FileStream、StreamReader、StreamWriter的使用及区别

 1         private void button1_Click(object sender, EventArgs e)
 2         {
 3             //FileStream可以读写任何文件，SteamReader、SteamWriter只适合读写文本文件
 4 
 5             using (FileStream fs = new FileStream("test.txt", FileMode.OpenOrCreate, FileAccess.Read))
 6             {
 7                 byte[] buffer = new byte[1024 * 1024];//Filestream读取、写入时需要以字节数组形式。
 8                 string ct = "";
 9                 while (true)//大的文件需要分几次读取，所以需要循环读取
10                 {
11                     int a = fs.Read(buffer, 0, buffer.Length);
12                     
13                     ct += Encoding.Unicode.GetString(buffer);
14                     if (a == 0)
15                     {
16                         break;
17                     }
18                 }
19                 textBox1.Text = ct;
20             }
21 
22 
23         }
24 
25         private void button2_Click(object sender, EventArgs e)
26         {
27             
28             //把文件test.pdf复制为test1.pdf
29             using (FileStream fsread = new FileStream("test.pdf", FileMode.OpenOrCreate, FileAccess.Read))
30             {
31                 using (FileStream fswriter = new FileStream("test1.pdf", FileMode.Create, FileAccess.Write))
32                 {
33                     byte[] bytes = new byte[1024 * 1024];
34                     while (true)
35                     {
36                         int a = fsread.Read(bytes, 0, bytes.Length);
37                         fswriter.Write(bytes, 0, a);
38                         if(a==0)
39                         {
40                         break ;
41                         }
42                     }
43                 }
44             }
45             MessageBox.Show("复制成功");
46         }
47 
48         private void button_sr_Click(object sender, EventArgs e)
49         {
50             string readers = "";
51             using (StreamReader sr = new StreamReader("test.txt", Encoding.Default))
52             {
53                 char [] buffer=new char [2014*2014];//准备一个char数组作为容器
54                 while (true )//当文本太多，一次没有读完，一直读取
55                 {
56                     int a = sr.Read(buffer, 0, buffer.Length);
57                     if(a==0)
58                     {break ;}
59                     readers += new string(buffer);//重新把char数组转换成文本
60                 }
61                 
62             }
63             textBox1.Text = readers;
64         }
65 
66         private void button_sw_Click(object sender, EventArgs e)
67         {
68             using (StreamReader sr=new StreamReader ("test.txt",Encoding .Default) )
69             {
70             using (StreamWriter sw=new StreamWriter ("test2.txt",false ,Encoding .Default))
71             {
72                 
73                 while (sr.Peek ()>=0)//用些方法判断是否读到了文件尾，不过好像会丢失空文本。
74                 {
75                    string a=  sr.ReadLine();
76 
77                    sw.WriteLine(a);
78                 }
79                 
80             }
81 
82             }
83         }