NIOä¹å°±æ¯New I/O,æ¯ä¸ç»æ©å±Java IOæä½çAPIéï¼ äºJava 1.4起被å¼å
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NIO2æä¾ä¸¤ç§ä¸»è¦çæ件读åæ¹æ³ï¼
使ç¨bufferåchannelç±»
使ç¨Path å File ç±»
NIO读åæ件æ以ä¸ä¸ç§æ¹å¼ï¼
1. æ§çNIOæ¹å¼ï¼ä½¿ç¨BufferedReader
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class WithoutNIOExample
{
public static void main(String[] args)
{
BufferedReader br = null;
String sCurrentLine = null;
try
{
br = new BufferedReader(
new FileReader("test.txt"));
while ((sCurrentLine = br.readLine()) != null)
{
System.out.println(sCurrentLine);
}
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
try
{
if (br != null)
br.close();
} catch (IOException ex)
{
ex.printStackTrace();
}
}
}
}
2. 使ç¨buffer读åå°æ件
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
public class ReadFileWithFileSizeBuffer
{
public static void main(String args[])
{
try
{
RandomAccessFile aFile = new RandomAccessFile(
"test.txt","r");
FileChannel inChannel = aFile.getChannel();
long fileSize = inChannel.size();
ByteBuffer buffer = ByteBuffer.allocate((int) fileSize);
inChannel.read(buffer);
buffer.rewind();
buffer.flip();
for (int i = 0; i < fileSize; i++)
{
System.out.print((char) buffer.get());
}
inChannel.close();
aFile.close();
}
catch (IOException exc)
{
System.out.println(exc);
System.exit(1);
}
}
}
3. åå读å大æ件
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
public class ReadFileWithFixedSizeBuffer
{
public static void main(String[] args) throws IOException
{
RandomAccessFile aFile = new RandomAccessFile
("test.txt", "r");
FileChannel inChannel = aFile.getChannel();
ByteBuffer buffer = ByteBuffer.allocate(1024);
while(inChannel.read(buffer) > 0)
{
buffer.flip();
for (int i = 0; i < buffer.limit(); i++)
{
System.out.print((char) buffer.get());
}
buffer.clear(); // do something with the data and clear/compact it.
}
inChannel.close();
aFile.close();
}
}
4. 使ç¨MappedByteBuffer读åæ件
import java.io.RandomAccessFile;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
public class ReadFileWithMappedByteBuffer
{
public static void main(String[] args) throws IOException
{
RandomAccessFile aFile = new RandomAccessFile
("test.txt", "r");
FileChannel inChannel = aFile.getChannel();
MappedByteBuffer buffer = inChannel.map(FileChannel.MapMode.READ_ONLY, 0, inChannel.size());
buffer.load();?
for (int i = 0; i < buffer.limit(); i++)
{
System.out.print((char) buffer.get());
}
buffer.clear(); // do something with the data and clear/compact it.
inChannel.close();
aFile.close();
}
}
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