ITask 接口

定义

此接口定义生成系统中的 "任务"。This interface defines a "task" in the build system. 任务是生成操作的原子单元。A task is an atomic unit of build operation. 所有任务类都必须实现此接口,才能由生成引擎识别。All task classes must implement this interface to be recognized by the build engine.

public interface class ITask
public interface ITask
type ITask = interface
Public Interface ITask
派生

示例

下面的示例演示了完整任务实现中的代码。The following example shows the code from a complete task implementation.

using System;
using System.IO;
using System.Security;
using System.Collections;
using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

namespace Microsoft.Build.Tasks
{
    /*
     * Class: MakeDir
     *
     * An MSBuild task that creates one or more directories.
     *
     */
    public class MakeDir : Task
    {
        // The Required attribute indicates the following to MSBuild:
        //	     - if the parameter is a scalar type, and it is not supplied, fail the build immediately
        //	     - if the parameter is an array type, and it is not supplied, pass in an empty array
        // In this case the parameter is an array type, so if a project fails to pass in a value for the
            // Directories parameter, the task will get invoked, but this implementation will do nothing,
            // because the array will be empty.
        [Required]
            // Directories to create.
        public ITaskItem[] Directories
        {
            get
            {
                return directories;
            }

            set
            {
                directories = value;
            }
        }

        // The Output attribute indicates to MSBuild that the value of this property can be gathered after the
        // task has returned from Execute(), if the project has an <Output> tag under this task's element for
        // this property.
        [Output]
        // A project may need the subset of the inputs that were actually created, so make that available here.
        public ITaskItem[] DirectoriesCreated
        {
            get
            {
                return directoriesCreated;
            }
        }

        private ITaskItem[] directories;
        private ITaskItem[] directoriesCreated;

        /// <summary>
        /// Execute is part of the Microsoft.Build.Framework.ITask interface.
        /// When it's called, any input parameters have already been set on the task's properties.
        /// It returns true or false to indicate success or failure.
        /// </summary>
        public override bool Execute()
        {
            ArrayList items = new ArrayList();
            foreach (ITaskItem directory in Directories)
            {
                // ItemSpec holds the filename or path of an Item
                if (directory.ItemSpec.Length > 0)
                {
                    try
                    {
                        // Only log a message if we actually need to create the folder
                        if (!Directory.Exists(directory.ItemSpec))
                        {
                            Log.LogMessage(MessageImportance.Normal, "Creating directory " + directory.ItemSpec);
                            Directory.CreateDirectory(directory.ItemSpec);
                        }

                        // Add to the list of created directories
                        items.Add(directory);
                    }
                    // If a directory fails to get created, log an error, but proceed with the remaining
                    // directories.
                    catch (Exception ex)
                    {
                        if (ex is IOException
                            || ex is UnauthorizedAccessException
                            || ex is PathTooLongException
                            || ex is DirectoryNotFoundException
                            || ex is SecurityException)
                        {
                            Log.LogError("Error trying to create directory " + directory.ItemSpec + ". " + ex.Message);
                        }
                        else
                        {
                            throw;
                        }
                    }
                }
            }

            // Populate the "DirectoriesCreated" output items.
            directoriesCreated = (ITaskItem[])items.ToArray(typeof(ITaskItem));

            // Log.HasLoggedErrors is true if the task logged any errors -- even if they were logged
            // from a task's constructor or property setter. As long as this task is written to always log an error
            // when it fails, we can reliably return HasLoggedErrors.
            return !Log.HasLoggedErrors;
        }
    }
}

注解

所有任务类都必须实现此接口,才能由生成引擎识别。All task classes must implement this interface to be recognized by the build engine. 你还可以从帮助器类派生类, Task 它提供某些成员的默认实现,而不是直接实现此接口 ITaskInstead of implementing this interface directly, you can also derive your class from the helper class, Task, which provides default implementations of some ITask members.

属性

BuildEngine

此属性由生成引擎设置为允许任务回调到其中。This property is set by the build engine to allow a task to call back into it.

HostObject

如果主机 IDE 具有与此特定任务关联的主机对象,则生成引擎会设置此属性。The build engine sets this property if the host IDE has associated a host object with this particular task.

方法

Execute()

此方法由生成引擎调用以开始执行任务。This method is called by the build engine to begin task execution. 任务使用返回值来指示是否成功。A task uses the return value to indicate whether it was successful. 如果任务在此方法中引发异常,则引擎将自动假定任务已失败。If a task throws an exception out of this method, the engine will automatically assume that the task has failed.

适用于