SpringBoot---杂七杂八---终篇

一、静态资源映射

       通过之前自动装配原理源码的分析思路，现在可以很容易就锁定对应SpringMVC相关的配置类。,找到MVC自动配置类中的适配器中的增加资源的处理器。

       访问路径会被映射为对应路径下的资源，SpringBoot牛逼！

		public void addResourceHandlers(ResourceHandlerRegistry registry) {
            if (!this.resourceProperties.isAddMappings()) {
                logger.debug("Default resource handling disabled");
            } else {
                Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
                CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
                if (!registry.hasMappingForPattern("/webjars/**")) {
					//说明/webjars/**路径下的资源会被映射为classpath:/META-INF/resources/webjars这个路径
                    this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{"/webjars/**"}).addResourceLocations(new String[]{"classpath:/META-INF/resources/webjars/"}).setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
                }
                    
                String staticPathPattern = this.mvcProperties.getStaticPathPattern();
                if (!registry.hasMappingForPattern(staticPathPattern)) {
                    this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{staticPathPattern}).addResourceLocations(WebMvcAutoConfiguration.getResourceLocations(this.resourceProperties.getStaticLocations())).setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
                }

            }
        }

       上面代码的第二种情况的请求路径，String staticPathPattern = this.mvcProperties.getStaticPathPattern();实际上就是WebMvcProperties类中的this.staticPathPattern = "/**";。一切好说，问题不大。

       对于上面代码的第二种情况的映射路径，点到对应的配置类里面看源码，其实就包括四个映射路径。问题不是很大。

	public class ResourceProperties {
		//这个还是按照优先级顺序排的, SpringBoot设计精妙啊！
	    private static final String[] CLASSPATH_RESOURCE_LOCATIONS = new String[]{"classpath:/META-INF/resources/", "classpath:/resources/", "classpath:/static/", "classpath:/public/"};
	    private String[] staticLocations;
	    private boolean addMappings;
	    private final ResourceProperties.Chain chain;
	    private final ResourceProperties.Cache cache;
	
	    public ResourceProperties() {
	        this.staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
	        this.addMappings = true;
	        this.chain = new ResourceProperties.Chain();
	        this.cache = new ResourceProperties.Cache();
	    }
	
	    public String[] getStaticLocations() {
	        return this.staticLocations;
	    }
	  	...
	}

二、首页

       加下来分析一波web的首页。以往的应用默认首页都是web.xml里面配置好的三个index。tomcat的conf文件夹下面的三大index。。。

 	<welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

       还是之前那个自动配置的大类，找到下面的方法。

       锁定这个方法，点进去看源码。发现另一个方法也和其相关。

		private Optional<Resource> getWelcomePage() {
            String[] locations = WebMvcAutoConfiguration.getResourceLocations(this.resourceProperties.getStaticLocations());
            return Arrays.stream(locations).map(this::getIndexHtml).filter(this::isReadable).findFirst();
        }

        private Resource getIndexHtml(String location) {
            return this.resourceLoader.getResource(location + "index.html");
        }

       this.resourceProperties.getStaticLocations()这些路径就是之前静态资源映射第二种情况的四种路径。所以这也就解释了，为什么我们没有在之前说的四个路径下面为SpringBoot配置默认页面(index.html)的时候，访问会报错了。

       总结：一般把静态的网站资源(HTML、CSS、JS)放在类路径下的static文件夹下面。

三、模板引擎视图解析部分

       so easy，继续跟踪源码。
       下面看一下模板引擎Thymeleaf的视图解析源码，这个更简单了。

	@Configuration(
	    proxyBeanMethods = false
	)
	@EnableConfigurationProperties({ThymeleafProperties.class})
	@ConditionalOnClass({TemplateMode.class, SpringTemplateEngine.class})
	@AutoConfigureAfter({WebMvcAutoConfiguration.class, WebFluxAutoConfiguration.class})
	public class ThymeleafAutoConfiguration {
	    public ThymeleafAutoConfiguration() {
	    }
	    ...
	}

       可以看到默认Thymeleaf解析的路径是类路径下templates路径下的html文件，去掉前后缀即可。

	@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";
	    private Charset encoding;
	    private boolean cache;
	    private Integer templateResolverOrder;
	    private String[] viewNames;
	    private String[] excludedViewNames;
	    private boolean enableSpringElCompiler;
	    private boolean renderHiddenMarkersBeforeCheckboxes;
	    private boolean enabled;
	    private final ThymeleafProperties.Servlet servlet;
	    private final ThymeleafProperties.Reactive reactive;
	
	    public ThymeleafProperties() {
	        this.encoding = DEFAULT_ENCODING;
	        this.cache = true;
	        this.renderHiddenMarkersBeforeCheckboxes = false;
	        this.enabled = true;
	        this.servlet = new ThymeleafProperties.Servlet();
	        this.reactive = new ThymeleafProperties.Reactive();
	    }
	    ...
	}

       还有一点很奇怪，为什么引入了模板引擎，首页会是templates目录下面的index.html？？？

四、扩展MVC部分

1、扩展视图解析器

       直接实现接口，加入到容器中，搞定，Debug前端控制器执行代码也是可以获取到自定义的视图解析器的。@Bean只能用于类内部，@Component可以放在类上面。

	@Component
	public class MyViewResolver implements ViewResolver {
	    @Override
	    public View resolveViewName(String s, Locale locale) throws Exception {
	        //添加自己代码
	        return null;
	    }
	}

2、扩展通用部分

       官方文档说自动扩展的时候不能加@EnableWebMvc，只要加上@Configuraiton。

       点进去分析这个注解，导入了某个类。

	@Retention(RetentionPolicy.RUNTIME)
	@Target({ElementType.TYPE})
	@Documented
	@Import({DelegatingWebMvcConfiguration.class})
	public @interface EnableWebMvc {
	}

       就是导入了DelegatingWebMvcConfiguration类。发现这个类是继承于WebMvcConfigurationSupport的。

	public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
	    private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();
	
	    public DelegatingWebMvcConfiguration() {
	    }
	    ...
	}

       IDEA全局搜索两下Shift键。

	@Configuration(
	    proxyBeanMethods = false
	)
	@ConditionalOnWebApplication(
	    type = Type.SERVLET
	)
	@ConditionalOnClass({Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class})
	@ConditionalOnMissingBean({WebMvcConfigurationSupport.class})
	@AutoConfigureOrder(-2147483638)
	@AutoConfigureAfter({DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class, ValidationAutoConfiguration.class})
	public class WebMvcAutoConfiguration {
	...
	}

       可以看到只有WebMvcConfigurationSupport这个类不存在的时候，默认配置才会生效，就相当于不能加上@EnableWebMvc，否则SpringBoot默认的MVC配置全崩了。

	public class DispatcherServlet extends FrameworkServlet {
	    public static final String MULTIPART_RESOLVER_BEAN_NAME = "multipartResolver";
	    public static final String LOCALE_RESOLVER_BEAN_NAME = "localeResolver";
	    public static final String THEME_RESOLVER_BEAN_NAME = "themeResolver";
	    public static final String HANDLER_MAPPING_BEAN_NAME = "handlerMapping";
	    public static final String HANDLER_ADAPTER_BEAN_NAME = "handlerAdapter";
	    public static final String HANDLER_EXCEPTION_RESOLVER_BEAN_NAME = "handlerExceptionResolver";
	    public static final String REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME = "viewNameTranslator";
	    public static final String VIEW_RESOLVER_BEAN_NAME = "viewResolver";
	    public static final String FLASH_MAP_MANAGER_BEAN_NAME = "flashMapManager";
	    public static final String WEB_APPLICATION_CONTEXT_ATTRIBUTE = DispatcherServlet.class.getName() + ".CONTEXT";
	    public static final String LOCALE_RESOLVER_ATTRIBUTE = DispatcherServlet.class.getName() + ".LOCALE_RESOLVER";
	    public static final String THEME_RESOLVER_ATTRIBUTE = DispatcherServlet.class.getName() + ".THEME_RESOLVER";
	    public static final String THEME_SOURCE_ATTRIBUTE = DispatcherServlet.class.getName() + ".THEME_SOURCE";
	    public static final String INPUT_FLASH_MAP_ATTRIBUTE = DispatcherServlet.class.getName() + ".INPUT_FLASH_MAP";
	    public static final String OUTPUT_FLASH_MAP_ATTRIBUTE = DispatcherServlet.class.getName() + ".OUTPUT_FLASH_MAP";
	    public static final String FLASH_MAP_MANAGER_ATTRIBUTE = DispatcherServlet.class.getName() + ".FLASH_MAP_MANAGER";
	    public static final String EXCEPTION_ATTRIBUTE = DispatcherServlet.class.getName() + ".EXCEPTION";
	    public static final String PAGE_NOT_FOUND_LOG_CATEGORY = "org.springframework.web.servlet.PageNotFound";
	    private static final String DEFAULT_STRATEGIES_PATH = "DispatcherServlet.properties";
	    private static final String DEFAULT_STRATEGIES_PREFIX = "org.springframework.web.servlet";
	    protected static final Log pageNotFoundLogger = LogFactory.getLog("org.springframework.web.servlet.PageNotFound");
	    private static final Properties defaultStrategies;
	    private boolean detectAllHandlerMappings = true;
	    private boolean detectAllHandlerAdapters = true;
	    private boolean detectAllHandlerExceptionResolvers = true;
	    private boolean detectAllViewResolvers = true;
	    private boolean throwExceptionIfNoHandlerFound = false;
	    private boolean cleanupAfterInclude = true;
	    @Nullable
	    private MultipartResolver multipartResolver;
	    @Nullable
	    private LocaleResolver localeResolver;
	    @Nullable
	    private ThemeResolver themeResolver;
	    @Nullable
	    private List<HandlerMapping> handlerMappings;
	    @Nullable
	    private List<HandlerAdapter> handlerAdapters;
	    @Nullable
	    private List<HandlerExceptionResolver> handlerExceptionResolvers;
	    @Nullable
	    private RequestToViewNameTranslator viewNameTranslator;
	    @Nullable
	    private FlashMapManager flashMapManager;
	    @Nullable
	    private List<ViewResolver> viewResolvers;
	    ...
	}

       问题不大，跟着DispatcherServlet配就可以了。

3、demo

       简单demo：

	@Configuration
	//@EnableWebMvc
	public class MyMVCConfig implements WebMvcConfigurer {
	
	    @Override
	    public void addViewControllers(ViewControllerRegistry registry) {
	        registry.addViewController("/index").setViewName("index");
	        registry.addViewController("/index.html").setViewName("index");
	    }
	
	    @Override
	    public void addInterceptors(InterceptorRegistry registry) {
	        registry.addInterceptor(new MyInterceptor())
	                .addPathPatterns("/**")
	                .excludePathPatterns("/index", "/", "index.html")
	                .excludePathPatterns("/asserts/js/**", "/asserts/css/**", "/asserts/img/**")
	//                .excludePathPatterns("/i18n/**")
	                .excludePathPatterns("/login");
	    }
	
	    @Bean
	    public MyLocaleResolver localeResolver() {
	        return new MyLocaleResolver();
	    }
	
	}

五、Boot的CRUD模板

       踩了坑，国际化出现乱码。。。


       昨晚试了，根本没用啊，TM今早可以了。。。RGL。

       链接：https://pan.baidu.com/s/1ONiJMDvSPrIYeMA4Labi9Q

       提取码：38bb

以后SpringBoot的CRUD简单的系统都问题不大了，该补补java基础去了。