osgi入门

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开发环境：Eclipse JEE 3.6（Helio）

开发步骤：
1、创建基于Equinox的plugin工程，工程名为DictQuery，用于定义一个字典查询的接口。

package org.sunny.dictQuery;

public interface QueryService {

	String queryWord(String word);

}

2、创建基于Equinox的plugin工程，工程名为RemoteDictQuery，实现了字典查询接口，在Activator类中注册服务。在Manifest.mf配置中导入org.sunny.dictQuery包。

package org.sunny.remote;

import java.util.concurrent.ConcurrentHashMap;

import org.sunny.dictQuery.QueryService;

public class RemoteDictQueryServiceImpl implements QueryService {

	private static final ConcurrentHashMap dict = new ConcurrentHashMap();

	static {
		dict.put("sky", "天空");
		dict.put("computer", "计算机");
	}

	@Override
	public String queryWord(String word) {
		System.out.println("RemoteDictQueryServiceImpl.queryWord called!");
		String result = dict.get(word);
		if (result == null)
			result = "N/A";
		return result;
	}

}

package org.sunny.remote;

import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceRegistration;
import org.sunny.dictQuery.QueryService;

public class Activator implements BundleActivator {

	private static BundleContext context;
	private ServiceRegistration sr = null;

	static BundleContext getContext() {
		return context;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.osgi.framework.BundleActivator#start(org.osgi.framework.BundleContext
	 * )
	 */
	public void start(BundleContext bundleContext) throws Exception {
		Activator.context = bundleContext;
		sr = context.registerService(QueryService.class.getName(),
				new RemoteDictQueryServiceImpl(), null);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.osgi.framework.BundleActivator#stop(org.osgi.framework.BundleContext)
	 */
	public void stop(BundleContext bundleContext) throws Exception {
		Activator.context = null;
		sr.unregister();
	}

}

3、创建基于Equinox的plugin工程，工程名为LocalDictQuery，实现了字典查询接口，采用Declarative Service方法注册服务，此工程不需要Activator类。在Manifest.mf配置中导入org.sunny.dictQuery包。

package org.sunny.ldq;

import java.util.concurrent.ConcurrentHashMap;

import org.sunny.dictQuery.QueryService;

public class LocalDictQueryServiceImpl implements QueryService {

	private static final ConcurrentHashMap dict = new ConcurrentHashMap();

	static {
		dict.put("test", "测试");
		dict.put("china", "中国");
	}

	@Override
	public String queryWord(String word) {
		System.out.println("LocalDictQueryServiceImpl.queryWord called!");
		String result = dict.get(word);
		if (result == null)
			result = "N/A";
		return result;
	}

}

工程下建目录OSGI-INF，Component.xm配置如下。


  
  
     
  


4、创建基于Equinox的plugin工程，工程名为QueryServlet，用于提供http服务。

在src目录下创建page目录，置放dictQuery.html，内容如下。

QueryServlet类注册servlet和resource，响应http请求。

package org.sunny.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.osgi.service.http.HttpService;
import org.sunny.dictQuery.QueryService;

public class QueryServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;
	private QueryService query = null;
	private HttpService http = null;

	public QueryServlet() {
	}

	public void setQueryService(QueryService query) {
		this.query = query;
	}

	public void unsetQueryService(QueryService query) {
		if (this.query != query)
			return;
		this.query = null;
	}

	public void setHttpService(HttpService http) {
		this.http = http;
		try {
			http.registerServlet("/query", this, null, null);
			http.registerResources("/static", "page", null);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public void unsetHttpService(HttpService http) {
		this.http.unregister("/query");
		this.http.unregister("/static");
		this.http = null;
	}

	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		String word = req.getParameter("query_word");
		resp.setCharacterEncoding("UTF-8");
		resp.setContentType("text/html;charset=UTF-8");
		PrintWriter out = resp.getWriter();

		if (query != null) {
			out.println(query.queryWord(word));
		} else {
			out.println("no impl for query servcie...");
			out.close();
			return;
		}
	}

}

在工程下建立OSGI-INF目录，配置component.xml，以declarative service方式引入QueryService和HttpService。


  
  
  


在Manifest.mf中要导入的包有java.servlet，java.servlet.http，org.sunny.dictQuery，org.osgi.service.http。

5、配置运行时环境。


在osgi控制台输入ss命令，可以看到以下内容。
osgi> ss

Framework is launched.

id State       Bundle
0 ACTIVE      org.eclipse.osgi_3.6.2.R36x_v20110210
1 ACTIVE      org.apache.commons.logging_1.0.4.v201005080501
2 ACTIVE      DictQuery_1.0.0.qualifier
3 ACTIVE      org.eclipse.equinox.http.jetty_2.0.0.v20100503
4 ACTIVE      LocalDictQuery_1.0.0.qualifier
5 ACTIVE      org.eclipse.osgi.services_3.2.100.v20100503
6 ACTIVE      javax.servlet_2.5.0.v200910301333
7 ACTIVE      RemoteDictQuery_1.0.0.qualifier
8 ACTIVE      QueryServlet_1.0.0.qualifier
9 ACTIVE      org.eclipse.equinox.http.servlet_1.1.0.v20100503
10 ACTIVE      org.eclipse.equinox.ds_1.2.1.R36x_v20100803
11 ACTIVE      org.mortbay.jetty.server_6.1.23.v201004211559
12 ACTIVE      org.mortbay.jetty.util_6.1.23.v201004211559
13 ACTIVE      org.eclipse.equinox.util_1.0.200.v20100503

在浏览器输入http://localhost/static/dictQuery.htm访问，填入sky查询，输出“天空”，后台打印“RemoteDictQueryServiceImpl.queryWord called!”。
在osgi控制台输入stop 7命令，停止运行RemoteDictQuery bundle。填入test查询，输出“测试”，后台打印“LocalDictQueryServiceImpl.queryWord called!”。

附件中是这四个工程的project文件，可download并运行，good luck！

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