SpringBoot學習筆記--Web

時間  2020-06-15
標籤 springboot 學習 筆記 web 欄目 Spring 简体版
原文   原文鏈接

4、Web

1. 簡介

使用SpringBootcss

  1. 建立Spring Boot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. 本身編寫業務代碼

自動配置原理？html

xxxAutoConfiguration自動給容器中配置組件

xxxProperties 配置類來封裝配置文件的內容前端

2. SpringBoot對靜態資源的映射規則

能夠設置和資源有關的參數java

@ConfigurationProperties(
    prefix = "spring.resources",
    ignoreUnknownFields = false
)
public class ResourceProperties implements ResourceLoaderAware
public void addResourceHandlers(ResourceHandlerRegistry registry) {
            if (!this.resourceProperties.isAddMappings()) {
                logger.debug("Default resource handling disabled");
            } else {
                Integer cachePeriod = this.resourceProperties.getCachePeriod();
                if (!registry.hasMappingForPattern("/webjars/**")) {
                    this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{"/webjars/**"}).addResourceLocations(new String[]{"classpath:/META-INF/resources/webjars/"}).setCachePeriod(cachePeriod));
                }

                String staticPathPattern = this.mvcProperties.getStaticPathPattern();
                if (!registry.hasMappingForPattern(staticPathPattern)) {
                    this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{staticPathPattern}).addResourceLocations(this.resourceProperties.getStaticLocations()).setCachePeriod(cachePeriod));
                }

            }
            }

  1. 全部/webjars/** 請求，都去classpath:/META-INF/resources/webjars/ 找資源jquery

    引入資源git

    <!-- 引入jquery的webjar -->
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>jquery</artifactId>
            <version>3.3.1</version>
        </dependency>

    webjars：是指以jar的方式導入資源github

    <img width="352" alt="wx20180518-205514 2x" src="https://user-images.githubuse...;>web

    如訪問：http://localhost:8080/webjars/jquery/3.3.1/jquery.jsspring

  2. "/**"訪問當前項目的任何資源（靜態資源的文件夾）express

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

    注意：目前SpringBoot下的resources是類路徑，並不是該路徑classpath:/resources/

    localhost:8080/abc 默認去靜態文件夾裏面找abc

  3. 歡迎頁：靜態資源證下全部的index.html，被/**映射

    @Bean
        public WelcomePageHandlerMapping welcomePageHandlerMapping(
                ResourceProperties resourceProperties) {
            return new WelcomePageHandlerMapping(resourceProperties.getWelcomePage(),
                    this.mvcProperties.getStaticPathPattern());
        }

  4. 全部的**/favicon.ico都是在靜態資源文件夾中找

    @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);
                mapping.setUrlMap(Collections.singletonMap("**/favicon.ico",
                        faviconRequestHandler()));
                return mapping;
            }

            @Bean
            public ResourceHttpRequestHandler faviconRequestHandler() {
                ResourceHttpRequestHandler requestHandler = new ResourceHttpRequestHandler();
                requestHandler
                        .setLocations(this.resourceProperties.getFaviconLocations());
                return requestHandler;
            }

        }
  5. 自定義靜態資源目錄
spring.resources.static-locations=classpath:/hello/,classpath:/meituan/

3. 模塊引擎

JSP、Welocity、Freemarker、Thymeleaf

template engine

Spring Boot推薦使用的模塊引擎Thymeleaf

3.1 引入Thymeleaf

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

使用Thymeleaf3

<properties>
    <thymeleaf.version>3.0.2.RELEASE</thymeleaf.version>
    <thymeleaf-layout-dialect.version>2.1.1</thymeleaf-layout-dialect.version>
</properties>

增長thymeleaf-layout支持

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

3.2 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");

//只要咱們把HTML頁面放在classpath:/templates/,thymeleaf就能夠自動渲染了
    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就能夠自動渲染了

  1. 導入thymeleaf的名稱空間
<html xmlns:th="http://www.thymeleaf.org">
  1. 使用thymeleaf語法
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>success</title>
</head>
<body>
    <h1>成功！</h1>
    <!--將div中的文本內容設置爲文本內指定的值-->
    <div th:text="${hello}">這是顯示歡迎信息</div>
</body>
</html>

3.3 語法規則

  1. th:text：改變當前元素裏面的文本內容

    th: 作生意html屬性，來替換原生屬性的值

    thymeleaf

  2. 表達式語法
Simple expressions:
       Variable Expressions: ${...}
           1. 獲取對象的屬性、調用方法
           2. 使用內置的基本對象
           3. 內置工具對象
       Selection Variable Expressions: *{...} 選擇表達式
           補充：配合th:object使用
           <div th:object="${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連接
       
       Fragment Expressions: ~{...}
       
   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）
       If-then: (if) ? (then)
       If-then-else: (if) ? (then) : (else)
       Default: (value) ?: (defaultvalue)
   Special tokens:
       Page 17 of 104
       No-Operation: _

4. SpringBoot對SpringMVC的自動配置

4.1 SpringBoot 對靜態資源的映射規則

Spring Boot provides auto-configuration for Spring MVC that works well with most applications.

The auto-configuration adds the following features on top of Spring’s defaults:

  • 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，轉發或重定向)
    • ContentNegotiatingViewResolver組合全部的視圖解析器
    • 如何定製：能夠本身給容器中添加一個視圖解析器，ContentNegotiatingViewResolver會自動將其組合起來
  • Support for serving static resources, including support for WebJars (see below).靜態資源文件夾路徑

  • Automatic registration of Converter, GenericConverter, Formatter beans.

    • Converter 轉換器 頁面接收的數據類型轉換使用Converter
    • Formatter 格式化器，例如2018.5.22=》Date
    • 本身添加的Convertor、Formattor只需放在容器中便可

  • Support for HttpMessageConverters (see below).

    • HttpMessageConverterSpringMVC用來轉換Http的請求和響應：User《=》json
    • HttpMessageConverters從容器中肯定；獲取全部的HttpmessageConverter
    • 本身給容器中添加HttpMessageConverter，只需將本身的組件註冊到容器中(@Bean @Component)
  • Automatic registration of MessageCodesResolver (see below).定義錯誤代碼生成規則
  • Static index.html support.靜態首頁訪問
  • Custom Favicon support (see below).

  • Automatic use of a ConfigurableWebBindingInitializer bean (see below).

    • 能夠配置一個ConfigurableWebBindingInitializer來替換默認的(添加的容器中)
    • ConfigurableWebBindingInitializer的做用是初始化WebDataBinder

org.springframework.boot.autoconfigure.web : web的全部自動配置場景

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.

4.2 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，也能使用自定義的擴展配置

@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/meituan").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({WebMvcAutoConfiguration.EnableWebMvcConfiguration.class})
@Configuration
    public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration
    
    
    @Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {

    private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();


    @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相關配置得了來一塊兒調用
            /**    @Override
                    public void addViewControllers(ViewControllerRegistry registry) {
                        for (WebMvcConfigurer delegate : this.delegates) {
                            delegate.addViewControllers(registry);
                        }
                    }
                    */
        }
    }
  1. 容器中全部的WebMvcConfigurer都會共同起做用
  2. 自定義的配置類也會被調用

    效果：SpringMVC的自動配置和自定義的擴展配置得了會起做用。

4.3 全面接管SpringMVC

SpringBoot對SpringMVC的自動配置不須要了，全部都手動配置

此時須要在配置類中添加@EnableWebMvc，SpringBoot對SpringMVC的自動配置都失效

原理：

  1. @Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(DelegatingWebMvcConfiguration.class)
public @interface EnableWebMvc
  2. @Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport

  3. WebMvcAutoConfiguration要求沒有WebMvcConfigurationSupport註解的類存在在容器中，而添加了@EnableWebMvc的註解偏偏是個WebMvcConfigurationSupport的子類

    @Configuration
@ConditionalOnWebApplication
@ConditionalOnClass({Servlet.class, DispatcherServlet.class, WebMvcConfigurerAdapter.class})
@ConditionalOnMissingBean({WebMvcConfigurationSupport.class})
@AutoConfigureOrder(-2147483638)
@AutoConfigureAfter({DispatcherServletAutoConfiguration.class, ValidationAutoConfiguration.class})
public class WebMvcAutoConfiguration
  4. 導入的WebMvcConfigurationSupport只是SpringMVC的基本功能

5. 如何修改Spring Boot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，若是有就用用戶配置的；若是沒有才自動配置；若是有些組件可能有多個(ViewResolver)，SpringBoot會將用戶配置的和本身默認配置的組合起來
  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

6.1 引入資源

<!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">Please sign in</h1>
            <label class="sr-only">Username</label>
            <input type="text" class="form-control" placeholder="Username" required="" autofocus="">
            <label class="sr-only">Password</label>
            <input type="password" class="form-control" placeholder="Password" required="">
            <div class="checkbox mb-3">
                <label>
          <input type="checkbox" value="remember-me"> Remember me
        </label>
            </div>
            <button class="btn btn-lg btn-primary btn-block" type="submit">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>

採用thymeleaf的寫法，如<link href="asserts/css/bootstrap.min.css" th:href="@{/webjars/bootstrap/4.0.0/css/bootstrap.css}" rel="stylesheet" />好處是更改項目目錄後不須要再修改代碼

6.2 國際化

在SpringMVC中須要如下幾個步驟

  1. 編寫國際化配置文件
  2. 使用ResourceBundleMessageSour管理國際化資源文件
  3. 在頁面使用fmt:message取出國際化內容

SpringBoot中的步驟爲：

  1. 編寫國際化配置文件，抽取頁面須要顯示的國際化消息

    20180211130721

  2. SpringBoot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 {

    private static final Resource[] NO_RESOURCES = {};

    /**
         * 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
*/
    private String basename = "messages";//咱們的配置文件能夠直接放在類路徑下，叫messages.properties，此時不須要作任何配置便可生效；如自定義，能夠在application.properties中添加配置spring.messages.basename=i18n.login

    @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;
    }

```
  1. 去頁面獲取國際化的值

    在idea中能夠經過修改Other-Settings ---> Default Settings來修改全局配置20180211134506

<!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" required="" autofocus="">
            <label class="sr-only" th:text="#{login.password}">Password</label>
            <input type="password" class="form-control" placeholder="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>

效果：根據瀏覽器語言設置的信息切換了國際化；

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;
        }
默認的區域信息解析器是根據請求頭帶來的區域信息獲取Locale進行國際化
  1. 點擊連接切換Locale

自定義LocaleResolver

/**
 * 能夠在連接上攜帶區域信息
 */

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) {

    }
}


//在MyMvcConfig中添加組件
    @Bean
    public LocaleResolver localeResolver() {
        return new MylocaleResolver();
    }

6.3 登錄

開發期間模板引擎頁面修改之後，要實時生效

  1. 禁用模板引擎的緩存

    #禁用緩存    
spring.thymeleaf.cache=false
  2. 頁面修改完成後ctrl+F9或cmd+F9:從新編譯

登錄錯誤消息提示

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

表單重複提交問題

//全部的WebMvcConfigurerAdapter組件都會共同起做用
    @Bean//將組件註冊在容器中
    public WebMvcConfigurerAdapter webMvcConfigurerAdapter() {
        WebMvcConfigurerAdapter adapter = new WebMvcConfigurerAdapter() {
            @Override
            public void addViewControllers(ViewControllerRegistry registry) {
                registry.addViewController("/").setViewName("login");
                registry.addViewController("/index.html").setViewName("login");
               
 //增長一條視圖映射
                registry.addViewController("/main.html").setViewName("dashboard");
            }
        };

重定向：

@PostMapping(value = "/user/login")
    public String login(@RequestParam("username") String username,
                        @RequestParam("password") String password,
                        Map<String, Object> map) {
        if (!StringUtils.isEmpty(username) && password.equals("123456")) {
            //登錄成功，防止表單重複提交，能夠重定向到主頁
            return "redirect:/main.html";
        } else {
            map.put("msg", "用戶名密碼錯誤");
            return "login";
        }
    }

6.4 攔截器進行登錄檢查

自定義攔截器

/**
 * 進行登錄檢查
 */
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
            //獲取轉發器，進行轉發操做
            request.setAttribute("msg", "沒有權限，請先登錄");
            request.getRequestDispatcher("/index.html").forward(request, response);
            return false;
        } else {
            //已登錄
            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 {

    }
}

攔截器的註冊

//全部的WebMvcConfigurerAdapter組件都會共同起做用
    @Bean//將組件註冊在容器中
    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");
            }

            @Override
            public void addInterceptors(InterceptorRegistry registry) {
                //靜態資源："*.css" "*.js"
                //SpringBoot已經作好了靜態資源映射，不須要排除
                registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**")
                        .excludePathPatterns("/index.html", "/user/login", "/");
            }
        };

        return adapter;
    }

6.5 CRUD-員工列表

實驗要求

  1. 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

    普通CRUD（uri來區分操做） RestfulCRUD
    查詢 getEMP emp---GET
    添加 addEMP?xxx emp---POST
    修改 updateEmp?id=xxx&xxx=xx emp/{id}---PUT
    刪除 deleteEmp?id=1 emp/{id}---DELETE

  2. 實驗的請求架構設計

    請求URI 請求方式
    查詢全部員工 emps GET
    查詢某個員工（來到修改頁面） emp/{id} 路徑變量 GET
    來到添加頁面 emp GET
    添加員工 emp POST
    來到修改頁面（查出員工進行信息回顯） emp/{id} GET
    修改員工 emp PUT
    刪除員工 emp/{id} DELETE

  3. 員工列表

    thymeleaf公共頁面元素抽取

<div th:fragment="copy">

&copy; 2011 The Good Thymes Virtual Grocery

</div>

  1. 引入公共片斷

<div th:insert="~{footer :: copy}"></div>
<!--或者-->
<div th:insert="footer :: copy"></div>

~{templatename::selector} 模板名::選擇器
~{templatename::fragmentname} 模板名::片斷名

  1. 默認效果

insert的功能片斷在div的標籤中
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

三種引入功能片斷的th屬性：

1. th:insert 將公共片斷整個插入到聲明引入的元素中
2.  th:replace 將聲明引入的片斷替換爲公共片斷
3.  th:include 將被引入的片斷的內容包含進標籤中 

區別：

<footer th:fragment="copy">

&copy; 2011 The Good Thymes Virtual Grocery

</footer>

引入方式
<body>

...
   <div th:insert="footer :: copy"></div>
   <div th:replace="footer :: copy"></div>
   <div th:include="footer :: copy"></div>

</body>

效果
<body>

...
   <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>

</body>

提交的數據格式不對問題：生日-日期

2017-12-12  2017/12/12  2017.12.12

日期的格式化：SpringMVC將頁面提交的值須要轉換爲指定的類型

2017-12-12---Date：類型轉換，格式化

默認使用/來分隔

spring.mvc.date-format=yyyy-MM-dd

添加頁面

<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>

提交的數據格式不對：生日：日期；

2017-12-12；2017/12/12；2017.12.12；

日期的格式化；SpringMVC將頁面提交的值須要轉換爲指定的類型;

2017-12-12---Date； 類型轉換，格式化;

默認日期是按照/的方式；

### 6.6 CRUD-員工修改

修改添加二合一表單
<!--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>
    ```

6.7 CRUD-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

    默認效果：

    ​ 瀏覽器：返回一個默認的錯誤頁面

    20180226173408

    瀏覽器發送請求時的請求頭

    20180226180347

    ​ 若是是其餘客戶端訪問，默認返回一個json數據

    20180226180504

    原理：

    ​ 參照 ErrorMvcAutoConfiguration

    ​ 給容器中添加了如下組件

    1. DefaultErrorAttributes
    2. BasicErrorController

@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {

@RequestMapping(produces = "text/html")//將會產生html類型的數據
    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數據的
    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";系統出現錯誤以後來到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);
    }

      步驟：

      一旦系統出現4xx或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；

      1. 響應頁面;去哪一個頁面是由DefaultErrorViewResolver解析到的

        protected ModelAndView resolveErrorView(HttpServletRequest request,
            HttpServletResponse response, HttpStatus status, Map<String, Object> model) {
        for (ErrorViewResolver resolver : this.errorViewResolvers) {
            ModelAndView modelAndView = resolver.resolveErrorView(request, status, model);
            if (modelAndView != null) {
                return modelAndView;
            }
        }
        return null;
    }

  2. 如何定製錯誤響應

    1. 如何定製錯誤頁面

      1. 有模板引擎的狀況下，error/狀態碼.html 【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

        可使用4xx和5xx做爲錯誤頁面的文件名來匹配這種類型的全部錯誤，精確優先（優先尋找 狀態碼.html 頁面）

        頁面能獲取的信息

        timestamp 時間戳

        status 狀態碼

        error 錯誤提示

        exception 異常

        message 異常消息

        errors JSR303數據校驗的錯誤都在這裏

      2. 沒有模板引擎的狀況下，在靜態資源文件夾下找
      3. 都沒有時，採用SpringBoot默認的錯誤頁面

    2. 如何定製錯誤的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
        /**
.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";
      }
  ```

  1. 將咱們的定製數據攜帶出去；

    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，

    20180228135513

8. 配置嵌入式Servlet容器

SpringBoot默認使用Tomcat做爲嵌入式的Servlet容器；

20180301142915

8.1 如何定製和修改Servlet容器的相關配置

  1. 修改和server有關的配置（ServerProperties【也是EmbeddedServletContainerCustomizer】）；
server.port=8081
server.context-path=/crud

server.tomcat.uri-encoding=UTF-8

//通用的Servlet容器設置
server.xxx
//Tomcat的設置
server.tomcat.xxx
  1. 編寫一個EmbeddedServletContainerCustomizer：嵌入式的Servlet容器的定製器；來修改Servlet容器的配置

8.2 註冊Servlet三大組件【Servlet、Filter、Listener】

因爲SpringBoot默認是以jar包的方式啓動嵌入式的Servlet容器來啓動SpringBoot的web應用，沒有web.xml文件。

註冊三大組件用如下方式

ServletRegistrationBean

//註冊三大組件
@Bean
public ServletRegistrationBean myServlet(){
    ServletRegistrationBean registrationBean = new ServletRegistrationBean(new MyServlet(),"/myServlet");
    return registrationBean;
}

FilterRegistrationBean

@Bean
public FilterRegistrationBean myFilter(){
    FilterRegistrationBean registrationBean = new FilterRegistrationBean();
    registrationBean.setFilter(new MyFilter());
    registrationBean.setUrlPatterns(Arrays.asList("/hello","/myServlet"));
    return registrationBean;
}

ServletListenerRegistrationBean

@Bean
public ServletListenerRegistrationBean myListener(){
    ServletListenerRegistrationBean<MyListener> registrationBean = new ServletListenerRegistrationBean<>(new MyListener());
    return registrationBean;
}

SpringBoot幫咱們自動SpringMVC的時候，自動的註冊SpringMVC的前端控制器；DIspatcherServlet；

DispatcherServletAutoConfiguration中：

@Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)
@ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
public ServletRegistrationBean dispatcherServletRegistration(
      DispatcherServlet dispatcherServlet) {
   ServletRegistrationBean registration = new ServletRegistrationBean(
         dispatcherServlet, this.serverProperties.getServletMapping());
    //默認攔截： 「/」 全部請求；包靜態資源，可是不攔截jsp請求；   「/*」會攔截jsp
    //能夠經過server.servletPath來修改SpringMVC前端控制器默認攔截的請求路徑
    
   registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
   registration.setLoadOnStartup(
         this.webMvcProperties.getServlet().getLoadOnStartup());
   if (this.multipartConfig != null) {
      registration.setMultipartConfig(this.multipartConfig);
   }
   return registration;
}

8.3 使用其餘Servlet容器

Jetty（長鏈接）

Undertow（不支持JSP，併發性能好）

20180302114401

默認支持：

Tomcat（默認使用）

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
   引入web模塊默認就是使用嵌入式的Tomcat做爲Servlet容器；
</dependency>

Jetty

<!-- 引入web模塊 -->
<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
   <exclusions>
      <exclusion>
         <artifactId>spring-boot-starter-tomcat</artifactId>
         <groupId>org.springframework.boot</groupId>
      </exclusion>
   </exclusions>
</dependency>

<!--引入其餘的Servlet容器-->
<dependency>
   <artifactId>spring-boot-starter-jetty</artifactId>
   <groupId>org.springframework.boot</groupId>
</dependency>

Undertow

<!-- 引入web模塊 -->
<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
   <exclusions>
      <exclusion>
         <artifactId>spring-boot-starter-tomcat</artifactId>
         <groupId>org.springframework.boot</groupId>
      </exclusion>
   </exclusions>
</dependency>

<!--引入其餘的Servlet容器-->
<dependency>
   <artifactId>spring-boot-starter-undertow</artifactId>
   <groupId>org.springframework.boot</groupId>
</dependency>

8.4 嵌入式Servlet容器自動配置原理

EmbeddedServletContainerAutoConfiguration：嵌入式的Servlet容器自動配置？

@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration
@ConditionalOnWebApplication
@Import(BeanPostProcessorsRegistrar.class)
//導入BeanPostProcessorsRegistrar：Spring註解版；給容器中導入一些組件
//導入了EmbeddedServletContainerCustomizerBeanPostProcessor：
//後置處理器：bean初始化先後（建立完對象，還沒賦值賦值）執行初始化工做
public class EmbeddedServletContainerAutoConfiguration {
    
    @Configuration
    @ConditionalOnClass({ Servlet.class, Tomcat.class })//判斷當前是否引入了Tomcat依賴；
    @ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)//判斷當前容器沒有用戶本身定義EmbeddedServletContainerFactory：嵌入式的Servlet容器工廠；做用：建立嵌入式的Servlet容器
    public static class EmbeddedTomcat {

        @Bean
        public TomcatEmbeddedServletContainerFactory tomcatEmbeddedServletContainerFactory() {
            return new TomcatEmbeddedServletContainerFactory();
        }

    }
    
    /**
     * Nested configuration if Jetty is being used.
     */
    @Configuration
    @ConditionalOnClass({ Servlet.class, Server.class, Loader.class,
            WebAppContext.class })
    @ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
    public static class EmbeddedJetty {

        @Bean
        public JettyEmbeddedServletContainerFactory jettyEmbeddedServletContainerFactory() {
            return new JettyEmbeddedServletContainerFactory();
        }

    }

    /**
     * Nested configuration if Undertow is being used.
     */
    @Configuration
    @ConditionalOnClass({ Servlet.class, Undertow.class, SslClientAuthMode.class })
    @ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)
    public static class EmbeddedUndertow {

        @Bean
        public UndertowEmbeddedServletContainerFactory undertowEmbeddedServletContainerFactory() {
            return new UndertowEmbeddedServletContainerFactory();
        }

    }

1）EmbeddedServletContainerFactory（嵌入式Servlet容器工廠）

public interface EmbeddedServletContainerFactory {

   //獲取嵌入式的Servlet容器
   EmbeddedServletContainer getEmbeddedServletContainer(
         ServletContextInitializer... initializers);

}

20180302144835

2）EmbeddedServletContainer：（嵌入式的Servlet容器）

20180302144910

3）以TomcatEmbeddedServletContainerFactory爲例

@Override
public EmbeddedServletContainer getEmbeddedServletContainer(
      ServletContextInitializer... initializers) {
    //建立一個Tomcat
   Tomcat tomcat = new Tomcat();
    
    //配置Tomcat的基本環節
   File baseDir = (this.baseDirectory != null ? this.baseDirectory
         : createTempDir("tomcat"));
   tomcat.setBaseDir(baseDir.getAbsolutePath());
   Connector connector = new Connector(this.protocol);
   tomcat.getService().addConnector(connector);
   customizeConnector(connector);
   tomcat.setConnector(connector);
   tomcat.getHost().setAutoDeploy(false);
   configureEngine(tomcat.getEngine());
   for (Connector additionalConnector : this.additionalTomcatConnectors) {
      tomcat.getService().addConnector(additionalConnector);
   }
   prepareContext(tomcat.getHost(), initializers);
    
    //將配置好的Tomcat傳入進去，返回一個EmbeddedServletContainer；而且啓動Tomcat服務器
   return getTomcatEmbeddedServletContainer(tomcat);
}

4）咱們對嵌入式容器的配置修改是怎麼生效？

ServerProperties、EmbeddedServletContainerCustomizer

EmbeddedServletContainerCustomizer：定製器幫咱們修改了Servlet容器的配置？

怎麼修改的原理？

5）容器中導入了EmbeddedServletContainerCustomizerBeanPostProcessor

//初始化以前
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName)
      throws BeansException {
    //若是當前初始化的是一個ConfigurableEmbeddedServletContainer類型的組件
   if (bean instanceof ConfigurableEmbeddedServletContainer) {
       //
      postProcessBeforeInitialization((ConfigurableEmbeddedServletContainer) bean);
   }
   return bean;
}

private void postProcessBeforeInitialization(
            ConfigurableEmbeddedServletContainer bean) {
    //獲取全部的定製器，調用每個定製器的customize方法來給Servlet容器進行屬性賦值；
    for (EmbeddedServletContainerCustomizer customizer : getCustomizers()) {
        customizer.customize(bean);
    }
}

private Collection<EmbeddedServletContainerCustomizer> getCustomizers() {
    if (this.customizers == null) {
        // Look up does not include the parent context
        this.customizers = new ArrayList<EmbeddedServletContainerCustomizer>(
            this.beanFactory
            //從容器中獲取全部這個類型的組件：EmbeddedServletContainerCustomizer
            //定製Servlet容器，給容器中能夠添加一個EmbeddedServletContainerCustomizer類型的組件
            .getBeansOfType(EmbeddedServletContainerCustomizer.class,
                            false, false)
            .values());
        Collections.sort(this.customizers, AnnotationAwareOrderComparator.INSTANCE);
        this.customizers = Collections.unmodifiableList(this.customizers);
    }
    return this.customizers;
}

ServerProperties也是定製器

步驟：

  1. SpringBoot根據導入的依賴狀況，給容器中添加相應的EmbeddedServletContainerFactory【TomcatEmbeddedServletContainerFactory】
  2. 容器中某個組件要建立對象就會驚動後置處理器；EmbeddedServletContainerCustomizerBeanPostProcessor；只要是嵌入式的Servlet容器工廠，後置處理器就工做；
  3. 後置處理器，從容器中獲取全部的EmbeddedServletContainerCustomizer，調用定製器的定製方法

8.5 嵌入式Servlet容器啓動原理

何時建立嵌入式的Servlet容器工廠？何時獲取嵌入式的Servlet容器並啓動Tomcat；

獲取嵌入式的Servlet容器工廠：

1）SpringBoot應用啓動運行run方法

2）refreshContext(context);SpringBoot刷新IOC容器【建立IOC容器對象，並初始化容器，建立容器中的每個組件】；若是是web應用建立AnnotationConfigEmbeddedWebApplicationContext，不然：AnnotationConfigApplicationContext

3）refresh(context);刷新剛纔建立好的ioc容器；

public void refresh() throws BeansException, IllegalStateException {
   synchronized (this.startupShutdownMonitor) {
      // Prepare this context for refreshing.
      prepareRefresh();

      // Tell the subclass to refresh the internal bean factory.
      ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

      // Prepare the bean factory for use in this context.
      prepareBeanFactory(beanFactory);

      try {
         // Allows post-processing of the bean factory in context subclasses.
         postProcessBeanFactory(beanFactory);

         // Invoke factory processors registered as beans in the context.
         invokeBeanFactoryPostProcessors(beanFactory);

         // Register bean processors that intercept bean creation.
         registerBeanPostProcessors(beanFactory);

         // Initialize message source for this context.
         initMessageSource();

         // Initialize event multicaster for this context.
         initApplicationEventMulticaster();

         // Initialize other special beans in specific context subclasses.
         onRefresh();

         // Check for listener beans and register them.
         registerListeners();

         // Instantiate all remaining (non-lazy-init) singletons.
         finishBeanFactoryInitialization(beanFactory);

         // Last step: publish corresponding event.
         finishRefresh();
      }

      catch (BeansException ex) {
         if (logger.isWarnEnabled()) {
            logger.warn("Exception encountered during context initialization - " +
                  "cancelling refresh attempt: " + ex);
         }

         // Destroy already created singletons to avoid dangling resources.
         destroyBeans();

         // Reset 'active' flag.
         cancelRefresh(ex);

         // Propagate exception to caller.
         throw ex;
      }

      finally {
         // Reset common introspection caches in Spring's core, since we
         // might not ever need metadata for singleton beans anymore...
         resetCommonCaches();
      }
   }
}

4）onRefresh(); web的ioc容器重寫了onRefresh方法

5）webioc容器會建立嵌入式的Servlet容器；createEmbeddedServletContainer();

6）獲取嵌入式的Servlet容器工廠：

EmbeddedServletContainerFactory containerFactory = getEmbeddedServletContainerFactory();

​ 從ioc容器中獲取EmbeddedServletContainerFactory 組件；TomcatEmbeddedServletContainerFactory建立對象，後置處理器一看是這個對象，就獲取全部的定製器來先定製Servlet容器的相關配置；

7）使用容器工廠獲取嵌入式的Servlet容器：this.embeddedServletContainer = containerFactory.getEmbeddedServletContainer(getSelfInitializer());

8）嵌入式的Servlet容器建立對象並啓動Servlet容器；

先啓動嵌入式的Servlet容器，再將ioc容器中剩下沒有建立出的對象獲取出來；

==IOC容器啓動建立嵌入式的Servlet容器==

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