C#解析一个非常不稳定的文件

如何解决C#解析一个非常不稳定的文件

我有一个非常大的文件，在不同的地方多次出现以下行。 这个文件没有真正的组织。但是，重复了以下行：

 <mcwb:Control ClassId="jdn8732d" ControldisplayName="Type" ControlId="asp_type" datafieldName="asp_type" IsSystemControl="False" IsUnbound="False" SystemStepType="0">

我需要提取以下内容：

1. ControldisplayName="Type"
2. ControlId="asp_type" 
3. datafieldName="asp_type"

我正在努力用 C# 解析这个文件，有人知道我该怎么做吗？

解决方法

一个非常简单的实现（有更好、更高效、更健壮的完成任务的方法）可以帮助您入门，如果您真的无法使用 xml 库来搜索原生 xml 功能。请记住在适当的情况下添加异常处理和特殊情况以及其他验证。

// usage
private static void Main(string[] args) {

    Searcher searcher = new Searcher();
    foreach (SearchExtract extract in searcher.GetOccurances(System.IO.File.ReadAllText(@"c:\temp\testfile.txt"))) {
        //do somethign with extract
    }
}

public class SearchExtract {

    // makes it easier to find in the document for checking,can even use to calculate lines
    public int StartIndex {
        get; set;
    }

    public string ControlDisplayName {
        get; set;
    }

    public string ControlId {
        get; set;
    }

    public string DataFieldName {
        get; set;
    }
}

// does not check for end of file 
public class Searcher {

    private const string Start = "<mcwb:Control "; // with the space 
    private const string End = ">";

    // use a stream as input and a stream reader (buffered) for large files
    public System.Collections.Generic.IEnumerable<SearchExtract> GetOccurances(string input) {

        int position = 0;
        int startIndex = input.IndexOf(Start,position,System.StringComparison.Ordinal);
        while (startIndex >= 0) {

            // first lets try find the end
            //  assuming the end string is never in a comment or included string literal value,else you need to accomodate for this 
            int endIndex = input.IndexOf(End,startIndex);

            // now the other values
            int controlDisplayNameIndex = input.IndexOf(nameof(SearchExtract.ControlDisplayName),startIndex,System.StringComparison.Ordinal);
            int controlIdIndex = input.IndexOf(nameof(SearchExtract.ControlId),System.StringComparison.Ordinal);
            int dataFieldNameIndex = input.IndexOf(nameof(SearchExtract.DataFieldName),System.StringComparison.Ordinal);

            // now make sure the values are all before the end character
            //  here the assumption is you need all for it to be a valid search extract
            //  and that every start has an end .. ie not malformed file in this regard
            if (controlDisplayNameIndex < endIndex && controlIdIndex < endIndex && dataFieldNameIndex < endIndex) {

                string controlDisplayNameValue = FindValue(controlDisplayNameIndex + nameof(SearchExtract.ControlDisplayName).Length,input);
                string controlIdValue = FindValue(controlIdIndex + nameof(SearchExtract.ControlId).Length,input);
                string dataFieldNameValue = FindValue(dataFieldNameIndex + nameof(SearchExtract.DataFieldName).Length,input);

                // validate
                if (controlDisplayNameValue != null && controlIdValue != null && dataFieldNameValue != null) {

                    // iterate
                    yield return new SearchExtract() {
                        StartIndex = startIndex,ControlDisplayName = controlDisplayNameValue,ControlId = controlIdValue,DataFieldName = dataFieldNameValue
                    };
                }
            }

            startIndex = input.IndexOf(Start,endIndex + 1,System.StringComparison.Ordinal);
        }
    }

    // introduce some additional terminal checks .. such as maximum value length 
    private string FindValue(int index,string input) {

        const string ValueDelimiter = "\"";

        string value = null;

        int startIndex = input.IndexOf(ValueDelimiter,index,System.StringComparison.Ordinal);

        int endIndex = -1;
        if (startIndex >= 0) {
            endIndex = input.IndexOf(ValueDelimiter,startIndex + 1,System.StringComparison.Ordinal);
        }

        if (endIndex > 0) {
            value = input.Substring(startIndex + 1,endIndex - startIndex - 1);

            // do some validation on value 
        }

        return value;
    }
}