【SpringBoot学习】Web开发

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【SpringBoot学习】Web开发

一、SpringBoot对静态资源的映射规则

静态资源的映射规则都在WebMvcAutoConfiguration中。

(1)webjars:以jar包的方式引入静态资源

所有 /webjars/** ,都在 classpath:/META-INF/resources/webjars/ 查找资源。

<!--引入jquery-webjar-->在访问的时候只需要写webjars下面资源的名称即可
<dependency>
<groupId>org.webjars</groupId>
<artifactId>jquery</artifactId>
<version>3.5.0</version>
</dependency>

webjars:以jar包的方式引入静态资源

访问 localhost:8080/webjars/jquery/3.5.0/jquery.js

(2) /** 访问当前项目的任何资源,都去(静态资源的文件夹)找映射。

静态资源文件,比如一些JS、CSS、jQuery文件,SpringBoot默认是从以下这些路径中读取的:

-- "classpath:/META-INF/resources/",
-- "classpath:/resources/",
-- "classpath:/static/",
-- "classpath:/public/"
"/":当前项目的根路径

例如:

(3)首页(欢迎页)

静态资源文件夹下的所有 index.html 页面,都被 /** 映射。

例如 localhost:8080/ 会去静态资源文件下找index页面。

(4)自定义图标图标

把ico格式的图标放在默认静态资源文件路径下,并以favicon.ico命名,应用图标会自动变成指定的图标。所有的 **/favicon.ico 都在静态资源文件下查找。

(5)在application.properties中手动配置静态资源访问路径。

在application.properties配置文件中如下编辑:

# 自定义静态资源访问路径,可以指定多个,之间用逗号隔开
spring.resources.static-locations=classpath:/test1/,classpath:/test2/

特别要注意: 自定义静态资源访问路径后,SpringBoot默认的静态资源路径将不再起作用

三、模板引擎

JSP、Velocity、Freemarker、Thymeleaf……

SpringBoot推荐的Thymeleaf:语法更简单,功能更强大。

1、引入Thymeleaf

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<!--发现默认用的2.3.4版本,需切换thymeleaf版本-->
<properties>
<thymeleaf.version>3.0.9.RELEASE</thymeleaf.version>
<!-- 布局功能的支持程序  thymeleaf3主程序  layout2以上版本 -->
<thymeleaf-layout-dialect.version>2.2.2</thymeleaf-layout-dialect.version>
</properties>

2、Thymeleaf使用

默认规则:

@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";

只要我们把HTML页面放在 classpath:/templates/ 下,thymeleaf就能自动渲染。

使用:

  1. 导入thymeleaf的名称空间
<html lang="en" xmlns:th="http://www.thymeleaf.org">
  1. 使用thymeleaf语法
<!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 将div里面的文本内容设置为指定的值 -->
<div th:text="${hello}">这是显示欢迎信息</div>
</body>
</html>

3、语法规则

(1)th:text——改变当前元素里面的文本内容

​ th:任意html属性——替换原生属性的值

(2)表达式

Simple expressions:(表达式语法)
Variable Expressions: ${...}:获取变量值;OGNL
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.
${session.foo}
3)内置的一些工具对象:
#execInfo : information about the template being processed.
#messages : methods for obtaining externalized messages inside variables expressions, in the                  same way as they would be obtained using #{…} syntax.
#uris : methods for escaping parts of URLs/URIs
#conversions : methods for executing the configured conversion service (if any).
#dates : methods for java.util.Date objects: formatting, component extraction, etc.
#calendars : analogous to #dates , but for java.util.Calendar objects.
#numbers : methods for formatting numeric objects.
#strings : methods for String objects: contains, startsWith, prepending/appending, etc.
#objects : methods for objects in general.
#bools : methods for boolean evaluation.
#arrays : methods for arrays.
#lists : methods for lists.
#sets : methods for sets.
#maps : methods for maps.
#aggregates : methods for creating aggregates on arrays or collections.
#ids : methods for dealing with id attributes that might be repeated (for example, as a                     result of an iteration).
Selection Variable Expressions: *{...}:选择表达式,其实和${}在功能上是一样
补充功能: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: #{...}:获取国际化内容
Link URL Expressions: @{...}:定义URL
@{/order/process(execId=${execId},execType='FAST')}
Fragment Expressions: ~{...}:片段引用表达式
<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(三元运算符)
If-then: (if) ? (then)
If-then-else: (if) ? (then) : (else)
Default: (value) ?: (defaultvalue)
Special tokens:
No-Operation: _

例如:

@RequestMapping("/success")
public String success(Map<String,Object> map){
map.put("hello","<h1>你好</h1>");
map.put("users", Arrays.asList("zhangsan","lisi","wangwu"));
return "success";
}
<!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>
<div th:text="${hello}"></div>
<div th:utext="${hello}"></div>
<!-- th:each每次遍历都会生成当前这个标签: 3个h4 -->
<h4 th:text="${user}" th:each="user:${users}"></h4>
</hr>
<h4>
<span th:each="user:${users}">[[${user}]]</span>
</h4>
</body>
</html>

输出结果:

四、SpringMVC自动配置

1、Spring MVC auto-configuration

SpringBoot对SpringMVC的默认配置: (WebMvcAutoConfiguration)

  • Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.

    • 自动配置了ViewResolver(视图解析器:根据方法的返回值得到视图对象(View),视图对象决定如何渲染(转发/重定向))
    • ContentNegotiatingViewResolver:组合所有的视图解析器。
    • ==如何定制:我们可以自己给容器中添加一个视图解析器,自动的将其组合进来。==
  • Support for serving static resources, including support for WebJars (see below).静态资源文件夹路径,webjars。
  • Static index.html support. 静态首页访问
  • Custom Favicon support (see below). favicon.ico
  • Automatic registration of Converter , GenericConverter , Formatter beans.

    Converter
    Formatter
    
@Bean
@ConditionalOnProperty(prefix = "spring.mvc", name = "date-format")//在文件中配置日期格式化的规则
public Formatter<Date> dateFormatter() {
return new DateFormatter(this.mvcProperties.getDateFormat());//日期格式化组件
}

​ ==添加的格式化器转换器,我们只需要放在容器中即可。==

  • Support for HttpMessageConverters (see below).

    • HttpMessageConverter :SpringMVC用来转换Http请求和响应的,User对象—Json数据;
    • HttpMessageConverters

      是从容器中确定,获取所有的HttpMessageConverter;

      ==给容器中添加HttpMessageConverter,只需要将自己的组件注册容器中(@Bean,@Component)==

  • Automatic registration of MessageCodesResolver (see below).定义错误代码生成规则。
  • Automatic use of a ConfigurableWebBindingInitializer

    bean (see below).

    ==可以自己配置一个ConfigurableWebBindingInitializer来替换默认的(添加到容器)==,初始化WebDataBinder数据绑定器,将请求数据绑定到JavaBean中

org.springframework.boot.autoconfigure.web:web的所有自动场景

2、扩展SpringMVC

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 .

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

==编写一个配置类(@Configuration),是WebMvcConfigurerAdapter类型,不能标注@EnableWebMvc==。

既保留了所有的自动配置,也能用我们扩展的配置。

//使用WebMvcConfigurerAdapter可以来扩展SpringMVC的功能
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
//浏览器发送 /kai 请求来到 success
registry.addViewController("/kai").setViewName("success");
}
}

原理:

​ 1)WebMvcAutoConfiguration是SpringMVC的自动配置类。

​ 2)在做其他自动配置时会导入,@Import( EnableWebMvcConfiguration .class)

@Configuration
public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {
private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();
//从容器中获取所有的WebMvcConfigurer
@Autowired(required = false)
public void setConfigurers(List<WebMvcConfigurer> configurers) {
if (!CollectionUtils.isEmpty(configurers)) {
this.configurers.addWebMvcConfigurers(configurers);
//一个参考实现;将所有的WebMvcConfigurer相关配置都来一起调用;
@Override
// public void addViewControllers(ViewControllerRegistry registry) {
//    for (WebMvcConfigurer delegate : this.delegates) {
//       delegate.addViewControllers(registry);
//   }
}
}
}

​ 3)容器中所有的WebMvcConfigurer都会一起起作用。

​ 4)我们的配置类也会被调用。

​ 效果:SpringMVC的自动配置和我们的扩展配置都会起作用。

3、全面接管SpringMVC

SpringBoot对SpringMVC的自动配置不需要了,所有都是我们自己配置,所有的SpringMVC的自动配置都失效了。

在配置类中添加@EnableWebMvc即可

//使用WebMvcConfigurerAdapter可以来扩展SpringMVC的功能
@EnableWebMvc
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
// super.addViewControllers(registry);
//浏览器发送 /kai 请求来到 success
registry.addViewController("/kai").setViewName("success");
}
}

原理:

为什么@EnableWebMvc自动配置就失效了。

(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 })
//容器中没有这个组件的时候,自动配置类才生效
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,
ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {

(2)可见,@EnableWebMvc将WebMvcConfigurationSupport组件导入进来,导入的WebMvcConfigurationSupport只是SpringMVC最基本的功能。

五、如何修改SpringBoot的默认配置

小结:

​ 1. SpringBoot在自动配置很多组件的时候,先看容器中有没有用户自己配置的(@Bean、@Component)如果有就用用户配置的,如果没有,才自动配置;如果有些组件可以有多个(ViewResolver)将用户配置的和自己默认的组合起来。

​ 2. 在SpringBoot中会有非常多的xxxConfigurer帮助我们进行扩展配置。

​ 3. 在SpringBoot中会有很多的xxxCustomizer帮助我们进行定制配置。

六、RestfulCRUD

1、默认访问首页

//使用WebMvcConfigurerAdapter可以来扩展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);
//浏览器发送 /kai 请求来到 success
registry.addViewController("/kai").setViewName("success");
}
//所有的WebMvcConfigurerAdapter组件都会一起起作用
@Bean //将组件注册在容器
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、国际化

1. 编写国际化配置文件

  1. 使用ResourceBundleMessageSource管理国际化资源文件
  2. 在页面使用fmt:message取出国际化内容

步骤:

(1)编写国际化配置文件,抽取页面需要显示的国际化消息

(2)SpringBoot自动配置好了管理国际化资源文件的组件;

@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";
//我们的配置文件可以直接放在类路径下叫messages.properties;
@Bean
public MessageSource messageSource() {
ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
if (StringUtils.hasText(this.basename)) {
//设置国际化资源文件的基础名(去掉语言国家代码的)
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;
}

(3)去页面获取国际化的值;

<!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="https://www.tuicool.com/articles/r22uiyz/asserts/css/bootstrap.min.css" th:href="https://www.tuicool.com/articles/r22uiyz/@{/webjars/bootstrap/4.0.0/css/bootstrap.css}" rel="stylesheet">
<!-- Custom styles for this template -->
<link href="https://www.tuicool.com/articles/r22uiyz/asserts/css/signin.css" th:href="https://www.tuicool.com/articles/r22uiyz/@{/asserts/css/signin.css}" rel="stylesheet">
</head>
<body>
<form action="dashboard.html">
![](@{/asserts/img/bootstrap-solid.svg})
<h1 th:text="#{login.tip}">Please sign in</h1>
<label th:text="#{login.username}">Username</label>
<input type="text" placeholder="Username" th:placeholder="#{login.username}" required="" autofocus="">
<label th:text="#{login.password}">Password</label>
<input type="password" placeholder="Password" th:placeholder="#{login.password}" required="">
<div>
<label>
<input type="checkbox" value="remember-me"/> [[#{login.remember}]]
</label>
</div>
<button type="submit" th:text="#{login.btn}">Sign in</button>
<p>© 2017-2018</p>
<a>中文</a>
<a>English</a>
</form>
</body>
</html>

效果:根据浏览器语言设置的信息切换了国际化。

原理:

​ 国际化Locale(区域信息对象),LocaleResolver(获取区域信息对象)。

@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;
}
默认的就是根据请求头带来的区域信息获取Locale进行国际化

(4)点击链接切换国际化

/**
* 可以在连接上携带区域信息
*/
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、登陆

开发期间模板引擎页面修改以后,要实时生效。

(1)禁用模板引擎的缓存

# 禁用缓存
spring.thymeleaf.cache=false

(2)页面修改完成以后ctrl+f9:重新编译。

登陆错误消息的显示

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

4、拦截器进行登陆检查

拦截器

/**
* 登陆检查,
*/
public class LoginHandlerInterceptor implements HandlerInterceptor {
//目标方法执行之前
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
Object user = request.getSession().getAttribute("loginUser");
if(user == null){
//未登陆,返回登陆页面
request.setAttribute("msg","没有权限请先登陆");
request.getRequestDispatcher("/index.html").forward(request,response);
return false;
}else{
//已登陆,放行请求
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 {
}
}

注册拦截器

//所有的WebMvcConfigurerAdapter组件都会一起起作用
@Bean //将组件注册在容器
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");
}
//注册拦截器
@Override
public void addInterceptors(InterceptorRegistry registry) {
//super.addInterceptors(registry);
//静态资源;  *.css , *.js
//SpringBoot已经做好了静态资源映射
registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**")
.excludePathPatterns("/index.html","/","/user/login");
}
};
return adapter;
}

5、CRUD-员工列表

实验要求:

(1)RestfulCRUD:CRUD满足Rest风格;

URI:/资源名称/资源标识 HTTP请求方式区分对资源CRUD操作

普通CRUD(URI来区分操作) RestfulCRUD
查询 getEmp emp—GET
添加 addEmp?xxx emp—POST
修改 updateEmp?id=xxx&xxx=xx emp/{id}—PUT
删除 deleteEmp?id=1 emp/{id}—DELETE

(2)实验的请求架构

实验功能 请求URI 请求方式
查询所有员工 emps GET
查询某个员工(来到修改页面) emp/1 GET
来到添加页面 emp GET
添加员工 emp POST
来到修改页面(查出员工进行信息回显) emp/1 GET
修改员工 emp PUT
删除员工 emp/1 DELETE

(3)员工列表

thymeleaf公共页面元素抽取

1、抽取公共片段
<div th:fragment="copy">
© 2011 The Good Thymes Virtual Grocery
</div>
2、引入公共片段
<div th:insert="~{footer :: copy}"></div>
~{templatename::selector}:模板名::选择器
~{templatename::fragmentname}:模板名::片段名
3、默认效果:
insert的公共片段在div标签中
如果使用th:insert等属性进行引入,可以不用写~{}:
行内写法可以加上:[[~{}]];[(~{})];

三种引入公共片段的th属性:

th:insert:将公共片段整个插入到声明引入的元素中

th:replace:将声明引入的元素替换为公共片段

th:include:将被引入的片段的内容包含进这个标签中

<footer th:fragment="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>
效果分别为
<div>
<footer>
© 2011 The Good Thymes Virtual Grocery
</footer>
</div>
<footer>
© 2011 The Good Thymes Virtual Grocery
</footer>
<div>
© 2011 The Good Thymes Virtual Grocery
</div>

引入片段的时候传入参数:

<nav id="sidebar">
<div>
<ul>
<li>
<a
th:class="${activeUri=='main.html'?'nav-link active':'nav-link'}"
href="#" th:href="https://www.tuicool.com/articles/r22uiyz/@{/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">
<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>(current)</span>
</a>
</li>
<!--引入侧边栏;传入参数-->
<div th:replace="commons/bar::#sidebar(activeUri='emps')"></div>

6、CRUD-员工添加

添加页面

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

提交的数据格式不对:生日:日期。

2017-12-12;2017/12/12;2017.12.12。

日期的格式化;SpringMVC将页面提交的值需要转换为指定的类型。

2017-12-12—Date; 类型转换,格式化。

默认日期是按照/的方式。

7、CRUD-员工修改

修改添加二合一表单

<!--需要区分是员工修改还是添加;-->
<form th:action="@{/emp}" method="post">
<!--发送put请求修改员工数据-->
<!--
1、SpringMVC中配置HiddenHttpMethodFilter;(SpringBoot自动配置好的)
2、页面创建一个post表单
3、创建一个input项,name="_method";值就是我们指定的请求方式
-->
<input type="hidden" name="_method" value="put" th:if="${emp!=null}"/>
<input type="hidden" name="id" th:if="${emp!=null}" th:value="${emp.id}">
<div>
<label>LastName</label>
<input name="lastName" type="text" placeholder="zhangsan" th:value="${emp!=null}?${emp.lastName}">
</div>
<div>
<label>Email</label>
<input name="email" type="email" placeholder="zhangsan@kai.com" th:value="${emp!=null}?${emp.email}">
</div>
<div>
<label>Gender</label><br/>
<div>
<input type="radio" name="gender" value="1" th:checked="${emp!=null}?${emp.gender==1}">
<label>男</label>
</div>
<div>
<input type="radio" name="gender" value="0" th:checked="${emp!=null}?${emp.gender==0}">
<label>女</label>
</div>
</div>
<div>
<label>department</label>
<!--提交的是部门的id-->
<select name="department.id">
<option th:selected="${emp!=null}?${dept.id == emp.department.id}" th:value="${dept.id}" th:each="dept:${depts}" th:text="${dept.departmentName}">1</option>
</select>
</div>
<div>
<label>Birth</label>
<input name="birth" type="text" placeholder="zhangsan" th:value="${emp!=null}?${#dates.format(emp.birth, 'yyyy-MM-dd HH:mm')}">
</div>
<button type="submit" th:text="${emp!=null}?'修改':'添加'">添加</button>
</form>

8、CRUD-员工删除

<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="${#dates.format(emp.birth, 'yyyy-MM-dd HH:mm')}"></td>
<td>
<a th:href="https://www.tuicool.com/articles/r22uiyz/@{/emp/}+${emp.id}">编辑</a>
<button th:attr="del_uri=@{/emp/}+${emp.id}">删除</button>
</td>
</tr>
<script>
$(".deleteBtn").click(function(){
//删除当前员工的
$("#deleteEmpForm").attr("action",$(this).attr("del_uri")).submit();
return false;
});
</script>

七、错误处理机制

1、SpringBoot默认的错误处理机制

默认效果:

​ 1. 浏览器,返回一个默认的错误页面。

浏览器发送请求的请求头:

​ 2. 如果是其他客户端,默认响应一个json数据

原理:

​ 可以参照ErrorMvcAutoConfiguration,错误处理的自动配置;

给容器中添加了以下组件

​ (1)DefaultErrorAttributes:

帮我们在页面共享信息;
@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:处理默认/error请求

@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {
@RequestMapping(produces = "text/html")//产生html类型的数据;浏览器发送的请求来到这个方法处理
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());
//去哪个页面作为错误页面;包含页面地址和页面内容
ModelAndView modelAndView = resolveErrorView(request, response, status, model);
return (modelAndView == null ? new ModelAndView("error", model) : modelAndView);
}
@RequestMapping
@ResponseBody    //产生json数据,其他客户端来到这个方法处理;
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";  系统出现错误以后来到error请求进行处理;(web.xml注册的错误页面规则)

​ (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) {
//默认SpringBoot可以去找到一个页面?  error/404
String errorViewName = "error/" + viewName;
//模板引擎可以解析这个页面地址就用模板引擎解析
TemplateAvailabilityProvider provider = this.templateAvailabilityProviders
.getProvider(errorViewName, this.applicationContext);
if (provider != null) {
//模板引擎可用的情况下返回到errorViewName指定的视图地址
return new ModelAndView(errorViewName, model);
}
//模板引擎不可用,就在静态资源文件夹下找errorViewName对应的页面   error/404.html
return resolveResource(errorViewName, model);
}

​ 步骤:

​ 一但系统出现4xx或者5xx之类的错误,ErrorPageCustomizer就会生效s(定制错误的响应规则),就会来到/error请求,就会被 BasicErrorController 处理。

(1)响应页面,去哪个页面是由 DefaultErrorViewResolver 解析得到的:

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

2、定制错误响应

2.1 定制错误的页面

(1)有模板引擎的情况下:error/状态码 【将错误页面命名为 错误状态码.html 放在模板引擎文件夹里面的 error文件夹下】,发生此状态码的错误就会来到 对应的页面。

​ 我们可以使用4xx和5xx作为错误页面的文件名来匹配这种类型的所有错误,精确优先(优先寻找精确的状态码.html)。

​ 页面能获取的信息;

​ timestamp:时间戳

​ status:状态码

​ error:错误提示

​ exception:异常对象

​ message:异常消息

​ errors:JSR303数据校验的错误都在这里

​ (2)没有模板引擎(模板引擎找不到这个错误页面),静态资源文件夹下找;

​ (3)以上都没有错误页面,就是默认来到SpringBoot默认的错误提示页面;

2.2 定制错误的json数据

​ (1)自定义异常处理&返回定制json数据;

@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;
}
}
//没有自适应效果...

​ (2)转发到/error进行自适应响应效果处理

@ExceptionHandler(UserNotExistException.class)
public String handleException(Exception e, HttpServletRequest request){
Map<String,Object> map = new HashMap<>();
//传入我们自己的错误状态码  4xx 5xx,否则就不会进入定制错误页面的解析流程
/**
* 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());
//转发到/error
return "forward:/error";
}

2.3 将定制数据携带出去

出现错误以后,会来到/error请求,会被BasicErrorController处理,响应出去可以获取的数据是由getErrorAttributes得到的(是AbstractErrorController(ErrorController)规定的方法);

​ 1、完全来编写一个ErrorController的实现类【或者是编写AbstractErrorController的子类】,放在容器中。

​ 2、页面上能用的数据,或者是json返回能用的数据都是通过errorAttributes.getErrorAttributes得到。

​ 容器中DefaultErrorAttributes.getErrorAttributes():默认进行数据处理的。

自定义ErrorAttributes

//给容器中加入我们自己定义的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","kai");
return map;
}
}

最终的效果:响应是自适应的,可以通过定制ErrorAttributes改变需要返回的内容。

八、配置嵌入式Servlet容器

SpringBoot默认使用Tomcat作为嵌入式的Servlet容器。

1、定制和修改Servlet容器的相关配置

(1)修改和server有关的配置(ServerProperties【也是EmbeddedServletContainerCustomizer】

server.port=8081
server.context-path=/crud
server.tomcat.uri-encoding=UTF-8
//通用的Servlet容器设置
server.xxx
//Tomcat的设置
server.tomcat.xxx

(2)编写一个 EmbeddedServletContainerCustomizer :嵌入式的Servlet容器的定制器,来修改Servlet容器的配置

@Bean  //一定要将这个定制器加入到容器中
public EmbeddedServletContainerCustomizer embeddedServletContainerCustomizer(){
return new EmbeddedServletContainerCustomizer() {
//定制嵌入式的Servlet容器相关的规则
@Override
public void customize(ConfigurableEmbeddedServletContainer container) {
container.setPort(8083);
}
};
}

2、注册Servlet三大组件【Servlet、Filter、Listener】

由于SpringBoot默认是以jar包的方式启动嵌入式的Servlet容器来启动SpringBoot的web应用,没有web.xml文件。

注册三大组件用以ServletRegistrationBean方式

//注册三大组件
@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帮我们自动SpringMVC的时候,自动的注册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());
//默认拦截:所有请求;包静态资源,但是不拦截jsp请求;   /*会拦截jsp
//可以通过server.servletPath来修改SpringMVC前端控制器默认拦截的请求路径
registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
registration.setLoadOnStartup(
this.webMvcProperties.getServlet().getLoadOnStartup());
if (this.multipartConfig != null) {
registration.setMultipartConfig(this.multipartConfig);
}
return registration;
}

3、替换为其他嵌入式Servlet容器

默认支持:

Tomcat(默认使用)

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
引入web模块默认就是使用嵌入式的Tomcat作为Servlet容器;
</dependency>

Jetty

<!-- 引入web模块 -->
<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>
<!--引入其他的Servlet容器-->
<dependency>
<artifactId>spring-boot-starter-jetty</artifactId>
<groupId>org.springframework.boot</groupId>
</dependency>

Undertow

<!-- 引入web模块 -->
<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>
<!--引入其他的Servlet容器-->
<dependency>
<artifactId>spring-boot-starter-undertow</artifactId>
<groupId>org.springframework.boot</groupId>
</dependency>

4、嵌入式Servlet容器自动配置原理

EmbeddedServletContainerAutoConfiguration:嵌入式的Servlet容器自动配置?

@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration
@ConditionalOnWebApplication
@Import(BeanPostProcessorsRegistrar.class)
//导入BeanPostProcessorsRegistrar:Spring注解版;给容器中导入一些组件
//导入了EmbeddedServletContainerCustomizerBeanPostProcessor:
//后置处理器:bean初始化前后(创建完对象,还没赋值赋值)执行初始化工作
public class EmbeddedServletContainerAutoConfiguration {
@Configuration
@ConditionalOnClass({ Servlet.class, Tomcat.class })//判断当前是否引入了Tomcat依赖;
@ConditionalOnMissingBean(value = EmbeddedServletContainerFactory.class, search = SearchStrategy.CURRENT)//判断当前容器没有用户自己定义EmbeddedServletContainerFactory:嵌入式的Servlet容器工厂;作用:创建嵌入式的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容器工厂)

public interface EmbeddedServletContainerFactory {
//获取嵌入式的Servlet容器
EmbeddedServletContainer getEmbeddedServletContainer(
ServletContextInitializer... initializers);
}

2)EmbeddedServletContainer:(嵌入式的Servlet容器)

3)以 TomcatEmbeddedServletContainerFactory 为例

@Override
public EmbeddedServletContainer getEmbeddedServletContainer(
ServletContextInitializer... initializers) {
//创建一个Tomcat
Tomcat tomcat = new Tomcat();
//配置Tomcat的基本环节
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);
//将配置好的Tomcat传入进去,返回一个EmbeddedServletContainer;并且启动Tomcat服务器
return getTomcatEmbeddedServletContainer(tomcat);
}

4)我们对嵌入式容器的配置修改是怎么生效?

ServerProperties、EmbeddedServletContainerCustomizer

EmbeddedServletContainerCustomizer:定制器帮我们修改了Servlet容器的配置?

怎么修改的原理?

5)容器中导入了 EmbeddedServletContainerCustomizerBeanPostProcessor

//初始化之前
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName)
throws BeansException {
//如果当前初始化的是一个ConfigurableEmbeddedServletContainer类型的组件
if (bean instanceof ConfigurableEmbeddedServletContainer) {
//
postProcessBeforeInitialization((ConfigurableEmbeddedServletContainer) bean);
}
return bean;
}
private void postProcessBeforeInitialization(
ConfigurableEmbeddedServletContainer bean) {
//获取所有的定制器,调用每一个定制器的customize方法来给Servlet容器进行属性赋值;
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
//从容器中获取所有这葛类型的组件:EmbeddedServletContainerCustomizer
//定制Servlet容器,给容器中可以添加一个EmbeddedServletContainerCustomizer类型的组件
.getBeansOfType(EmbeddedServletContainerCustomizer.class,
false, false)
.values());
Collections.sort(this.customizers, AnnotationAwareOrderComparator.INSTANCE);
this.customizers = Collections.unmodifiableList(this.customizers);
}
return this.customizers;
}
ServerProperties也是定制器

步骤:

  • SpringBoot根据导入的依赖情况,给容器中添加相应的EmbeddedServletContainerFactory【TomcatEmbeddedServletContainerFactory】
  • 容器中某个组件要创建对象就会惊动后置处理器;EmbeddedServletContainerCustomizerBeanPostProcessor;

只要是嵌入式的Servlet容器工厂,后置处理器就工作

  • 后置处理器,从容器中获取所有的 EmbeddedServletContainerCustomizer ,调用定制器的定制方法

5、嵌入式Servlet容器启动原理

什么时候创建嵌入式的Servlet容器工厂?什么时候获取嵌入式的Servlet容器并启动Tomcat?

获取嵌入式的Servlet容器工厂:

1)SpringBoot应用启动运行run方法。

2)refreshContext(context),SpringBoot刷新IOC容器【创建IOC容器对象,并初始化容器,创建容器中的每一个组件】,如果是web应用创建 AnnotationConfigEmbeddedWebApplicationContext ,否则: AnnotationConfigApplicationContext

3)refresh(context); 刷新刚才创建好的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容器重写了onRefresh方法

5)webioc容器会创建嵌入式的Servlet容器; createEmbeddedServletContainer ();

6)获取嵌入式的Servlet容器工厂:

EmbeddedServletContainerFactory containerFactory = getEmbeddedServletContainerFactory();

从ioc容器中获取EmbeddedServletContainerFactory 组, TomcatEmbeddedServletContainerFactory 创建对象,后置处理器一看是这个对象,就获取所有的定制器来先定制Servlet容器的相关配置;

7)使用容器工厂获取嵌入式的Servlet容器**:this.embeddedServletContainer = containerFactory .getEmbeddedServletContainer(getSelfInitializer());

8)嵌入式的Servlet容器创建对象并启动Servlet容器。

先启动嵌入式的Servlet容器,再将ioc容器中剩下没有创建出的对象获取出来

==IOC容器启动创建嵌入式的Servlet容器==。

九、使用外置的Servlet容器

嵌入式Servlet容器:应用打成可执行的jar

​ 优点:简单、便携;

​ 缺点:默认不支持JSP、优化定制比较复杂(使用定制器【ServerProperties、自定义EmbeddedServletContainerCustomizer】,自己编写嵌入式Servlet容器的创建工厂【EmbeddedServletContainerFactory】)。

外置的Servlet容器:外面安装Tomcat—应用war包的方式打包

步骤

1)必须创建一个war项目;(利用idea创建好目录结构)

2)将嵌入式的Tomcat指定为provided;

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>

3)必须编写一个 SpringBootServletInitializer 的子类,并调用configure方法

public class ServletInitializer extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
//传入SpringBoot应用的主程序
return application.sources(SpringBoot04WebJspApplication.class);
}
}

4)启动服务器就可以使用。

原理

jar包:执行SpringBoot主类的main方法,启动ioc容器,创建嵌入式的Servlet容器;

war包:启动服务器, 服务器启动SpringBoot应用 【SpringBootServletInitializer】,启动ioc容器;

servlet3.0(Spring注解版):

8.2.4 Shared libraries / runtimes pluggability:

规则:

​ 1)服务器启动(web应用启动)会创建当前web应用里面每一个jar包里面ServletContainerInitializer实例;

​ 2)ServletContainerInitializer的实现放在jar包的META-INF/services文件夹下,有一个名为javax.servlet.ServletContainerInitializer的文件,内容就是ServletContainerInitializer的实现类的全类名;

​ 3)还可以使用@HandlesTypes,在应用启动的时候加载我们感兴趣的类。

流程:

1)启动Tomcat

2)orgspringframeworkspring-web4.3.14.RELEASEspring-web-4.3.14.RELEASE.jar!META-INFservicesjavax.servlet.ServletContainerInitializer:

Spring的web模块里面有这个文件: org.springframework.web.SpringServletContainerInitializer

3)SpringServletContainerInitializer将@HandlesTypes(WebApplicationInitializer.class)标注的所有这个类型的类都传入到onStartup方法的Set<Class<?>>;为这些WebApplicationInitializer类型的类创建实例;

4)每一个WebApplicationInitializer都调用自己的onStartup;

5)相当于我们的SpringBootServletInitializer的类会被创建对象,并执行onStartup方法

6)SpringBootServletInitializer实例执行onStartup的时候会createRootApplicationContext;创建容器

protected WebApplicationContext createRootApplicationContext(
ServletContext servletContext) {
//1、创建SpringApplicationBuilder
SpringApplicationBuilder builder = createSpringApplicationBuilder();
StandardServletEnvironment environment = new StandardServletEnvironment();
environment.initPropertySources(servletContext, null);
builder.environment(environment);
builder.main(getClass());
ApplicationContext parent = getExistingRootWebApplicationContext(servletContext);
if (parent != null) {
this.logger.info("Root context already created (using as parent).");
servletContext.setAttribute(
WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, null);
builder.initializers(new ParentContextApplicationContextInitializer(parent));
}
builder.initializers(
new ServletContextApplicationContextInitializer(servletContext));
builder.contextClass(AnnotationConfigEmbeddedWebApplicationContext.class);
//调用configure方法,子类重写了这个方法,将SpringBoot的主程序类传入了进来
builder = configure(builder);
//使用builder创建一个Spring应用
SpringApplication application = builder.build();
if (application.getSources().isEmpty() && AnnotationUtils
.findAnnotation(getClass(), Configuration.class) != null) {
application.getSources().add(getClass());
}
Assert.state(!application.getSources().isEmpty(),
"No SpringApplication sources have been defined. Either override the "
+ "configure method or add an @Configuration annotation");
// Ensure error pages are registered
if (this.registerErrorPageFilter) {
application.getSources().add(ErrorPageFilterConfiguration.class);
}
//启动Spring应用
return run(application);
}

7)Spring的应用就启动并且创建IOC容器

public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
FailureAnalyzers analyzers = null;
configureHeadlessProperty();
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(
args);
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
Banner printedBanner = printBanner(environment);
context = createApplicationContext();
analyzers = new FailureAnalyzers(context);
prepareContext(context, environment, listeners, applicationArguments,
printedBanner);
//刷新IOC容器
refreshContext(context);
afterRefresh(context, applicationArguments);
listeners.finished(context, null);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
.logStarted(getApplicationLog(), stopWatch);
}
return context;
}
catch (Throwable ex) {
handleRunFailure(context, listeners, analyzers, ex);
throw new IllegalStateException(ex);
}
}

==启动Servlet容器,再启动SpringBoot应用==。

参考

视频教程

webjars官网

Thymeleaf官方文档

Spring Web MVC Framework

微信扫一扫,分享到朋友圈

【SpringBoot学习】Web开发

Java常见的一些经典面试题(附答案解析)

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