14.OSGI企业应用开发-整合Spring、Mybatis、Spring MVC

柔光的暖阳◎ 2022-10-29 05:19 178阅读 0赞

作为一个企业级的Web应用，MVC框架是必不可少的。Spring MVC目前使用也比较广泛，本文就来介绍一下如何在OSGI应用中实现Spring、Mybatis、Spring MVC框架的整合，其中Spring MVC的整合比较困难，原因是Spring整合到OSGI中后，每个Bundle都拥有一个孤立的ApplicationContext，也就是说不同Bundle中实例化的Bean之间的依赖注入就存在一定的问题，前面文章中提到过，这个问题可以通过Bean的注册和引用机制解决。

而实例化Spring MVC框架中的org.springframework.web.servlet.DispatcherServlet类时也需要指定Bean的配置文件，Spring MVC框架启动后会实例化配置文件中的Bean（例如Controller实例），Spring MVC框架启动后实例化的Bean与Bundle中实例化的Bean属于不同的类加载器，所以Bundle中实例化的Bean无法注入到Spring MVC框架启动时实例化的Bean，比较直接的例子就是Mybatis操作数据库的SqlSession实例无法注入到Spring MVC的Controller中，网上比较多的解决方案是使用Virgo，笔者经过一番钻研，解决了Spring MVC框架与OSGI应用的整合，如果发现有什么问题，可以一起探讨下\_。

接下来就介绍OSGI应用中Spring、Mybatis、Spring MVC框架的整合，我们依然使用前面文章中已经搭建好的工作空间。

首先新建一个Bundle，名称为com.csdn.osgi.user.web，整个工作空间结构如下图所示：  
![这里写图片描述][SouthEast]  
由于OSGI应用中资源与Servlet都需要注册后才能被客户端访问，我们可以编写几个类专门用于注册Web资源。

首先是图片、CSS、JS等静态资源的注册，在com.csdn.osgi.user.web这个Bundle中新建一个类，名称为com.csdn.osgi.user.web.registry.ResourceRegistry，代码如下：

package com.csdn.osgi.user.web.registry;
     
    import java.util.Iterator;
    import java.util.Map;
    import java.util.Set;
     
    import org.eclipse.gemini.blueprint.context.BundleContextAware;
    import org.osgi.framework.BundleContext;
    import org.osgi.framework.ServiceReference;
    import org.osgi.service.http.HttpContext;
    import org.osgi.service.http.HttpService;
    import org.osgi.service.http.NamespaceException;
    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
     
    public class ResourceRegistry implements ApplicationContextAware,
            BundleContextAware {
     
        Map resMapping;
     
        BundleContext bundleContext;
     
        ApplicationContext applicationContext;
     
        @Override
        public void setBundleContext(BundleContext bundleContext) {
            this.bundleContext = bundleContext;
        }
     
        @Override
        public void setApplicationContext(ApplicationContext applicationContext)
                throws BeansException {
            this.applicationContext = applicationContext;
        }
     
        public void setResMapping(Map resMapping) {
            this.resMapping = resMapping;
        }
     
        public void init() {
            ServiceReference serviceReference = bundleContext.getServiceReference(HttpService.class.getName());
            HttpService httpService = (HttpService) bundleContext.getService(serviceReference);
            HttpContext commonContext = httpService.createDefaultHttpContext();
     
            try {
                Set keySet = resMapping.keySet();
                Iterator<String> it = keySet.iterator();
                while(it.hasNext()){
                    String key = it.next();
                    String value = (String) resMapping.get(key);
                    httpService.registerResources(key, value, commonContext);
                }
            } catch (NamespaceException e) {
                e.printStackTrace();
            }
        }
    }

我们可以通过Spring来实例化这个类，Bean的配置如下：

这样就可以完成静态资源的注册，这种方式比较灵活，如果有新的资源类型，只需要在map标签中增加一个新的entry标签即可。

接下来是JSP的注册，我们在com.csdn.osgi.user.web这个Bundle中新建一个类，名称为 com.csdn.osgi.user.web.registry.JspRegistry，代码如下：

package com.csdn.osgi.user.web.registry;
     
    import java.util.Dictionary;
    import java.util.Hashtable;
     
    import javax.servlet.ServletException;
     
    import org.eclipse.equinox.jsp.jasper.JspServlet;
    import org.eclipse.gemini.blueprint.context.BundleContextAware;
    import org.osgi.framework.BundleContext;
    import org.osgi.framework.ServiceReference;
    import org.osgi.service.http.HttpContext;
    import org.osgi.service.http.HttpService;
    import org.osgi.service.http.NamespaceException;
    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
     
    public class JspRegistry implements ApplicationContextAware,
            BundleContextAware {
     
     
        BundleContext bundleContext;
     
        ApplicationContext appContext;
     
        @Override
        public void setBundleContext(BundleContext bundleContext) {
            this.bundleContext = bundleContext;
        }
     
        @Override
        public void setApplicationContext(ApplicationContext appContext)
                throws BeansException {
            this.appContext = appContext;
        }
     
        public void init() {
     
            ServiceReference serviceReference = bundleContext.getServiceReference(HttpService.class.getName());
            HttpService httpService = (HttpService) bundleContext.getService(serviceReference);
            HttpContext commonContext = httpService.createDefaultHttpContext();
     
     
            Dictionary initparams = new Hashtable<String, String>();
     
            JspServlet jspServlet = new JspServlet(bundleContext.getBundle(), "/WebContent/WEB-INF/jsp", "/jsp");
            try {
                httpService.registerServlet("/jsp", jspServlet, initparams, commonContext);
            } catch (ServletException e) {
                e.printStackTrace();
            } catch (NamespaceException e) {
                e.printStackTrace();
            }
        }
    }

同样，也是在Spring中实例化JspRegistry，Bean的配置如下：

最后就是Servlet资源的注册了，使用Spring MVC框架，我们需要实例化一个DispatcherServlet对象，需要注意的是，DispatcherServlet对象不能通过new关键字创建，应该由Spring框架实例化，在com.csdn.osgi.user.web这个Bundle中新建一个类，名称为com.csdn.osgi.user.web.registry.DispatcherServletRegistry，代码如下：

package com.csdn.osgi.user.web.registry;
     
    import java.util.Dictionary;
    import java.util.Hashtable;
     
    import javax.servlet.ServletException;
     
    import org.eclipse.gemini.blueprint.context.BundleContextAware;
    import org.osgi.framework.BundleContext;
    import org.osgi.framework.ServiceReference;
    import org.osgi.service.http.HttpContext;
    import org.osgi.service.http.HttpService;
    import org.osgi.service.http.NamespaceException;
    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    import org.springframework.web.servlet.DispatcherServlet;
     
    public class DispatcherServletRegistry implements ApplicationContextAware, BundleContextAware {
     
        String urlPattern;
     
        String servletName;
     
        BundleContext bundleContext;
     
        ApplicationContext applicationContext;
     
        DispatcherServlet dispatcherServlet;
     
        @Override
        public void setBundleContext(BundleContext bundleContext) {
            this.bundleContext = bundleContext;
        }
     
        @Override
        public void setApplicationContext(ApplicationContext applicationContext)
                throws BeansException {
            this.applicationContext = applicationContext;
        }
     
        public void setServletName(String servletName) {
            this.servletName = servletName;
        }
     
        public void setUrlPattern(String urlPattern) {
            this.urlPattern = urlPattern;
        }
     
        public void setDispatcherServlet(DispatcherServlet dispatcherServlet) {
            this.dispatcherServlet = dispatcherServlet;
        }
     
        public void init() {
     
            ServiceReference serviceReference = bundleContext.getServiceReference(HttpService.class.getName());
            HttpService httpService = (HttpService) bundleContext.getService(serviceReference);
            HttpContext commonContext = httpService.createDefaultHttpContext();
     
     
            Dictionary<String, String> initparams = new Hashtable<String, String>();
            initparams.put("load-on-startup", "1");
            initparams.put("servlet-name", servletName);
            try {
                httpService.registerServlet(urlPattern, dispatcherServlet, initparams, commonContext);
            }
            catch (ServletException e) {
                e.printStackTrace();
            } catch (NamespaceException e)
            {
                e.printStackTrace();
            }
        }
    }

DispatcherServletRegistry 类的实例化也是通过Spring来完成，Bean的配置如下：

<bean name="dispatcherServlet" class="org.springframework.web.servlet.DispatcherServlet">
            <property name="contextConfigLocation">
                <value>/META-INF/spring/*.xml</value>
            </property>
        </bean>    
     
        <bean name="servletRegistry" class="com.csdn.osgi.user.web.registry.DispatcherServletRegistry" init-method="init">
            <property name="urlPattern" value="/*.do"></property>
            <property name="servletName" value="dispatcherServlet"></property>
            <property name="dispatcherServlet" ref="dispatcherServlet"></property>
        </bean>

接下来在com.csdn.osgi.user.web这个Bundle中，新建META-INF/spring/registry.xml文件，用于配置注册Web资源的Bean，内容如下：

<?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:osgix="http://www.springframework.org/schema/osgi-compendium"
       xmlns:ctx="http://www.springframework.org/schema/context"
       xmlns:osgi="http://www.eclipse.org/gemini/blueprint/schema/blueprint"
       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
        http://www.springframework.org/schema/osgi-compendium 
          http://www.springframework.org/schema/osgi-compendium/spring-osgi-compendium.xsd
          http://www.eclipse.org/gemini/blueprint/schema/blueprint 
           http://www.eclipse.org/gemini/blueprint/schema/blueprint/gemini-blueprint.xsd">
     
        <bean name="dispatcherServlet" class="org.springframework.web.servlet.DispatcherServlet">
            <property name="contextConfigLocation">
                <value>/META-INF/spring/*.xml</value>
            </property>
        </bean>    
     
        <bean name="servletRegistry" class="com.csdn.osgi.user.web.registry.DispatcherServletRegistry" init-method="init">
            <property name="urlPattern" value="/*.do"></property>
            <property name="servletName" value="dispatcherServlet"></property>
            <property name="dispatcherServlet" ref="dispatcherServlet"></property>
        </bean>
     
        <bean name="resourceRegistry" class="com.csdn.osgi.user.web.registry.ResourceRegistry" init-method="init">
            <property name="resMapping">
                <map>  
                    <entry key="/js" value="/WebContent/js"/>  
                    <entry key="/css" value="/WebContent/css"/>
                    <entry key="/images" value="/WebContent/images"/>
                </map> 
            </property>
        </bean>
     
        <bean name="jspRegistry" class="com.csdn.osgi.user.web.registry.JspRegistry" init-method="init">
        </bean>
     
    </beans>

然后新建一个META-INF/spring/dmconfig.xml文件，用于引用其他Bundle中注册的Bean，内容如下：

然后还需要新建一个META-INF/spring/controllers.xml文件，实例化Spring MVC中的Controller及ViewResolver等，配置如下：

上面配置中，我们实例化了一个TestController对象，用于测试Spring MVC框架是否整合成功，TestController代码如下：

package com.csdn.osgi.web.controllers;
     
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
     
    import org.springframework.web.servlet.ModelAndView;
    import org.springframework.web.servlet.mvc.Controller;
     
    public class TestController implements Controller{
     
        @Override
        public ModelAndView handleRequest(HttpServletRequest req,
                HttpServletResponse resp) throws Exception {
     
            System.out.println("Test Controller");
            ModelAndView mv = new ModelAndView();
            mv.setViewName("test");
            return mv;
        }
     
    }

接下来还需要增加一个WebContent/WEB-INF/jsp/test.jsp页面，代码如下：

<%@ page language="java" contentType="text/html; charset=utf-8"
        pageEncoding="utf-8"%>
    <!DOCTYPE html>
    <html>
    <head>
    <title>Spring MVC测试页面</title>
    </head>
    <body>
    <h1>这是Spring MVC测试页面！</h1>
    </body>
    </html>

到此为止Spring MVC框架已经整合完毕，同时我们实例化了一个用于测试的TestController对象，整个工程结构如下图所示：  
![这里写图片描述][SouthEast 1]

最后，启动OSGI容器，打开浏览器，访问[http://localhost:8080/test.do][http_localhost_8080_test.do]，如下图所示：  
![这里写图片描述][SouthEast 2]

可以发现Spring MVC已经成功整合到OSGI应用中，下篇文章，笔者带领大家基于Spring、Mybatis、Spring MVC实现一个简单的登录功能。

注意：不需要启动前面文章演示使用的com.csdn.osgi.test.web这个Bundle，否则JSP注册时指定的URL会有冲突。

本文源码地址：[http://download.csdn.net/detail/rongbo\_j/9753640][http_download.csdn.net_detail_rongbo_j_9753640]

[SouthEast]: /images/20221024/d30f3fca587b4d5c9455d38285a0abb4.png
[SouthEast 1]: /images/20221024/1619a76ebdeb43a98cd10bb8b2ca2719.png
[http_localhost_8080_test.do]: http://localhost:8080/test.do
[SouthEast 2]: /images/20221024/bbd5b5837c2249589e2af0021adafcba.png
[http_download.csdn.net_detail_rongbo_j_9753640]: http://download.csdn.net/detail/rongbo_j/9753640