SpringMVC同时支持多视图(JSP,Velocity,Freemarker等)的一种思路实现

在基于SpringMVC的项目中有时需要同时使用多种视图格式，如jsp,velocity及freemarker等，通过不同的请求路径配置规则，映射到不同的视图文件。下面我提供一种思路，通过视图模板文件后缀名的方式来进行处理。例如：

@RequestMapping(value = "/hello")
public String jspTest(HttpServletRequest request, ModelMap map) {
    return "demo.jsp";
}
将通过”demo.jsp”的后缀自动使用jsp的视图解析器。

下面描述下详细思路：

一.自定义视图解析器

package com.jeedev.common.web.springmvc.view;

import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.ViewResolver;

/**
 * 自定义视图解析(通过配置实现多视图整合,如jsp,velocity,freemarker,pdf,excel...)
 * @author huligong
 *
 */
public class JeeDevViewResolver implements ViewResolver  {

    private static Log logger = LogFactory.getLog(JeeDevViewResolver.class);

    public View resolveViewName(String viewName, Locale locale) throws Exception {
       for(Map.Entry<Set<String>, ViewResolver> map : viewResolverMap.entrySet()){
           Set<String> suffixs = map.getKey();
           for(String suffix : suffixs){
               if (viewName.endsWith(suffix)){
                   ViewResolver viewResolver = map.getValue();
                   if(null != viewResolver){
                       if (logger.isDebugEnabled()) {
                            logger.debug("found viewResolver '" + viewResolver + "' for viewName '" + viewName+ "'");
                        }
                       return viewResolver.resolveViewName(viewName, locale);
                   }
               }
           }
       }

       if(defaultViewResolver != null){
           return defaultViewResolver.resolveViewName(viewName, locale);
       }
       // to allow for ViewResolver chaining
       return null;
    }

    private Map<Set<String>,ViewResolver> viewResolverMap = new HashMap<Set<String>,ViewResolver>();

    private ViewResolver defaultViewResolver = null;

    public Map<Set<String>, ViewResolver> getViewResolverMap() {
        return viewResolverMap;
    }

    public void setViewResolverMap(Map<Set<String>, ViewResolver> viewResolverMap) {
        this.viewResolverMap = viewResolverMap;
    }

    public ViewResolver getDefaultViewResolver() {
        return defaultViewResolver;
    }

    public void setDefaultViewResolver(ViewResolver defaultViewResolver) {
        this.defaultViewResolver = defaultViewResolver;
    }
}

在自定义视图解析器(其实是视图中转器)中，通过对视图文件的后缀判断(而不是请求地址的后缀)而返回给不同的视图解析器处理。

二.视图映射配置dispather-servlet.xml

<bean id="viewResolver" class="com.jeedev.common.web.springmvc.view.JeeDevViewResolver">
        <property name="defaultViewResolver" ref="beanNameViewResolver"/>
        <property name="viewResolverMap">
            <map>
                <entry>
                    <key>
                        <set>
                            <value>.jsp</value>
                        </set>
                    </key>
                    <ref bean="jspViewResolver"/>
                </entry>
                <entry>
                    <key>
                        <set>
                            <value>.vm</value>
                            <value>.htm</value>
                        </set>
                    </key>
                    <ref bean="velocityViewResolver"/>
                </entry>
                <entry>
                    <key><value>.ftl</value></key>
                    <ref bean="freeMarkerViewResolver"/>
                </entry>
            </map>
        </property>
    </bean>

    <bean id="beanNameViewResolver" class="org.springframework.web.servlet.view.BeanNameViewResolver"/>

    <bean id="jspViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <!--<property name="suffix" value=".jsp"/>-->
    </bean>

    <!--  Velocity ViewResolver Configuration -->
    <bean id="velocityViewResolver" class = "org.springframework.web.servlet.view.velocity.VelocityViewResolver">
         <property name="order" value="0" />
         <property name="contentType" value="text/html;charset=UTF-8" />
         <property name="requestContextAttribute" value="req"/>
    </bean>

    <!-- Velocity Configuration -->
    <bean id="velocityConfig" class = "org.springframework.web.servlet.view.velocity.VelocityConfigurer">
         <property name="configLocation" value="/WEB-INF/velocity.properties"/>
         <property name="resourceLoaderPath" value="/" />
    </bean>

    <!--  FreeMarker ViewResolver Configuration -->
    <bean id="freeMarkerViewResolver" class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">
        <property name="order" value="0" />
        <property name="viewClass" value="org.springframework.web.servlet.view.freemarker.FreeMarkerView"/>
    </bean> 

    <!-- FreeMarker Configuration -->
    <bean id="freemarkerConfig"  class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer">
       <property name="configLocation" value="/WEB-INF/freemarker.properties"/>
        <property name="templateLoaderPath" value="/WEB-INF/ftl/"/>
         <property name="freemarkerVariables">
             <map>
                <entry key="xml_escape" value-ref="fmXmlEscape"/>
            </map>
         </property>
    </bean>   

    <bean id="fmXmlEscape" class="freemarker.template.utility.XmlEscape"/>

这里我配置成所有返回.jsp的视图模板请求都转到JSP视图解析器jspViewResolver中去处理，返回.htm,.vm视图模板请求都转到velocity视图解析器中去处理。

三.控制器代码示例

package com.jeedev.demo.view;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;

/**
 * 多视图解析器支持示例
 * @author huligong
 *
 */
@Controller
@RequestMapping(value = "/demo")
public class JeeDevViewResolverTestController {
    private static Log logger = LogFactory.getLog(JeeDevViewResolverTestController.class);

    @RequestMapping(value = "/test1")
    public String test1(HttpServletRequest request, ModelMap map) {
        logger.info("使用JSP视图解析器");
        map.put("name", "hello world");
        return "jspTest.jsp";
    }

    @RequestMapping(value = "/test2")
    public String test2(HttpServletRequest request, ModelMap map) {
        logger.info("使用Freemarker视图解析器");
        map.put("name", "hello world");
        return "hello.ftl";
    }

    @RequestMapping(value = "/test3")
    public String test3(HttpServletRequest request, ModelMap map) {
        logger.info("使用Velocity视图解析器");
        map.put("name", "hello world");
        return "/html/demo.htm";
    }
}

四.测试请求

我在web.xml里给DispatcherServlet添加了/view/*，所以，只要在请求前加上/view就可以了。

http://localhost:8080/view/demo/test1

http://localhost:8080/view/demo/test2

http://localhost:8080/view/demo/test3

皆验证通过。