我的初衷是这样的：在多线程环境下，每个数据库编号对应一个DbHelper对象。
下面是代码，不知道这样写有什么问题。
namespace TestDAL
{
public class DB
{
private static string[] ConnString = new[]
{
"unknown", "Data Source=163.163.1.100;Initial Catalog=xiaomi;User Id=sa;Password=1234567890;",
"Data Source=163.163.1.101;Initial Catalog=xiaomi;User Id=sa;Password=1234567890;"
};
private static readonly ConcurrentDictionary<int, DbHelperSQLP> concurentDictionary;
static DB()
{
concurentDictionary = new ConcurrentDictionary<int, DbHelperSQLP>();
}
private DB()
{
}
public static DbHelperSQLP GetDBHelper(int id)
{
if (!concurentDictionary.ContainsKey(id))
concurentDictionary.TryAdd(id, new DbHelperSQLP(ConnString[id]));
DbHelperSQLP db;
bool result = concurentDictionary.TryGetValue(id, out db);
return result ? db : null;
}
}
}
调用方法是：
/// <summary>
/// 得到一个对象实体
/// </summary>
public xiaomi GetModel(int dbno, int id)
{
StringBuilder strSql = new StringBuilder();
strSql.Append("select top 1 id,username,password,email,ip from xiaomi ");
strSql.Append(" where id=@id");
SqlParameter[] parameters = {
)
};
parameters[].Value = id;
DbHelperSQLP helper = DB.GetDBHelper(dbno);
if (helper == null)
throw new SqlNullValueException("没有找到数据库地址");
DataSet ds = helper.Query(strSql.ToString(), parameters);
].Rows.Count > ? DataRowToModel(ds.Tables[].Rows[]) : null;
}