如何输入异常捕获？

Question

我有下面的代码，它通过并返回磁盘信息。在运行时，我注意到我的计算机(即FirmwareRevision)上没有一些WMI属性。

所以，当我运行代码VS时，它会崩溃，说明“找不到”。是否知道如何将异常捕获到对象输出的状态，而不被发现为"Not Available“。

我一直在阅读异常捕获，但到目前为止，我的业余方法是明确定义我想要的异常，use...this程序打算在不同的服务器负载上运行，因此希望它能够智能地计算出任何一台服务器可能没有的WMI对象。

代码如下，目前它在(最后一行)上失败：

"lblFirmware.Text =“固件：”+moDisk"FirmwareRevision".ToString();“

代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Management;
using Microsoft.Win32;

namespace diskdrive_info
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            //Get all the disk drives
            ManagementObjectSearcher mosDisk = new ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive");
            // Loop through each object (disk) retrieved by WMI
            foreach (ManagementObject moDisk in mosDisk.Get())
            {
                cmbHdd.Items.Add(moDisk["Model"].ToString());
            }
        }

        private void cmbHdd_SelectedIndexChanged(object sender,EventArgs e)
        {
            ManagementObjectSearcher mosDisks = new ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive WHERE Model = '" + cmbHdd.SelectedItem + "'");
            foreach (ManagementObject moDisk in mosDisks.Get())
            {
                lblType.Text = "Type: " + moDisk["MediaType"].ToString();
                lblModel.Text = "Model: " + moDisk["Model"].ToString();
                lblCapacity.Text = "Capacity: " + moDisk["Size"].ToString();
                lblPartitions.Text = "Partitions: " + moDisk["Partitions"].ToString();
                lblSectors.Text = "Sectors: " + moDisk["SectorsPerTrack"].ToString();
                lblSignature.Text = "Signatures: " +moDisk["Signature"].ToString();
                lblFirmware.Text = "Firmware: " +moDisk["FirmwareRevision"].ToString();
            }
        }


    }
}

Answer 1

尝尝这个

private void Form1_Load(object sender, EventArgs e)
    {
        try
        {
            //Get all the disk drives
            ManagementObjectSearcher mosDisk = new ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive");
            // Loop through each object (disk) retrieved by WMI
            foreach (ManagementObject moDisk in mosDisk.Get())
            {
                 cmbHdd.Items.Add(moDisk["Model"].ToString());
            }
        }
        catch(Exception exp)
        {

        }
    }

    private void cmbHdd_SelectedIndexChanged(object sender,EventArgs e)
    {
        try
        {
            ManagementObjectSearcher mosDisks = new ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive WHERE Model = '" + cmbHdd.SelectedItem + "'");
            foreach (ManagementObject moDisk in mosDisks.Get())
            {
                 lblType.Text = "Type: " + moDisk["MediaType"].ToString();
                 lblModel.Text = "Model: " + moDisk["Model"].ToString();
                 lblCapacity.Text = "Capacity: " + moDisk["Size"].ToString();
                 lblPartitions.Text = "Partitions: " + moDisk["Partitions"].ToString();
                 lblSectors.Text = "Sectors: " + moDisk["SectorsPerTrack"].ToString();
                 lblSignature.Text = "Signatures: " +moDisk["Signature"].ToString();
                 lblFirmware.Text = "Firmware: " +moDisk["FirmwareRevision"].ToString();
            }
        }
        catch(Exception exp)
        {

        }
    }

Answer 2

试着替换：

lblFirmware.Text = "Firmware: " +moDisk["FirmwareRevision"].ToString();

通过以下方式：

lblFirmware.Text = "Firmware: " + moDisk["FirmwareRevision"] == null ? "Not Available" :  moDisk["FirmwareRevision"].ToString();

Answer 3

这不是对你问题的直接回答，但更好的答案是，你不应该依赖于尝试/抓住。Catch语句适用于您无法忽略或您的程序无法优雅处理的情况。这两种属性都不适用于此--通过在WMI参考中查找哪些属性，您实际上可以提前知道哪些属性会在哪个操作系统上引起问题。

编写应用程序的更健壮的方法是检查正在运行的操作系统，并且只尝试检索已知可用的属性。您仍然应该像其他答案中所示的那样，将其包装在一个try/catch中，以防发生其他意想不到的事情，但这种特殊情况是您可以预料到的，应该编写代码，而不是抛出和捕获异常。