javaNIO入门学习

package hb.nio;
import java.nio.CharBuffer;
public class BufferTest {
public static void main(String[] args) {
CharBuffer buff &＃61; CharBuffer.allocate(8);
//容量为8
System.out.println("capacity &＃xff1a;" &＃43; buff.capacity());
//在没有加入数据的时候&＃xff0c;可以读写长度为8
System.out.println("limit &＃xff1a;" &＃43; buff.limit());
//在没有加入数据的时候&＃xff0c;position当前位置为0
System.out.println("position &＃xff1a;" &＃43; buff.position());
buff.put("a");
buff.put("b");
buff.put("c");
//加入数据之后position会向后移动&＃xff0c;位置为3
System.out.println("加入三个元素之后&＃xff0c;position &＃xff1a;" &＃43; buff.position());
//调用flip()方法
buff.flip();
//可读写的长度是3
System.out.println("执行flip()方法&＃xff0c;limit&＃xff1a;" &＃43; buff.limit());
//取出第一个元素
System.out.println("第一个元素&＃xff08;position&＃61;0&＃xff09;: " &＃43; buff.get());
System.out.println("取出第一个元素后&＃xff0c;position&＃xff1a;"&＃43;buff.position());
//调用clear()方法
buff.clear();
System.out.println("执行clear()后,limit&＃61;"&＃43;buff.limit());
System.out.println("执行clear()后,position&＃61;"&＃43;buff.position());
System.out.println("执行clear()后,缓冲区域的数据没有被清除:"&＃43;buff.get(2));
System.out.println("执行绝对读取后&＃xff0c;position&＃61;"&＃43;buff.position());
}
}
 

package hb.nio;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
public class RandomFileChannelTest {
public static void main(String[] args) {
File f &＃61; new File("c:\\MyClient.java");
try {
FileInputStream fis &＃61; new FileInputStream(f);
FileChannel fileChannel &＃61; fis.getChannel();
ByteBuffer bb &＃61; fileChannel.map(FileChannel.MapMode.READ_ONLY, 0, f.length());
while (bb.hasRemaining()) {
System.out.print((char) bb.get());
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// try {
// RandomAccessFile fis &＃61; new RandomAccessFile(f, "rw");
// // FileInputStream fis &＃61; new FileInputStream(f);
// FileChannel fileChannel &＃61; fis.getChannel();
//
// ByteBuffer bb &＃61; ByteBuffer.allocate(1024);
//
// while (fileChannel.read(bb) !&＃61; -1) {
// bb.flip();
// Charset charset &＃61; Charset.forName("GBK");
// CharsetDecoder decoder &＃61; charset.newDecoder();
// CharBuffer charBuffer &＃61; decoder.decode(bb);
// System.out.print(charBuffer);
// // System.out.println(bb);
// bb.clear();
// }
//
// } catch (FileNotFoundException e) {
// // TODO Auto-generated catch block
// e.printStackTrace();
// } catch (Exception e) {
// // TODO Auto-generated catch block
// e.printStackTrace();
// }
}
}