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");
		}
	}
}