基于ORACLE的事件通知示例代码( ORACLE DEPENDECY)

【核心代码】

using Oracle.DataAccess.Client;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        OracleDependency dep;
        OracleConnection conn;
        public Form1()
        {
            InitializeComponent();
            //设置App的监听端口，即使用哪个端口接收Change Notification。
            OracleDependency.Port = 49501;
            string cs = "User Id = hiip; Password=hiip;Data Source = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.10.3)(PORT = 1521)))(CONNECT_DATA = (SERVICE_NAME = orcl)))";
            conn = new OracleConnection(cs);
            conn.Open();
        }

        //
        private void btnReg_Click(object sender, EventArgs e)
        {
            if (dep == null || !dep.IsEnabled)
            {
                OracleCommand cmd = new OracleCommand("select * from userinfo", conn);
                //绑定OracleDependency实例与OracleCommand实例
                dep = new OracleDependency(cmd);
                //指定Notification是object-based还是query-based，前者表示表（本例中为tab_cn）中任意数据变化时都会发出Notification；后者提供更细粒度的Notification，例如可以在前面的sql语句中加上where子句，从而指定Notification只针对查询结果里的数据，而不是全表。
                //dep.QueryBasedNotification = false;
                //dep.QueryBasedNotification = true;
                //是否在Notification中包含变化数据对应的RowId
                //dep.RowidInfo = OracleRowidInfo.Include;
                //指定收到Notification后的事件处理方法
                dep.OnChange  = new OnChangeEventHandler(OnNotificaton);
                //是否在一次Notification后立即移除此次注册
                cmd.Notification.IsNotifiedOnce = false;
                //此次注册的超时时间（秒），超过此时间，注册将被自动移除。0表示不超时。
                cmd.Notification.Timeout = 0;
                //False表示Notification将被存于内存中，True表示存于数据库中，选择True可以保证即便数据库重启之后，消息仍然不会丢失
                cmd.Notification.IsPersistent = true;
                //
                cmd.ExecuteNonQuery();
                //
                rtb1.AppendText("Registration completed. "   DateTime.Now.ToLongTimeString()   Environment.NewLine);
            }
        }

        private void btnUnreg_Click(object sender, EventArgs e)
        {
            //注销
            if (dep.IsEnabled)
            {
                dep.RemoveRegistration(conn);
                rtb1.AppendText("Registration Removed. "   DateTime.Now.ToLongTimeString()   Environment.NewLine);
            }
        }

        private void OnNotificaton(object src, OracleNotificationEventArgs arg)
        {
            //可以从arg.Details中获得通知的具体信息，比如变化数据的RowId
            DataTable dt = arg.Details;
            //......
            rtb1.BeginInvoke(
                new Action(() =>
                {
                    rtb1.AppendText("Notification Received. "   DateTime.Now.ToLongTimeString()   "  Changed data(rowid): "   arg.Details.Rows[0]["rowid"].ToString()   Environment.NewLine);
                }));
        }
    }
}