SpringMVC4零配置--web.xml

servlet3.0+规范后，允许servlet，filter，listener不必声明在web.xml中，而是以硬编码的方式存在，实现容器的零配置。

ServletContainerInitializer：启动容器时负责加载相关配置

1. package javax.servlet;
2. import java.util.Set;
3. public interface ServletContainerInitializer {
4. public void onStartup(Set<Class<?>> c, ServletContext ctx)
5. throws ServletException;
6. }

容器启动时会自动扫描当前服务中ServletContainerInitializer的实现类，并调用其onStartup方法，其参数Set<Class<?>> c，可通过在实现类上声明注解javax.servlet.annotation.HandlesTypes(xxx.class)注解自动注入，@HandlesTypes会自动扫描项目中所有的xxx.class的实现类，并将其全部注入Set。

Spring为其提供了一个实现类：

SpringServletContainerInitializer

1. package org.springframework.web;
2. import java.lang.reflect.Modifier;
3. import java.util.LinkedList;
4. import java.util.List;
5. import java.util.ServiceLoader;
6. import java.util.Set;
7. import javax.servlet.ServletContainerInitializer;
8. import javax.servlet.ServletContext;
9. import javax.servlet.ServletException;
10. import javax.servlet.annotation.HandlesTypes;
11. import org.springframework.core.annotation.AnnotationAwareOrderComparator;
12. @HandlesTypes(WebApplicationInitializer.class)
13. public class SpringServletContainerInitializer implements ServletContainerInitializer {
14. @Override
15. public void onStartup(Set<Class<?>> webAppInitializerClasses, ServletContext servletContext)
16. throws ServletException {
17. List<WebApplicationInitializer> initializers = new LinkedList<WebApplicationInitializer>();
18. if (webAppInitializerClasses != null) {
19. for (Class<?> waiClass : webAppInitializerClasses) {
20. // Be defensive: Some servlet containers provide us with invalid classes,
21. // no matter what @HandlesTypes says...
22. if (!waiClass.isInterface() && !Modifier.isAbstract(waiClass.getModifiers()) &&
23. WebApplicationInitializer.class.isAssignableFrom(waiClass)) {
24. try {
25. initializers.add((WebApplicationInitializer) waiClass.newInstance());
26. }
27. catch (Throwable ex) {
28. throw new ServletException("Failed to instantiate WebApplicationInitializer class", ex);
29. }
30. }
31. }
32. }
33. if (initializers.isEmpty()) {
34. servletContext.log("No Spring WebApplicationInitializer types detected on classpath");
35. return;
36. }
37. AnnotationAwareOrderComparator.sort(initializers);
38. servletContext.log("Spring WebApplicationInitializers detected on classpath: " + initializers);
39. for (WebApplicationInitializer initializer : initializers) {
40. initializer.onStartup(servletContext);
41. }
42. }
43. }

从中可以看出，WebApplicationInitializer才是我们需要关心的接口，我们只需要将相应的servlet，filter，listener等硬编码到该接口的实现类中即可。比如：

xml配置：

1. <!-- Log4jConfigListener -->
2. <context-param>
3. <param-name>log4jConfigLocation</param-name>
4. <param-value>classpath:config/properties/log4j.properties</param-value>
5. </context-param>
6. <listener>
7. <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
8. </listener>
9. <!-- OpenSessionInViewFilter -->
10. <filter>
11. <filter-name>hibernateFilter</filter-name>
12. <filter-class>
13. org.springframework.orm.hibernate4.support.OpenSessionInViewFilter
14. </filter-class>
15. </filter>
16. <filter-mapping>
17. <filter-name>hibernateFilter</filter-name>
18. <url-pattern>/*</url-pattern>
19. </filter-mapping>
20. <!-- DemoServlet -->
21. <servlet>
22. <servlet-name>demoServlet</servlet-name>
23. <servlet-class>web.function.servlet.DemoServlet</servlet-class>
24. <load-on-startup>2</load-on-startup>
25. </servlet>
26. <servlet-mapping>
27. <servlet-name>demoServlet</servlet-name>
28. <url-pattern>/demo_servlet</url-pattern>
29. </servlet-mapping>

编码配置：

1. @Order(1)
2. public class CommonInitializer implements WebApplicationInitializer{
3. @Override
4. public void onStartup(ServletContext servletContext)
5. throws ServletException {
6. //Log4jConfigListener
7. servletContext.setInitParameter("log4jConfigLocation", "classpath:config/properties/log4j.properties");
8. servletContext.addListener(Log4jConfigListener.class);
9. //OpenSessionInViewFilter
10. OpenSessionInViewFilter hibernateSessionInViewFilter = new OpenSessionInViewFilter();
11. FilterRegistration.Dynamic filterRegistration = servletContext.addFilter(
12. "hibernateFilter", hibernateSessionInViewFilter);
13. filterRegistration.addMappingForUrlPatterns(
14. EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.INCLUDE), false, "/");
15. //DemoServlet
16. DemoServlet demoServlet = new DemoServlet();
17. ServletRegistration.Dynamic dynamic = servletContext.addServlet(
18. "demoServlet", demoServlet);
19. dynamic.setLoadOnStartup(2);
20. dynamic.addMapping("/demo_servlet");
21. }
22. }

Spring为我们提供了一些WebApplicationInitializer的抽象类，我们只需要继承并按需修改即可，比如：

1）org.springframework.security.web.context.AbstractSecurityWebApplicationInitializer ： SpringSecurity相关配置

xml配置：

1. <listener>
2. <listener-class>org.springframework.security.web.session.HttpSessionEventPublisher</listener-class>
3. </listener>
4. <filter>
5. <filter-name>springSecurityFilterChain</filter-name>
6. <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
7. </filter>
8. <filter-mapping>
9. <filter-name>springSecurityFilterChain</filter-name>
10. <url-pattern>/*</url-pattern>
11. </filter-mapping>

编码配置：

1. @Order(2)
2. public class WebAppSecurityInitializer  extends AbstractSecurityWebApplicationInitializer
3. {
4. //servletContext.addListener("org.springframework.security.web.session.HttpSessionEventPublisher");
5. //session监听器
6. @Override
7. protected boolean enableHttpSessionEventPublisher() {
8. return true;
9. }
10. }

2）org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer：MVC相关配置，比如加载spring配置文件，声明DispatcherServlet等等，参看下面的对比：

xml配置：

1. <context-param>
2. <param-name>contextConfigLocation</param-name>
3. <param-value>
4. classpath:config/context/applicationContext-AppConfig.xml,
5. classpath:config/context/applicationContext-SpringSecurityConfig.xml
6. </param-value>
7. </context-param>
8. <listener>
9. <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
10. </listener>
11. <filter>
12. <filter-name>Set Character Encoding</filter-name>
13. <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
14. <init-param>
15. <param-name>encoding</param-name>
16. <param-value>UTF-8</param-value>
17. </init-param>
18. <init-param>
19. <param-name>forceEncoding</param-name>
20. <param-value>true</param-value>
21. </init-param>
22. </filter>
23. <filter-mapping>
24. <filter-name>Set Character Encoding</filter-name>
25. <url-pattern>/*</url-pattern>
26. </filter-mapping>
27. <servlet>
28. <servlet-name>webmvc</servlet-name>
29. <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
30. <init-param>
31. <param-name>contextConfigLocation</param-name>
32. <param-value>classpath:config/context/applicationContext-MvcConfig.xml</param-value>
33. </init-param>
34. <load-on-startup>1</load-on-startup>
35. </servlet>
36. <servlet-mapping>
37. <servlet-name>webmvc</servlet-name>
38. <url-pattern>/</url-pattern>
39. </servlet-mapping>

编码方式：

1. @Order(3)
2. //spring DispatcherServlet的配置,其它servlet和监听器等需要额外声明，用@Order注解设定启动顺序
3. public class WebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
4. /*
5. * DispatcherServlet的映射路径
6. */
7. @Override
8. protected String[] getServletMappings() {
9. return new String[]{"/"};
10. }
11. /*
12. * 应用上下文，除web部分
13. */
14. @SuppressWarnings({ "unchecked", "rawtypes" })
15. @Override
16. protected Class[] getRootConfigClasses() {
17. //加载配置文件类，这里与上面的xml配置是对应的，需要使用@Configuration注解进行标注，稍后介绍
18. return new Class[] {AppConfig.class, SpringSecurityConfig.class};
19. }
20. /*
21. * web上下文
22. */
23. @SuppressWarnings({ "unchecked", "rawtypes" })
24. @Override
25. protected Class[] getServletConfigClasses() {
26. return new Class[] {MvcConfig.class};
27. }
28. /*
29. * 注册过滤器，映射路径与DispatcherServlet一致，路径不一致的过滤器需要注册到另外的WebApplicationInitializer中
30. */
31. @Override
32. protected Filter[] getServletFilters() {
33. CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
34. characterEncodingFilter.setEncoding("UTF-8");
35. characterEncodingFilter.setForceEncoding(true);
36. return new Filter[] {characterEncodingFilter};
37. }
38. }

SpringMVC4零配置 ：代码下载

SpringMVC4零配置--web.xml

SpringMVC4零配置--应用上下文配置【AppConfig】

SpringMVC4零配置--SpringSecurity相关配置【SpringSecurityConfig】

SpringMVC4零配置--Web上下文配置【MvcConfig】