C# 从表列中读取二进制文件到 byte[] 数组中
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/13332960/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Reading binary from table column into byte[] array
提问by James Dawson
I'm using PBKDF2 in my application to store users passwords. In my Users table, I have a Saltand Passwordcolumn which is determined like this:
我在我的应用程序中使用 PBKDF2 来存储用户密码。在我的用户表中，我有一个Salt和Password列，它是这样确定的：
// Hash the users password using PBKDF2
var DeriveBytes = new Rfc2898DeriveBytes(_Password, 20);
byte[] _Salt = DeriveBytes.Salt;
byte[] _Key = DeriveBytes.GetBytes(20); // _Key is put into the Password column
On my login page I need to retrieve this salt and password. Because they're byte[] arrays, I store them in my table as varbinary(MAX). Now I need to retrieve them to compare against the users entered password. How would I do that using SqlDataReader? At the moment I have this:
在我的登录页面上，我需要检索此盐和密码。因为它们是 byte[] 数组，所以我将它们作为varbinary(MAX). 现在我需要检索它们以与用户输入的密码进行比较。我将如何使用SqlDataReader？目前我有这个：
cn.Open();
SqlCommand Command = new SqlCommand("SELECT Salt, Password FROM Users WHERE Email = @Email", cn);
Command.Parameters.Add("@Email", SqlDbType.NVarChar).Value = _Email;
SqlDataReader Reader = Command.ExecuteReader(CommandBehavior.CloseConnection);
Reader.Read();
if (Reader.HasRows)
{
// This user exists, check their password with the one entered
byte[] _Salt = Reader.GetBytes(0, 0, _Salt, 0, _Salt.Length);
}
else
{
// No user with this email exists
Feedback.Text = "No user with this email exists, check for typos or register";
}
But I know for a fact that it's wrong. Other methods in Readerhave only one parameter being the index of the column to retrieve.
但我知道这是错误的。中的其他方法Reader只有一个参数，即要检索的列的索引。
采纳答案by cmd.prompt
Casting it directly to a byte[]has worked for me so far.
byte[]到目前为止，将它直接投射到 a对我有用。
using (SqlConnection c = new SqlConnection("FOO"))
{
c.Open();
String sql = @"
SELECT Salt, Password
FROM Users
WHERE (Email = @Email)";
using (SqlCommand cmd = new SqlCommand(sql, c))
{
cmd.Parameters.Add("@Email", SqlDbType.NVarChar).Value = _Email;
using (SqlDataReader d = cmd.ExecuteReader())
{
if (d.Read())
{
byte[] salt = (byte[])d["Salt"];
byte[] pass = (byte[])d["Password"];
//Do stuff with salt and pass
}
else
{
// NO User with email exists
}
}
}
}
回答by Blachshma
I'm not sure why you think the code you wrote is wrong (please explain). But specifically for the error:
Notice that GetBytesreturns a longnot a byte array.
我不确定你为什么认为你写的代码是错误的（请解释）。但专门针对错误：
请注意GetBytes返回一个long非字节数组。
So, you should use:
Reader.GetBytes(0, 0, _Salt, 0, _Salt.Length);
所以，你应该使用：
Reader.GetBytes(0, 0, _Salt, 0, _Salt.Length);
orlong bytesRead = Reader.GetBytes(0, 0, _Salt, 0, _Salt.Length);
或者long bytesRead = Reader.GetBytes(0, 0, _Salt, 0, _Salt.Length);
