatename::selector}：模板名::選擇器
~{templatename::fragmentname}:模板名::片斷名
三、默認效果：
insert的公共片斷在div標籤中
若是使用th:insert等屬性進行引入，能夠不用寫~{}：
行內寫法能夠加上：[[~{}]];[(~{})]；

三種引入公共片斷的th屬性：

th:insert：將公共片斷整個插入到聲明引入的元素中
th:replace：將聲明引入的元素替換爲公共片斷
th:include：將被引入的片斷的內容包含進這個標籤中

<footer th:fragment="copy">
&copy; 2011 The Good Thymes Virtual Grocery
</footer>
引入方式
<div th:insert="footer :: copy"></div>
<div th:replace="footer :: copy"></div>
<div th:include="footer :: copy"></div>
效果
<div>
<footer>
&copy; 2011 The Good Thymes Virtual Grocery
</footer>
</div>
<footer>
&copy; 2011 The Good Thymes Virtual Grocery
</footer>
<div>
&copy; 2011 The Good Thymes Virtual Grocery
</div>

引入片斷的時候傳入參數：

<nav class="col‐md‐2 d‐none d‐md‐block bg‐light sidebar" id="sidebar">
<div class="sidebar‐sticky">
<ul class="nav flex‐column">
<li class="nav‐item">
<a class="nav‐link active"
th:class="${activeUri=='main.html'?'nav‐link active':'nav‐link'}"
href="#" th:href="@{/main.html}">
<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24"
viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke‐width="2" stroke‐
linecap="round" stroke‐linejoin="round" class="feather feather‐home">
<path d="M3 9l9‐7 9 7v11a2 2 0 0 1‐2 2H5a2 2 0 0 1‐2‐2z"></path>
<polyline points="9 22 9 12 15 12 15 22"></polyline>
</svg>
Dashboard <span class="sr‐only">(current)</span>
</a>
</li>
<!‐‐引入側邊欄;傳入參數‐‐>
<div th:replace="commons/bar::#sidebar(activeUri='emps')"></div>

6. CRUD-員工添加

<form>
    <div class="form-group">
        <label>LastName</label>
        <input type="text" class="form-control" placeholder="zhangsan">
    </div>
    <div class="form-group">
        <label>Email</label>
        <input type="email" class="form-control" placeholder="zhangsan@atguigu.com">
    </div>
    <div class="form-group">
        <label>Gender</label><br/>
        <div class="form-check form-check-inline">
            <input class="form-check-input" type="radio" name="gender"  value="1">
            <label class="form-check-label">男</label>
        </div>
        <div class="form-check form-check-inline">
            <input class="form-check-input" type="radio" name="gender"  value="0">
            <label class="form-check-label">女</label>
        </div>
    </div>
    <div class="form-group">
        <label>department</label>
        <select class="form-control">
            <option>1</option>
            <option>2</option>
            <option>3</option>
            <option>4</option>
            <option>5</option>
        </select>
    </div>
    <div class="form-group">
        <label>Birth</label>
        <input type="text" class="form-control" placeholder="zhangsan">
    </div>
    <button type="submit" class="btn btn-primary">添加</button>
</form>

7. CRUD-員工修改

<!--須要區分是員工修改仍是添加；-->
<form th:action="@{/emp}" method="post">
    <!--發送put請求修改員工數據-->
    <!--
一、SpringMVC中配置HiddenHttpMethodFilter;（SpringBoot自動配置好的）
二、頁面建立一個post表單
三、建立一個input項，name="_method";值就是咱們指定的請求方式
-->
    <input type="hidden" name="_method" value="put" th:if="${emp!=null}"/>
    <input type="hidden" name="id" th:if="${emp!=null}" th:value="${emp.id}">
    <div class="form-group">
        <label>LastName</label>
        <input name="lastName" type="text" class="form-control" placeholder="zhangsan" th:value="${emp!=null}?${emp.lastName}">
    </div>
    <div class="form-group">
        <label>Email</label>
        <input name="email" type="email" class="form-control" placeholder="zhangsan@atguigu.com" th:value="${emp!=null}?${emp.email}">
    </div>
    <div class="form-group">
        <label>Gender</label><br/>
        <div class="form-check form-check-inline">
            <input class="form-check-input" type="radio" name="gender" value="1" th:checked="${emp!=null}?${emp.gender==1}">
            <label class="form-check-label">男</label>
        </div>
        <div class="form-check form-check-inline">
            <input class="form-check-input" type="radio" name="gender" value="0" th:checked="${emp!=null}?${emp.gender==0}">
            <label class="form-check-label">女</label>
        </div>
    </div>
    <div class="form-group">
        <label>department</label>
        <!--提交的是部門的id-->
        <select class="form-control" name="department.id">
            <option th:selected="${emp!=null}?${dept.id == emp.department.id}" th:value="${dept.id}" th:each="dept:${depts}" th:text="${dept.departmentName}">1</option>
        </select>
    </div>
    <div class="form-group">
        <label>Birth</label>
        <input name="birth" type="text" class="form-control" placeholder="zhangsan" th:value="${emp!=null}?${#dates.format(emp.birth, 'yyyy-MM-dd HH:mm')}">
    </div>
    <button type="submit" class="btn btn-primary" th:text="${emp!=null}?'修改':'添加'">添加</button>
</form>

8. CURD-員工刪除

<tr th:each="emp:${emps}">
    <td th:text="${emp.id}"></td>
    <td>[[${emp.lastName}]]</td>
    <td th:text="${emp.email}"></td>
    <td th:text="${emp.gender}==0?'女':'男'"></td>
    <td th:text="${emp.department.departmentName}"></td>
    <td th:text="${#dates.format(emp.birth, 'yyyy-MM-dd HH:mm')}"></td>
    <td>
        <a class="btn btn-sm btn-primary" th:href="@{/emp/}+${emp.id}">編輯</a>
        <button th:attr="del_uri=@{/emp/}+${emp.id}" class="btn btn-sm btn-danger deleteBtn">刪除</button>
    </td>
</tr>


<script>
    $(".deleteBtn").click(function(){
        //刪除當前員工的
        $("#deleteEmpForm").attr("action",$(this).attr("del_uri")).submit();
        return false;
    });
</script>

7. 錯誤處理機制

1. SpringBoot默認的錯誤處理機制

1️⃣ 瀏覽器,返回一個默認的錯誤頁面

瀏覽器發送請求頭信息:

2️⃣ 其餘客戶端(如:postman),默認響應一個json數據

3️⃣ 能夠參照ErrorMvcAutoConfiguration；錯誤處理的自動配置

① DefaultErrorAttributes

@Override
	public Map<String, Object> getErrorAttributes(RequestAttributes requestAttributes,
			boolean includeStackTrace) {
		Map<String, Object> errorAttributes = new LinkedHashMap<String, Object>();
		errorAttributes.put("timestamp", new Date());
		addStatus(errorAttributes, requestAttributes);
		addErrorDetails(errorAttributes, requestAttributes, includeStackTrace);
		addPath(errorAttributes, requestAttributes);
		return errorAttributes;
	}

② BasicErrorController：處理默認/error請求

@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {
    
    @RequestMapping(produces = "text/html")//產生html類型的數據；瀏覽器發送的請求來到這個方法處理
	public ModelAndView errorHtml(HttpServletRequest request,
			HttpServletResponse response) {
		HttpStatus status = getStatus(request);
		Map<String, Object> model = Collections.unmodifiableMap(getErrorAttributes(
				request, isIncludeStackTrace(request, MediaType.TEXT_HTML)));
		response.setStatus(status.value());
        
        //去哪一個頁面做爲錯誤頁面；包含頁面地址和頁面內容
		ModelAndView modelAndView = resolveErrorView(request, response, status, model);
		return (modelAndView == null ? new ModelAndView("error", model) : modelAndView);
	}

	@RequestMapping
	@ResponseBody    //產生json數據，其餘客戶端來到這個方法處理；
	public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
		Map<String, Object> body = getErrorAttributes(request,
				isIncludeStackTrace(request, MediaType.ALL));
		HttpStatus status = getStatus(request);
		return new ResponseEntity<Map<String, Object>>(body, status);
	}

③ ErrorPageCustomizer

@Value("${error.path:/error}")
	private String path = "/error";  系統出現錯誤之後來到error請求進行處理；（web.xml註冊的錯誤頁面規則）

④ DefaultErrorViewResolver

@Override
	public ModelAndView resolveErrorView(HttpServletRequest request, HttpStatus status,
			Map<String, Object> model) {
		ModelAndView modelAndView = resolve(String.valueOf(status), model);
		if (modelAndView == null && SERIES_VIEWS.containsKey(status.series())) {
			modelAndView = resolve(SERIES_VIEWS.get(status.series()), model);
		}
		return modelAndView;
	}

	private ModelAndView resolve(String viewName, Map<String, Object> model) {
        //默認SpringBoot能夠去找到一個頁面？  error/404
		String errorViewName = "error/" + viewName;
        
        //模板引擎能夠解析這個頁面地址就用模板引擎解析
		TemplateAvailabilityProvider provider = this.templateAvailabilityProviders
				.getProvider(errorViewName, this.applicationContext);
		if (provider != null) {
            //模板引擎可用的狀況下返回到errorViewName指定的視圖地址
			return new ModelAndView(errorViewName, model);
		}
        //模板引擎不可用，就在靜態資源文件夾下找errorViewName對應的頁面   error/404.html
		return resolveResource(errorViewName, model);
	}

系統出現4xx或者5xx之類的錯誤；ErrorPageCustomizer就會生效（定製錯誤的響應規則）；就會來到/error請求；就會被BasicErrorController處理

2. 定製錯誤響應

1️⃣ 定製錯誤頁面

① 模板引擎

將錯誤頁面命名爲錯誤狀態碼.html,放在模板引擎文件夾裏面的 error文件夾下，發生此狀態碼的錯誤就會來到對應的頁面；

② 靜態資源文件夾

沒有模板引擎（模板引擎找不到這個錯誤頁面），靜態資源文件夾下找；

③ 默認頁面

以上都沒有錯誤頁面，就是默認來到SpringBoot默認的錯誤提示頁面

2️⃣ 定製錯誤的json數據

① 自定義異常處理&返回定製json數據；

@ControllerAdvice
public class MyExceptionHandler {

    @ResponseBody
    @ExceptionHandler(UserNotExistException.class)
    public Map<String,Object> handleException(Exception e){
        Map<String,Object> map = new HashMap<>();
        map.put("code","user.notexist");
        map.put("message",e.getMessage());
        return map;
    }
}
//沒有自適應效果

② 轉發到/error進行自適應響應效果處理

@ExceptionHandler(UserNotExistException.class)
    public String handleException(Exception e, HttpServletRequest request){
        Map<String,Object> map = new HashMap<>();
        //傳入咱們本身的錯誤狀態碼  4xx 5xx，不然就不會進入定製錯誤頁面的解析流程
        /**
         * Integer statusCode = (Integer) request
         .getAttribute("javax.servlet.error.status_code");
         */
        request.setAttribute("javax.servlet.error.status_code",500);
        map.put("code","user.notexist");
        map.put("message",e.getMessage());
        //轉發到/error
        return "forward:/error";
    }

3️⃣ 定製數據攜帶出去

出現錯誤之後，會來到/error請求，會被BasicErrorController處理，響應出去能夠獲取的數據是由getErrorAttributes獲得的（是AbstractErrorController（ErrorController）規定的方法）；
​一、徹底來編寫一個ErrorController的實現類【或者是編寫AbstractErrorController的子類】，放在容器中；
二、頁面上能用的數據，或者是json返回能用的數據都是經過errorAttributes.getErrorAttributes獲得；
容器中DefaultErrorAttributes.getErrorAttributes()；默認進行數據處理的；
自定義ErrorAttributes

//給容器中加入咱們本身定義的ErrorAttributes
@Component
public class MyErrorAttributes extends DefaultErrorAttributes {

    @Override
    public Map<String, Object> getErrorAttributes(RequestAttributes requestAttributes, boolean includeStackTrace) {
        Map<String, Object> map = super.getErrorAttributes(requestAttributes, includeStackTrace);
        map.put("company","atguigu");
        return map;
    }
}

最終的效果：響應是自適應的，能夠經過定製ErrorAttributes改變須要返回的內容