它是注冊到osgi的一个java对象

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

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

通过BundleContext::ungetService(ServiceReference reference)

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

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 {

}

}

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Service
sf=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 {
}

}

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A
Hashtable<String, String> dict=new Hashtable<String, String>();
dict.put("name", "a");
context.registerService(IStudentManage.class.getName(),
new StudentManageA(), dict);
//注冊B
dict=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 {

}

}

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Service
String 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 {
}

}