iodemo.out

thinking in Java书中 的源代码

1: //: c11:IOStreamDemo.java
2: // From 'Thinking in Java, 2nd ed.' by Bruce Eckel
3: // www.BruceEckel.com. See copyright notice in CopyRight.txt.
4: // Typical I/O stream configurations.
5: import java.io.*;
6: 
7: public class IOStreamDemo {
8:   // Throw exceptions to console:
9:   public static void main(String[] args) 
10:   throws IOException {
11:     // 1. Reading input by lines:
12:     BufferedReader in =
13:       new BufferedReader(
14:         new FileReader("IOStreamDemo.java"));
15:     String s, s2 = new String();
16:     while((s = in.readLine())!= null)
17:       s2 += s + "\n";
18:     in.close();
19: 
20:     // 1b. Reading standard input:
21:     BufferedReader stdin =
22:       new BufferedReader(
23:         new InputStreamReader(System.in));      
24:     System.out.print("Enter a line:");
25:     System.out.println(stdin.readLine());
26: 
27:     // 2. Input from memory
28:     StringReader in2 = new StringReader(s2);
29:     int c;
30:     while((c = in2.read()) != -1)
31:       System.out.print((char)c);
32: 
33:     // 3. Formatted memory input
34:     try {
35:       DataInputStream in3 =
36:         new DataInputStream(
37:           new ByteArrayInputStream(s2.getBytes()));
38:       while(true)
39:         System.out.print((char)in3.readByte());
40:     } catch(EOFException e) {
41:       System.err.println("End of stream");
42:     }
43: 
44:     // 4. File output
45:     try {
46:       BufferedReader in4 =
47:         new BufferedReader(
48:           new StringReader(s2));
49:       PrintWriter out1 =
50:         new PrintWriter(
51:           new BufferedWriter(
52:             new FileWriter("IODemo.out")));
53:       int lineCount = 1;
54:       while((s = in4.readLine()) != null )
55:         out1.println(lineCount++ + ": " + s);
56:       out1.close();
57:     } catch(EOFException e) {
58:       System.err.println("End of stream");
59:     }
60: 
61:     // 5. Storing & recovering data
62:     try {
63:       DataOutputStream out2 =
64:         new DataOutputStream(
65:           new BufferedOutputStream(
66:             new FileOutputStream("Data.txt")));
67:       out2.writeDouble(3.14159);
68:       out2.writeChars("That was pi\n");
69:       out2.writeBytes("That was pi\n");
70:       out2.close();
71:       DataInputStream in5 =
72:         new DataInputStream(
73:           new BufferedInputStream(
74:             new FileInputStream("Data.txt")));
75:       BufferedReader in5br =
76:         new BufferedReader(
77:           new InputStreamReader(in5));
78:       // Must use DataInputStream for data:
79:       System.out.println(in5.readDouble());
80:       // Can now use the "proper" readLine():
81:       System.out.println(in5br.readLine());
82:       // But the line comes out funny.
83:       // The one created with writeBytes is OK:
84:       System.out.println(in5br.readLine());
85:     } catch(EOFException e) {
86:       System.err.println("End of stream");
87:     }
88: 
89:     // 6. Reading/writing random access files
90:     RandomAccessFile rf =
91:       new RandomAccessFile("rtest.dat", "rw");
92:     for(int i = 0; i < 10; i++)
93:       rf.writeDouble(i*1.414);
94:     rf.close();
95: 
96:     rf =
97:       new RandomAccessFile("rtest.dat", "rw");
98:     rf.seek(5*8);
99:     rf.writeDouble(47.0001);
100:     rf.close();
101: 
102:     rf =
103:       new RandomAccessFile("rtest.dat", "r");
104:     for(int i = 0; i < 10; i++)
105:       System.out.println(
106:         "Value " + i + ": " +
107:         rf.readDouble());
108:     rf.close();
109:   }
110: } ///:~