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如何在C＃中读写INI文件

INI文件就是扩展名为“ini”的文件。在Windows系统中，INI文件是很多，最重要的就是“System.ini”、“System32.ini”和“Win.ini”。该文件主要存放用户所做的选择以及系统的各种参数。用户可以通过修改INI文件，来改变应用程序和系统的很多配置。但自从Windows 95的退出，在Windows系统中引入了注册表的概念，INI文件在Windows系统的地位就开始不断下滑，这是因为注册表的独特优点，使应用程序和系统都把许多参数和初始化信息放进了注册表中。但在某些场合，INI文件还拥有其不可替代的地位。本文就来探讨一下C＃是如何对INI进行读写操作。

INI文件的结构

INI文件是一种按照特点方式排列的文本文件。每一个INI文件构成都非常类似，由若干段落（section）组成，在每个带括号的标题下面，是若干个以单个单词开头的关键词（keyword）和一个等号，等号右边的就是关键字对应的值（value）。其一般形式如下：

[Section1]
KeyWord1 = Valuel
KeyWord2 = Value2
　……
[Section2]
KeyWord3 = Value3
KeyWord4 = Value4

本文中介绍的程序设计及运行环境：

  • 微软视窗2000 高级服务器版
  • .Net Framework SDK正式版

C＃和Win32 API函数

C＃并不像C＋＋，拥有属于自己的类库。C＃使用的类库是.Net框架为所有.Net程序开发提供的一个共有的类库——.Net FrameWork SDK。虽然.Net FrameWork SDK内容十分庞大，功能也非常强大，但还不能面面俱到，至少它并没有提供直接操作INI文件所需要的相关的类。在本文中，C＃操作INI文件使用的是Windows系统自带Win32的API函数——WritePrivateProfileString（）和GetPrivateProfileString（）函数。这二个函数都位于“kernel32.dll”文件中。

我们知道在C＃中使用的类库都是托管代码（Managed Code）文件，而Win32的API函数所处的文件，都是非托管代码（Unmanaged Code）文件。这就导致了在C＃中不可能直接使用这些非托管代码文件中的函数。好在.Net框架为了保持对下的兼容，也为了充分利用以前的资源，提出了互操作，通过互操作可以实现对Win32的API函数的调用。互操作不仅适用于Win32的API函数，还可以用来访问托管的COM对象。C＃中对Win32的API函数的互操作是通过命名空间“System.Runtime.InteropServices”中的“DllImport”特征类来实现的。它的主要作用是指示此属性化方法是作为非托管DLL的输出实现的。下面代码就是在C＃利用命名空间“System.Runtime.InteropServices”中的“DllImport”特征类申明上面二个Win32的API函数：

C＃申明INI文件的写操作函数WritePrivateProfileString()：

[DllImport("kernel32")]
private static extern long WritePrivateProfileString(string section ,
                       string key , string val , string filePath) ;

参数说明：section：INI文件中的段落；key：INI文件中的关键字；val：INI文件中关键字的数值；filePath：INI文件的完整的路径和名称。

C＃申明INI文件的读操作函数GetPrivateProfileString()：

[DllImport("kernel32")]
private static extern int GetPrivateProfileString(string section ,
               string key , string def , StringBuilder retVal ,
               int size , string filePath);

参数说明：section：INI文件中的段落名称；key：INI文件中的关键字；def：无法读取时候时候的缺省数值；retVal：读取数值；size：数值的大小；filePath：INI文件的完整路径和名称。

C＃对INI文件进行写操作：

对INI文件进行写操作，是通过组件button2的"Click"事件来实现的。这里有一点应该注意，当在调用WritePrivateProfileString()对INI文件进行写操作的时候，如果此时在INI文件中存在和要写入的信息相同的段落名称和关键字，则将覆盖此INI信息。下面是button2组件的"Click"事件对应的代码清单：

private void button2_Click(object sender , System.EventArgs e)
{
    string FileName = textBox1.Text;
    string section = textBox2.Text;
    string key = textBox3.Text;
    string keyValue = textBox4.Text;
    WritePrivateProfileString(section , key , keyValue , FileName);
    MessageBox.Show("成功写入INI文件！" , "信息");
}

C＃对INI文件进行读操作：

正确读取INI的必须满足三个前提：INI文件的全路径、段落名称和关键字名称。否则就无法正确读取。你可以设定读取不成功后的缺省数值，在下面的程序中，为了直观设定的是“无法读取对应数值！”字符串，读取INI文件是通过button3组件的“Click”事件来实现的，下面是其对应的代码清单：

private void button3_Click(object sender , System.EventArgs e)
{
    StringBuilder temp = new StringBuilder(255);
    string FileName = textBox1.Text ;
    string section = textBox2.Text ;
    string key = textBox3.Text ;
    int i = GetPrivateProfileString(section , key ,"无法读取对应数值！", temp , 255 , FileName);
    //显示读取的数值
    textBox4.Text = temp.ToString();
}

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Runtime.InteropServices;
using System.Text;
using static System.Net.Mime.MediaTypeNames;

namespace C_操作INI文件__写操作
{
    public class Form1 : System.Windows.Forms.Form
    {
        private System.Windows.Forms.Button button1;
        private System.Windows.Forms.TextBox textBox1;
        private System.Windows.Forms.Button button2;
        private System.Windows.Forms.TextBox textBox2;
        private System.Windows.Forms.TextBox textBox3;
        private System.Windows.Forms.TextBox textBox4;
        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.Label label2;
        private System.Windows.Forms.Label label3;
        private System.Windows.Forms.Button button3;
        private System.Windows.Forms.OpenFileDialog openFileDialog1;
        private System.ComponentModel.Container components = null;

        public Form1()
        {
            InitializeComponent();
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (components != null)
                {
                    components.Dispose();
                }
            }
            base.Dispose(disposing);
        }

        [DllImport("kernel32")]
        private static extern long WritePrivateProfileString(string section,
                string key, string val, string filePath);

        [DllImport("kernel32")]
        private static extern int GetPrivateProfileString(string section,
                string key, string def, StringBuilder retVal,
                int size, string filePath);

        private void InitializeComponent()
        {
            this.button1 = new System.Windows.Forms.Button();
            this.textBox1 = new System.Windows.Forms.TextBox();
            this.button2 = new System.Windows.Forms.Button();
            this.textBox2 = new System.Windows.Forms.TextBox();
            this.textBox3 = new System.Windows.Forms.TextBox();
            this.textBox4 = new System.Windows.Forms.TextBox();
            this.label1 = new System.Windows.Forms.Label();
            this.label2 = new System.Windows.Forms.Label();
            this.label3 = new System.Windows.Forms.Label();
            this.button3 = new System.Windows.Forms.Button();
            this.openFileDialog1 = new System.Windows.Forms.OpenFileDialog();
            this.SuspendLayout();
            this.button1.FlatStyle = System.Windows.Forms.FlatStyle.Flat;
            this.button1.Location = new System.Drawing.Point(238, 20);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(100, 32);
            this.button1.TabIndex = 0;
            this.button1.Text = "选择INI文件";
            this.button1.Click += new System.EventHandler(this.button1_Click);
            this.textBox1.Location = new System.Drawing.Point(58, 22);
            this.textBox1.Name = "textBox1";
            this.textBox1.Size = new System.Drawing.Size(162, 21);
            this.textBox1.TabIndex = 1;
            this.textBox1.Text = "";
            this.button2.FlatStyle = System.Windows.Forms.FlatStyle.Flat;
            this.button2.Location = new System.Drawing.Point(86, 168);
            this.button2.Name = "button2";
            this.button2.Size = new System.Drawing.Size(98, 30);
            this.button2.TabIndex = 3;
            this.button2.Text = "写入INI文件";
            this.button2.Click += new System.EventHandler(this.button2_Click);
            this.textBox2.Location = new System.Drawing.Point(160, 62);
            this.textBox2.Name = "textBox2";
            this.textBox2.Size = new System.Drawing.Size(176, 21);
            this.textBox2.TabIndex = 5;
            this.textBox2.Text = "";
            this.textBox3.Location = new System.Drawing.Point(160, 94);
            this.textBox3.Name = "textBox3";
            this.textBox3.Size = new System.Drawing.Size(176, 21);
            this.textBox3.TabIndex = 6;
            this.textBox3.Text = "";
            this.textBox4.Location = new System.Drawing.Point(160, 128);
            this.textBox4.Name = "textBox4";
            this.textBox4.Size = new System.Drawing.Size(176, 21);
            this.textBox4.TabIndex = 7;
            this.textBox4.Text = "";
            this.label1.Location = new System.Drawing.Point(56, 62);
            this.label1.Name = "label1";
            this.label1.TabIndex = 8;
            this.label1.Text = "段落名称：";
            this.label2.Location = new System.Drawing.Point(66, 96);
            this.label2.Name = "label2";
            this.label2.TabIndex = 9;
            this.label2.Text = "关键字：";
            this.label3.Location = new System.Drawing.Point(42, 130);
            this.label3.Name = "label3";
            this.label3.TabIndex = 10;
            this.label3.Text = "关键字数值：";
            this.button3.FlatStyle = System.Windows.Forms.FlatStyle.Flat;
            this.button3.Location = new System.Drawing.Point(208, 168);
            this.button3.Name = "button3";
            this.button3.Size = new System.Drawing.Size(98, 30);
            this.button3.TabIndex = 11;
            this.button3.Text = "读取INI数值";
            this.button3.Click += new System.EventHandler(this.button3_Click);
            this.openFileDialog1.Filter = "INI 文件|*.ini";
            this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
            this.ClientSize = new System.Drawing.Size(366, 217);
            this.Controls.AddRange(new System.Windows.Forms.Control[] {
                 this.button3 ,
                 this.textBox4 ,
                 this.textBox3 ,
                 this.textBox2 ,
                 this.button2 ,
                 this.textBox1 ,
                 this.button1 ,
                 this.label3 ,
                 this.label2 ,
                 this.label1 });
            this.MaximizeBox = false;
            this.Name = "Form1";
            this.Text = "C＃操作INI文件--写操作";
            this.ResumeLayout(false);
        }

        [STAThread]
        static void Main()
        {
            Application.Run(new Form1());
        }

        private void button1_Click(object sender, System.EventArgs e)
        {
            openFileDialog1.ShowDialog();
            textBox1.Text = openFileDialog1.FileName;
        }

        //写入INI文件
        private void button2_Click(object sender, System.EventArgs e)
        {
            string FileName = textBox1.Text;
            string section = textBox2.Text;
            string key = textBox3.Text;
            string keyValue = textBox4.Text;
            WritePrivateProfileString(section, key, keyValue, FileName);
            MessageBox.Show("成功写入INI文件！", "信息");
        }

        //读取指定INI文件的特定段落中的关键字的数值
        private void button3_Click(object sender, System.EventArgs e)
        {
            this.Controls.AddRange(new System.Windows.Forms.Control[] {
                 this.button3 ,
                 this.textBox4 ,
                 this.textBox3 ,
                 this.textBox2 ,
                 this.button2 ,
                 this.textBox1 ,
                 this.button1 ,
                 this.label3 ,
                 this.label2 ,
                 this.label1 });
            this.MaximizeBox = false;
            this.Name = "Form1";
            this.Text = "C＃操作INI文件--写操作";
            this.ResumeLayout(false);
        }

        [STAThread]
        static void Main()
        {
            Application.Run(new Form1());
        }

        private void button1_Click(object sender, System.EventArgs e)
        {
            openFileDialog1.ShowDialog();
            textBox1.Text = openFileDialog1.FileName;
        }

        //写入INI文件
        private void button2_Click(object sender, System.EventArgs e)
        {
            string FileName = textBox1.Text;
            string section = textBox2.Text;
            string key = textBox3.Text;
            string keyValue = textBox4.Text;
            WritePrivateProfileString(section, key, keyValue, FileName);
            MessageBox.Show("成功写入INI文件！", "信息");
        }

        //读取指定INI文件的特定段落中的关键字的数值
        private void button3_Click(object sender, System.EventArgs e)
        {
            StringBuilder temp = new StringBuilder(255);
            string FileName = textBox1.Text;
            string section = textBox2.Text;
            string key = textBox3.Text;
            int i = GetPrivateProfileString(section, key, "无法读取对应数值！", emp, 255, FileName);
            //显示读取的数值
            textBox4.Text = temp.ToString();
        }
    }
}

下图是ini.cs编译后的运行界面：

img_1

总结

通过上面的这些介绍，可以看成C＃操作INI文件的过程，其实就是C＃调用Win32的API函数的过程。掌握了如何在C＃申明Win32的API函数，再来操作INI就显得非常简单。

Contributors: FHL