public void Reload() { var dbName = _configurationRoot.GetSection("SqliteConnection").Value; var dirPath = Path.GetDirectoryName(dbName.Substring(dbName.IndexOf("=")+1)); if (!Directory.Exists(dirPath)) { Directory.CreateDirectory(dirPath); } dbName = dbName.Substring(0, dbName.LastIndexOf(@"\") == -1 ? 0 : dbName.LastIndexOf(@"\") + 1); dbName = $"{dbName}MigrateDb_{DateTime.Now.ToString("yyyyMMddHHmmss")}.db"; MigrateDbContext.DbName = dbName; string json = File.ReadAllText("appsettings.json"); var setting = JsonSerializer.Deserialize<SettingProperties>(json); setting.SqliteConnection = dbName; var serialize = JsonSerializer.Serialize(setting); using var stream = new FileStream("appsettings.json", FileMode.Create, FileAccess.ReadWrite); using StreamWriter streamWriter = new StreamWriter(stream); streamWriter.WriteLine(serialize); _context?.Dispose(); _context = new MigrateDbContext(); _context.Database.EnsureCreatedAsync(); } 优化这段代码

首先，我们可以把一些重复的代码提取出来，比如获取数据库名和创建目录的部分，可以写成一个单独的方法，代码如下：

private string GetDbNameAndCreateDirectory(string connectionString)
{
    var dbName = connectionString.Substring(connectionString.IndexOf("=") + 1);
    var dirPath = Path.GetDirectoryName(dbName);
    if (!Directory.Exists(dirPath))
    {
        Directory.CreateDirectory(dirPath);
    }
    dbName = dbName.Substring(0, dbName.LastIndexOf(@"\") == -1 ? 0 : dbName.LastIndexOf(@"\") + 1);
    dbName = $"{dbName}MigrateDb_{DateTime.Now:yyyyMMddHHmmss}.db";
    return dbName;
}

然后，我们可以将获取连接字符串和更新配置文件的部分也提取出来，写成一个方法：

private void UpdateConnectionString(string newConnectionString)
{
    string json = File.ReadAllText("appsettings.json");
    var setting = JsonSerializer.Deserialize<SettingProperties>(json);
    setting.SqliteConnection = newConnectionString;
    var serialize = JsonSerializer.Serialize(setting);
    using var stream = new FileStream("appsettings.json", FileMode.Create, FileAccess.ReadWrite);
    using StreamWriter streamWriter = new StreamWriter(stream);
    streamWriter.WriteLine(serialize);
}

最后，我们可以将 Reload 方法中的代码进行重构，将每个步骤都提取出来，使代码更加清晰易懂，代码如下：

public void Reload()
{
    var connectionString = _configurationRoot.GetSection("SqliteConnection").Value;
    var newConnectionString = GetDbNameAndCreateDirectory(connectionString);
    UpdateConnectionString(newConnectionString);
    _context?.Dispose();
    _context = new MigrateDbContext();
    _context.Database.EnsureCreatedAsync();
}

这样，我们就将代码进行了优化，使其更加清晰易懂、易于维护。