Spring整合web学习(三十六)-Spring通过注解整合Springmvc

末蓝、 2024-02-19 16:16 37阅读 0赞

Spring Web MVC是基于Servlet API构建的原始Web框架，从一开始就包含在Spring Framework中。正式名称“Spring Web MVC”来自其源模块（[`spring-webmvc`][spring-webmvc]）的名称，但它通常被称为“Spring MVC”。

原先在项目中ssm项目，我们需要配置web.xml。进行大量的配置xml文件方式，在spring项目中整合web容器。如：

<web-app>
        
        <listener>
            <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
        </listener>
    
        <context-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/app-context.xml</param-value>
        </context-param>
    
       
        <servlet>
            <servlet-name>app</servlet-name>
            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
            <init-param>
                <param-name>contextConfigLocation</param-name>
                <param-value></param-value>
            </init-param>
            <load-on-startup>1</load-on-startup>
        </servlet>
       
       
        <servlet-mapping>
            <servlet-name>app</servlet-name>
            <url-pattern>/app/*</url-pattern>
        </servlet-mapping>
    
    </web-app>

通过这种方式整合web.

在Servlet 3.0+环境中，我们可以以编程方式配置Servlet容器作为替代`web.xml`文件。

import org.springframework.web.WebApplicationInitializer;
    
    public class MyWebApplicationInitializer implements WebApplicationInitializer {
    
        @Override
        public void onStartup(ServletContext container) {
            //读取配置文件
            XmlWebApplicationContext appContext = new XmlWebApplicationContext();
            appContext.setConfigLocation("/WEB-INF/spring/dispatcher-config.xml");
            //注册 dispatcher
            ServletRegistration.Dynamic registration = container.addServlet("dispatcher", new DispatcherServlet(appContext));
            registration.setLoadOnStartup(1);
            //添加映射
            registration.addMapping("/");
        }
    }

结构图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70][]

在以前的Springweb项目工作中，我们知道，springweb项目启动的时候会读取扫描每个jar包下的META-INF/services/javax.servlet.ServletContainerInitializer并且会加载这个文件指定的类SpringServletContainerInitializer。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 1][]

SpringServletContainerInitializer：

//@HandlesTypes Servlet 3.0 以后 容器启动的时候会将@HandlesTypes指定的这个类型下面的子类（实现类，子接口等）传递过来；
    @HandlesTypes(WebApplicationInitializer.class)
    public class SpringServletContainerInitializer implements ServletContainerInitializer {
    
        //加载感兴趣的WebApplicationInitializer接口的下的所有组件
    	@Override
    	public void onStartup(Set<Class<?>> webAppInitializerClasses, ServletContext servletContext)
    			throws ServletException {
    
    		List<WebApplicationInitializer> initializers = new LinkedList<WebApplicationInitializer>();
    
    		if (webAppInitializerClasses != null) {
    			for (Class<?> waiClass : webAppInitializerClasses) {
    				if (!waiClass.isInterface() && !Modifier.isAbstract(waiClass.getModifiers()) &&
    						WebApplicationInitializer.class.isAssignableFrom(waiClass)) {
    					try 
    					   // WebApplicationInitializer组件创建对象
    						initializers.add((WebApplicationInitializer) waiClass.newInstance());
    					}
    					catch (Throwable ex) {
    						throw new ServletException("Failed to instantiate WebApplicationInitializer class", ex);
    					}
    				}
    			}
    		}
    
    		if (initializers.isEmpty()) {
    			servletContext.log("No Spring WebApplicationInitializer types detected on classpath");
    			return;
    		}
    
    		servletContext.log(initializers.size() + " Spring WebApplicationInitializers detected on classpath");
    		//排序
    		AnnotationAwareOrderComparator.sort(initializers);
    		for (WebApplicationInitializer initializer : initializers) {
    			//启动Servlet容器
    			initializer.onStartup(servletContext);
    		}
    	}
    
    }

WebApplicationInitializer：

public interface WebApplicationInitializer {
        //启动服务 ，加载上下文
    	void onStartup(ServletContext servletContext) throws ServletException;
    
    }

同时会加载其子类信息：

![20190122134431383.png][]

AbstractContextLoaderInitializer：创建根容器

public abstract class AbstractContextLoaderInitializer implements WebApplicationInitializer {
    
    	/** Logger available to subclasses */
    	protected final Log logger = LogFactory.getLog(getClass());
    
    
    	@Override
    	public void onStartup(ServletContext servletContext) throws ServletException {
    		registerContextLoaderListener(servletContext);
    	}
    
    	//注册容器加载监听器
    	protected void registerContextLoaderListener(ServletContext servletContext) {
    		WebApplicationContext rootAppContext = createRootApplicationContext();
    		if (rootAppContext != null) {
    			ContextLoaderListener listener = new ContextLoaderListener(rootAppContext);
    			listener.setContextInitializers(getRootApplicationContextInitializers());
    			servletContext.addListener(listener);
    		}
    		else {
    			logger.debug("No ContextLoaderListener registered, as " +
    					"createRootApplicationContext() did not return an application context");
    		}
    	}
    
    	//创建跟容器
    	protected abstract WebApplicationContext createRootApplicationContext();
    
    	/**
    	 * Specify application context initializers to be applied to the root application
    	 * context that the {@code ContextLoaderListener} is being created with.
    	 * @since 4.2
    	 * @see #createRootApplicationContext()
    	 * @see ContextLoaderListener#setContextInitializers
    	 */
    	protected ApplicationContextInitializer<?>[] getRootApplicationContextInitializers() {
    		return null;
    	}
    
    }

AbstractDispatcherServletInitializer：

//AbstractContextLoaderInitializer 的子类
    public abstract class AbstractDispatcherServletInitializer extends AbstractContextLoaderInitializer {
    
    	/**
    	 * The default servlet name. Can be customized by overriding {@link #getServletName}.
    	 */
    	public static final String DEFAULT_SERVLET_NAME = "dispatcher";
    
    
    	@Override
    	public void onStartup(ServletContext servletContext) throws ServletException {
    		super.onStartup(servletContext);
    		registerDispatcherServlet(servletContext);
    	}
    
    	//容器启动注册 DispatcherServlet
    	protected void registerDispatcherServlet(ServletContext servletContext) {
    		String servletName = getServletName();
    		Assert.hasLength(servletName, "getServletName() must not return empty or null");
    
    		WebApplicationContext servletAppContext = createServletApplicationContext();
    		Assert.notNull(servletAppContext,
    				"createServletApplicationContext() did not return an application " +
    				"context for servlet [" + servletName + "]");
    
    		FrameworkServlet dispatcherServlet = createDispatcherServlet(servletAppContext);
    		dispatcherServlet.setContextInitializers(getServletApplicationContextInitializers());
    
    		ServletRegistration.Dynamic registration = servletContext.addServlet(servletName, dispatcherServlet);
    		Assert.notNull(registration,
    				"Failed to register servlet with name '" + servletName + "'." +
    				"Check if there is another servlet registered under the same name.");
    
    		registration.setLoadOnStartup(1);
    		registration.addMapping(getServletMappings());
    		registration.setAsyncSupported(isAsyncSupported());
    
    		Filter[] filters = getServletFilters();
    		if (!ObjectUtils.isEmpty(filters)) {
    			for (Filter filter : filters) {
    				registerServletFilter(servletContext, filter);
    			}
    		}
    
    		customizeRegistration(registration);
    	}
    
    	
    	protected String getServletName() {
    		return DEFAULT_SERVLET_NAME;
    	}
    
    	//创建一个web的ioc容器
    	protected abstract WebApplicationContext createServletApplicationContext();
    
    	//创建了DispatcherServlet
    	protected FrameworkServlet createDispatcherServlet(WebApplicationContext servletAppContext) {
    		//将创建的DispatcherServlet添加到ServletContext中；
    		return new DispatcherServlet(servletAppContext);
    	}
    
    	
    	protected ApplicationContextInitializer<?>[] getServletApplicationContextInitializers() {
    		return null;
    	}
    
    	/**
    	 * Specify the servlet mapping(s) for the {@code DispatcherServlet} —
    	 * for example {@code "/"}, {@code "/app"}, etc.
    	 * @see #registerDispatcherServlet(ServletContext)
    	 */
    	protected abstract String[] getServletMappings();
    
    	
    	protected Filter[] getServletFilters() {
    		return null;
    	}
    
        //注册拦截器 filter
    	protected FilterRegistration.Dynamic registerServletFilter(ServletContext servletContext, Filter filter) {
    		String filterName = Conventions.getVariableName(filter);
    		Dynamic registration = servletContext.addFilter(filterName, filter);
    		if (registration == null) {
    			int counter = -1;
    			while (counter == -1 || registration == null) {
    				counter++;
    				registration = servletContext.addFilter(filterName + "#" + counter, filter);
    				Assert.isTrue(counter < 100,
    						"Failed to register filter '" + filter + "'." +
    						"Could the same Filter instance have been registered already?");
    			}
    		}
    		registration.setAsyncSupported(isAsyncSupported());
    		registration.addMappingForServletNames(getDispatcherTypes(), false, getServletName());
    		return registration;
    	}
        //DispatcherTypes 类型
    	private EnumSet<DispatcherType> getDispatcherTypes() {
    		return (isAsyncSupported() ?
    				EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.INCLUDE, DispatcherType.ASYNC) :
    				EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.INCLUDE));
    	}
    
    	//是否支持同步
    	protected boolean isAsyncSupported() {
    		return true;
    	}
    
    	//定制注册
    	protected void customizeRegistration(ServletRegistration.Dynamic registration) {
    	}
    
    }

AbstractAnnotationConfigDispatcherServletInitializer：

//AbstractDispatcherServletInitializer 的子类
    public abstract class AbstractAnnotationConfigDispatcherServletInitializer
    		extends AbstractDispatcherServletInitializer {
    
    	//创建根容器
    	@Override
    	protected WebApplicationContext createRootApplicationContext() {
    		Class<?>[] configClasses = getRootConfigClasses();
    		if (!ObjectUtils.isEmpty(configClasses)) {
    			AnnotationConfigWebApplicationContext rootAppContext = new AnnotationConfigWebApplicationContext();
    			rootAppContext.register(configClasses);
    			return rootAppContext;
    		}
    		else {
    			return null;
    		}
    	}
    
    	//创建web的ioc容器
    	@Override
    	protected WebApplicationContext createServletApplicationContext() {
    		AnnotationConfigWebApplicationContext servletAppContext = new AnnotationConfigWebApplicationContext();
    		Class<?>[] configClasses = getServletConfigClasses();
    		if (!ObjectUtils.isEmpty(configClasses)) {
    			servletAppContext.register(configClasses);
    		}
    		return servletAppContext;
    	}
    
    	//获取配置类
    	protected abstract Class<?>[] getRootConfigClasses();
    
    	
    	protected abstract Class<?>[] getServletConfigClasses();
    
    }

总结：  
以注解方式来启动SpringMVC；继承AbstractAnnotationConfigDispatcherServletInitializer；  
实现抽象方法指定DispatcherServlet的配置信息；

测试：

创建AbstractAnnotationConfigDispatcherServletInitializer的子类。

package com.spring;
    
    import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
    
    import com.spring.config.AppConfig;
    import com.spring.config.RootConfig;
    
    //web容器启动的时候创建对象；调用方法来初始化容器以前前端控制器
    public class MyWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
    
    	//获取根容器的配置类；（Spring的配置文件）   父容器；
    	@Override
    	protected Class<?>[] getRootConfigClasses() {
    		// TODO Auto-generated method stub
    		return new Class<?>[]{RootConfig.class};
    	}
    
    	//获取web容器的配置类（SpringMVC配置文件）  子容器；
    	@Override
    	protected Class<?>[] getServletConfigClasses() {
    		// TODO Auto-generated method stub
    		return new Class<?>[]{AppConfig.class};
    	}
    
    	//获取DispatcherServlet的映射信息
    	//  /：拦截所有请求（包括静态资源（xx.js,xx.png）），但是不包括*.jsp；
    	//  /*：拦截所有请求；连*.jsp页面都拦截；jsp页面是tomcat的jsp引擎解析的；
    	@Override
    	protected String[] getServletMappings() {
    		// TODO Auto-generated method stub
    		return new String[]{"/"};
    	}
    
    }

根容器配置：

package com.spring.config;
    
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.ComponentScan.Filter;
    import org.springframework.context.annotation.FilterType;
    import org.springframework.stereotype.Controller;
    
    //Spring的容器不扫描controller;父容器
    @ComponentScan(value="com.spring",excludeFilters={
    		@Filter(type=FilterType.ANNOTATION,classes={Controller.class})
    })
    public class RootConfig {
    
    }

子容器配置：

//SpringMVC只扫描Controller；子容器
    //useDefaultFilters=false 禁用默认的过滤规则；
    @ComponentScan(value="com.spring",includeFilters={
    		@Filter(type=FilterType.ANNOTATION,classes={Controller.class})
    },useDefaultFilters=false)
    @EnableWebMvc //启用MVC配置 p配置如下 需要实现 WebMvcConfigurerAdapter 
    public class AppConfig  extends WebMvcConfigurerAdapter  {
    	
    	/**
    	 * 请求转发给/名为的视图home
    	 */
    	@Override
    	public void addViewControllers(ViewControllerRegistry registry) {
    		 registry.addViewController("/").setViewName("index");
    	}
    
    	
    	/**
    	 * 类型转换
    	 */
    	@Override
        public void addFormatters(FormatterRegistry registry) {
            // ...
        }
    	
    	/**
    	 * 验证规则
    	 */
    	@Override
        public Validator getValidator() {
    		return null;
    	}
    	
    	/**
    	 * 消息转换器
    	 */
    	/*
    	 * @Override public void
    	 * configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    	 * Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder()
    	 * .indentOutput(true) .dateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"))
    	 * .modulesToInstall(new ParameterNamesModule()); converters.add(new
    	 * MappingJackson2HttpMessageConverter(builder.build())); converters.add(new
    	 * MappingJackson2XmlHttpMessageConverter(builder.createXmlMapper(true).build())
    	 * ); }
    	 */
    	
    	//视图解析器
    	@Override
    	public void configureViewResolvers(ViewResolverRegistry registry) {
    		// TODO Auto-generated method stub
    		//默认所有的页面都从 /WEB-INF/ xxx .jsp
    		//registry.jsp();
    		 registry.enableContentNegotiation(new MappingJackson2JsonView());
    		registry.jsp("/WEB-INF/views/", ".jsp");
    	}
    	/**
    	 * <mvc:resources mapping="/resources/**"
        location="/public, classpath:/static/"
        cache-period="31556926" />
    	 */
    	//静态资源访问
    	@Override
    	public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
    		// TODO Auto-generated method stub
    		
    		/*
    		 * registry.addResourceHandler("/resources/**") .addResourceLocations("/public",
    		 * "classpath:/static/") .setCachePeriod(31556926);
    		 * 。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。
    		 * registry.addResourceHandler("/resources/**")
                    .addResourceLocations("/public/")
                    .resourceChain(true)
                    .addResolver(new VersionResourceResolver().addContentVersionStrategy("/**"));
    		 * 
    		 */
    		//使用默认的
    		configurer.enable();
    	}
    	
    	//拦截器
    	@Override
    	public void addInterceptors(InterceptorRegistry registry) {
    		// TODO Auto-generated method stub
    		//super.addInterceptors(registry);
    		registry.addInterceptor(new MyFirstInterceptor()).addPathPatterns("/**");
    	}
    	
    	/*
    	 * @Bean public FreeMarkerConfigurer freeMarkerConfigurer() {
    	 * FreeMarkerConfigurer configurer = new FreeMarkerConfigurer();
    	 * configurer.setTemplateLoaderPath("/freemarker"); return configurer; }
    	 */
    
    }

配置拦截器：

public class MyFirstInterceptor implements HandlerInterceptor {
    
    	//目标方法运行之前执行
    	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
    			throws Exception {
    		// TODO Auto-generated method stub
    		System.out.println("preHandle..."+request.getRequestURI());
    		return true;
    	}
    
    	//目标方法执行正确以后执行
    
    	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
    			ModelAndView modelAndView) throws Exception {
    		// TODO Auto-generated method stub
    		System.out.println("postHandle...");
    
    	}
    
    	//页面响应以后执行
    
    	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
    			throws Exception {
    		// TODO Auto-generated method stub
    		System.out.println("afterCompletion...");
    	}
    
    }

配置controller:

@Controller
    public class HelloController {
    	
    	@Autowired
    	HelloService helloService;
    	
    	
    	@ResponseBody
    	@RequestMapping("/hello")
    	public String hello(){
    		String hello = helloService.sayHello("tomcat..");
    		return hello;
    	}
    	
    	//  /WEB-INF/views/success.jsp
    	@RequestMapping("/suc")
    	public String success(){
    		return "success";
    	}
    	
    
    }

配置service:

@Service
    public class HelloService {
    	
    	public String sayHello(String name){
    		
    		return "Hello "+name;
    	}
    
    }

pom:

<dependencies>
      	<dependency>
      		<groupId>org.springframework</groupId>
      		<artifactId>spring-webmvc</artifactId>
      		<version>4.3.11.RELEASE</version>
      	</dependency>
      	
      	<dependency>
      		<groupId>javax.servlet</groupId>
      		<artifactId>servlet-api</artifactId>
      		<version>3.0-alpha-1</version>
      		<scope>provided</scope>
      	</dependency>
    
      </dependencies>
    
      <build>
      	<plugins>
      		<plugin>
      			<groupId>org.apache.maven.plugins</groupId>
      			<artifactId>maven-war-plugin</artifactId>
      			<version>2.4</version>
      			<configuration>
      				<failOnMissingWebXml>false</failOnMissingWebXml>
      			</configuration>
      		</plugin>
      	</plugins>
      </build>

[spring-webmvc]: https://github.com/spring-projects/spring-framework/tree/master/spring-webmvc
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/dc80d6f90b9c47ba87102f84e00f8466.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzU0OTU3OA_size_16_color_FFFFFF_t_70 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/fce0f489a3d74c2e8840bbf7ec80ebeb.png
[20190122134431383.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/ba1f729e447e4882a17b91b9603daa0e.png