c#异步读取数据库与异步更新ui的代码实现

异步读取数据库,在数据绑定的时候会出现点问题,就是窗体界面会无法关闭,要结束任务才能结束进程。例如下面代码

首先按习惯的方法，设定线程更新ui

a2.checkforillegalcrossthreadcalls = false;  //a2为窗体名称

下面的代码就是从数据库里取得数据并绑定

private void button1_click(object sender, eventargs e)
        {
            sqlconnection con;
            sqlcommand com;
            try
            {
                con = new sqlconnection("uid=sa;password=123;initial catalog=ad;data source=192.168.1.1;asynchronous processing=true");
                con.open();
                com = new sqlcommand("select top 100 * from tb_user", con);
                com.beginexecutereader(new asynccallback(deldatabin), com);
            }
            catch (exception ex)
            {
                messagebox.show("程序发生错误,信息: " + ex.message);
            }

        }

        private void deldatabin(iasyncresult ar)
        {
            if (ar.iscompleted)
            {
                sqlcommand com = (sqlcommand)ar.asyncstate;
                sqldatareader dr = com.endexecutereader(ar);
                datatable dt = new datatable();
                dt.load(dr);
                dr.close();

                this.datagridview1.datasource = dt;  //绑定数据           

            }
        }

到这里完成的绑定的工作，运行查看一下效果，其实这样是会出现窗体假死的现象。

下面通过invoke 来实现

首先声明委托  public delegate void updatedg(datatable dt);

然后通过databin来绑定datagridview

        public void databin(datatable dt)
        {
            datagridview1.datasource = dt;
            return;
        } 

在线程里面调用下面方法

//绑定数据
                if (this.invokerequired)
                {
                    updatedg ur = new updatedg(databin);
                    this.invoke(ur, dt);
                }

完整的代码如下:

        private void button1_click(object sender, eventargs e)
        {
            sqlconnection con;
            sqlcommand com;
            try
            {
                con = new sqlconnection("uid=sa;password=123;initial catalog=ad;data source=192.168.1.1;asynchronous processing=true");
                con.open();
                com = new sqlcommand("select top 100 * from tb_user", con);
                com.beginexecutereader(new asynccallback(deldatabin), com);
            }
            catch (exception ex)
            {
                messagebox.show("程序发生错误,信息: " + ex.message);
            }

        }

        private void deldatabin(iasyncresult ar)
        {
            if (ar.iscompleted)
            {
                sqlcommand com = (sqlcommand)ar.asyncstate;
                sqldatareader dr = com.endexecutereader(ar);
                datatable dt = new datatable();
                dt.load(dr);
                dr.close();

                //this.datagridview1.datasource = dt;//绑定数据

                if (this.invokerequired)
                {
                    updatedg ur = new updatedg(databin);
                    this.invoke(ur, dt);
                }
            }
        }

        public delegate void updatedg(datatable dt);

        public void databin(datatable dt)
        {
            datagridview1.datasource = dt;
            return;
        }           

查运行查看一下，你就会发现结果了