毕向东_Java基础视频教程第19天_IO流（01~03）

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;

/*
缓冲区是为了提高流的操作效率而出现的,

所以在创建缓冲区之前,必须要先有流对象.

该缓冲区中提供了一个跨平台的换行符：newLine();
*/

public class BufferedWriterDemo {
    public static void main(String[] args) throws IOException {
        FileWriter fw = new FileWriter("buf.txt");
        BufferedWriter bufw = new BufferedWriter(fw);

        for (int x = 1; x < 5; x++) {
            bufw.write("abcde" + x);
            bufw.newLine();
        }

        bufw.flush();   //记住,只要用到缓冲区,就要记得刷新

        bufw.close();   //关闭缓冲区,就是在关闭缓冲区中的流对象
    }
}

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

/*
字符读取流缓冲区：该缓冲区提供一个一次读一行的readLine，方便对于对文本数据的获取。
返回包含该行内容的字符串,不包含任何行终止符。如果已达到流末尾，则返回null。
*/
public class BufferedReaderDemo {
    public static void main(String[] args) throws IOException {
        FileReader fr = new FileReader("buf.txt");
        BufferedReader bufr = new BufferedReader(fr);

        String line;
        while ((line = bufr.readLine()) != null) {
            System.out.println(line);
        }
    }
}

import java.io.*;

public class CopyTextByBuf {
    public static void main(String[] args) throws IOException {
        BufferedReader bufr = null;
        BufferedWriter bufw = null;

        try {
            bufr = new BufferedReader(new FileReader("buf.txt"));
            bufw = new BufferedWriter(new FileWriter("buf_Copy.txt"));

            String line;
            while ((line = bufr.readLine()) != null) {
                bufw.write(line);
                bufw.newLine();    //readLine()返回包含该行内容的字符串,不包含任何行终止符。所以需要插入newLine()
                bufw.flush();
            }
        } catch (IOException e) {
            throw new RuntimeException("读写失败");
        } finally {
            try {
                if (bufr != null) {
                    bufr.close();
                }
            } catch (IOException e) {
                throw new RuntimeException("读取关闭失败");
            }

            try {
                if (bufw != null) {
                    bufw.close();
                }
            } catch (IOException e) {
                throw new RuntimeException("写入关闭失败");
            }
        }
    }
}