十三、注解配置SpringMVC_springboot defaultservlet-优快云博客

本文链接：https://blog.youkuaiyun.com/m0_62520968/article/details/125540981

使用配置类和注解代替web.xml和SpringMVC配置文件的功能

1、创建初始化类，代替web.xml

在Servlet3.0环境中，容器会在类路径中查找实现javax.servlet.ServletContainerInitializer接口的类，如果找到的话就用它来配置Servlet容器。 Spring提供了这个接口的实现，名为SpringServletContainerInitializer，这个类反过来又会查找实现WebApplicationInitializer的类并将配置的任务交给它们来完成。Spring3.2引入了一个便利的WebApplicationInitializer基础实现，名为AbstractAnnotationConfigDispatcherServletInitializer，当我们的类扩展了AbstractAnnotationConfigDispatcherServletInitializer并将其部署到Servlet3.0容器的时候，容器会自动发现它，并用它来配置Servlet上下文。

//web工程初始化类，代替web.xml
public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {

    /**
     * 指定spring的配置类
     * @return
     */
    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

    /**
     * 指定SpringMVC的配置类
     * @return
     */
    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{SpringMVCConfig.class};
    }

    /**
     * 指定DispatcherServlet的映射规则，即url-pattern
     * @return
     */
    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    /**
     * control+o
     * 添加过滤器
     * @return
     */
    @Override
    protected Filter[] getServletFilters() {
//        配置编码过滤器
        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        characterEncodingFilter.setEncoding("UTF-8");
        characterEncodingFilter.setForceResponseEncoding(true);

//        配置HiddenHttpMethodFilter
        HiddenHttpMethodFilter hiddenHttpMethodFilter = new HiddenHttpMethodFilter();
        return new Filter[]{characterEncodingFilter, hiddenHttpMethodFilter};
    }
}

2、创建SpringConfig配置类，代替spring的配置文件

@Configuration//标识为配置类
public class SpringConfig {
	//ssm整合之后，spring的配置信息写在此类中
}

3、创建WebConfig配置类，代替SpringMVC的配置文件

/**
 * 代替springMVC的配置文件
 * 1.扫描组件
 * 2.视图解析器
 * 3.view-controller
 * 4.default-servlet-handler
 * 5.mvc注解驱动
 * 6.文件上传解析器
 * 7.异常处理
 * 8.拦截器
 */

@Configuration//将当前类标识为一个配置类
@ComponentScan("com.controller")//1.扫描组件
@EnableWebMvc//5.mvc注解驱动
public class SpringMVCConfig implements WebMvcConfigurer {

    //4.default-servlet-handler使用默认的servlet处理静态资源
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
//        WebMvcConfigurer.super.configureDefaultServletHandling(configurer);
        configurer.enable();
    }

    //8.拦截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        TestInterceptor testInterceptor = new TestInterceptor();
        registry.addInterceptor(testInterceptor).addPathPatterns("/**");
    }

    //3.view-controller
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/hello").setViewName("hello");
    }

//    6.文件上传解析器
    @Bean
    public MultipartResolver multipartResolver(){
        CommonsMultipartResolver commonsMultipartResolver = new CommonsMultipartResolver();
        return commonsMultipartResolver;
    }

//    7.异常处理
    @Override
    public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
        SimpleMappingExceptionResolver exceptionResolver = new SimpleMappingExceptionResolver();
        Properties properties = new Properties();
        properties.setProperty("java.lang.ArithmeticException","error");
        exceptionResolver.setExceptionMappings(properties);
        exceptionResolver.setExceptionAttribute("exception");
        resolvers.add(exceptionResolver);
    }

    //2.视图解析器
    //配置生成模板解析器
    @Bean
    public ITemplateResolver templateResolver(){
        WebApplicationContext webApplicationContext = ContextLoader.getCurrentWebApplicationContext();
        // ServletContextTemplateResolver需要一个ServletContext作为构造参数，可通过WebApplicationContext 的方法获得
        ServletContextTemplateResolver templateResolver = new ServletContextTemplateResolver(webApplicationContext.getServletContext());
        templateResolver.setPrefix("/WEB-INF/templates/");
        templateResolver.setSuffix(".html");
        templateResolver.setCharacterEncoding("UTF-8");
        templateResolver.setTemplateMode(TemplateMode.HTML);
        return templateResolver;
    }

    //生成模板引擎并为模板引擎注入模板解析器
    @Bean
    public SpringTemplateEngine templateEngine(ITemplateResolver templateResolver){
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        templateEngine.setTemplateResolver(templateResolver);
        return templateEngine;
    }

    //生成视图解析器并未解析器注入模板引擎
    @Bean
    public ViewResolver viewResolver(SpringTemplateEngine templateEngine){
        ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
        viewResolver.setCharacterEncoding("UTF-8");
        viewResolver.setTemplateEngine(templateEngine);
        return viewResolver;
    }
}

4、测试功能

@RequestMapping("/")
public String index(){
    return "index";
}