友好的注释能提高代码的可读性，几乎所有的编程语言都支持注释。
在C#中，注释不是可执行代码的一部分，因此注释不会被编译到程序集中去，但是我们可以提取注释【右键项目】-【属性】-【生成】-【输出】-【Xml文档文件】：
如果勾选了输出注释，那么VS在没有注释的方法、类型、属性等地方将会抛出警告，提醒添加注释，而添加1591代码可以取消这种无注释警告。
一般时候，我们并不会在代码中操作注释，但是如果需要，我们可以从这个生成的xml文件中去获取注释，swagger也是这么做的。
首先，创建一个辅助类：
/// <summary>
/// 注释辅助类
/// </summary>
public class XmlCommentHelper
{
private static Regex RefTagPattern = new Regex(@"<(see|paramref) (name|cref)=""([TPF]{1}:)?(?<display>.+?)"" ?/>");
private static Regex CodeTagPattern = new Regex(@"<c>(?<display>.+?)</c>");
private static Regex ParaTagPattern = new Regex(@"<para>(?<display>.+?)</para>", RegexOptions.Singleline);
List<XPathNavigator> navigators = new List<XPathNavigator>();
/// <summary>
/// 从当前dll文件中加载所有的xml文件
/// </summary>
public void LoadAll()
{
var files = Directory.GetFiles(Directory.GetCurrentDirectory());
foreach (var file in files)
{
if (string.Equals(Path.GetExtension(file), ".xml", StringComparison.OrdinalIgnoreCase))
{
Load(file);
}
}
}
/// <summary>
/// 从xml中加载
/// </summary>
/// <param name="xmls"></param>
public void LoadXml(params string[] xmls)
{
foreach (var xml in xmls)
{
Load(new MemoryStream(Encoding.UTF8.GetBytes(xml)));
}
}
/// <summary>
/// 从文件中加载
/// </summary>
/// <param name="xmlFiles"></param>
public void Load(params string[] xmlFiles)
{
foreach (var xmlFile in xmlFiles)
{
var doc = new XPathDocument(xmlFile);
navigators.Add(doc.CreateNavigator());
}
}
/// <summary>
/// 从流中加载
/// </summary>
/// <param name="streams"></param>
public void Load(params Stream[] streams)
{
foreach (var stream in streams)
{
var doc = new XPathDocument(stream);
navigators.Add(doc.CreateNavigator());
}
}
/// <summary>
/// 读取类型中的注释
/// </summary>
/// <param name="type">类型</param>
/// <param name="xPath">注释路径</param>
/// <param name="humanize">可读性优化(比如：去掉xml标记)</param>
/// <returns></returns>
public string GetTypeComment(Type type, string xPath = "summary", bool humanize = true)
{
var typeMemberName = GetMemberNameForType(type);
return GetComment(typeMemberName, xPath, humanize);
}
/// <summary>
/// 读取字段或者属性的注释
/// </summary>
/// <param name="fieldOrPropertyInfo">字段或者属性</param>
/// <param name="xPath">注释路径</param>
/// <param name="humanize">可读性优化(比如：去掉xml标记)</param>
/// <returns></returns>
public string GetFieldOrPropertyComment(MemberInfo fieldOrPropertyInfo, string xPath = "summary", bool humanize = true)
{
var fieldOrPropertyMemberName = GetMemberNameForFieldOrProperty(fieldOrPropertyInfo);
return GetComment(fieldOrPropertyMemberName, xPath, humanize);
}
/// <summary>
/// 读取方法中的注释
/// </summary>
/// <param name="methodInfo">方法</param>
/// <param name="xPath">注释路径</param>
/// <param name="humanize">可读性优化(比如：去掉xml标记)</param>
/// <returns></returns>
public string GetMethodComment(MethodInfo methodInfo, string xPath = "summary", bool humanize = true)
{
var methodMemberName = GetMemberNameForMethod(methodInfo);
return GetComment(methodMemberName, xPath, humanize);
}
/// <summary>
/// 读取方法中的返回值注释
/// </summary>
/// <param name="methodInfo">方法</param>
/// <param name="humanize">可读性优化(比如：去掉xml标记)</param>
/// <returns></returns>
public string GetMethodReturnComment(MethodInfo methodInfo, bool humanize = true)
{
return GetMethodComment(methodInfo, "returns", humanize);
}
/// <summary>
/// 读取参数的注释
/// </summary>
/// <param name="parameterInfo">参数</param>
/// <param name="humanize">可读性优化(比如：去掉xml标记)</param>
/// <returns></returns>
public string GetParameterComment(ParameterInfo parameterInfo, bool humanize = true)
{
if (!(parameterInfo.Member is MethodInfo methodInfo)) return string.Empty;
var methodMemberName = GetMemberNameForMethod(methodInfo);
return GetComment(methodMemberName, $"param[@name='{parameterInfo.Name}']", humanize);
}
/// <summary>
/// 读取方法的所有参数的注释
/// </summary>
/// <param name="methodInfo">方法</param>
/// <param name="humanize">可读性优化(比如：去掉xml标记)</param>
/// <returns></returns>
public Dictionary<string, string> GetParameterComments(MethodInfo methodInfo, bool humanize = true)
{
var parameterInfos = methodInfo.GetParameters();
Dictionary<string, string> dict = new Dictionary<string, string>();
foreach (var parameterInfo in parameterInfos)
{
dict[parameterInfo.Name] = GetParameterComment(parameterInfo, humanize);
}
return dict;
}
/// <summary>
/// 读取指定名称节点的注释
/// </summary>
/// <param name="name">节点名称</param>
/// <param name="xPath">注释路径</param>
/// <param name="humanize">可读性优化(比如：去掉xml标记)</param>
/// <returns></returns>
public string GetComment(string name, string xPath, bool humanize = true)
{
foreach (var _xmlNavigator in navigators)
{
var typeSummaryNode = _xmlNavigator.SelectSingleNode($"/doc/members/member[@name='{name}']/{xPath.Trim('/', '\\')}");
if (typeSummaryNode != null)
{
return humanize ? Humanize(typeSummaryNode.InnerXml) : typeSummaryNode.InnerXml;
}
}
return string.Empty;
}
/// <summary>
/// 读取指定节点的summary注释
/// </summary>
/// <param name="name">节点名称</param>
/// <param name="humanize">可读性优化(比如：去掉xml标记)</param>
/// <returns></returns>
public string GetSummary(string name, bool humanize = true)
{
return GetComment(name, "summary", humanize);
}
/// <summary>
/// 读取指定节点的example注释
/// </summary>
/// <param name="name">节点名称</param>
/// <param name="humanize">可读性优化(比如：去掉xml标记)</param>
/// <returns></returns>
public string GetExample(string name, bool humanize = true)
{
return GetComment(name, "example", humanize);
}
/// <summary>
/// 获取方法的节点名称
/// </summary>
/// <param name="method"></param>
/// <returns></returns>
public string GetMemberNameForMethod(MethodInfo method)
{
var builder = new StringBuilder("M:");
builder.Append(QualifiedNameFor(method.DeclaringType));
builder.Append($".{method.Name}");
var parameters = method.GetParameters();
if (parameters.Any())
{
var parametersNames = parameters.Select(p =>
{
return p.ParameterType.IsGenericParameter
? $"`{p.ParameterType.GenericParameterPosition}"
: QualifiedNameFor(p.ParameterType, expandGenericArgs: true);
});
builder.Append($"({string.Join(",", parametersNames)})");
}
return builder.ToString();
}
/// <summary>
/// 获取类型的节点名称
/// </summary>
/// <param name="type"></param>
/// <returns></returns>
public string GetMemberNameForType(Type type)
{
var builder = new StringBuilder("T:");
builder.Append(QualifiedNameFor(type));
return builder.ToString();
}
/// <summary>
/// 获取字段或者属性的节点名称
/// </summary>
/// <param name="fieldOrPropertyInfo"></param>
/// <returns></returns>
public string GetMemberNameForFieldOrProperty(MemberInfo fieldOrPropertyInfo)
{
var builder = new StringBuilder(((fieldOrPropertyInfo.MemberType & MemberTypes.Field) != 0) ? "F:" : "P:");
builder.Append(QualifiedNameFor(fieldOrPropertyInfo.DeclaringType));
builder.Append($".{fieldOrPropertyInfo.Name}");
return builder.ToString();
}
private string QualifiedNameFor(Type type, bool expandGenericArgs = false)
{
if (type.IsArray)
return $"{QualifiedNameFor(type.GetElementType(), expandGenericArgs)}[]";
var builder = new StringBuilder();
if (!string.IsNullOrEmpty(type.Namespace))
builder.Append($"{type.Namespace}.");
if (type.IsNested)
{
builder.Append($"{string.Join(".", GetNestedTypeNames(type))}.");
}
if (type.IsConstructedGenericType && expandGenericArgs)
{
var nameSansGenericArgs = type.Name.Split('`').First();
builder.Append(nameSansGenericArgs);
var genericArgsNames = type.GetGenericArguments().Select(t =>
{
return t.IsGenericParameter
? $"`{t.GenericParameterPosition}"
: QualifiedNameFor(t, true);
});
builder.Append($"{{{string.Join(",", genericArgsNames)}}}");
}
else
{
builder.Append(type.Name);
}
return builder.ToString();
}
private IEnumerable<string> GetNestedTypeNames(Type type)
{
if (!type.IsNested || type.DeclaringType == null) yield break;
foreach (var nestedTypeName in GetNestedTypeNames(type.DeclaringType))
{
yield return nestedTypeName;
}
yield return type.DeclaringType.Name;
}
private string Humanize(string text)
{
if (text == null)
throw new ArgumentNullException("text");
//Call DecodeXml at last to avoid entities like < and > to break valid xml
text = NormalizeIndentation(text);
text = HumanizeRefTags(text);
text = HumanizeCodeTags(text);
text = HumanizeParaTags(text);
text = DecodeXml(text);
return text;
}
private string NormalizeIndentation(string text)
{
string[] lines = text.Split('\n');
string padding = GetCommonLeadingWhitespace(lines);
int padLen = padding == null ? 0 : padding.Length;
// remove leading padding from each line
for (int i = 0, l = lines.Length; i < l; ++i)
{
string line = lines[i].TrimEnd('\r'); // remove trailing '\r'
if (padLen != 0 && line.Length >= padLen && line.Substring(0, padLen) == padding)
line = line.Substring(padLen);
lines[i] = line;
}
// remove leading empty lines, but not all leading padding
// remove all trailing whitespace, regardless
return string.Join("\r\n", lines.SkipWhile(x => string.IsNullOrWhiteSpace(x))).TrimEnd();
}
private string GetCommonLeadingWhitespace(string[] lines)
{
if (null == lines)
throw new ArgumentException("lines");
if (lines.Length == 0)
return null;
string[] nonEmptyLines = lines
.Where(x => !string.IsNullOrWhiteSpace(x))
.ToArray();
if (nonEmptyLines.Length < 1)
return null;
int padLen = 0;
// use the first line as a seed, and see what is shared over all nonEmptyLines
string seed = nonEmptyLines[0];
for (int i = 0, l = seed.Length; i < l; ++i)
{
if (!char.IsWhiteSpace(seed, i))
break;
if (nonEmptyLines.Any(line => line[i] != seed[i]))
break;
++padLen;
}
if (padLen > 0)
return seed.Substring(0, padLen);
return null;
}
private string HumanizeRefTags(string text)
{
return RefTagPattern.Replace(text, (match) => match.Groups["display"].Value);
}
private string HumanizeCodeTags(string text)
{
return CodeTagPattern.Replace(text, (match) => "{" + match.Groups["display"].Value + "}");
}
private string HumanizeParaTags(string text)
{
return ParaTagPattern.Replace(text, (match) => "<br>" + match.Groups["display"].Value);
}
private string DecodeXml(string text)
{
return System.Net.WebUtility.HtmlDecode(text);
}
}
比如有下面的类注释：
/// <summary>
/// MyClass注释
/// </summary>
public class MyClass
{
/// <summary>
/// FieldName1字段注释
/// </summary>
int FieldName1;
/// <summary>
/// FieldName2字段注释
/// </summary>
string FieldName2;
/// <summary>
/// PropertyName1属性注释
/// </summary>
public int PropertyName1 { get; set; }
/// <summary>
/// PropertyName2属性注释
/// </summary>
public string PropertyName2 { get; set; }
/// <summary>
/// MyMethod方法注释
/// </summary>
/// <param name="intParameter">整型参数<see cref="int"/></param>
/// <param name="stringParameter">字符串类型参数<see cref="string"/></param>
/// <returns>返回值类型是字符串</returns>
public string MyMethod(int intParameter, string stringParameter)
{
return string.Empty;
}
}
首先，安装上面的操作，将注释输出到xml文档中，然后使用这个XmlCommentHelper类来加载读取注释：
static void Main(string[] args)
{
var xmlCommentHelper = new XmlCommentHelper();
xmlCommentHelper.LoadAll();
Type type = typeof(MyClass);
var typeComment = xmlCommentHelper.GetTypeComment(type);
Console.WriteLine($"{type.Name}的注释：{typeComment}");
var fields = type.GetFields(bindingAttr: System.Reflection.BindingFlags.NonPublic);
foreach (var field in fields)
{
var fieldComment = xmlCommentHelper.GetFieldOrPropertyComment(field);
Console.WriteLine($"{field.Name}字段的注释：{fieldComment}");
}
var properties = type.GetProperties();
foreach (var property in properties)
{
var propertyComment = xmlCommentHelper.GetFieldOrPropertyComment(property);
Console.WriteLine($"{property.Name}属性的注释：{propertyComment}");
}
var method = type.GetMethod(nameof(MyClass.MyMethod));
var methodComment = xmlCommentHelper.GetMethodComment(method);
Console.WriteLine($"{nameof(MyClass.MyMethod)}方法的注释：{methodComment}");
var dict = xmlCommentHelper.GetParameterComments(method);
foreach (var pair in dict)
{
Console.WriteLine($"{nameof(MyClass.MyMethod)}方法的参数{pair.Key}注释：{pair.Value}");
}
}
输出结果：
本文章为转载内容，我们尊重原作者对文章享有的著作权。如有内容错误或侵权问题，欢迎原作者联系我们进行内容更正或删除文章。
