MethodBody 类

定义

提供对方法体的元数据和 MSIL 的访问权限。Provides access to the metadata and MSIL for the body of a method.

public ref class MethodBody
public ref class MethodBody sealed
public class MethodBody
[System.Runtime.InteropServices.ComVisible(true)]
public sealed class MethodBody
[System.Runtime.InteropServices.ComVisible(true)]
public class MethodBody
type MethodBody = class
[<System.Runtime.InteropServices.ComVisible(true)>]
type MethodBody = class
Public Class MethodBody
Public NotInheritable Class MethodBody
继承
MethodBody
属性

示例

下面的代码示例定义一个名为的测试方法 MethodBodyExample ,并显示其本地变量信息和异常处理子句。The following code example defines a test method named MethodBodyExample and displays its local variable information and exception-handling clauses. MethodBase.GetMethodBody方法用于获取 MethodBody 测试方法的对象。The MethodBase.GetMethodBody method is used to obtain a MethodBody object for the test method.

该示例使用 LocalVariables 属性获取对象的列表 LocalVariableInfo ,然后显示对象的类型和索引顺序。The example uses the LocalVariables property to obtain a list of LocalVariableInfo objects and then displays their types and index order. ExceptionHandlingClauses属性用于获取异常处理子句的列表。The ExceptionHandlingClauses property is used to obtain a list of exception-handling clauses.

#using <System.dll>

using namespace System;
using namespace System::Reflection;

public ref class Example
{
    // The Main method contains code to analyze this method, using
    // the properties and methods of the MethodBody class.
public:
    void MethodBodyExample(Object^ arg)
    {
        // Define some local variables. In addition to these variables,
        // the local variable list includes the variables scoped to 
        // the catch clauses.
        int var1 = 42;
        String^ var2 = "Forty-two";

        try
        {
            // Depending on the input value, throw an ArgumentException or 
            // an ArgumentNullException to test the Catch clauses.
            if (arg == nullptr)
            {
                throw gcnew ArgumentNullException("The argument cannot " +
                    "be null.");
            }
            if (arg->GetType() == String::typeid)
            {
                throw gcnew ArgumentException("The argument cannot " + 
                    "be a string.");
            }        
        }

        // There is no Filter clause in this code example. See the Visual 
        // Basic code for an example of a Filter clause.

        // This catch clause handles the ArgumentException class, and
        // any other class derived from Exception.
        catch (ArgumentException^ ex)
        {
            Console::WriteLine("Ordinary exception-handling clause caught:" +
                " {0}", ex->GetType());
        }        
        finally
        {
            var1 = 3033;
            var2 = "Another string.";
        }
    }
};

int main()
{ 
    // Get method body information.
    MethodInfo^ mi = 
        Example::typeid->GetMethod("MethodBodyExample");

    MethodBody^ mb = mi->GetMethodBody();
    Console::WriteLine("\r\nMethod: {0}", mi);

    // Display the general information included in the 
    // MethodBody object.
    Console::WriteLine("    Local variables are initialized: {0}", 
        mb->InitLocals);
    Console::WriteLine("    Maximum number of items on the operand " +
        "stack: {0}", mb->MaxStackSize);

    // Display information about the local variables in the
    // method body.
    Console::WriteLine();
    for each (LocalVariableInfo^ lvi in mb->LocalVariables)
    {
        Console::WriteLine("Local variable: {0}", lvi);
    }

    // Display exception handling clauses.
    Console::WriteLine();
    for each(ExceptionHandlingClause^ exhc in mb->ExceptionHandlingClauses)
    {
        Console::WriteLine(exhc->Flags.ToString());

        // The FilterOffset property is meaningful only for Filter
        // clauses. The CatchType property is not meaningful for 
        // Filter or Finally clauses. 
        switch(exhc->Flags)
        {
        case ExceptionHandlingClauseOptions::Filter:
            Console::WriteLine("        Filter Offset: {0}", 
                exhc->FilterOffset);
            break;
        case ExceptionHandlingClauseOptions::Finally:
            break;
        default:
            Console::WriteLine("    Type of exception: {0}", 
                exhc->CatchType);
            break;
        }

        Console::WriteLine("       Handler Length: {0}",
            exhc->HandlerLength);
        Console::WriteLine("       Handler Offset: {0}", 
            exhc->HandlerOffset);
        Console::WriteLine("     Try Block Length: {0}", exhc->TryLength);
        Console::WriteLine("     Try Block Offset: {0}", exhc->TryOffset);
    }
}

//This code example produces output similar to the following:
//
//Method: Void MethodBodyExample(System.Object)
//    Local variables are initialized: False
//    Maximum number of items on the operand stack: 4
//
//Local variable: System.ArgumentException (0)
//Local variable: System.String (1)
//Local variable: System.Int32 (2)
//Clause
//    Type of exception: System.ArgumentException
//       Handler Length: 29
//       Handler Offset: 78
//     Try Block Length: 65
//     Try Block Offset: 13
//Finally
//       Handler Length: 13
//       Handler Offset: 113
//     Try Block Length: 100
//     Try Block Offset: 13
using System;
using System.Reflection;

public class Example
{
    public static void Main()
    {
        // Get method body information.
        MethodInfo mi = typeof(Example).GetMethod("MethodBodyExample");
        MethodBody mb = mi.GetMethodBody();
        Console.WriteLine("\r\nMethod: {0}", mi);

        // Display the general information included in the
        // MethodBody object.
        Console.WriteLine("    Local variables are initialized: {0}",
            mb.InitLocals);
        Console.WriteLine("    Maximum number of items on the operand stack: {0}",
            mb.MaxStackSize);

        // Display information about the local variables in the
        // method body.
        Console.WriteLine();
        foreach (LocalVariableInfo lvi in mb.LocalVariables)
        {
            Console.WriteLine("Local variable: {0}", lvi);
        }

        // Display exception handling clauses.
        Console.WriteLine();
        foreach (ExceptionHandlingClause ehc in mb.ExceptionHandlingClauses)
        {
            Console.WriteLine(ehc.Flags.ToString());

            // The FilterOffset property is meaningful only for Filter
            // clauses. The CatchType property is not meaningful for
            // Filter or Finally clauses.
            switch (ehc.Flags)
            {
                case ExceptionHandlingClauseOptions.Filter:
                    Console.WriteLine("        Filter Offset: {0}",
                        ehc.FilterOffset);
                    break;
                case ExceptionHandlingClauseOptions.Finally:
                    break;
                default:
                    Console.WriteLine("    Type of exception: {0}",
                        ehc.CatchType);
                    break;
            }

            Console.WriteLine("       Handler Length: {0}", ehc.HandlerLength);
            Console.WriteLine("       Handler Offset: {0}", ehc.HandlerOffset);
            Console.WriteLine("     Try Block Length: {0}", ehc.TryLength);
            Console.WriteLine("     Try Block Offset: {0}", ehc.TryOffset);
        }
    }

    // The Main method contains code to analyze this method, using
    // the properties and methods of the MethodBody class.
    public void MethodBodyExample(object arg)
    {
        // Define some local variables. In addition to these variables,
        // the local variable list includes the variables scoped to
        // the catch clauses.
        int var1 = 42;
        string var2 = "Forty-two";

        try
        {
            // Depending on the input value, throw an ArgumentException or
            // an ArgumentNullException to test the Catch clauses.
            if (arg == null)
            {
                throw new ArgumentNullException("The argument cannot be null.");
            }
            if (arg.GetType() == typeof(string))
            {
                throw new ArgumentException("The argument cannot be a string.");
            }
        }

        // This filter clause selects only exceptions that derive
        // from the ArgumentException class.
        // Other exceptions, including ArgumentException itself,
        // are not handled by this filter clause.
        catch (ArgumentException ex) when (ex.GetType().IsSubclassOf(typeof(ArgumentException)))
        {
            Console.WriteLine("Filter clause caught: {0}", ex.GetType());
        }

        // This catch clause handles the ArgumentException class, and
        // any other class derived from Exception.
        catch(Exception ex)
        {
            Console.WriteLine("Ordinary exception-handling clause caught: {0}",
                ex.GetType());
        }
        finally
        {
            var1 = 3033;
            var2 = "Another string.";
        }
    }
}

// This code example produces output similar to the following:
//
//Method: Void MethodBodyExample(System.Object)
//    Local variables are initialized: True
//    Maximum number of items on the operand stack: 2
//
//Local variable: System.Int32 (0)
//Local variable: System.String (1)
//Local variable: System.Exception (2)
//Local variable: System.Boolean (3)
//
//Filter
//      Filter Offset: 71
//      Handler Length: 23
//      Handler Offset: 116
//      Try Block Length: 61
//      Try Block Offset: 10
//Clause
//    Type of exception: System.Exception
//       Handler Length: 21
//       Handler Offset: 70
//     Try Block Length: 61
//     Try Block Offset: 9
//Finally
//       Handler Length: 14
//       Handler Offset: 94
//     Try Block Length: 85
//     Try Block Offset: 9
Imports System.Reflection

Public Class Example

    Public Shared Sub Main()

        ' Demonstrate the effect of the Visual Basic When keyword, which
        ' generates a Filter clause in the Try block.
        Dim e As New Example()
        Console.WriteLine()
        e.MethodBodyExample("String argument")
        e.MethodBodyExample(Nothing)

        ' Get method body information.
        Dim mi As MethodInfo = _
            GetType(Example).GetMethod("MethodBodyExample")
        Dim mb As MethodBody = mi.GetMethodBody()
        Console.WriteLine(vbCrLf & "Method: {0}", mi)

        ' Display the general information included in the 
        ' MethodBody object.
        Console.WriteLine("    Local variables are initialized: {0}", _
            mb.InitLocals)
        Console.WriteLine("    Maximum number of items on the operand stack: {0}", _
            mb.MaxStackSize)

        ' Display information about the local variables in the
        ' method body.
        Console.WriteLine()
        For Each lvi As LocalVariableInfo In mb.LocalVariables
            Console.WriteLine("Local variable: {0}", lvi)
        Next

        ' Display exception handling clauses.
        Console.WriteLine()
        For Each ehc As ExceptionHandlingClause In mb.ExceptionHandlingClauses
            Console.WriteLine(ehc.Flags.ToString())

            ' The FilterOffset property is meaningful only for Filter
            ' clauses. The CatchType property is not meaningful for 
            ' Filter or Finally clauses. 
            Select Case ehc.Flags
                Case ExceptionHandlingClauseOptions.Filter
                    Console.WriteLine("        Filter Offset: {0}", _
                        ehc.FilterOffset)
                Case ExceptionHandlingClauseOptions.Finally
                Case Else
                    Console.WriteLine("    Type of exception: {0}", _
                        ehc.CatchType)
            End Select

            Console.WriteLine("       Handler Length: {0}", ehc.HandlerLength)
            Console.WriteLine("       Handler Offset: {0}", ehc.HandlerOffset)
            Console.WriteLine("     Try Block Length: {0}", ehc.TryLength)
            Console.WriteLine("     Try Block Offset: {0}", ehc.TryOffset)
        Next
    End Sub

    ' This test method is executed at the beginning of Main, to show
    ' how the Filter clause works. The Filter clause is generated by 
    ' a Visual Basic When expression. If arg is Nothing, this method
    ' throws ArgumentNullException, which is caught by the filter
    ' clause. If arg is a string, the method throws ArgumentException,
    ' which does not match the filter clause.
    '
    ' Sub Main also contains code to analyze this method, using 
    ' the properties and methods of the MethodBody class.
    Public Sub MethodBodyExample(ByVal arg As Object)

        ' Define some local variables. In addition to these variables,
        ' the local variable list includes the variables scoped to 
        ' the catch clauses.
        Dim var1 As Integer = 42
        Dim var2 As String = "Forty-two"

        Try
            ' Depending on the input value, throw an ArgumentException or 
            ' an ArgumentNullException to test the Catch clauses.
            '
            If arg Is Nothing Then
                Throw New ArgumentNullException("The argument cannot be Nothing.")
            End If
            If arg.GetType() Is GetType(String) Then
                Throw New ArgumentException("The argument cannot be a string.")
            End If
        
        ' The When expression makes this a filter clause. The expression 
        ' selects only exceptions that derive from the ArgumentException
        ' class. Other exceptions, including ArgumentException itself, 
        ' are not handled by this filter clause.
        Catch ex As ArgumentException _
            When ex.GetType().IsSubclassOf(GetType(ArgumentException))

            Console.WriteLine("Filter clause caught: {0}", ex.GetType())
        
        ' This catch clause handles the ArgumentException class, and
        ' any other class derived from Exception.
        Catch ex As Exception
            Console.WriteLine("Ordinary exception-handling clause caught: {0}", _
                ex.GetType())

        Finally
            var1 = 3033
            var2 = "Another string."
        End Try
    End Sub
End Class

' This code example produces output similar to the following:
'
'Ordinary exception-handling clause caught: System.ArgumentException
'Filter clause caught: System.ArgumentNullException
'
'Method: Void MethodBodyExample(System.Object)
'    Local variables are initialized: True
'    Maximum number of items on the operand stack: 3
'
'Local variable: System.Int32 (0)
'Local variable: System.String (1)
'Local variable: System.ArgumentException (2)
'Local variable: System.Exception (3)
'
'Filter
'        Filter Offset: 0
'       Handler Length: 19
'       Handler Offset: 99
'     Try Block Length: 45
'     Try Block Offset: 9
'Clause
'    Type of exception: System.Exception
'       Handler Length: 25
'       Handler Offset: 118
'     Try Block Length: 45
'     Try Block Offset: 9
'Finally
'       Handler Length: 13
'       Handler Offset: 153
'     Try Block Length: 144
'     Try Block Offset: 9

注解

MethodBody类提供对方法体中的局部变量和异常处理子句的信息的访问,以及对构成方法体的 Microsoft 中间语言 (MSIL) 的访问。The MethodBody class provides access to information about the local variables and exception-handling clauses in a method body, and to the Microsoft intermediate language (MSIL) that makes up the method body.

您可以使用 module 类的标记解析方法(如 ResolveTypeResolveMethodResolveType )将方法体中的标记解析为 Type 对象、 MethodInfo 对象和 FieldInfo 对象,这些对象提供有关方法体中的 MSIL 访问的类型、方法和字段的详细信息。You can use the token-resolution methods of the module class, such as ResolveType, ResolveMethod, and ResolveType, to resolve the tokens in the method body to Type objects, MethodInfo objects, and FieldInfo objects that provide detailed information about the types, methods, and fields accessed by the MSIL in the method body.

备注

分析方法体需要透彻地了解元数据和 MSIL 指令格式。Parsing method bodies requires a thorough understanding of metadata and MSIL instruction formats. 有关信息,请参阅公共语言基础结构 (CLI) 文档,尤其是 "第二部分:元数据定义和语义" 和 "第三部分: CIL 指令集"。Information can be found in the Common Language Infrastructure (CLI) documentation, especially "Partition II: Metadata Definition and Semantics" and "Partition III: CIL Instruction Set". 可联机获取该文档;请参阅 MSDN 上的 ECMA C# 和公共语言基础结构标准和 Ecma International 网站上的标准 ECMA-335 - 公共语言基础结构 (CLI)The documentation is available online; see ECMA C# and Common Language Infrastructure Standards on MSDN and Standard ECMA-335 - Common Language Infrastructure (CLI) on the Ecma International Web site.

若要获取 MethodBody 给定方法的对象,请首先获取 MethodInfo 该方法的对象,然后调用该 MethodInfo 对象的 GetMethodBody 方法。To obtain a MethodBody object for a given method, first obtain a MethodInfo object for the method, then call the MethodInfo object's GetMethodBody method.

构造函数

MethodBody()

初始化 MethodBody 类的新实例。Initializes a new instance of the MethodBody class.

属性

ExceptionHandlingClauses

获取在方法主体中包含所有异常处理的子句的列表。Gets a list that includes all the exception-handling clauses in the method body.

InitLocals

获取一个值,该值指示方法体中的局部变量是否初始化为相应类型的默认值。Gets a value indicating whether local variables in the method body are initialized to the default values for their types.

LocalSignatureMetadataToken

获取签名的元数据标记,该签名描述元数据中的方法的局部变量。Gets a metadata token for the signature that describes the local variables for the method in metadata.

LocalVariables

获取方法体中声明的局部变量的列表。Gets the list of local variables declared in the method body.

MaxStackSize

执行方法时,获取操作堆栈上的项的最大数目。Gets the maximum number of items on the operand stack when the method is executing.

方法

Equals(Object)

确定指定对象是否等于当前对象。Determines whether the specified object is equal to the current object.

(继承自 Object)
GetHashCode()

作为默认哈希函数。Serves as the default hash function.

(继承自 Object)
GetILAsByteArray()

以字节数组的形式返回用于方法体的 MSIL。Returns the MSIL for the method body, as an array of bytes.

GetType()

获取当前实例的 TypeGets the Type of the current instance.

(继承自 Object)
MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(继承自 Object)
ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(继承自 Object)

适用于