SpringMVC源码阅读-dispatcher组件初始化过程(三)

说明

前面我们看到了是dispatcher负责组件的初始化

调用链:

org.springframework.web.servlet.HttpServletBean#init

->

org.springframework.web.servlet.FrameworkServlet#initServletBean

->

org.springframework.web.servlet.FrameworkServlet#initWebApplicationContext

->

org.springframework.web.servlet.DispatcherServlet#onRefresh

protected void onRefresh(ApplicationContext context) {
        this.initStrategies(context);
    }
    /**
     * 初始化spring mvc组件
     * @param context
     */
    protected void initStrategies(ApplicationContext context) {
        //<1>初始化上传文件Resolver
        this.initMultipartResolver(context);
        //<2>初始化国际化Resolver 不同区域显示不同视图
        this.initLocaleResolver(context);
        //<3>初始化控制页面主题的Resolver
        this.initThemeResolver(context);
        //<4>初始化url映射 mapping
        this.initHandlerMappings(context);
        //<5>初始化Handler适配器
        this.initHandlerAdapters(context);
        //<6>初始化全局异常处理HandlerExceptionResolver
        this.initHandlerExceptionResolvers(context);
        //<7>
        this.initRequestToViewNameTranslator(context);
        //<8>
        this.initViewResolvers(context);
        //<9>
        this.initFlashMapManager(context);
    }

<1>initMultipartResolver

这个组件主要用于解析Content-Type为 multipart/*

 private void initMultipartResolver(ApplicationContext context) {
        try {
            //<1>从当前容器里面获取MultipartResolver实现类
            this.multipartResolver = (MultipartResolver)context.getBean("multipartResolver", MultipartResolver.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Using MultipartResolver [" + this.multipartResolver + "]");
            }
        } catch (NoSuchBeanDefinitionException var3) {
            this.multipartResolver = null;
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Unable to locate MultipartResolver with name 'multipartResolver': no multipart request handling provided");
            }
        }

    }

主要处理请求头类型( Content-Type )为 multipart/* 的请求

<1>

   <!-- mulitipart -->
    <bean id="multipartResolver"
          class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="UTF-8"/>
        <property name="maxUploadSize" value="5242880"/>
    </bean>

<2>initLocaleResolver

private void initLocaleResolver(ApplicationContext context) {
        try {
            this.localeResolver = (LocaleResolver)context.getBean("localeResolver", LocaleResolver.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Using LocaleResolver [" + this.localeResolver + "]");
            }
        } catch (NoSuchBeanDefinitionException var3) {
            this.localeResolver = (LocaleResolver)this.getDefaultStrategy(context, LocaleResolver.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Unable to locate LocaleResolver with name 'localeResolver': using default [" + this.localeResolver + "]");
            }
        }

    }

初始化国际化组件 使用例子:https://www.cnblogs.com/liukemng/p/3750117.html

<3>initThemeResolver

  private void initThemeResolver(ApplicationContext context) {
        try {
            this.themeResolver = (ThemeResolver)context.getBean("themeResolver", ThemeResolver.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Using ThemeResolver [" + this.themeResolver + "]");
            }
        } catch (NoSuchBeanDefinitionException var3) {
            this.themeResolver = (ThemeResolver)this.getDefaultStrategy(context, ThemeResolver.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Unable to locate ThemeResolver with name 'themeResolver': using default [" + this.themeResolver + "]");
            }
        }

    }

<4>initHandlerMappings

private void initHandlerMappings(ApplicationContext context) {
        this.handlerMappings = null;
        //默认为true可以通过inin-parameter修改 前面容器初始化过程 BeanWapper
        if (this.detectAllHandlerMappings) {
            /**
             * 从容器获取HandlerMapping的实现类
             * 这里会获取到
             * org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping
             * org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping
             */
            Map<String, HandlerMapping> matchingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerMapping.class, true, false);
            if (!matchingBeans.isEmpty()) {
                this.handlerMappings = new ArrayList(matchingBeans.values());
                //这里会获取Mapping的的Order注解的value进行排序
                AnnotationAwareOrderComparator.sort(this.handlerMappings);
            }
        } else {
            try {
                //直接获取容器名称为handlerMapping
                HandlerMapping hm = (HandlerMapping)context.getBean("handlerMapping", HandlerMapping.class);
                this.handlerMappings = Collections.singletonList(hm);
            } catch (NoSuchBeanDefinitionException var3) {
                ;
            }
        }

        //这里应该是获取默认的HandlerMapping
        if (this.handlerMappings == null) {

            this.handlerMappings = this.getDefaultStrategies(context, HandlerMapping.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("No HandlerMappings found in servlet '" + this.getServletName() + "': using default");
            }
        }

    }

使用例子:https://blog.csdn.net/neweastsun/article/details/79213867

<5>initHandlerAdapters

适配器模式 因为conroller不止是@Controller还有可能是servlte 再或者我们自定义注解@MyController

  private void initHandlerAdapters(ApplicationContext context) {
        this.handlerAdapters = null;
        /**
         * 默认为true 可以通过init-parameter修改
         */
        if (this.detectAllHandlerAdapters) {
            /**
             * 从容器获取HandlerAdapter 我这里获取到的是
             * org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter
             * org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter
             * org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter
             */
            Map<String, HandlerAdapter> matchingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerAdapter.class, true, false);
            if (!matchingBeans.isEmpty()) {
                this.handlerAdapters = new ArrayList(matchingBeans.values());
                //读取sort注解标签进行排序
                AnnotationAwareOrderComparator.sort(this.handlerAdapters);
            }
        } else {
            try {
                //从容器获取id为handlerAdapter的
                HandlerAdapter ha = (HandlerAdapter)context.getBean("handlerAdapter", HandlerAdapter.class);
                this.handlerAdapters = Collections.singletonList(ha);
            } catch (NoSuchBeanDefinitionException var3) {
                ;
            }
        }
        //加载默认额
        if (this.handlerAdapters == null) {
            this.handlerAdapters = this.getDefaultStrategies(context, HandlerAdapter.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("No HandlerAdapters found in servlet '" + this.getServletName() + "': using default");
            }
        }

    }

<6>initHandlerExceptionResolvers

用于全局捕获异常处理器

 private void initHandlerExceptionResolvers(ApplicationContext context) {
        this.handlerExceptionResolvers = null;
        if (this.detectAllHandlerExceptionResolvers) {
            Map<String, HandlerExceptionResolver> matchingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerExceptionResolver.class, true, false);
            if (!matchingBeans.isEmpty()) {
                this.handlerExceptionResolvers = new ArrayList(matchingBeans.values());
                AnnotationAwareOrderComparator.sort(this.handlerExceptionResolvers);
            }
        } else {
            try {
                HandlerExceptionResolver her = (HandlerExceptionResolver)context.getBean("handlerExceptionResolver", HandlerExceptionResolver.class);
                this.handlerExceptionResolvers = Collections.singletonList(her);
            } catch (NoSuchBeanDefinitionException var3) {
                ;
            }
        }

        if (this.handlerExceptionResolvers == null) {
            this.handlerExceptionResolvers = this.getDefaultStrategies(context, HandlerExceptionResolver.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("No HandlerExceptionResolvers found in servlet '" + this.getServletName() + "': using default");
            }
        }

    }

<7>initRequestToViewNameTranslator

ViewResolver是根据ViewName查找VIew，但有的Handler处理完后并没有设置View也没有ViewName，这时需要从request获取viewName，RequestToViewNameTranslator就是做这个事情。

 private void initRequestToViewNameTranslator(ApplicationContext context) {
        try {
            this.viewNameTranslator = (RequestToViewNameTranslator)context.getBean("viewNameTranslator", RequestToViewNameTranslator.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Using RequestToViewNameTranslator [" + this.viewNameTranslator + "]");
            }
        } catch (NoSuchBeanDefinitionException var3) {
            this.viewNameTranslator = (RequestToViewNameTranslator)this.getDefaultStrategy(context, RequestToViewNameTranslator.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Unable to locate RequestToViewNameTranslator with name 'viewNameTranslator': using default [" + this.viewNameTranslator + "]");
            }
        }

    }

<8>initViewResolvers

ViewResolver是根据ViewName查找VIew

private void initViewResolvers(ApplicationContext context) {
        this.viewResolvers = null;
        if (this.detectAllViewResolvers) {
            Map<String, ViewResolver> matchingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, ViewResolver.class, true, false);
            if (!matchingBeans.isEmpty()) {
                this.viewResolvers = new ArrayList(matchingBeans.values());
                AnnotationAwareOrderComparator.sort(this.viewResolvers);
            }
        } else {
            try {
                ViewResolver vr = (ViewResolver)context.getBean("viewResolver", ViewResolver.class);
                this.viewResolvers = Collections.singletonList(vr);
            } catch (NoSuchBeanDefinitionException var3) {
                ;
            }
        }

        if (this.viewResolvers == null) {
            this.viewResolvers = this.getDefaultStrategies(context, ViewResolver.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("No ViewResolvers found in servlet '" + this.getServletName() + "': using default");
            }
        }

    }

<9>initFlashMapManager

我们都知道，重定向时一般都是不传数据的，如果一定要传数据，只能在URL中拼接字符串来传递，但是通过拼接字符串有缺点，比如长度问题，安全问题  

通过FlashManager异常发送

 private void initFlashMapManager(ApplicationContext context) {
        try {
            this.flashMapManager = (FlashMapManager)context.getBean("flashMapManager", FlashMapManager.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Using FlashMapManager [" + this.flashMapManager + "]");
            }
        } catch (NoSuchBeanDefinitionException var3) {
            this.flashMapManager = (FlashMapManager)this.getDefaultStrategy(context, FlashMapManager.class);
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Unable to locate FlashMapManager with name 'flashMapManager': using default [" + this.flashMapManager + "]");
            }
        }

    }