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
* */
@Test
public void test(){
PrintStream ps = System.out;//属性out的类型就是PrintStream
ps.println("i m shadow u r light");
}

@Test
public 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();
}
}

@Test
public 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();
}
}
}