iostreamdemo.java

DES RSA MD5 实现身份认证

//: c11:IOStreamDemo.java
// Typical I/O stream configurations. 

import java.io.*;


public class IOStreamDemo {
	
// Throw exceptions to console:
	
public static void main(String[] args)
throws IOException {
// 1. Reading input by lines: 
	

BufferedReader in =new BufferedReader(new FileReader("IOStreamDemo.java")); 
String s, s2 = new String();
while((s = in.readLine())!= null)
s2 += s + "\n";
in.close();


// 1b. Reading standard input: 
BufferedReader stdin =new BufferedReader(new InputStreamReader(System.in)); 
System.out.print("Enter a line:"); 
System.out.println(stdin.readLine());


// 2. Input from memory
StringReader in2 = new StringReader(s2);
int c;
while((c = in2.read()) != -1) 
	System.out.print((char)c);


// 3. Formatted memory input 
try 
{
DataInputStream in3 =new DataInputStream(new ByteArrayInputStream(s2.getBytes())); 
while(true) 
	System.out.print((char)in3.readByte());

} catch(EOFException e) 

{ 
	System.err.println("End of stream");
}


// 4. File output 
try {
BufferedReader in4 =new BufferedReader(new StringReader(s2)); 
PrintWriter out1 =new PrintWriter(new BufferedWriter(new FileWriter("IODemo.out")));
int lineCount = 1;
while((s = in4.readLine()) != null ) 
	out1.println(lineCount++ + ": " + s); 
out1.close();
} catch(EOFException e) 
{ System.err.println("End of stream");
}


// 5. Storing & recovering data 
try {
DataOutputStream out2 =new DataOutputStream(new BufferedOutputStream(new FileOutputStream("Data.txt"))); 
out2.writeDouble(3.14159); 
out2.writeChars("That was pi\n"); 
out2.writeBytes("That was pi\n");
out2.close();
DataInputStream in5 =new DataInputStream(new BufferedInputStream(new FileInputStream("Data.txt"))); 
BufferedReader in5br =new BufferedReader(new InputStreamReader(in5));

// Must use DataInputStream for data: System.out.println(in5.readDouble());
 

// Can now use the "proper" readLine():
System.out.println(in5br.readLine());
// But the line comes out funny.
// The one created with writeBytes is OK: System.out.println(in5br.readLine());
} catch(EOFException e) { System.err.println("End of stream");
}


// 6. Reading/writing random access files

RandomAccessFile rf=new RandomAccessFile("rtest.dat", "rw");
for(int i = 0; i < 10; i++) rf.writeDouble(i*1.414);
rf.close();


rf =
new RandomAccessFile("rtest.dat", "rw");
rf.seek(5*8); rf.writeDouble(47.0001); rf.close();


rf =new RandomAccessFile("rtest.dat", "r"); 
for(int i = 0; i < 10; i++) 
	System.out.println("Value " + i + ": " +rf.readDouble());

rf.close();

}
}