20.管理及扩展SpringMVC组件

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管理及扩展SpringMVC组件

1. 管理SpringMVC的组件

1，前端控制器的自动管理

找到WebMvcAutoConfiguration，找到DispatcherServletAutoConfiguration.class

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@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class,
		ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {

	/**
	 * The default Spring MVC view prefix.
	 */
	public static final String DEFAULT_PREFIX = "";

	/**
	 * The default Spring MVC view suffix.
	 */
	public static final String DEFAULT_SUFFIX = "";

	private static final String SERVLET_LOCATION = "/";

    ...
}

DispatcherServletAutoConfiguration，public DispatcherServlet dispatcherServlet(WebMvcProperties webMvcProperties)方法

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@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass(DispatcherServlet.class)
@AutoConfigureAfter(ServletWebServerFactoryAutoConfiguration.class)
public class DispatcherServletAutoConfiguration {

	/**
	 * The bean name for a DispatcherServlet that will be mapped to the root URL "/".
	 */
	public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";

	/**
	 * The bean name for a ServletRegistrationBean for the DispatcherServlet "/".
	 */
	public static final String DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME = "dispatcherServletRegistration";

	@Configuration(proxyBeanMethods = false)
	@Conditional(DefaultDispatcherServletCondition.class)
	@ConditionalOnClass(ServletRegistration.class)
	@EnableConfigurationProperties(WebMvcProperties.class)
	protected static class DispatcherServletConfiguration {

		@Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
		public DispatcherServlet dispatcherServlet(WebMvcProperties webMvcProperties) {
			DispatcherServlet dispatcherServlet = new DispatcherServlet();
			dispatcherServlet.setDispatchOptionsRequest(webMvcProperties.isDispatchOptionsRequest());
			dispatcherServlet.setDispatchTraceRequest(webMvcProperties.isDispatchTraceRequest());
			dispatcherServlet.setThrowExceptionIfNoHandlerFound(webMvcProperties.isThrowExceptionIfNoHandlerFound());
			dispatcherServlet.setPublishEvents(webMvcProperties.isPublishRequestHandledEvents());
			dispatcherServlet.setEnableLoggingRequestDetails(webMvcProperties.isLogRequestDetails());
			return dispatcherServlet;
		}
		/**
		以上配置是创建前端控制器对象
		**/

        ...
    }

	@Configuration(proxyBeanMethods = false)
	@Conditional(DispatcherServletRegistrationCondition.class)
	@ConditionalOnClass(ServletRegistration.class)
	@EnableConfigurationProperties(WebMvcProperties.class)
	@Import(DispatcherServletConfiguration.class)
	protected static class DispatcherServletRegistrationConfiguration {

		@Bean(name = DEFAULT_DISPATCHER_SERVLET_REGISTRATION_BEAN_NAME)
		@ConditionalOnBean(value = DispatcherServlet.class, name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
		public DispatcherServletRegistrationBean dispatcherServletRegistration(DispatcherServlet dispatcherServlet,
				WebMvcProperties webMvcProperties, ObjectProvider<MultipartConfigElement> multipartConfig) {
			DispatcherServletRegistrationBean registration = new DispatcherServletRegistrationBean(dispatcherServlet,
					webMvcProperties.getServlet().getPath());
			registration.setName(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
			registration.setLoadOnStartup(webMvcProperties.getServlet().getLoadOnStartup());
			multipartConfig.ifAvailable(registration::setMultipartConfig);
			return registration;
		}
		/**
		以上配置是进行注册
		**/

	}

    ...
}
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@Component和@Bean注解
1.@Component不能初始化属性值，@Bean可以初始化属性值
2.@Component比@Bean的优先级高
3.当class类位于jar中，无法添加@Component注解，这时可以通过@Bean注解向IOC容器中创建一个该类的对象

2，控制器[controller]的自动管理

直接扫描@ComponentScan(basePackages = {})

3，视图解析器的自动管理

创建视图解析器

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public class WebMvcAutoConfiguration {

	/**
	 * The default Spring MVC view prefix.
	 */
	public static final String DEFAULT_PREFIX = "";

	/**
	 * The default Spring MVC view suffix.
	 */
	public static final String DEFAULT_SUFFIX = "";
	
	...

	public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer {

		...

		@Bean
		@ConditionalOnMissingBean
		public InternalResourceViewResolver defaultViewResolver() {
			InternalResourceViewResolver resolver = new InternalResourceViewResolver();
			resolver.setPrefix(this.mvcProperties.getView().getPrefix());
			resolver.setSuffix(this.mvcProperties.getView().getSuffix());
			return resolver;
		}

		@Bean
		@ConditionalOnBean(View.class)
		@ConditionalOnMissingBean
		public BeanNameViewResolver beanNameViewResolver() {
			BeanNameViewResolver resolver = new BeanNameViewResolver();
			resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
			return resolver;
		}

		@Bean
		@ConditionalOnBean(ViewResolver.class)
		@ConditionalOnMissingBean(name = "viewResolver", value = ContentNegotiatingViewResolver.class)
		public ContentNegotiatingViewResolver viewResolver(BeanFactory beanFactory) {
			ContentNegotiatingViewResolver resolver = new ContentNegotiatingViewResolver();
			resolver.setContentNegotiationManager(beanFactory.getBean(ContentNegotiationManager.class));
			// ContentNegotiatingViewResolver uses all the other view resolvers to locate
			// a view so it should have a high precedence
			resolver.setOrder(Ordered.HIGHEST_PRECEDENCE);
			return resolver;
		}

		...

	}

	...
}

contentNegotiationViewResolver是一个管理所有视图解析器的对象

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public class ContentNegotiatingViewResolver {

	...

	@Override
	protected void initServletContext(ServletContext servletContext) {
		Collection<ViewResolver> matchingBeans =
				BeanFactoryUtils.beansOfTypeIncludingAncestors(obtainApplicationContext(), ViewResolver.class).values();
		...
	}

	...

}

4.自定义前缀和后缀

SpringBoot默认不支持jsp

application.yml

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#配置视图解析器的前缀和后缀
spring:
  mvc:
    view:
      prefix: /WEB-INF/view/
      suffix: .jsp

创建jsp页面

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<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
This is a jsp file.
</body>
</html>

在pom文件中加入相关依赖

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<!--加入内嵌入tomcat对jsp的支持 -->
<dependency>
	<groupId>org.apache.tomcat.embed</groupId>
	<artifactId>tomcat-embed-jasper</artifactId>
	<scope>provided</scope>
</dependency>

创建controller

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@Controller
@RequestMapping("index")
public class IndexController {
	
	@RequestMapping("hello")
	public String hello() {
		return "hello";
	}

}

5.文件上传和下载的自动配置

查看MultipartAutoConfiguration

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@Configuration(proxyBeanMethods = false)
// 必须有这些字节码存在
@ConditionalOnClass({ Servlet.class, StandardServletMultipartResolver.class, MultipartConfigElement.class })
// 如果条件都成立，默认开启文件上传的支持
@ConditionalOnProperty(prefix = "spring.servlet.multipart", name = "enabled", matchIfMissing = true)
// 必须是一个web应用程序
@ConditionalOnWebApplication(type = Type.SERVLET)
@EnableConfigurationProperties(MultipartProperties.class)
public class MultipartAutoConfiguration {
	...
}

查看MultipartProperties

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@ConfigurationProperties(prefix = "spring.servlet.multipart", ignoreUnknownFields = false)
public class MultipartProperties {

	/**
	 * Whether to enable support of multipart uploads.
	 */
	private boolean enabled = true;

	/**
	 * Intermediate location of uploaded files.
	 */
	private String location;

	/**
	 * Max file size.
	 */
	private DataSize maxFileSize = DataSize.ofMegabytes(1);

	/**
	 * Max request size.
	 */
	private DataSize maxRequestSize = DataSize.ofMegabytes(10);

	...
}

application.yml

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# 文件上传的配置
  servlet:
    multipart:
      enabled: true
      location: 
      max-file-size: 10MB

文件大小的单位必须为MB(大写)

6.消息转化和格式化转化

6.1 消息转化【接收页面参数并类型转化】

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public class WebMvcAutoConfiguration {
	public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer {
		@Override
		public void addFormatters(FormatterRegistry registry) {
			ApplicationConversionService.addBeans(registry, this.beanFactory);
		}

	}
}
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public class ApplicationConversionService extends FormattingConversionService {
	public static void addBeans(FormatterRegistry registry, ListableBeanFactory beanFactory) {
		Set<Object> beans = new LinkedHashSet<>();
		beans.addAll(beanFactory.getBeansOfType(GenericConverter.class).values());
		beans.addAll(beanFactory.getBeansOfType(Converter.class).values());
		beans.addAll(beanFactory.getBeansOfType(Printer.class).values());
		beans.addAll(beanFactory.getBeansOfType(Parser.class).values());
		for (Object bean : beans) {
			if (bean instanceof GenericConverter) {
				registry.addConverter((GenericConverter) bean);
			}
			else if (bean instanceof Converter) {
				registry.addConverter((Converter<?, ?>) bean);
			}
			else if (bean instanceof Formatter) {
				registry.addFormatter((Formatter<?>) bean);
			}
			else if (bean instanceof Printer) {
				registry.addPrinter((Printer<?>) bean);
			}
			else if (bean instanceof Parser) {
				registry.addParser((Parser<?>) bean);
			}
		}
	}
}

标出的部分为接收前台参数，将前台参数进行类型转换。

6.2 消息格式化转化【接收页面参数并格式化转化】

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#配置日期格式化的格式
spring:
  mvc:
    format:
      date: yyyy-MM-dd
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@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student {

	private Integer id;
	private String name;
	
	@DateTimeFormat(pattern = "yyyy/MM/dd-HH:mm:ss")
	private Date birthday;
	
}
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@Controller
@RequestMapping("index")
public class IndexController {
	
	@RequestMapping("showDateTime")
	public String showDateTime(Date date) {
		System.out.println(date);
		/*
		 * http://127.0.0.1:8080/index/showDateTime?date=2020-12-12
		 * Sat Dec 12 00:00:00 CST 2020
		 * 
		 * http://127.0.0.1:8080/index/showDateTime?date=2020-12-12-10-10-10
		 * Sat Dec 12 00:00:00 CST 2020
		 */
		return "hello";
	}

	@RequestMapping("showDateTime2")
	public String showDateTime2(@DateTimeFormat(pattern = "yyyy:MM:dd:HH:mm:ss")Date date) {
		System.out.println(date);
		/*
		 * http://127.0.0.1:8080/index/showDateTime2?date=2020:12:12:11:11:11
		 * Sat Dec 12 11:11:11 CST 2020
		 */
		return "hello";
	}

	@RequestMapping(value = "showStudentInfo", method = RequestMethod.GET)
	public String showStudentInfo(Student student) {
		System.out.println(student);
		/*
		 * http://127.0.0.1:8080/index/showStudentInfo?id=1&name=Tom&birthday=2001/10/10-09:02:01
		 * Student(id=1, name=Tom, birthday=Wed Oct 10 09:02:01 CST 2001)
		 */
		return "hello";
	}

}

7.欢迎页面的默认配置

以前欢迎页面的配置：web.xml

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<welcome-file-list>

	<welcome-file>index.jsp</welcome-file>

	<welcome-file>login.jsp</welcome-file>

	<welcome-file>index.html</welcome-file>

	<welcome-file>index.htm</welcome-file>

	<welcome-file>default.html</welcome-file>

	<welcome-file>default.htm</welcome-file>

	<welcome-file>default.jsp</welcome-file>

</welcome-file-list>

欢迎页面默认为src/main/resources/static/目录下的index.html

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<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
This is the welcome index.html.
</body>
</html>
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public class WebMvcAutoConfiguration {
	public static class EnableWebMvcConfiguration {
		@Bean
		public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext,
				FormattingConversionService mvcConversionService, ResourceUrlProvider mvcResourceUrlProvider) {
			WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(
					new TemplateAvailabilityProviders(applicationContext), applicationContext, getWelcomePage(),
					this.mvcProperties.getStaticPathPattern());
			welcomePageHandlerMapping.setInterceptors(getInterceptors(mvcConversionService, mvcResourceUrlProvider));
			welcomePageHandlerMapping.setCorsConfigurations(getCorsConfigurations());
			return welcomePageHandlerMapping;
		}

		private Resource getWelcomePage() {
			for (String location : this.resourceProperties.getStaticLocations()) {
				Resource indexHtml = getIndexHtml(location);
				if (indexHtml != null) {
					return indexHtml;
				}
			}
			ServletContext servletContext = getServletContext();
			if (servletContext != null) {
				return getIndexHtml(new ServletContextResource(servletContext, SERVLET_LOCATION));
			}
			return null;
		}

		private Resource getIndexHtml(String location) {
			return getIndexHtml(this.resourceLoader.getResource(location));
		}

		private Resource getIndexHtml(Resource location) {
			try {
				Resource resource = location.createRelative("index.html");
				if (resource.exists() && (resource.getURL() != null)) {
					return resource;
				}
			}
			catch (Exception ex) {
			}
			return null;
		}
		
	}
}