SpringMVC基于代码的配置方式（零配置，无web.xml）直接继承WebMvcConfigurerAdapter

基于配置文件的web项目维护起来可能会更方便，但是有时候我们会有一些特殊的需求，比如防止客户胡乱更改配置，这时候我们需要给配置隐藏到代码中。

1.创建一个动态web项目（无需web.xml）

2.右键项目添加几个package: com.easyweb.config (保存项目配置) com.easyweb.controller （保存springMvc controller）

3.在 com.easyweb.config 新建一个类 WebApplicationStartup ，这个类实现WebApplicationInitializer 接口，是项目的入口，作用类似于web.xml，具体代码如下：

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<code class="hljs" java="">package com.easyweb.config;   import javax.servlet.MultipartConfigElement; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRegistration.Dynamic;   import org.springframework.web.WebApplicationInitializer; import org.springframework.web.context.support.AnnotationConfigWebApplicationContext; import org.springframework.web.servlet.DispatcherServlet;   /**  * 服务器启动入口类  *  * @author Administrator  *  */ public class WebApplicationStartup implements WebApplicationInitializer {     private static final String SERVLET_NAME = Spring-mvc;     private static final long MAX_FILE_UPLOAD_SIZE = 1024 * 1024 * 5; // 5 Mb     private static final int FILE_SIZE_THRESHOLD = 1024 * 1024; // After 1Mb     private static final long MAX_REQUEST_SIZE = -1L; // No request size limit     /**    * 服务器启动调用此方法，在这里可以做配置 作用与web.xml相同    */   @Override   public void onStartup(ServletContext servletContext) throws ServletException {     // 注册springMvc的servlet     this.addServlet(servletContext);     // 注册过滤器     // servletContext.addFilter(arg0, arg1)     // 注册监听器     // servletContext.addListener(arg0);   }     /**    * 注册Spring servlet    *    * @param servletContext    */   private void addServlet(ServletContext servletContext) {     // 构建一个application context     AnnotationConfigWebApplicationContext webContext = createWebContext(SpringMVC.class, ViewConfiguration.class);     // 注册spring mvc 的 servlet     Dynamic dynamic = servletContext.addServlet(SERVLET_NAME, new DispatcherServlet(webContext));     // 添加springMVC 允许访问的Controller后缀     dynamic.addMapping(*.html, *.ajax, *.css, *.js, *.gif, *.jpg, *.png);     // 全部通过请用 “/”     // dynamic.addMapping(/);     dynamic.setLoadOnStartup(1);     dynamic.setMultipartConfig(new MultipartConfigElement(null, MAX_FILE_UPLOAD_SIZE, MAX_REQUEST_SIZE, FILE_SIZE_THRESHOLD));   }     /**    * 通过自定义的配置类来实例化一个Web Application Context    *    * @param annotatedClasses    * @return    */   private AnnotationConfigWebApplicationContext createWebContext(Class<!--?-->... annotatedClasses) {     AnnotationConfigWebApplicationContext webContext = new AnnotationConfigWebApplicationContext();     webContext.register(annotatedClasses);       return webContext;   }   }</code>

4.在com.easyweb.config 下添加类 SpringMVC 继承 WebMvcConfigurerAdapter，这个类的作用是进行SpringMVC的一些配置，代码如下：

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<code class="hljs" java="">package com.easyweb.config;   import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer; import org.springframework.web.servlet.config.annotation.EnableWebMvc; import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry; import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;   @Configuration @EnableWebMvc //指明controller所在的包名 @ComponentScan(basePackages = {com.easyweb.controller}) public class SpringMVC extends WebMvcConfigurerAdapter {     /**    * 非必须    */   @Override   public void configureDefaultServletHandling(final DefaultServletHandlerConfigurer configurer) {     configurer.enable();   }     /**    * 如果项目的一些资源文件放在/WEB-INF/resources/下面    * 在浏览器访问的地址就是类似：https://host:port/projectName/WEB-INF/resources/xxx.css    * 但是加了如下定义之后就可以这样访问：    * https://host:port/projectName/resources/xxx.css    * 非必须    */   @Override   public void addResourceHandlers(final ResourceHandlerRegistry registry) {     registry.addResourceHandler(/resources/**/*).addResourceLocations(/WEB-INF/resources/);   } }</code>

5.添加view配置文件com.easyweb.config下新建类ViewConfiguration，里面可以根据自己的需要定义视图拦截器：

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<code avrasm="" class="hljs">package com.easyweb.config;   import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.web.servlet.ViewResolver; import org.springframework.web.servlet.view.JstlView; import org.springframework.web.servlet.view.UrlBasedViewResolver; import org.springframework.web.servlet.view.tiles2.TilesConfigurer; import org.springframework.web.servlet.view.tiles2.TilesView;   @Configuration public class ViewConfiguration {       @Bean     public ViewResolver urlBasedViewResolver() {         UrlBasedViewResolver viewResolver;         viewResolver = new UrlBasedViewResolver();         viewResolver.setOrder(2);         viewResolver.setPrefix(/WEB-INF/);         viewResolver.setSuffix(.jsp);         viewResolver.setViewClass(JstlView.class);         // for debug envirment         viewResolver.setCache(false);         return viewResolver;     }     @Bean     public ViewResolver tilesViewResolver() {         UrlBasedViewResolver urlBasedViewResolver = new UrlBasedViewResolver();         urlBasedViewResolver.setOrder(1);         urlBasedViewResolver.setViewClass(TilesView.class);         //urlBasedViewResolver.         return urlBasedViewResolver;     }     @Bean     public TilesConfigurer tilesConfigurer() {         TilesConfigurer tilesConfigurer = new TilesConfigurer();         tilesConfigurer.setDefinitions(new String[] { classpath:tiles.xml });         return tilesConfigurer;     } }</code>

6.本例中还用了tiles视图解析器，替换了原始的include方式