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今天就跟大家聊聊有关怎么在.net中利用standard 实现一个动态编译功能，可能很多人都不太了解，为了让大家更加了解，小编给大家总结了以下内容，希望大家根据这篇文章可以有所收获。
在上篇文章[基于.net core 微服务的另类实现]结尾处，提到了如何方便自动的生成微服务的客户端代理，使对于调用方透明，同时将枯燥的东西使用框架集成，以提高使用便捷性。在尝试了基于 Emit 中间语言
private static StringBuilder CreateApiProxyCode()
{
var path = GetBinPath();
var dir = new DirectoryInfo(path);
//获取项目中微服务接口文件
var files = dir.GetFiles("XZL*.Api.dll");
var codeStringBuilder = new StringBuilder(1024);
//添加必要的using
codeStringBuilder
.AppendLine("using System;")
.AppendLine("using System.Collections.Generic;")
.AppendLine("using System.Text;")
.AppendLine("using XZL.Infrastructure.ApiService;")
.AppendLine("using XZL.Infrastructure.Defines;")
.AppendLine("using XZL.Model;")
.AppendLine("namespace XZL.ApiClientProxy")
.AppendLine("{"); //namespace begin
//处理每个文件中的接口信息
foreach (var file in files)
{
CreateApiProxyCodeFromFile(codeStringBuilder, file);
}
codeStringBuilder.AppendLine("}"); //namespace end
return codeStringBuilder;
}处理每个文件中的接口类型，并将每个程序集的依赖程序集找出来，方便后面动态编译
private static void CreateApiProxyCodeFromFile(StringBuilder fileCodeBuilder, FileInfo file)
{
try
{
Assembly apiAssembly = Assembly.Load(file.Name.Substring(0, file.Name.Length - 4));
var types = apiAssembly
.GetTypes()
.Where(c => c.IsInterface && c.IsPublic)
.ToList();
var apiSvcType = typeof(IApiService);
bool isNeed = false;
foreach (Type type in types)
{
//找出期望的接口类型
if (!apiSvcType.IsAssignableFrom(type))
{
continue;
}
//找出接口的所有方法
var methods = type.GetMethods(BindingFlags.Public
| BindingFlags.FlattenHierarchy
| BindingFlags.Instance);
if (!methods.Any())
{
continue;
}
//定义代理类名,以及实现接口和继承RemoteServiceProxy
fileCodeBuilder.AppendLine($"public class {type.FullName.Replace(".", "_")}Proxy :" +
$"RemoteServiceProxy, {type.FullName}")
.AppendLine("{"); //class begin
//处理每个方法
foreach (var mth in methods)
{
CreateApiProxyCodeFromMethod(fileCodeBuilder, type, mth);
}
fileCodeBuilder.AppendLine("}"); //class end
isNeed = true;
}
if (isNeed)
{
var apiRefAsms = apiAssembly.GetReferencedAssemblies();
refAssemblyList.Add(apiAssembly.GetName());
refAssemblyList.AddRange(apiRefAsms);
}
}
catch
{
}
}处理接口中的每个方法
private static void CreateApiProxyCodeFromMethod(
StringBuilder fileCodeBuilder,
Type type,
MethodInfo mth)
{
var isMthReturn = !mth.ReturnType.Equals(typeof(void));
fileCodeBuilder.Append("public ");
//添加返回值
if (isMthReturn)
{
fileCodeBuilder.Append(GetFriendlyTypeName(mth.ReturnType)).Append(" ");
}
else
{
fileCodeBuilder.Append(" void ");
}
//方法参数开始
fileCodeBuilder.Append(mth.Name).Append("(");
var mthParams = mth.GetParameters();
if (mthParams.Any())
{
var mthparaList = new List();
foreach (var p in mthParams)
{
mthparaList.Add(GetFriendlyTypeName(p.ParameterType) + " " + p.Name);
}
fileCodeBuilder.Append(string.Join(",", mthparaList));
}
//方法参数结束
fileCodeBuilder.Append(")");
//方法体开始
fileCodeBuilder.AppendLine("{");
if (isMthReturn)
{
//返回值
fileCodeBuilder.Append("return Invoke<")
.Append(GetFriendlyTypeName(mth.ReturnType))
.Append(">");
}
else
{
fileCodeBuilder.Append(" InvokeWithoutReturn");
}
//拼接接口名及方法名
fileCodeBuilder.Append($"(\"{type.FullName}\",\"{mth.Name}\"");
//方法本身参数
if (mthParams.Any())
{
fileCodeBuilder.Append(",").Append(string.Join(",", mthParams.Select(t => t.Name)));
}
fileCodeBuilder.Append(");");
//方法体结束
fileCodeBuilder.AppendLine("}");
} 获取泛型类型字符串
private static string GetFriendlyTypeName(Type type)
{
if (!type.IsGenericType)
{
return type.FullName;
}
string friendlyName = type.Name;
int iBacktick = friendlyName.IndexOf('`');
if (iBacktick > 0)
{
friendlyName = friendlyName.Remove(iBacktick);
}
friendlyName += "<";
Type[] typeParameters = type.GetGenericArguments();
for (int i = 0; i < typeParameters.Length; ++i)
{
string typeParamName = GetFriendlyTypeName(typeParameters[i]);
friendlyName += (i == 0 ? typeParamName : "," + typeParamName);
}
friendlyName += ">";
return friendlyName;
}如何添加依赖
既然是要编译源码，那么源码中的依赖必不可少，在上一步中我们已经将每个程序集的依赖一并找出，接下来我们将这些依赖全部整理出来
//缓存程序集依赖 var references = new List(); var refAsmFiles = new List (); //系统依赖 var sysRefLocation = typeof(Enumerable).GetTypeInfo().Assembly.Location; refAsmFiles.Add(sysRefLocation); //refAsmFiles原本缓存的程序集依赖 refAsmFiles.Add(typeof(object).GetTypeInfo().Assembly.Location); refAsmFiles.AddRange(refAssemblyList.Select(t => Assembly.Load(t).Location).Distinct().ToList()); //传统.NetFramework 需要添加mscorlib.dll var coreDir = Directory.GetParent(sysRefLocation); var mscorlibFile = coreDir.FullName + Path.DirectorySeparatorChar + "mscorlib.dll"; if (File.Exists(mscorlibFile)) { references.Add(MetadataReference.CreateFromFile(mscorlibFile)); } var apiAsms = refAsmFiles.Select(t => MetadataReference.CreateFromFile(t)).ToList(); references.AddRange(apiAsms); //当前程序集依赖 var thisAssembly = Assembly.GetEntryAssembly(); if (thisAssembly != null) { var referencedAssemblies = thisAssembly.GetReferencedAssemblies(); foreach (var referencedAssembly in referencedAssemblies) { var loadedAssembly = Assembly.Load(referencedAssembly); references.Add(MetadataReference.CreateFromFile(loadedAssembly.Location)); } }
编译
有了代码片段, 也有了编译程序集依赖, 接下来就是最重要的编译了.
//定义编译后文件名
var path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Proxy");
if (!Directory.Exists(path))
{
Directory.CreateDirectory(path);
}
var apiRemoteProxyDllFile = Path.Combine(path,
apiRemoteAsmName + DateTime.Now.ToString("yyyyMMddHHmmssfff") + ".dll");
var tree = SyntaxFactory.ParseSyntaxTree(codeBuilder.ToString());
var compilation = CSharpCompilation.Create(apiRemoteAsmName)
.WithOptions(new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary))
.AddReferences(references)
.AddSyntaxTrees(tree);
//执行编译
EmitResult compilationResult = compilation.Emit(apiRemoteProxyDllFile);
if (compilationResult.Success)
{
// Load the assembly
apiRemoteAsm = Assembly.LoadFrom(apiRemoteProxyDllFile);
}
else
{
foreach (Diagnostic codeIssue in compilationResult.Diagnostics)
{
string issue = $"ID: {codeIssue.Id}, Message: {codeIssue.GetMessage()}," +
$" Location: { codeIssue.Location.GetLineSpan()}, " +
$"Severity: { codeIssue.Severity}";
AppRuntimes.Instance.Loger.Error("自动编译代码出现异常," + issue);
}
}结语
在经过以上处理后，虽算不上完美，但顺利的实现了我们期望的样子，在之前的GetService中，当发现属于远程服务的时候，只需要类似如下形式返回代理对象即可。同时为增加调用更加顺畅，我们将此编译的时机定在了发生在程序启动的时候，ps 当然或许还有一些其他更合适的时机.