IO之Print流举例

import java.io.*;
public class TestPrintStream1 { 
  public static void main(String[] args) {
    PrintStream ps = null;
    try {
      FileOutputStream fos = 
              new FileOutputStream("d:\bak\log.dat");
      ps = new PrintStream(fos);
    } catch (IOException e) {
      e.printStackTrace();
    }
    if(ps != null){
      System.setOut(ps);
    }
    int ln = 0;
    for(char c = 0; c <= 60000; c++){
      System.out.print(c+ " ");
      if(ln++ >=100){ System.out.println(); ln = 0;}
    }
  }
}

import java.io.*;
public class TestPrintStream2 {
  public static void main(String[] args) {
    String filename = args[0];
    if(filename!=null){list(filename,System.out);}
  }
  public static void list(String f,PrintStream fs){
    try {
      BufferedReader br = 
                  new BufferedReader(new FileReader(f));
      String s = null; 
      while((s=br.readLine())!=null){
        fs.println(s);            
      }
      br.close();
    } catch (IOException e) {
      fs.println("无法读取文件");
    }
  }
}

import java.util.*; 
import java.io.*;
public class TestPrintStream3 {
  public static void main(String[] args) {
    String s = null;
    BufferedReader br = new BufferedReader(
                        new InputStreamReader(System.in));
    try {
      FileWriter fw = new FileWriter
                           ("d:\bak\logfile.log", true); //Log4J
      PrintWriter log = new PrintWriter(fw);
      while ((s = br.readLine())!=null) {
        if(s.equalsIgnoreCase("exit")) break;
        System.out.println(s.toUpperCase());
        log.println("-----");
        log.println(s.toUpperCase()); 
        log.flush();
      }
      log.println("==="+new Date()+"==="); 
      log.flush();
      log.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}