SpringMVC之注解配置SpringMVC

使用配置类和注解代替web.xml和SpringMVC配置文件的功能

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。

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[]{WebConfig.class};
 }
  /**
  * 指定DispatcherServlet的映射规则，即url-pattern
  * @return
  */
  @Override
  protected String[] getServletMappings() {
    return new String[]{"/"};
 }
  /**
  * 添加过滤器
  * @return
  */
  @Override
  protected Filter[] getServletFilters() {
    CharacterEncodingFilter encodingFilter = new CharacterEncodingFilter();
    encodingFilter.setEncoding("UTF-8");
    encodingFilter.setForceRequestEncoding(true);
    HiddenHttpMethodFilter hiddenHttpMethodFilter = new
HiddenHttpMethodFilter();
    return new Filter[]{encodingFilter, hiddenHttpMethodFilter};
 }
}

创建SpringConfig配置类，代替spring的配置文件 

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

创建WebConfig配置类，代替SpringMVC的配置文件 

@Configuration
//扫描组件
@ComponentScan("com.atguigu.mvc.controller")
//开启MVC注解驱动
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
  //使用默认的servlet处理静态资源
  @Override
  public void configureDefaultServletHandling(DefaultServletHandlerConfigurer
configurer) {
    configurer.enable();
 }
  //配置文件上传解析器
  @Bean
  public CommonsMultipartResolver multipartResolver(){
    return new CommonsMultipartResolver();
 }
  //配置拦截器
  @Override
  public void addInterceptors(InterceptorRegistry registry) {
    FirstInterceptor firstInterceptor = new FirstInterceptor();
    registry.addInterceptor(firstInterceptor).addPathPatterns("/**");
 }
 
  //配置视图控制
 
  /*@Override
  public void addViewControllers(ViewControllerRegistry registry) {
    registry.addViewController("/").setViewName("index");
  }*/
 
  //配置异常映射
  /*@Override
  public void
configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
    SimpleMappingExceptionResolver exceptionResolver = new
SimpleMappingExceptionResolver();
    Properties prop = new Properties();
    prop.setProperty("java.lang.ArithmeticException", "error");
    //设置异常映射
    exceptionResolver.setExceptionMappings(prop);
    //设置共享异常信息的键
    exceptionResolver.setExceptionAttribute("ex");
    resolvers.add(exceptionResolver);
}*/
  //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;
 }
}

测试功能 

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