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JAVA I/O有那么多的类，平时该怎么用啊？
请举例说明！！！
package myprojects.fileio;
import java.io.FileReader;
public class FileIO {
public FileIO() {
}
public void getFileStrings() {
try {
char[] b= new char[100];
FileReader fr = new FileReader("c:/abc.txt");
fr.read(b) ;
System.out.println(b);
//fr.read(b, 1, 100);
} catch (Exception e) {
}
}
public static void main(String args[]) {
System.out.println("Starting FileIO...");
FileIO FileIO1 = new FileIO();
FileIO1.getFileStrings();
}
}
我认为比较经典的一个I/O的例子,着重看关于IO的代码
//: c12:IOStreamDemo.java
// Typical I/O stream configurations.
// {RunByHand}
// {Clean: IODemo.out,Data.txt,rtest.dat}
import com.bruceeckel.simpletest.*;
import java.io.*;
public class IOStreamDemo {
private static Test monitor = new Test();
// 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.writeUTF("That was pi");
out2.writeDouble(1.41413);
out2.writeUTF("Square root of 2");
out2.close();
DataInputStream in5 = new DataInputStream(
new BufferedInputStream(
new FileInputStream("Data.txt")));
// Must use DataInputStream for data:
System.out.println(in5.readDouble());
// Only readUTF() will recover the
// Java-UTF String properly:
System.out.println(in5.readUTF());
// Read the following double and String:
System.out.println(in5.readDouble());
System.out.println(in5.readUTF());
} catch(EOFException e) {
throw new RuntimeException(e);
}
// 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();
monitor.expect("IOStreamDemo.out");
}
} ///:~
