自定义监听器监听数据库中数据的变化

自定义监听器监听数据库中数据的变化
此程序只是一个简单的例子，主要监听数据库中Location的数据。

先写一个Event继承EventObject
Java代码
package com.lbx.listong.servlet; import
java.util.EventObject; public class LocationEvent extends EventObject { private static final long serialVersionUID = 1L; private Object obj;
public LocationEvent(Object source)
{ super(source); obj = source; } public Object getSource(){ return
obj; } }
然后写一个接口继承EventListener
Java代码
package com.lbx.listong.servlet; import
java.util.EventListener; public interface LocationListener extends EventListener
{ public void locationEvent(LocationEvent le); }
测试这个监听，实现他的接口
Java代码
package com.lbx.listong.servlet; import
java.util.concurrent.Executors; import
java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; import
com.lbx.listong.service.LocationService; import
com.lbx.listong.thread.ListThread; public class TestLocationListener implements LocationListener
{ private LocationService ls; public TestLocationListener() { ls = new LocationService(); ls.addLocationListener(this);
//注册监听System.out.println("添加监听器完毕"); try { // 调用此方法触发事件,触发的事件就
是执行locationEvent(接口的方法)的方法
ls.addLocation("insert into tb_location
(companyId,mobile,longitude,latitude,locationTime)
values(2,'444','4','4','2011-03-23 11:03:04')"); } catch (Exception ex)
{ ex.printStackTrace(); } } @Override public void locationEvent(LocationEvent le) { // TODO Auto-generated method stub ScheduledExecutorService executor =
Executors.newSingleThreadScheduledExecutor(); executor.scheduleWithFixedDelay(new ListThread(), 0, 2, TimeUnit.SECONDS); } }
LocationService的代码，主要是一些业务的代码，里面只写了增加一个记录触发一个事件
Java代码
package com.lbx.listong.service; import
java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.Enumeration; import java.util.List; import java.util.Vector; import com.lbx.listong.DBUtil.DB; import
com.lbx.listong.servlet.LocationEvent; import
com.lbx.listong.servlet.LocationListener; import
com.lbx.listong.servlet.TestLocationListener; public class LocationService { private Connection conn = null; List list = new ArrayList(); String sql = "select * from tb_location"; Statement st = null; private Vector repository = new Vector(); private LocationListener ll; public LocationService()
{ } //注册监听器，如果这里没有使用Vector而是使用ArrayList那么要注意同步问题public void addLocationListener(LocationListener ll)
{ repository.addElement(ll);//这步要注意同步问题} //如果这里没有使用Vector而是使用ArrayList那么要注意同步问题public void notifyLocationEvent(LocationEvent event)
{ Enumeration e = repository.elements();//这步要注意同步问题while(e.hasMoreElements())
{ ll = (LocationListener)e.nextElement();
ll.locationEvent(event); } } //删除监听器，如果这里没有使用Vector而是使用ArrayList那么要注意同步问题public void removeLocationListener(LocationListener ll)
{ repository.remove(ll);//这步要注意同步问
题} public List
getLocationList(){ conn = DB.getConnection(); try { st = conn.createStatement(); ResultSet rs = st.executeQuery(sql);
while(rs.next()){ String longitude = rs.getString("longitude");
list.add(longitude); } } catch (SQLException e) { // TODO
Auto-generated catch block
e.printStackTrace(); } return
list; } public void addLocation(String sql){ boolean b = false; conn = DB.getConnection(); try { st = conn.createStatement(); int id =
st.executeUpdate(sql);
if(id>0){ b =
true; } } catch (SQLException e) { // TODO Auto-generated catch block
e.printStackTrace(); } //添加一个记录成功就通知事件,然后执行接口的方法
if(b){ System.out.println("sss"); notifyLocationEvent(new
LocationEvent(this)); } }
public static void main(String[] args){ new TestLocationListener(); } }。