自定义BuufferedReader中的readLine方法。

import java.io.FileReader;
import java.io.IOException;
public class MyBufferedReader {
private FileReader fr;
//定义一个缓冲区
private char[] buf = new char[1024];
//定义一个角标，用来读写数组的元素
private int pos = 0;
//定义一个计数器。
private int count = 0;
MyBufferedReader(FileReader fr){
this.fr = fr;
}
//一次来读取一个字符
public int myRead() throws IOException{
if (count == 0) {
count = fr.read(buf);
pos = 0;
}
if (count < 0) {
return -1;
}
char ch = buf[pos];
pos++;
count--;
return ch;
}
public String myReadLine() throws IOException{
StringBuilder sb = new StringBuilder();
int ch = 0;
while((ch = myRead()) != -1){
if((char)ch == '\r')
continue;
if((char)ch == '\n')
return sb.toString();
sb.append((char)ch);
}
if(sb.length() != 0){
return sb.toString();
}
return null;
}

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

}

import java.io.FileReader;
import java.io.IOException;
public class MyReadLinDemo {
public static void main(String[] args) {
FileReader fr = null;
MyBufferedReader mbr = null;
try {
fr = new FileReader("E:\\yzq.txt");
mbr = new MyBufferedReader(fr);
String len = null;
while((len = mbr.myReadLine()) != null){
System.out.println(len);
}
} catch (IOException e) {
e.printStackTrace();
}finally{
if(mbr != null)
try {
mbr.myClose();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}