SpringBoot与Web开发（超详细）【篇一】

向右看齐 2022-11-05 08:38 150阅读 0赞

### SpringBoot与Web开发（超详细） ###

*  一、简介
 *  二、SpringBoot对静态资源的映射规则
 *   *  1、所有 /webjars/\*\* ，都去 classpath:/META-INF/resources/webjars/ 找资源
     *  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
     *  3、欢迎页： 静态资源文件夹下的所有index.html页面，被"/\*\*"映射
 *  三、模板引擎
 *   *  1、引入Thymeleaf
     *  2、Thymeleaf的使用
     *   *  1、导入thymeleaf的名称空间
         *  2、使用thymeleaf语法
     *  3、Thymeleaf的语法规则
 *  四、SpringMVC自动配置
 *   *  1、Spring MVC auto-configuration
     *  2、扩展SpringMVC
     *   *  原理
     *  3、全面接管SpringMVC
     *   *  原理
 *  五、如何修改SpringBoot的默认配置

# 一、简介 #

**使用SpringBoot的步骤：**

> **1、创建SpringBoot应用，选中我们需要的模块。**  
> **2、SpringBoot已经默认将这些场景配置好了，只需要在配置文件中指定少量配置就可以运行起来。**  
> **3、自己编写业务代码。**

**自动配置原理：**

xxxxAutoConfiguration：帮我们给容器中自动配置组件
    xxxxProperties:配置类来封装配置文件的内容

# 二、SpringBoot对静态资源的映射规则 #

@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
    public class ResourceProperties implements ResourceLoaderAware { 
      //可以设置和静态资源有关的参数，缓存时间等

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();
             	//静态资源文件夹映射
    		if (!registry.hasMappingForPattern(staticPathPattern)) { 
    			customizeResourceHandlerRegistration(
    					registry.addResourceHandler(staticPathPattern)
    							.addResourceLocations(
    									this.resourceProperties.getStaticLocations())
    					.setCachePeriod(cachePeriod));
    		}
    	}
    
           //配置欢迎页映射
    	@Bean
    	public WelcomePageHandlerMapping welcomePageHandlerMapping(
    			ResourceProperties resourceProperties) { 
    		return new WelcomePageHandlerMapping(resourceProperties.getWelcomePage(),
    				this.mvcProperties.getStaticPathPattern());
    	}
    
          //配置喜欢的图标
    	@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);
                 	//所有  **/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、所有 /webjars/\*\* ，都去 classpath:/META-INF/resources/webjars/ 找资源 ##

**webjars：以jar包的方式引入静态资源。[WebJars][]**

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70]  
**访问`localhost:8080/webjars/jquery/3.3.1/jquery.js`的结果：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 1]

## 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 ##

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

**例子：访问localhost:8080/abc 就是去静态资源文件夹里面找abc**

**例如我们访问js文件夹下的Chart.min.js：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 2]  
**访问结果：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 3]

## 3、欢迎页： 静态资源文件夹下的所有index.html页面，被"/\*\*"映射 ##

**编写index.html文件。**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 4]  
**访问结果：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 5]

# 三、模板引擎 #

**常见的模板引擎：JSP、Velocity、Freemarker、Thymeleaf（springboot推荐，语法更简单，功能更强大）**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 6]

## 1、引入Thymeleaf ##

**[Thymeleaf官网][Thymeleaf]**

**在pom.xml中添加以下依赖：**

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

## 2、Thymeleaf的使用 ##

@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";

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

**success.html：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 7]  
**HelloController：**

package com.keafmd.springboot.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    /** * Keafmd * * @ClassName: HelloController * @Description: * @author: 牛哄哄的柯南 * @date: 2021-03-04 19:54 */
    
    @Controller
    public class HelloController { 
    
        @ResponseBody
        @RequestMapping("/hello")
        public String hello(){ 
            return "Hello World";
        }
    
        @RequestMapping("/success")
        public String success() { 
            return "success";
        }
    }

**访问success的结果：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 8]

### 1、导入thymeleaf的名称空间 ###

### 2、使用thymeleaf语法 ###

**HelloController：**

package com.keafmd.springboot.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    import java.util.Map;
    
    /** * Keafmd * * @ClassName: HelloController * @Description: * @author: 牛哄哄的柯南 * @date: 2021-03-04 19:54 */
    
    @Controller
    public class HelloController { 
    
        @ResponseBody
        @RequestMapping("/hello")
        public String hello(){ 
            return "Hello World";
        }
    
        /** * 查出一些数据在页面显示 * @param map * @return */
        @RequestMapping("/success")
        public String success(Map<String,Object> map) { 
            map.put("hello","你好");
            return "success";
        }
    }

**success.html：**

**运行结果：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 9]

## 3、Thymeleaf的语法规则 ##

**1、th：任意html属性，来替换原生属性的值**

**th:text — 改变当前元素里面的文本内容**  
**更多参考下图：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 10]  
**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：和${ }在功能上是一样；
        	补充：配合 th:object="${ 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: #{ ...}：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: _

**注意**：**内容过多，详细内容参考[官方文档][Link 1]。**

> **示例：↓**

**HelloController：**

package com.keafmd.springboot.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.ResponseBody;
    
    import java.util.Arrays;
    import java.util.Map;
    
    /** * Keafmd * * @ClassName: HelloController * @Description: * @author: 牛哄哄的柯南 * @date: 2021-03-04 19:54 */
    
    @Controller
    public class HelloController { 
    
        @ResponseBody
        @RequestMapping("/hello")
        public String hello(){ 
            return "Hello World";
        }
    
        /** * 查出一些数据在页面显示 * @param map * @return */
        @RequestMapping("/success")
        public String success(Map<String,Object> map) { 
            map.put("hello","你好");
            map.put("hello1","<h1>你好</h1>");
            map.put("users", Arrays.asList("柯南","小兰","基德"));
            return "success";
        }
    }

**success.html：**

<!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 id="div01" class="myDiv" th:id="${hello}" th:class="${hello}" th:text="${hello}">这里的内容被覆盖</div>
    
        <hr/>
        <div th:text="${hello1}"></div>
        <div th:utext="${hello1}"></div>
        <hr/>
        
        <h4 th:text="${user}" th:each="user:${users}"></h4>
        <hr/>
        <h4>
            <span th:each="user:${users}"> [[${user}]] </span>
        </h4>
    </body>
    </html>

**效果：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 11]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 12]

# 四、SpringMVC自动配置 #

## 1、Spring MVC auto-configuration ##

**参考官方文档：[点这里][Link 2]**

> **Spring Boot 自动配置好了SpringMVC**

**以下是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的。**
     *  **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**
 *  **自动注册了 of `Converter`, `GenericConverter`, `Formatter` beans.**
    
     *  **`Converter`：转换器； public String hello(User user)：类型转换使用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规则
    public Formatter<Date> dateFormatter() { 
        return new DateFormatter(this.mvcProperties.getDateFormat());//日期格式化组件
    }

**自己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—Json**
     *  **`HttpMessageConverters` 是从容器中确定；获取所有的HttpMessageConverter**

自己给容器中添加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).**

我们可以配置一个ConfigurableWebBindingInitializer来替换默认的（添加到容器）

初始化WebDataBinder
    请求数据=====JavaBean

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

**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.**

> **如果你想保持Spring Boot MVC 功能,你只是想添加额外的(MVC配置)(https://docs.spring.io/spring/docs/4.3.14.RELEASE/spring-framework-reference/htmlsingle MVC)(拦截器,格式器,视图控制器等)您可以添加自己的@ configuration类WebMvcConfigurerAdapter类型,但没有@EnableWebMvc。如果你想提供RequestMappingHandlerMapping, RequestMappingHandlerAdapter或ExceptionHandlerExceptionResolver的自定义实例，你可以声明一个WebMvcRegistrationsAdapter实例来提供这样的组件。**

**If you want to take complete control of Spring MVC, you can add your own `@Configuration` annotated with `@EnableWebMvc`.**

> **如果你想完全控制Spring MVC，你可以添加你自己的@Configuration注解@EnableWebMvc。**

## 2、扩展SpringMVC ##

**实现如下功能：**

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

**做法：编写一个配置类（@Configuration），是WebMvcConfigurerAdapter类型；不能标注@EnableWebMvc**

> **特点：既保留了所有的自动配置，也能用我们扩展的配置。**

**在config包下创建个MyMvcConfig。**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 13]  
**代码实现：**

package com.keafmd.springboot.config;
    
    import org.springframework.context.annotation.Configuration;
    import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
    import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
    
    
    /** * Keafmd * * @ClassName: MyMvcConfig * @Description: * @author: 牛哄哄的柯南 * @date: 2021-03-17 20:26 */
    @Configuration
    public class MyMvcConfig implements WebMvcConfigurer { 
        @Override
        public void addViewControllers(ViewControllerRegistry registry) { 
            //浏览器发送 /keafmd 请求 来到success页面
            registry.addViewController("/keafmd").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。**

**做法：我们需要在配置类中添加@EnableWebMvc即可。**

@EnableWebMvc
    @Configuration
    public class MyMvcConfig implements WebMvcConfigurer { 
        @Override
        public void addViewControllers(ViewControllerRegistry registry) { 
            //浏览器发送 /keafmd 请求 来到success页面
            registry.addViewController("/keafmd").setViewName("success");
        }
    }

**全面接管后，静态资源失效。**  
**不推荐这样全面接管。**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzg4MzkxNw_size_16_color_FFFFFF_t_70 14]

### 原理 ###

**加了@EnableWebMvc自动配置就失效了。**

**1、@EnableWebMvc的核心：**

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

**2、DelegatingWebMvcConfiguration**

@Configuration(
        proxyBeanMethods = false
    )
    public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {

**3、WebMvcAutoConfiguration**

@Configuration(
        proxyBeanMethods = false
    )
    @ConditionalOnWebApplication(
        type = Type.SERVLET
    )
    @ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class})
    //容器中没有这个组件的时候，这个自动配置类才生效
    @ConditionalOnMissingBean({ WebMvcConfigurationSupport.class})
    @AutoConfigureOrder(-2147483638)
    @AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class, ValidationAutoConfiguration.class})
    public class WebMvcAutoConfiguration {

**4、@EnableWebMvc将WebMvcConfigurationSupport组件导入进来，自动配置类失效了。**

**5、导入的WebMvcConfigurationSupport只是SpringMVC最基本的功能。**

# 五、如何修改SpringBoot的默认配置 #

** 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。**

> **以上就是SpringBoot与Web开发（超详细）篇一的全部内容。**

**看完如果对你有帮助，感谢点赞支持！  
如果你是电脑端的话，看到右下角的 “一键三连” 了吗，没错点它\[哈哈\]**  
![在这里插入图片描述][20210115230629703.gif_pic_center]

**加油！**

**共同努力！**

**Keafmd**

[WebJars]: https://www.webjars.org/
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[Thymeleaf]: https://www.thymeleaf.org/
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[Link 1]: https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html
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[Link 2]: https://docs.spring.io/spring-boot/docs/1.5.10.RELEASE/reference/htmlsingle/#boot-features-developing-web-applications
[MVC configuration]: https://docs.spring.io/spring/docs/4.3.14.RELEASE/spring-framework-reference/htmlsingle#mvc
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