C# 温故而知新：Stream篇（三）

//有关数字格式化隐性使用IFomatProvider的例子
#if true
            //货币
            Console.WriteLine(string.Format("显示货币格式{0:c3}",12));
            //十进制
            Console.WriteLine("显示货币十进制格式{0:d10}", 12);
            //科学计数法
            Console.WriteLine("科学计数法{0:e5}",12);
            //固定点格式
            Console.WriteLine("固定点格式 {0:f10}",12);
            //常规格式
            Console.WriteLine("常规格式{0:g10}",12);
            //数字格式(用分号隔开)
            Console.WriteLine("数字格式 {0:n5}:",666666666);
            //百分号格式
            Console.WriteLine("百分号格式(不保留小数){0:p0}",0.55);
            //16进制
            Console.WriteLine("16进制{0:x0}", 12);
           // 0定位器  此示例保留5位小数，如果小数部分小于5位，用0填充
            Console.WriteLine("0定位器{0:000.00000}",1222.133);
            //数字定位器
            Console.WriteLine("数字定位器{0:(#).###}", 0200.0233000);
             //小数
            Console.WriteLine("小数保留一位{0:0.0}", 12.222);
            //百分号的另一种写法，注意小数的四舍五入
            Console.WriteLine("百分号的另一种写法，注意小数的四舍五入{0:0%.00}", 0.12345);
            Console.WriteLine("nn");
 #endif

#if true
            //显性使用IFomatProvider
            Console.WriteLine("显性使用IFomatProvider的例子");
            //实例化numberFomatProvider对象
            NumberFormatInfo numberFomatProvider = new NumberFormatInfo();
            //设置该provider对于货币小数的显示长度
            numberFomatProvider.CurrencyDecimalDigits = 10;
            //注意：我们可以使用C+数字形式来改变provider提供的格式
            Console.WriteLine(string.Format(numberFomatProvider, "provider设置的货币格式{0:C}", 12));
            Console.WriteLine(string.Format(numberFomatProvider, "provider设置的货币格式被更改了：{0:C2}", 12));
            Console.WriteLine(string.Format(numberFomatProvider, "默认百分号和小数形式{0:p2}", 0.12));
            //将小数 “.”换成"?" 
             numberFomatProvider.PercentDecimalSeparator = "?";
             Console.WriteLine(string.Format(numberFomatProvider, "provider设置的百分号和小数形式{0:p2}", 0.12));
            Console.ReadLine();
#endif

const string txtFilePath = "D:\TextWriter.txt";


        static void Main(string[] args)
        {


            NumberFormatInfo numberFomatProvider = new NumberFormatInfo();
            //将小数 “.”换成"?" 
            numberFomatProvider.PercentDecimalSeparator = "?";
            StreamWriterTest test = new StreamWriterTest(Encoding.Default, txtFilePath, numberFomatProvider);
            //StreamWriter
            test.WriteSomthingToFile();
            //TextWriter
            test.WriteSomthingToFileByUsingTextWriter();
            Console.ReadLine();
        }
    }


    /// <summary>
    ///  TextWriter和StreamWriter的举例
    /// </summary>
    public class StreamWriterTest
    {
        /// <summary>
        /// 编码
        /// </summary>
        private Encoding _encoding;


        /// <summary>
        /// IFomatProvider
        /// </summary>
        private IFormatProvider _provider;


        /// <summary>
        /// 文件路径
        /// </summary>
        private string _textFilePath;




        public StreamWriterTest(Encoding encoding, string textFilePath)
            : this(encoding, textFilePath, null)
        {


        }


        public StreamWriterTest(Encoding encoding, string textFilePath, IFormatProvider provider)
        {
            this._encoding = encoding;
            this._textFilePath = textFilePath;
            this._provider = provider;
        }


        /// <summary>
        ///  我们可以通过FileStream 或者 文件路径直接对该文件进行写操作
        /// </summary>
        public void WriteSomthingToFile()
        {
            //获取FileStream
            using (FileStream stream = File.OpenWrite(_textFilePath))
            {
                //获取StreamWriter
                using (StreamWriter writer = new StreamWriter(stream, this._encoding))
                {
                    this.WriteSomthingToFile(writer);
                }


                //也可以通过文件路径和设置bool append，编码和缓冲区来构建一个StreamWriter对象
                using (StreamWriter writer = new StreamWriter(_textFilePath, true, this._encoding, 20))
                {
                    this.WriteSomthingToFile(writer);
                }
            }
        }


        /// <summary>
        ///  具体写入文件的逻辑
        /// </summary>
        /// <param name="writer">StreamWriter对象</param>
        public void WriteSomthingToFile(StreamWriter writer)
        {
            //需要写入的数据
            string[] writeMethodOverloadType =
           {
              "1.Write(bool);",
              "2.Write(char);",
              "3.Write(Char[])",
              "4.Write(Decimal)",
              "5.Write(Double)",
              "6.Write(Int32)",
              "7.Write(Int64)",
              "8.Write(Object)",
              "9.Write(Char[])",
              "10.Write(Single)",
              "11.Write(Char[])",
              "12.Write(String)",
              "13Write(UInt32)",
              "14.Write(string format,obj)",
              "15.Write(Char[])"
           };


            //定义writer的AutoFlush属性，如果定义了该属性，就不必使用writer.Flush方法
            writer.AutoFlush = true;
            writer.WriteLine("这个StreamWriter使用了{0}编码", writer.Encoding.HeaderName);
            //这里重新定位流的位置会导致一系列的问题
            //writer.BaseStream.Seek(1, SeekOrigin.Current);
            writer.WriteLine("这里简单演示下StreamWriter.Writer方法的各种重载版本");


            writeMethodOverloadType.ToList().ForEach
                (
                    (name) => { writer.WriteLine(name); }
                );
            writer.WriteLine("StreamWriter.WriteLine()方法就是在加上行结束符，其余和上述方法是用一致");
            //writer.Flush();
            writer.Close();
        }
 
        public void WriteSomthingToFileByUsingTextWriter()
        {
            using (TextWriter writer = new StringWriter(_provider))
            {
                writer.WriteLine("这里简单介绍下TextWriter 怎么使用用户设置的IFomatProvider，假设用户设置了NumberFormatInfoz.PercentDecimalSeparator属性");
                writer.WriteLine("看下区别吧 {0:p10}", 0.12);
                Console.WriteLine(writer.ToString());
                writer.Flush();
                writer.Close();
            }


        }
    }