OSGI企业应用开发（十四）整合Spring、Mybatis、Spring MVC

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：



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：

    <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>

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：

<bean name="jspRegistry" class="com.csdn.osgi.user.web.registry.JspRegistry" init-method="init">
</bean>

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：

<?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">

   <osgi:reference  id="sqlMapService" interface="org.apache.ibatis.session.SqlSession" />

</beans>

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：

<?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 id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <bean name="/test.do" class="com.csdn.osgi.web.controllers.TestController">
    </bean>

</beans>

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：

最后，启动OSGI容器，打开浏览器，访问http://localhost:8080/test.do，如下图所示：

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。

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