c# - 未在 Task.Factory.StartNew() 中创建日志文件

Question

对于以下示例代码，我没有看到在 C: 驱动器中创建的日志文件“ParallelLog.txt”。 (为大量代码道歉!)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.IO;

namespace Logger
{
    internal class Program
    {
        static List<Employee> employees = new List<Employee>()
        {
            new Employee{Name = "William", Age=30, RollNo=1234},
            new Employee{Name = "Martin", Age=29, RollNo=1235},
            new Employee{Name = "Richard", Age=28, RollNo=1236},
            new Employee{Name = "Baldwin", Age=27, RollNo=1237}
        };

        static void Main(string[] args)
        {
            Task task = Task.Factory.StartNew(() =>
            {
                foreach (Employee employee in employees.AsParallel().AsOrdered())
                {
                    WriteToLog(employee);
                }
            });
        }

        public static void WriteToLog(Employee employee)
        {            
            static string fileName = @"C:\ParallelLog.txt";
            private static object lockObject = new object();

            lock (lockObject)
            {
                StreamWriter writer = new StreamWriter(fileName, true);
                writer.WriteLine("{0} - {1} - {2}", employee.Name, employee.Age, employee.RollNo);
                writer.Close();
                writer.Dispose();
                writer = null;
            }
        }
    }

    internal class Employee
    {
        public int Age { get; set; }
        public string Name { get; set; }
        public int RollNo { get; set; }
    } 
}

我上面的代码有问题吗？此示例是我实际项目的日志文件创建过程的基础。

Answer 1

试试下面的代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.IO;

namespace Logger
{
    internal class Program
    {
        static List<Employee> employees = new List<Employee>()
        {
            new Employee{Name = "William", Age=30, RollNo=1234},
            new Employee{Name = "Martin", Age=29, RollNo=1235},
            new Employee{Name = "Richard", Age=28, RollNo=1236},
            new Employee{Name = "Baldwin", Age=27, RollNo=1237}
        };

        static void Main(string[] args)
        {
            Task task = Task.Factory.StartNew(() =>
            {
                WriteToLog();
            });
        }

        public static void WriteToLog()
        {            
            static string fileName = @"C:\ParallelLog.txt";
            using (StreamWriter writer = new StreamWriter(fileName, true))
            {
                foreach (Employee employee in employees.AsParallel().AsOrdered())
                    writer.WriteLine("{0} - {1} - {2}", employee.Name, employee.Age, employee.RollNo);
            }
        }
    }

    internal class Employee
    {
        public int Age { get; set; }
        public string Name { get; set; }
        public int RollNo { get; set; }
    } 
}

在这种情况下，不需要使用锁。这会将 StreamWriter 对象的连续实例化为一个。在这里您不必担心管理，因为这是由 using 关键字处理的。请看MSDN有关使用 StreamWriter 类的推荐方法。

希望对您有所帮助。