打印流 - 码农教程

通过使用PrintStream实例输出到文件

原有System.out.println 现改为PrintStream类型的实例.println以完成输出到文件

完整代码

package cn.hxh.io.other;

import java.io.*;

public class PrintStreamDemo01 {

	public static void main(String[] args) throws IOException {
		System.out.println("test");
		PrintStream ps = System.out;
		ps.println("111");
		
		File src = new File("D:/aa/a.txt");
		ps = new PrintStream(new BufferedOutputStream(new FileOutputStream(src)), true);
		ps.println("test1");
	}
}

使用System的setOut方法重定向

通过向setOut方法PrintStream实例进行重新定向到文件重新定向到控制台：FileDescriptor.out(将原来的file对象替换为这个)

完整代码

package cn.hxh.io.other;

import java.io.*;
import java.util.*;

public class SystemDemo01 {	

	public static void main(String[] args) throws IOException {
//		Scanner in = new Scanner(new BufferedInputStream(new FileInputStream(new File("D:/aa/a.txt"))));
		System.setOut(new PrintStream(new BufferedOutputStream(new FileOutputStream(new File("d:/aa/a.txt"))), true));
		System.out.println();
		System.out.println("test");
		System.out.println("err");
		System.setOut(new PrintStream(new BufferedOutputStream(new FileOutputStream(FileDescriptor.out)), true));
		System.out.println("err");
	}
	public static void test1() throws IOException {
		Scanner in = new Scanner(new BufferedInputStream(new FileInputStream(new File("D:/aa/a.txt"))));
		System.out.println(in.nextLine());
		System.out.println("test");
		System.err.println("err");
	}
}

将字节流输入转为字符流，运用字符流方法进行操作

完整代码

package cn.hxh.io.other;

import java.io.*;

public class bufferedIn {

	public static void main(String[] args) throws IOException {
		InputStream is = System.in;
		BufferedReader bis = new BufferedReader(new InputStreamReader(is));
		System.out.println(bis.readLine());

	}

}