03.视图层开发

@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties {}

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

@ConfigurationProperties(prefix = "spring.thymeleaf")
public class ThymeleafProperties {

	private static final Charset DEFAULT_ENCODING = StandardCharsets.UTF_8;

	public static final String DEFAULT_PREFIX = "classpath:/templates/";

	public static final String DEFAULT_SUFFIX = ".html";
    //前后缀,只要把html页面放在classpath:/templates/，thymeleaf就能自动渲染了
}

@Controller
public class HelloController {
    @GetMapping("/hello")
    public String hello(Map<String,Object> map){
        map.put("hello","<h1>你好</h1>");
        map.put("users", Arrays.asList("张三","李四","王五"));
        return "message";
    }
}

@Configuration
public class MyMvcConfig implements WebMvcConfigurer{

    @Override
    public void addViewControllers(ViewControllerRegistry registry){
        //浏览器发送 /hello请求，来到message页面
        registry.addViewController("/ooyhao").setViewName("message");
    }
}

@Configuration
public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {
    
    
@Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {

    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相关的配置都一起调用起来
        	//@Override
		 //public void addViewControllers(ViewControllerRegistry registry) {
			//for (WebMvcConfigurer delegate : this.delegates) {
				//delegate.addViewControllers(registry);
			//}
			//}
        }
    }
}

/**
 * @author ooyhao
 */
@EnableWebMvc
@Configuration
public class MyMvcConfig implements WebMvcConfigurer{

    @Override
    public void addViewControllers(ViewControllerRegistry registry){
        //浏览器发送 /hello请求，来到message页面
        registry.addViewController("/ooyhao").setViewName("message");
    }
}

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

@Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {

@Configuration
@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(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,
      ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {

//所有的webMvcConfigurer组件都会一起起作用
@Bean
public WebMvcConfigurer webMvcConfigurer(){
    return new WebMvcConfigurer(){
        @Override
        public void addViewControllers(ViewControllerRegistry registry) {
            //注意：urlPath=RequestMapping(value)
            //     viewName=return "";(原handler中返回的视图名)
            registry.addViewController("/").setViewName("login");
            registry.addViewController("/index").setViewName("login");
            registry.addViewController("/index.html").setViewName("login");
        }
    };
}

// 或者是
@RequestMapping(value = {"/","/index.html"})
public String index(){
    return "index";
}

public class MessageSourceAutoConfiguration {
    private String basename = "messages";
    //我们的配置文件可以直接放在类路径下叫message.properties;
}

@Bean
@ConditionalOnMissingBean
@ConditionalOnProperty(prefix = "spring.mvc", name = "locale")
public LocaleResolver localeResolver() {
    if (this.mvcProperties
            .getLocaleResolver() == WebMvcProperties.LocaleResolver.FIXED) {
        return new FixedLocaleResolver(this.mvcProperties.getLocale());
    }
    AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
    localeResolver.setDefaultLocale(this.mvcProperties.getLocale());
    return localeResolver;
}

//默认的就是根据请求头带来的区域信息获取Locale进行国际化

/**
 * 可以在连接上携带区域信息
 */
public class MyLocaleResolver implements LocaleResolver{

    @Override
    public Locale resolveLocale(HttpServletRequest request) {
        //解析区域信息
        String l = request.getParameter("l");
        Locale locale = Locale.getDefault();
        if(!StringUtils.isEmpty(l)){
            String[] strings = l.split("_");
            locale = new Locale(strings[0],strings[1]);
        }
        return locale;
    }

    @Override
    public void setLocale(HttpServletRequest request, 
                          HttpServletResponse response, 
                          Locale locale) {}
}

 //添加组件
@Bean
public LocaleResolver localeResolver(){
    return new MyLocaleResolver();
}

/**
 * 登录检查
 */
public class LoginHandlerInterceptor implements HandlerInterceptor {
    /**
     * 目标方法执行之前
     */
    @Override
    public boolean preHandle(HttpServletRequest request, 
                             HttpServletResponse response, 
                             Object handler) throws ServletException, IOException {
        String loginUser = (String) request.getSession().getAttribute("loginUser");
        if(loginUser != null){
            return true;
        }
        request.setAttribute("msg","没有权限，请登录");
        request.getRequestDispatcher("/index.html").forward(request,response);
        return false;
    }
}

//@EnableWebMvc  //不要完全接管SpringMVC的功能
@Configuration
public class MyMvcConfig implements WebMvcConfigurer{

    @Override
    public void addViewControllers(ViewControllerRegistry registry){
        //浏览器发送 /hello请求，来到message页面
        registry.addViewController("/ooyhao").setViewName("message");
    }

    //所有的webMvcConfigurer组件都会一起起作用
    @Bean
    public WebMvcConfigurer webMvcConfigurer(){
        return new WebMvcConfigurer(){
            @Override
            public void addViewControllers(ViewControllerRegistry registry) {
                //注意：urlPath=RequestMapping(value)
                //     viewName=return "";(原handler中返回的视图名)
                registry.addViewController("/").setViewName("login");
                registry.addViewController("/index").setViewName("login");
                registry.addViewController("/index.html").setViewName("login");
                registry.addViewController("/main.html").setViewName("dashboard");
            }

            //添加拦截器
            @Override
            public void addInterceptors(InterceptorRegistry registry) {

                registry.addInterceptor(new LoginHandlerInterceptor())
                        .addPathPatterns("/**") //拦截任意请求
                        .excludePathPatterns("/index.html","/","index","/user/login","/webjars/**","/asserts/**") //排除拦截请求
                //静态资源不用排除，SpringBoot已经做好了静态资源映射，拦截器处理是可以不用考虑静态资源
                ;
            }
        };
    }

    //添加组件国际化
    @Bean
    public LocaleResolver localeResolver(){
        return new MyLocaleResolver();
    }
}