Uri.EscapeDataString() -无效URI: Uri字符串太长

Question

我在windows mobile上使用了紧凑的框架/C#。

在我的应用程序中，我通过序列化对象并使用HttpWebRequest/POST请求将信息发送到服务器，将数据上传到服务器。在服务器上，post数据被反序列化并保存到数据库中。

前几天，我意识到我在post数据(符号等)中的特殊字符有问题。所以我在方法中引入了Uri.EscapeDataString()，一切都很好。

然而，今天我发现，当应用程序试图上传大量数据时，存在一个问题(我不知道目前到底什么是“大”！)

现有代码(某种形式)

var uploadData = new List<Things>();

uploadData.Add(new Thing() { Name = "Test 01" });
uploadData.Add(new Thing() { Name = "Test 02" });
uploadData.Add(new Thing() { Name = "Test with an & Ampersand " }); // Do this a lot!!

var postData = "uploadData=" + Uri.EscapeDataString(JsonConvert.SerializeObject(uploadData, new IsoDateTimeConverter()));

问题

对Uri.EscapeDataString()的调用将导致以下异常：

System.UriFormatException:无效URI: Uri字符串太长。

问题

是否有其他方法来准备上传的数据？

据我所见，HttpUtility (它有自己的编码/解码方法)无法用于紧凑的框架。

Answer 1

或者您可以简单地拆分字符串并为每个块调用Uri.EscapeDataString(string)，以避免重新实现该函数。

示例代码：

        String value = "large string to encode";
        int limit = 2000;

        StringBuilder sb = new StringBuilder();
        int loops = value.Length / limit;

        for (int i = 0; i <= loops; i++)
        {
            if (i < loops)
            {
                sb.Append(Uri.EscapeDataString(value.Substring(limit * i, limit)));
            }
            else
            {
                sb.Append(Uri.EscapeDataString(value.Substring(limit * i)));
            }
        }

Answer 2

“阿尔贝托·德·保拉”的答案是好的。

尽管如此，解除转义数据的难度要大一些，因为您必须避免在编码字符中间剪切编码的字符串(否则会破坏原始字符串的完整性)。

下面是我解决这个问题的方法：

public static string EncodeString(string str)
{
    //maxLengthAllowed .NET < 4.5 = 32765;
    //maxLengthAllowed .NET >= 4.5 = 65519;
    int maxLengthAllowed = 65519;
    StringBuilder sb = new StringBuilder();
    int loops = str.Length / maxLengthAllowed;

    for (int i = 0; i <= loops; i++)
    {
        sb.Append(Uri.EscapeDataString(i < loops
            ? str.Substring(maxLengthAllowed * i, maxLengthAllowed)
            : str.Substring(maxLengthAllowed * i)));
    }

    return sb.ToString();
}

public static string DecodeString(string encodedString)
{
    //maxLengthAllowed .NET < 4.5 = 32765;
    //maxLengthAllowed .NET >= 4.5 = 65519;
    int maxLengthAllowed = 65519;

    int charsProcessed = 0;
    StringBuilder sb = new StringBuilder();

    while (encodedString.Length > charsProcessed)
    {
        var stringToUnescape = encodedString.Substring(charsProcessed).Length > maxLengthAllowed
            ? encodedString.Substring(charsProcessed, maxLengthAllowed)
            : encodedString.Substring(charsProcessed);

        // If the loop cut an encoded tag (%xx), we cut before the encoded char to not loose the entire char for decoding
        var incorrectStrPos = stringToUnescape.Length == maxLengthAllowed ? stringToUnescape.IndexOf("%", stringToUnescape.Length - 4, StringComparison.InvariantCulture) : -1;
        if (incorrectStrPos > -1)
        {
            stringToUnescape = encodedString.Substring(charsProcessed).Length > incorrectStrPos
                ? encodedString.Substring(charsProcessed, incorrectStrPos)
                : encodedString.Substring(charsProcessed);
        }

        sb.Append(Uri.UnescapeDataString(stringToUnescape));
        charsProcessed += stringToUnescape.Length;
    }

    var decodedString = sb.ToString();

    // ensure the string is sanitized here or throw exception if XSS / SQL Injection is found
    SQLHelper.SecureString(decodedString);
    return decodedString;
}

为了测试这些功能：

var testString = "long string to encode";
var encodedString = EncodeString(testString);
var decodedString = DecodeString(encodedString);

Console.WriteLine(decodedString == testString ? "integrity respected" : "integrity broken");

希望这能帮助避免头痛;)

Answer 3

StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < originalString.Length; i++)
{
    if ((originalString[i] >= 'a' && originalString[i] <= 'z') || 
        (originalString[i] >= 'A' && originalString[i] <= 'Z') || 
        (originalString[i] >= '0' && originalString[i] <= '9'))
    {
        stringBuilder.Append(originalString[i]);
    }
    else
    {
        stringBuilder.AppendFormat("%{0:X2}", (int)originalString[i]);
    }
}

string result = stringBuilder.ToString();