使用eclipse開發felix的OSGI插件

時間  2019-11-11
標籤 使用 eclipse 開發 felix osgi 插件 欄目 Eclipse 简体版
原文   原文鏈接

一、官網下載http://felix.apache.org/downloads.cgi，
當前最新版本6.0.3
運行felix窗口有兩種方式
(1) 能夠直接下載發佈版本
Felix Framework Distribution（org.apache.felix.main.distribution-6.0.3.zip）html

解壓後目錄java

進入項目目錄，命令行下執行apache

java -jar ./bin/felix.jar

felix.jar 默認會在當前運行目錄的 bundle 文件夾內加載啓動所需的插件jar，config 目錄下的 config.propeties 和 system.properties 裏面加載環境變量，若是將其餘目錄做爲啓動根目錄，該目錄下不存在 felix 啓動所需信息，啓動就會有問題。項目第一次啓動的時候會在啓動目錄下建立一個felix-cache的目錄，用於存放框架運行過程產生的數據，固然該目錄能夠在啓動的時候配置，使用 java -jar ./bin/felix.jar <felix-dir> 便可。api

(2) 源碼導入eclipse運行
下載子項目Main（org.apache.felix.main-6.0.3-project.zip）瀏覽器


解壓org.apache.felix.main-6.0.3-project.zip，進入目錄，命令行下
運行mvn eclipse:eclipse工程文件，
再輸入mvn package，打包編譯
File->Import導入到eclipsebash

在eclipse的org.apache.felix.main.Main類右鍵運行Run As Java Application框架

經常使用命令eclipse

lb:查看已裝插件包
start:運行插件包
stop:中止運行插件包
install:安裝插件包
uninstall:刪除插件包
其它命令能夠經過help查看

二、felix開發插件
參考是felix官方例子代碼apache-felix-osgi-tutorial裏的
apache-felix-tutorial-example-2
apache-felix-tutorial-example-2b
apache-felix-tutorial-example-3
這是一個檢查輸入單詞(英文、中文....)是否正確的例子功能ide

先定義一個服務類：工具

package test.penngo.service;
 
/**
 * 簡單的定義了一個字典服務接口，該接口的功能只是簡單的驗證一個詞是否正確。
**/
public interface DictionaryService
{
    /**
            * 檢查 單詞是否存在
    **/
    public boolean checkWord(String word);
}

英文詞典插件包開發

package tutorial.example2;

import java.util.Hashtable;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import test.penngo.service.DictionaryService;

/**
 * 英文字典服務插件
 **/
public class Activator implements BundleActivator {
	/**
	 * 服務啓動
	 * 
	 * @param context the framework context for the bundle.
	 **/
	public void start(BundleContext context) {
		Hashtable<String, String> props = new Hashtable<String, String>();
		props.put("Language", "English");
		context.registerService(DictionaryService.class.getName(), new DictionaryImpl(), props);
	}

	/**
	 * 服務中止
	 * 
	 * @param context the framework context for the bundle.
	 **/
	public void stop(BundleContext context) {
		// NOTE: The service is automatically unregistered.
	}

	/**
	 * 英文詞典服務實現
	 **/
	private static class DictionaryImpl implements DictionaryService {
		String[] m_dictionary = { "welcome", "to", "the", "osgi", "tutorial" };

		/**
		 * 英文單詞檢測
		 **/
		public boolean checkWord(String word) {
			word = word.toLowerCase();
			for (int i = 0; i < m_dictionary.length; i++) {
				if (m_dictionary[i].equals(word)) {
					return true;
				}
			}
			return false;
		}
	}
}

META-INF.MF

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-SymbolicName: English
Bundle-Name: English dictionary
Bundle-Description: A bundle that registers an English dictionary service
Bundle-Vendor: penngo
Bundle-Version: 1.0.0
Bundle-Activator: tutorial.example2.Activator
Import-Package: org.osgi.framework, test.penngo.service

英文詞典插件打包導出，eclipse自帶的export打包會有問題，本文使用fatjar工具打包，

中文詞典插件包開發

package tutorial.example2b;
 
import java.util.Hashtable;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import test.penngo.service.DictionaryService;

/**
 * 中文詞典包
**/
public class Activator implements BundleActivator
{
    public void start(BundleContext context)
    {
        Hashtable<String, String> props = new Hashtable<String, String>();
        props.put("Language", "Chinese");
        context.registerService(
            DictionaryService.class.getName(), new DictionaryImpl(), props);
    }
 
    public void stop(BundleContext context)
    {
        // NOTE: The service is automatically unregistered.
    }
 
    /**
            *  中文詞典服務實現
    **/
    private static class DictionaryImpl implements DictionaryService
    {
        // The set of words contained in the dictionary.
        String[] m_dictionary =
            { "歡迎", "你好", "教程", "模塊" };
 
        public boolean checkWord(String word)
        {
            word = word.toLowerCase();
            for (int i = 0; i < m_dictionary.length; i++)
            {
                if (m_dictionary[i].equals(word))
                {
                    return true;
                }
            }
            return false;
        }
    }
}
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-SymbolicName: Chinese
Bundle-Name: Chinese dictionary
Bundle-Description: A bundle that registers a Chinese dictionary service
Bundle-Vendor: penngo
Bundle-Version: 1.1.0
Bundle-Activator: tutorial.example2b.Activator
Import-Package: org.osgi.framework, test.penngo.service

插件打包

客戶端調用詞典開發，也是做爲一個felix插件

package tutorial.example3;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import test.penngo.service.DictionaryService;
 
/**
 * 此客戶端在啓動時，接收控制檯輸入，檢查輸入的單詞是否正確，而且打印初相應的檢測結果，
  * 注意：當咱們沒有輸入任何信息的時候，單詞檢測便會結束，若是須要從新進入單詞檢測程序，咱們須要從新啓動插件。
**/
public class Activator implements BundleActivator
{
 
    public void start(BundleContext context) throws Exception
    {
        // 獲取全部詞典插件
        ServiceReference[] refs = context.getServiceReferences(
            DictionaryService.class.getName(), "(Language=*)");
        
        if (refs != null)
        {
        	System.out.println("=======當前可用詞典插件:" + refs.length);
            try
            {
                System.out.println("Enter a blank line to exit.");
                BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
                String word = "";
                while (true)
                {
                    System.out.print("Enter word: ");
                    word = in.readLine();
                    if (word.length() == 0)
                    {
                        break;
                    }
 
                    boolean isCorrect = false;
                    for(ServiceReference service:refs) {
                    	DictionaryService dictionary =
                                (DictionaryService) context.getService(service);
                            if (dictionary.checkWord(word))
                            {
                            	isCorrect = true;
                                System.out.println("Correct.");
                            }
                          
                    }
                    if(isCorrect == false)
                    {
                        System.out.println("Incorrect.");
                    }
                }
            } catch (IOException ex) { 
            	ex.printStackTrace();
            }
        }
        else
        {
            System.out.println("Couldn't find any dictionary service...");
        }
    }
 
    /**
     * Implements BundleActivator.stop(). Does nothing since
     * the framework will automatically unget any used services.
     * @param context the framework context for the bundle.
    **/
    public void stop(BundleContext context)
    {
        // NOTE: The service is automatically released.
    }
}
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-SymbolicName: client
Bundle-Name: Dictionary client
Bundle-Description: A bundle that uses the dictionary service if it finds it at startup
Bundle-Vendor: penngo
Bundle-Version: 1.3.0
Bundle-Activator: tutorial.example3.Activator
Export-Package: test.penngo.service
Import-Package: org.osgi.framework
#//注意：test.penngo.service這個包與tutorial.example3打在同一個jar中，若是example3.jar更新，其它依賴test.penngo.service的也須要更新或重啓felix.

安裝插件
把上邊生成的插件包example2.jar,example2b.jar,example3.jar入到org.apache.felix.main-6.0.3項目的plugins文件夾中
安裝和運行效果：

經過插件方式開發，後期繼續擴展增長其它語言詞典（日語，俄語，韓語），不須要重啓服務，也不影響已存在的語言詞典功能（英文、中文）。

三、開發http服務插件

package test.penngo.http.example;

import java.io.IOException;

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

public class TestServlet extends HttpServlet {
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		resp.getWriter().write("hello penngo");
	}
}
package test.penngo.http.example;

import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.service.http.HttpService;
import org.osgi.util.tracker.ServiceTracker;

public class Activator implements BundleActivator {
	private ServiceTracker httpTracker;

	public void start(BundleContext context) throws Exception {
		httpTracker = new ServiceTracker(context, HttpService.class.getName(), null) {
			public void removedService(ServiceReference reference, Object service) {
				// HTTP service is no longer available, unregister our servlet...
				try {
					((HttpService) service).unregister("/hello");
				} catch (IllegalArgumentException exception) {
					// Ignore; servlet registration probably failed earlier on...
				}
			}

			public Object addingService(ServiceReference reference) {
				// HTTP service is available, register our servlet...
				HttpService httpService = (HttpService) this.context.getService(reference);
				try {
					httpService.registerServlet("/hello", new TestServlet(), null, null);
				} catch (Exception exception) {
					exception.printStackTrace();
				}
				return httpService;
			}
		};
		// start tracking all HTTP services...
		httpTracker.open();
	}

	public void stop(BundleContext context) throws Exception {
		// stop tracking all HTTP services...
		httpTracker.close();
	}
}
#MANIFEST.MF
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-SymbolicName: hello
Bundle-Name: hello penngo
Bundle-Description: Http Hello World
Bundle-Vendor: penngo
Bundle-Version: 1.0.0
Bundle-Activator: test.penngo.http.example.Activator
Import-Package: org.osgi.framework,
 org.osgi.service.http,
 org.osgi.util.tracker,
 javax.servlet.http,
 javax.servlet

注意htpp插件包依賴:

org.apache.felix.http.base-4.0.6.jar,
org.apache.felix.http.bridge-4.0.8.jar,
org.apache.felix.http.jetty-4.0.10.jar,
org.apache.felix.http.servlet-api-1.1.2.jar,
org.apache.felix.http.whiteboard-4.0.0.jar

須要先安裝上邊的插件包，才能正常在felix中運行http功能。
安裝運行效果

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