下面是用户控件的代码：

using System;using System.Collections.Generic;using System.ComponentModel;using System.Drawing;using System.Data;using System.Linq;using System.Text;using System.Windows.Forms;namespace winform_test.UserControls{    public partial class conYMPC : UserControl    {        private string sb_ym;        public string Sb_ym        {            get { return sb_ym; }        }        private string sb_pc;        public string Sb_pc        {            get { return sb_pc; }        }        //委托        public delegate void MyChangeEventHandler();        //事件        public event MyChangeEventHandler MyChange;        //方法        public void OnMyChange()        {            if (MyChange != null)                MyChange();        }        public conYMPC()        {            InitializeComponent();        }        /// 
        ///窗体初始化        /// 
        ///         ///         private void conYM_Load(object sender, EventArgs e)        {            BindYear();        }        /// 
        /// 得到年份        /// 
        private void BindYear()        {            string sql = "select distinct left(sb_ym,4)+'年' as sb_year from sb_ympc order by sb_year desc";            DataSet ds = SqlHelp.GetDataSet(sql);            foreach (DataRow dr in ds.Tables[0].Rows)            {                cboY.Properties.Items.Add(dr["sb_year"].ToString());            }            cboY.SelectedIndex = 0;        }        /// 
        /// 得到月份        /// 
        private void BindMonth()        {            cboM.Properties.Items.Clear();            string sql = "select distinct right(sb_ym,2)+'月' as sb_month from sb_ympc where sb_ym like '" + cboY.Text.Substring(0, 4) + "%' order by sb_month desc";            DataSet ds = SqlHelp.GetDataSet(sql);            foreach (DataRow dr in ds.Tables[0].Rows)            {                cboM.Properties.Items.Add(dr["sb_month"].ToString());            }            cboM.SelectedIndex = 0;        }        /// 
        /// 得到批次        /// 
        private void BindPC()        {            cboPC.Properties.Items.Clear();            string sql = "select sb_pc from sb_ympc where sb_ym='" + cboY.Text.Substring(0, 4) + cboM.Text.Substring(0, 2) + "' order by sb_pc";            DataSet ds = SqlHelp.GetDataSet(sql);            foreach (DataRow dr in ds.Tables[0].Rows)            {                cboPC.Properties.Items.Add(dr["sb_pc"].ToString());            }            cboPC.SelectedIndex = 0;        }        /// 
        /// 年份下拉列表框改变事件        /// 
        ///         ///         private void cboY_SelectedIndexChanged(object sender, EventArgs e)        {            BindMonth();            CheckChange();        }        /// 
        /// 月份下拉列表框改变事件        /// 
        ///         ///         private void cboM_SelectedIndexChanged(object sender, EventArgs e)        {            BindPC();            CheckChange();        }        /// 
        /// 批次下拉列表框改变事件        /// 
        ///         ///         private void cboPC_SelectedIndexChanged(object sender, EventArgs e)        {            CheckChange();        }        /// 
        /// 检查下拉列表框的值是否改变，改变的话更新        /// 
        private void CheckChange()        {            string _sb_ym = cboY.Text.Substring(0, 4) + cboM.Text.Substring(0, 2);            string _sb_pc = cboPC.Text;            if (_sb_ym != sb_ym || _sb_pc != sb_pc)            {                sb_ym = _sb_ym;                sb_pc = _sb_pc;                OnMyChange();//触发这个方法            }        }    }}

这个图片是用户控件的截图：

 

下面是调用用户控件窗体的代码：

 

private void frmStart_Load(object sender, EventArgs e)        {            //给控件绑定事件            conYMPC1.MyChange += new UserControls.conYMPC.MyChangeEventHandler(aa);        }        void aa()        {            MessageBox.Show("申报年月：" + conYMPC1.Sb_ym + "  申报批次：" + conYMPC1.Sb_pc);        }

这样在改变用户控件中的值的时候，在窗体终究可以监听到这个事件什么时候触发。

 

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