java例程练习（打印流）

import java.util.*; import java.io.*; //简单的日志功能 public class Test { public static void main(String[] args) { String s = null; BufferedReader br = new BufferedReader ( new InputStreamReader(System.in));//标准输入 try { FileWriter fw = new FileWriter("C:/java/logfile.txt",true); 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(); } } } import java.io.*; //改变输出流的方向 public class Test { public static void main(String[] args) { PrintStream ps = null; try { FileOutputStream fos = new FileOutputStream("C:/java/log.txt"); ps = new PrintStream(fos); } catch (FileNotFoundException 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 Test { public static void main(String[] args) { String filename = args[0]; if(filename != null) { list(filename, System.out);//函数使用方式 } } 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"); } } }