java 自定义BufferedReader_readLine

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

public class BufferedReaderDemo {

	public static void main(String[] args) {
		MyBufferedReader mbr = null;
		try {
			mbr = new MyBufferedReader(new FileReader("src/D.java"));
			for (String line; (line = mbr.myReadLine()) != null;)
				System.out.println(line);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				if (mbr != null) {
					mbr.myClose();
					mbr = null;
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

}

/*
 * 自定义字符输入流缓冲区
 */
class MyBufferedReader {
	//缓冲区中的字符流
	private Reader r = null;

	public MyBufferedReader(Reader r) {
		this.r = r;
	}

	public String myReadLine() throws IOException {
		//该方法缓冲数据的容器
		StringBuilder sb = new StringBuilder();
		
		/*
		 * 未读到回车换行就把读到的数据添加到
		 * 容器中，读到回车换行就把数据返回
		 */
		for (int ch; (ch = r.read()) != -1;) {
			if (ch == '\r')
				continue;
			if (ch == '\n')
				return sb.toString();
			else {
				sb.append((char) ch);
			}
		}
		
		/*
		 * 为了避免文件结尾无回车换行
		 * 只要容器中有数据最后就返回
		 */
		if (sb.length() != 0) {
			return sb.toString();
		}
		return null;
	}

	public void myClose() throws IOException {
		r.close();
	}

}