Java基础之IO流，按指定行号范围读取文本文件内容，带行业、带缓冲
import java.io.*;
class MyReaderLineNumberDemo
{
public static void main(String[] args)
{
MyReaderForLineNumber mrln = null;
try
{
mrln = new MyReaderForLineNumber("MyReaderLineNumberDemo.java");
String line = null;
mrln.setStartLineNumber(1);
mrln.setEndLineNumber(-1);
while((line=mrln.readLine())!=null)
{
System.out.println(mrln.getLineNumber() +":"+ line);
}
}
catch(IOException e)
{
System.err.println(e.getMessage());
}
finally
{
try
{
if(null!=mrln)
mrln.close();
}
catch(IOException e)
{
System.err.println(e.getMessage());
}
}
}
}
class MyBufferedReader
{
private FileReader fileReader = null;
public MyBufferedReader(String fileName) throws IOException
{
this.fileReader = new FileReader(new File(fileName));
}
public String readLine() throws IOException
{
StringBuilder sb = new StringBuilder();
int ch = 0;
while((ch=fileReader.read())!=-1)
{
if('\r'==ch)
continue;
if('\n'==ch)
return sb.toString();
else
sb.append((char)ch);
}
if(sb.length()!=0)
return sb.toString();
return null;
}
public void close() throws IOException
{
if(null!=fileReader)
this.fileReader.close();
}
}
class MyReaderLineNumber extends MyBufferedReader
{
private int lineNumber = 0;
public MyReaderLineNumber(String fileName) throws IOException
{
super(fileName);
}
public String readLine() throws IOException
{
lineNumber++;
return super.readLine();
}
public void setLineNumber(int lineNumber)
{
this.lineNumber = lineNumber;
}
public int getLineNumber()
{
return lineNumber;
}
}
class MyReaderForLineNumber extends MyReaderLineNumber
{
private int startLineNumber = 0;
private int endLineNumber = Integer.MAX_VALUE;
public MyReaderForLineNumber(String fileName) throws IOException
{
super(fileName);
}
public String readLine() throws IOException
{
String result = null;
while((result=super.readLine())!=null)
{
if(super.getLineNumber()>=this.startLineNumber && this.endLineNumber>=super.getLineNumber())
return result;
}
return null;
}
public int getStartLineNumber()
{
return this.startLineNumber;
}
public void setStartLineNumber(int s)
{
if(s>=0)
this.startLineNumber = s;
}
public int getEndLineNumber()
{
return this.endLineNumber;
}
public void setEndLineNumber(int e)
{
if(e>0)
this.endLineNumber = e;
}
}