java.se.io.12.关于标准输出输入流

package com.knock.io;import java.io.BufferedInputStream;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.PrintStream;import java.util.Scanner;import org.junit.Test;/** * @date 160803am * printStream类 *  * */public class KmPrint {/* * 打印流的三个常量in,out,err * 可以通过setIn,setOut等方法对其进行重定向 * */@Testpublic void test(){PrintStream ps = System.out;//属性out的类型就是PrintStreamps.println("i m shadow u r light");}@Testpublic void test2(){//改变输出位置（重定向）,相似地，封装一下就是一个日志工具try {System.setOut(new PrintStream(new FileOutputStream("E:/test/a.txt"),true));System.out.println("i m shadow u r light");System.out.println("i m shadow u r light");System.out.println("i m shadow u r light");System.out.println("i m shadow u r light");System.out.println("i m shadow u r light");} catch (FileNotFoundException e) {e.printStackTrace();}}@Testpublic void test3(){/*Scanner scan = new Scanner(System.in);System.out.println("please input:");System.out.println(scan.nextLine());*//* * Scanner类应是一个装饰模式的处理流 * 往里面丢一个输入流，实现从文档输入 * */try {Scanner scan = new Scanner(new BufferedInputStream(new FileInputStream("D:/test/a.txt")));System.out.println(scan.nextLine());} catch (FileNotFoundException e) {e.printStackTrace();}}}