用wpf写一个表格，第一列表示时间，第二列表示报警信息，并且数据源可以动态添加，数量达到一定值本地储存

实现这个功能，首先需要在WPF中创建一个DataGrid控件，并设置两列，分别为时间和报警信息。然后，需要创建一个类来表示报警信息，包含时间和报警内容两个属性。

接着，需要将报警信息添加到数据源中。可以使用ObservableCollection来保存报警信息，这样当有新的报警信息添加时，DataGrid会自动更新显示。同时，为了达到本地存储的目的，可以将ObservableCollection序列化为XML，并保存到本地文件中。

下面是一个简单的示例代码：

MainWindow.xaml:

<Window x:Class="WpfApp1.MainWindow"
        ...
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <DataGrid x:Name="dataGrid" AutoGenerateColumns="False">
            <DataGrid.Columns>
                <DataGridTextColumn Header="Time" Binding="{Binding Time}" />
                <DataGridTextColumn Header="Alarm" Binding="{Binding Alarm}" />
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

MainWindow.xaml.cs:

using System;
using System.Collections.ObjectModel;
using System.IO;
using System.Xml.Serialization;
using System.Windows;
using System.Windows.Threading;

namespace WpfApp1
{
    public partial class MainWindow : Window
    {
        private ObservableCollection<Alarm> alarms;

        public MainWindow()
        {
            InitializeComponent();

            // Load alarms from file
            alarms = LoadAlarms();

            // Set data source for the DataGrid
            dataGrid.ItemsSource = alarms;

            // Start timer to add new alarms
            DispatcherTimer timer = new DispatcherTimer();
            timer.Interval = TimeSpan.FromSeconds(1);
            timer.Tick += Timer_Tick;
            timer.Start();
        }

        private void Timer_Tick(object sender, EventArgs e)
        {
            // Add a new alarm to the collection
            alarms.Add(new Alarm() { Time = DateTime.Now, Alarm = "New alarm" });

            // Save alarms to file
            SaveAlarms(alarms);
        }

        private void SaveAlarms(ObservableCollection<Alarm> alarms)
        {
            // Serialize alarms to XML and save to file
            XmlSerializer serializer = new XmlSerializer(typeof(ObservableCollection<Alarm>));
            using (StreamWriter writer = new StreamWriter("alarms.xml"))
            {
                serializer.Serialize(writer, alarms);
            }
        }

        private ObservableCollection<Alarm> LoadAlarms()
        {
            // Load alarms from file
            if (File.Exists("alarms.xml"))
            {
                XmlSerializer serializer = new XmlSerializer(typeof(ObservableCollection<Alarm>));
                using (StreamReader reader = new StreamReader("alarms.xml"))
                {
                    return (ObservableCollection<Alarm>)serializer.Deserialize(reader);
                }
            }
            else
            {
                return new ObservableCollection<Alarm>();
            }
        }
    }

    public class Alarm
    {
        public DateTime Time { get; set; }
        public string Alarm { get; set; }
    }
}