模拟字符缓冲读入流:BufferedReader

/*
 * 模拟字符缓冲读入流:BufferedReader
 * 
 * 分析:
 * 1.要属于流的体系
 * 2.要有一个Reader类型的成员变量
 * 3.要有一个带参数的构造方法接收外部传入的流对象
 * 4.模拟readLine(),实现读一行的功能
 * 5.关闭流
 */

import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
//1.要属于流的体系
class MyBufferedReader extends Reader{
    //2.要有一个Reader类型的成员变量
    Reader reader;
    //3.要有一个带参数的构造方法接收外部传入的流对象
    public MyBufferedReader(Reader reader) {
        this.reader = reader;
    }
    //4.模拟readLine(),实现读一行的功能
    public String readLine() throws IOException {
        //a.创建一个临时的可变字符串,用于装当前行的字符
        StringBuffer stringBuffer = new StringBuffer();
        //b.使用read()方法读
        int num = 0;
        while ((num = this.reader.read()) != -1) {
            if (num == '\r') {
                continue;
            }else if (num == '\n') {
                return stringBuffer.toString();
            }else {
                stringBuffer.append((char)num);
            }
        }
        
        //当文本为空时
        if (stringBuffer.length() == 0) {
            return null;
        }
        
        //当文本只有一行,没有换行符
        return stringBuffer.toString();
        
        //增加效率的代码
    }
    //5.关闭流
    public void close() throws IOException {
        //关闭自己
        this.reader.close();    
    }
    @Override
    public int read(char[] cbuf, int off, int len) throws IOException {
        // TODO Auto-generated method stub
        return 0;
    }
    
    
}
public class Demo11 {
    public static void main(String[] args) throws IOException {
        MyBufferedReader myBufferedReader = new MyBufferedReader(new FileReader("text3.txt"));
        String data = null;
        while ((data = myBufferedReader.readLine()) != null) {
            System.out.print(data);
            System.out.println();
        }
        myBufferedReader.close();
    }
}