利用WebApplicationInitializer配置SpringMVC取代web.xml

对于Spring MVC的DispatcherServlet配置方式，传统的是基于XML方式的，也就是官方说明的XML-based,如下:

<servlet>
<servlet-name>springMVC</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-mvc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springMVC</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

但是Spring文档建议我们采用code-based这种方式，当然，核心就是实现WebApplicationInitializer这个接口，查看这个接口的源码，里面也非常简单，只有一个方法,传入的参数是ServletContext:

void onStartup(ServletContext servletContext) throws ServletException;

下面是一个小例子：

1.项目结构：



2.MyWebAppInitializer.java

public class MyWebAppInitializer implements WebApplicationInitializer {
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
XmlWebApplicationContext appContext = new XmlWebApplicationContext();
appContext.setConfigLocation("classpath:spring-mvc.xml");
ServletRegistration.Dynamic dispatcher = servletContext.addServlet("dispatcher", new DispatcherServlet(appContext));
dispatcher.setLoadOnStartup(1);
dispatcher.addMapping("/");
}
}

3.UserController.java

@Controller
public class UserController {
@RequestMapping("/show")
public String show() {
return "show";
}
}

4.spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> 
<!-- 扫描注解的base package -->
<context:component-scan base-package="com.springmvc" />

<!-- 对模型视图名称的解析，即在模型视图名称添加前后缀 -->
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="viewClass"
value="org.springframework.web.servlet.view.JstlView" />
<property name="prefix" value="/" />
<property name="suffix" value=".jsp" />
</bean>
</beans>

5.show.jsp

6.启动Tomcat后输入url后发现是会出现结果的，code-based是成功的！

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion>
<groupId>com.springmvc</groupId>
<artifactId>MyWebAppInitializer</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>

<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.0</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
<encoding>utf8</encoding>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.7.2</version>
<configuration>
<forkMode>once</forkMode>
<argLine>-Dfile.encoding=UTF-8</argLine>
</configuration>
</plugin>
</plugins>
</build>

<properties>
<spring-version>4.3.1.RELEASE</spring-version>
</properties>

<dependencies>

<!-- spring相关 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>${spring-version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring-version}</version>
</dependency>

<!-- log4j日志相关 -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>

<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>tomcat-servlet-api</artifactId>
<version>7.0.54</version>
<scope>provided</scope>
</dependency>

<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>

</dependencies>
</project>