【转】C# 将字符串或表达式直接转为可执行代码的办法

using System;  
using System.Data;  
using System.Configuration;  
using System.Text;  
using System.CodeDom.Compiler;  
using Microsoft.CSharp;  
using System.Reflection;  
  
namespace SSEC.Math  
{  
    /// <summary>     
    /// 本类用来将字符串转为可执行文本并执行     
    /// </summary>     
    public class MyEvaluator  
    {  
        #region 构造函数  
  
        /// <summary>     
        /// 可执行串的构造函数     
        /// </summary>     
        /// <param name="items">     
        /// 可执行字符串数组     
        /// </param>     
        public MyEvaluator(EvaluatorItem[] items)  
        {  
            ConstructEvaluator(items);      //调用解析字符串构造函数进行解析     
        }  
  
        /// <summary>     
        /// 可执行串的构造函数     
        /// </summary>     
        /// <param name="returnType">返回值类型</param>     
        /// <param name="expression">执行表达式</param>     
        /// <param name="name">执行字符串名称</param>     
        public MyEvaluator(Type returnType, string expression, string name)  
        {  
            //创建可执行字符串数组     
            EvaluatorItem[] items = { new EvaluatorItem(returnType, expression, name) };  
            ConstructEvaluator(items);      //调用解析字符串构造函数进行解析     
        }  
  
        /// <summary>     
        /// 可执行串的构造函数     
        /// </summary>     
        /// <param name="item">可执行字符串项</param>     
        public MyEvaluator(EvaluatorItem item)  
        {  
            EvaluatorItem[] items = { item };//将可执行字符串项转为可执行字符串项数组     
            ConstructEvaluator(items);      //调用解析字符串构造函数进行解析     
        }  
  
        /// <summary>     
        /// 解析字符串构造函数     
        /// </summary>     
        /// <param name="items">待解析字符串数组</param>     
        private void ConstructEvaluator(EvaluatorItem[] items)  
        {  
            //创建C#编译器实例  
            CodeDomProvider provider = CodeDomProvider.CreateProvider("C#");  
              
            //过时了  
            //ICodeCompiler comp = provider.CreateCompiler();  
              
            //编译器的传入参数     
            CompilerParameters cp = new CompilerParameters();  
            cp.ReferencedAssemblies.Add("system.dll");              //添加程序集 system.dll 的引用     
            cp.ReferencedAssemblies.Add("system.data.dll");         //添加程序集 system.data.dll 的引用     
            cp.ReferencedAssemblies.Add("system.xml.dll");          //添加程序集 system.xml.dll 的引用     
            cp.GenerateExecutable = false;                          //不生成可执行文件     
            cp.GenerateInMemory = true;                             //在内存中运行     
  
            StringBuilder code = new StringBuilder();               //创建代码串     
            /*   
             *  添加常见且必须的引用字符串   
             */  
            code.Append("using System; /n");  
            code.Append("using System.Data; /n");  
            code.Append("using System.Data.SqlClient; /n");  
            code.Append("using System.Data.OleDb; /n");  
            code.Append("using System.Xml; /n");  
  
            code.Append("namespace SSEC.Math { /n");                  //生成代码的命名空间为EvalGuy，和本代码一样     
  
            code.Append("  public class _Evaluator { /n");          //产生 _Evaluator 类，所有可执行代码均在此类中运行     
            foreach (EvaluatorItem item in items)               //遍历每一个可执行字符串项     
            {  
                code.AppendFormat("    public {0} {1}() ",          //添加定义公共函数代码     
                                  item.ReturnType.Name,             //函数返回值为可执行字符串项中定义的返回值类型     
                                  item.Name);                       //函数名称为可执行字符串项中定义的执行字符串名称     
                code.Append("{ ");                                  //添加函数开始括号     
                code.AppendFormat("return ({0});", item.Expression);//添加函数体，返回可执行字符串项中定义的表达式的值     
                code.Append("}/n");                                 //添加函数结束括号     
            }  
            code.Append("} }");                                 //添加类结束和命名空间结束括号     
  
            //得到编译器实例的返回结果     
            CompilerResults cr = provider.CompileAssemblyFromSource(cp, code.ToString());//comp  
  
            if (cr.Errors.HasErrors)                            //如果有错误     
            {  
                StringBuilder error = new StringBuilder();          //创建错误信息字符串     
                error.Append("编译有错误的表达式: ");                //添加错误文本     
                foreach (CompilerError err in cr.Errors)            //遍历每一个出现的编译错误     
                {  
                    error.AppendFormat("{0}/n", err.ErrorText);     //添加进错误文本，每个错误后换行     
                }  
                throw new Exception("编译错误: " + error.ToString());//抛出异常     
            }  
            Assembly a = cr.CompiledAssembly;                       //获取编译器实例的程序集     
            _Compiled = a.CreateInstance("SSEC.Math._Evaluator");     //通过程序集查找并声明 SSEC.Math._Evaluator 的实例     
        }  
        #endregion  
 
        #region 公有成员  
        /// <summary>     
        /// 执行字符串并返回整型值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        public int EvaluateInt(string name)  
        {  
            return (int)Evaluate(name);  
        }  
        /// <summary>     
        /// 执行字符串并返回双精度值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        public double EvaluateDouble(string name)  
        {  
            return (double)Evaluate(name);  
        }  
        /// <summary>     
        /// 执行字符串并返回长整型数值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        public long EvaluateLong(string name)  
        {  
            return (long)Evaluate(name);  
        }  
        /// <summary>     
        /// 执行字符串并返回十进制数值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        public decimal EvaluateDecimal(string name)  
        {  
            return (decimal)Evaluate(name);  
        }  
        /// <summary>     
        /// 执行字符串并返回字符串型值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        public string EvaluateString(string name)  
        {  
            return (string)Evaluate(name);  
        }  
        /// <summary>     
        /// 执行字符串并返回布尔型值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        public bool EvaluateBool(string name)  
        {  
            return (bool)Evaluate(name);  
        }  
        /// <summary>     
        /// 执行字符串并返 object 型值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        public object Evaluate(string name)  
        {  
            MethodInfo mi = _Compiled.GetType().GetMethod(name);//获取 _Compiled 所属类型中名称为 name 的方法的引用     
            return mi.Invoke(_Compiled, null);                  //执行 mi 所引用的方法     
        }  
        #endregion  
 
        #region 静态成员  
        /// <summary>     
        /// 执行表达式并返回整型值     
        /// </summary>     
        /// <param name="code">要执行的表达式</param>     
        /// <returns>运算结果</returns>     
        static public int EvaluateToInteger(string code)  
        {  
            MyEvaluator eval = new MyEvaluator(typeof(int), code, staticMethodName);//生成 Evaluator 类的对像     
            return (int)eval.Evaluate(staticMethodName);                        //执行并返回整型数据     
        }  
        /// <summary>     
        /// 执行表达式并返回双精度值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        static public double EvaluateToDouble(string code)  
        {  
            MyEvaluator eval = new MyEvaluator(typeof(double), code, staticMethodName);//生成 Evaluator 类的对像     
            return (double)eval.Evaluate(staticMethodName);   
        }  
        /// <summary>     
        /// 执行表达式并返回长整型数值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        static public long EvaluateToLong(string code)  
        {  
            MyEvaluator eval = new MyEvaluator(typeof(long), code, staticMethodName);//生成 Evaluator 类的对像     
            return (long)eval.Evaluate(staticMethodName);   
        }  
        /// <summary>     
        /// 执行表达式并返回十进制数值     
        /// </summary>     
        /// <param name="name">执行字符串名称</param>     
        /// <returns>执行结果</returns>     
        static public decimal EvaluateToDecimal(string code)  
        {  
            MyEvaluator eval = new MyEvaluator(typeof(decimal), code, staticMethodName);//生成 Evaluator 类的对像     
            return (decimal)eval.Evaluate(staticMethodName);   
        }  
        /// <summary>     
        /// 执行表达式并返回字符串型值     
        /// </summary>     
        /// <param name="code">要执行的表达式</param>     
        /// <returns>运算结果</returns>     
        static public string EvaluateToString(string code)  
        {  
            MyEvaluator eval = new MyEvaluator(typeof(string), code, staticMethodName);//生成 Evaluator 类的对像     
            return (string)eval.Evaluate(staticMethodName);                     //执行并返回字符串型数据     
        }  
        /// <summary>     
        /// 执行表达式并返回布尔型值     
        /// </summary>     
        /// <param name="code">要执行的表达式</param>     
        /// <returns>运算结果</returns>     
        static public bool EvaluateToBool(string code)  
        {  
            MyEvaluator eval = new MyEvaluator(typeof(bool), code, staticMethodName);//生成 Evaluator 类的对像     
            return (bool)eval.Evaluate(staticMethodName);                       //执行并返回布尔型数据     
        }  
        /// <summary>     
        /// 执行表达式并返回 object 型值     
        /// </summary>     
        /// <param name="code">要执行的表达式</param>     
        /// <returns>运算结果</returns>     
        static public object EvaluateToObject(string code)  
        {  
            MyEvaluator eval = new MyEvaluator(typeof(object), code, staticMethodName);//生成 Evaluator 类的对像     
            return eval.Evaluate(staticMethodName);                             //执行并返回 object 型数据     
        }  
        #endregion  
 
        #region 私有成员  
        /// <summary>     
        /// 静态方法的执行字符串名称     
        /// </summary>     
        private const string staticMethodName = "__foo";  
        /// <summary>     
        /// 用于动态引用生成的类，执行其内部包含的可执行字符串     
        /// </summary>     
        object _Compiled = null;  
        #endregion  
    }  
  
  
    /// <summary>     
    /// 可执行字符串项（即一条可执行字符串）     
    /// </summary>     
    public class EvaluatorItem  
    {  
        /// <summary>     
        /// 返回值类型     
        /// </summary>     
        public Type ReturnType;  
        /// <summary>     
        /// 执行表达式     
        /// </summary>     
        public string Expression;  
        /// <summary>     
        /// 执行字符串名称     
        /// </summary>     
        public string Name;  
        /// <summary>     
        /// 可执行字符串项构造函数     
        /// </summary>     
        /// <param name="returnType">返回值类型</param>     
        /// <param name="expression">执行表达式</param>     
        /// <param name="name">执行字符串名称</param>     
        public EvaluatorItem(Type returnType, string expression, string name)  
        {  
            ReturnType = returnType;  
            Expression = expression;  
            Name = name;  
        }  
    }  
}  

class Test  
    {  
        /// <summary>  
        /// The main entry point for the application.  
        /// </summary>  
        [STAThread]  
        static void Main(string[] args)  
        {  
            Console.WriteLine("Test0: {0}", MyEvaluator.EvaluateToInteger("(30 + 4) * 2"));  
            Console.WriteLine("Test1: {0}", MyEvaluator.EvaluateToString("/"Hello /" + /"There/""));  
            Console.WriteLine("Test2: {0}", MyEvaluator.EvaluateToBool("30 == 40"));  
            Console.WriteLine("Test3: {0}", MyEvaluator.EvaluateToObject("new DataSet()"));  
            Console.WriteLine("Test4: {0}", MyEvaluator.EvaluateToDouble("(12.4+2.2)*0.4"));  
            Console.WriteLine("Test5: {0}", MyEvaluator.EvaluateToLong("(12+1000)*1000"));  
            Console.WriteLine("Test6: {0}", MyEvaluator.EvaluateToString("/"double max==/"+double.MaxValue"));//decimal.MaxValue+/",/"+  
              
  
            EvaluatorItem[] items = {  
                                    new EvaluatorItem(typeof(int), "(30 + 4) * 2", "GetNumber"),  
                                    new EvaluatorItem(typeof(string), "/"Hello /" + /"There/"", "GetString"),  
                                    new EvaluatorItem(typeof(bool), "30 == 40", "GetBool"),  
                                    new EvaluatorItem(typeof(object), "new DataSet()", "GetDataSet")  
                                    };  
  
            MyEvaluator eval = new MyEvaluator(items);  
            Console.WriteLine("TestStatic0: {0}", eval.EvaluateInt("GetNumber"));  
            Console.WriteLine("TestStatic1: {0}", eval.EvaluateString("GetString"));  
            Console.WriteLine("TestStatic2: {0}", eval.EvaluateBool("GetBool"));  
            Console.WriteLine("TestStatic3: {0}", eval.Evaluate("GetDataSet"));  
            Console.ReadLine();  
        }  
    }