BufferedReader的实现

import java.io.*;

public class MyBufferedReader {
	private FileReader fr;
	MyBufferedReader(FileReader fr)
	{
		this.fr = fr;
	}
	
	//可以一次性读一行数据的方法
	public String myReadLine() throws IOException
	{
		//定义一个临时容器。原BufferReader封装的是字符数组。
		//为了演示方便，定义一个StringBuilder容器。因为最终还是要将数据变成字符串
		StringBuilder sb = new StringBuilder();
		int ch = 0;
		while((ch = fr.read()) != -1)
		{
			if(ch == '\r')
				continue;
			if(ch == '\n')
				return sb.toString();
			else
				sb.append((char)ch);
		}
		if(sb.length() != 0)  //若有数据，则把剩下的数据返回
			return sb.toString();
		
		return null;
	}
	
	public void myClose() throws IOException
	{
		fr.close();
	}
	
	
	
	public static void main(String[] args) throws IOException {
		MyBufferedReader mbr = new MyBufferedReader(new FileReader("buf_copy.txt"));
		String str = null;
		while((str = mbr.myReadLine()) != null)
		{
			System.out.println(str);
		}
		mbr.myClose();
	}
}