SpringMVC基于代码的配置方式（零配置，无web.xml）

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：

<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：

<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：http://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：
   * http://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：

<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