什么是Service?

它是注冊到osgi的一个java对象

Service注冊:

通过BundleContext::registerService(java.lang.String[] clazzes, java.lang.Object service, java.util.Dictionary properties)

Service查找及使用:

通过BundleContext::getServiceReference(java.lang.String clazz),返回ServiceReference
通过BundleContext::getService(ServiceReference reference) ,返回注冊的服务对象

Service释放:

通过BundleContext::ungetService(ServiceReference reference) 

LADP:

轻量级文件夹訪问协议（Lightweight Directory Access Protocol）

1个Service相应一个实现类的注冊与使用demo:

服务提供者:

student-manage/IStudentManage.java

package com.demo.service;public interface IStudentManage {void add();
}

student-manage/Activator.java

package com.demo.service;import java.util.Dictionary;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;import com.demo.service.impl.StudentManage;public class Activator implements BundleActivator {public void start(BundleContext context) throws Exception {System.out.println("注冊服务開始....");context.registerService(IStudentManage.class.getName(),new StudentManage(), null);System.out.println("注冊服务结束....");}public void stop(BundleContext context) throws Exception {}}

服务使用者:

student-action/Activator.java

package com.demo.action;import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;import com.demo.service.IStudentManage;public class Activator implements BundleActivator{public void start(BundleContext context) throws Exception {System.out.println("action  begin...");ServiceReference sf=null;try {//查找Servicesf=context.getServiceReference(IStudentManage.class.getName());//调用服务IStudentManage studentManage = (IStudentManage)context.getService(sf);studentManage.add();} finally {context.ungetService(sf);}System.out.println("action  end...");}public void stop(BundleContext context) throws Exception {}}

部署至karaf并查看结果:

一个Service相应多个实现(基于LDAP)demo2

服务提供者

student-manage/Activator.java

package com.demo.service;import java.util.Dictionary;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;import com.demo.service.impl.StudentManageA;
import com.demo.service.impl.StudentManageB;public class Activator implements BundleActivator {public void start(BundleContext context) throws Exception {System.out.println("注冊服务開始....");//注冊AHashtable<String, String> dict=new Hashtable<String, String>();dict.put("name", "a");context.registerService(IStudentManage.class.getName(),new StudentManageA(), dict);//注冊Bdict=new Hashtable<String, String>();dict.put("name", "b");context.registerService(IStudentManage.class.getName(),new StudentManageB(), dict);System.out.println("注冊服务结束....");}public void stop(BundleContext context) throws Exception {}}

服务使用者

student-action/Activator.java

package com.demo.action;import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceFactory;
import org.osgi.framework.ServiceReference;import com.demo.service.IStudentManage;public class Activator implements BundleActivator{public void start(BundleContext context) throws Exception {System.out.println("action  begin...");ServiceReference[] references=null;try {System.out.println("服务调用------------------");//查找ServiceString filter="(name=b)";references=context.getServiceReferences(IStudentManage.class.getName(), filter);//调用服务if(references.length==1){IStudentManage studentManage = (IStudentManage)context.getService(references[0]);studentManage.add();}else {throw new IllegalArgumentException("IStudentManage查找到多个实现类");}} finally {for(ServiceReference sf:references){context.ungetService(sf);}}System.out.println("action  end...");}public void stop(BundleContext context) throws Exception {}}

部署到karaf及查看结果: