java io 学习笔记

使用缓冲读写

import java.io.*;
class BufferIo
{
	public static void main(String[] args) throws IOException
	{
		FileWriter fw = new FileWriter("demoBuffer.txt");
		BufferedWriter bfw = new BufferedWriter(fw);
		for(int x=0;x<5;x++)
		{
			bfw.write("abc"+x);
			bfw.newLine();
			bfw.flush();
		}
		bfw.close();
		bufferRead();
	}
	
	public static void bufferRead() throws IOException
	{
		FileReader fr = new FileReader("demoBuffer.txt");
		BufferedReader br = new BufferedReader(fr);
		String str = "";
		while((str = br.readLine())!=null){ //读一行，如果不存在则返回null
			System.out.println(str);
		}
		br.close(); //只需关闭缓冲区
	}
}

使用缓冲复制文件

import java.io.*;
class CopyBuffer 
{
	public static void main(String[] args)
	{
		BufferedReader br = null;
		BufferedWriter bw = null;
		try{
			br = new BufferedReader(new FileReader("bufferIo.java"));
			bw = new BufferedWriter(new FileWriter("copy_bufferIo.txt"));
			String line = null;
			while((line = br.readLine()) != null){
				bw.write(line);
				bw.newLine();
				bw.flush();
			}
		}catch(IOException e){
			throw new RuntimeException("读写失败");
		}finally{
			try{
				if(br != null){
					br.close();
				}
			}catch(IOException e){
				throw new RuntimeException("关闭读流失败");
			}
			try{
				if(bw != null){
					bw.close();
				}
			}catch(IOException e){
				throw new RuntimeException("关闭写流失败");
			}
		}

	}
}