Spring MVC 实现-优快云博客

同Struts 2框架一样，Spring也可以给Web开发者提供一个MVC框架。虽然Web框架只是Spring的一个模块，但是它却应用的非常广泛。

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
	<context-param>
		<param-name>contextConfigLocation</param-name>
		<param-value>
			classpath:Spring-beans.xml
		</param-value>
	</context-param>
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>

	<servlet>
		<servlet-name>dispatcherServlet</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<!--
			不给参数的话自动查找的xml名称格式是 <servlet-name>-servlet.xml
			例如：dispatcherServlet-servlet.xml
		-->
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>classpath:Spring-beans.xml</param-value>
		</init-param>
	</servlet>
	<servlet-mapping>
		<servlet-name>dispatcherServlet</servlet-name>
		<url-pattern>*.do</url-pattern>
	</servlet-mapping>
</web-app>

创建控制器：

public class HelloAction implements Controller {
	private String helloWorld;
	private String viewPage;

	public String getHelloWorld() {
		return helloWorld;
	}

	public void setHelloWorld(String helloWorld) {
		this.helloWorld = helloWorld;
	}

	public String getViewPage() {
		return viewPage;
	}

	public void setViewPage(String viewPage) {
		this.viewPage = viewPage;
	}

	@Override
	public ModelAndView handleRequest(HttpServletRequest arg0,
			HttpServletResponse arg1) throws Exception {
		// TODO Auto-generated method stub
		Map model = new HashMap();
		model.put("helloWorld", getHelloWorld());
		return new ModelAndView(this.viewPage, model);
	}

}

Spring配置：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

	<!--指定控制器的实现类，并且配置其参数的值-->
	<bean name="/helloworld.do" class="org.han.actions.HelloAction">
		<property name="helloWorld">
			<value>Hello Spring World!</value>
		</property>
		<property name="viewPage">
			<value>/success.jsp</value>
		</property>
	</bean>
</beans>

注意不是为该控制器设置id属性，而是设置name属性，并且该name是一个URL，由于URL中含有XML id属性中非法字符-斜杠，所以name属性不能使用id，只要进入org.springframework.web.servlet.DispatcherServlet的请求URL是以“helloworld.do”结尾的，DispatcherServlet就会分发给自定义的控制器处理。这个Bean的name属性使用的是URL样式的唯一原因是我们还没又配置处理器映射Bean，DispatcherServlet默认的处理器映射器映射是BeanNameUrlHandlerMapping，它使用URL样式的名字。

view:

	<body>
		This is my JSP page.
		<br>
		<%=request.getAttribute("helloWorld")%>
	</body>

上面代码就实现了一个最简单的SpringMVC了

声明一个视图解析器：

先修改下Spring配置:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
	<!--配置控制器的映射-->
	<bean id="urlMapping"
		class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
		<property name="mappings">
			<props>
				<prop key="helloWorld.do">helloAction</prop>
			</props>
		</property>
	</bean>
	<!--配置视图-->
	<bean id="viewResolver"
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/" />
		<property name="suffix" value=".jsp"></property>
	</bean>
	<!--指定控制器的实现类，并且配置其参数的值-->
	<bean id="helloAction" class="org.han.actions.HelloAction">
		<property name="helloWorld">
			<value>Hello Spring World!</value>
		</property>
	</bean>
</beans>

配置好视图解析器后就只需要传入一个视图名字了

public class HelloAction implements Controller {
	private String helloWorld;

	public String getHelloWorld() {
		return helloWorld;
	}

	public void setHelloWorld(String helloWorld) {
		this.helloWorld = helloWorld;
	}

	public ModelAndView handleRequest(HttpServletRequest arg0,
			HttpServletResponse arg1) throws Exception {
		// TODO Auto-generated method stub
		Map model = new HashMap();
		model.put("mess", getHelloWorld());
		return new ModelAndView("success", model);
	}
}

InternalResourceViewResolver在ModelAndView返回的视图名前加上prefix属性配置前缀，再在最后加上suffix属性设置后缀，本例中由于HelloAction返回的视图名是success，InternalResourceViewResolver将会在根节点上查找该视图。

原理图：