package com.slp.nio; import org.junit.Test; import java.io.*;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.Map;
import java.util.Set; /**
* Created by sanglp on 2017/3/1.
* 一、通道：用于源节点与目标节点的连接，在Java NIO中负责缓冲区中数据的传输。通道本身是不存储任何数据的，因此需要配合缓冲区进行传输数据
* 二、通道的一些主要实现类
* java.nio.Channel接口
* |--FileChannel
* |--SocketChannel
* |--ServerSocketChannel
* |--DatagramChannel
* 三、获取通道
* 1.java针对支持通道的类提供了getChannel()方法
* 本地IO:
* FileInputStream/FileOutputStream/RandomAccessFile
* 网络IO:
* Socket
* ServerSocket
* DategramSocket
* 2.在jdk1.7中的NIO2针对各个通道提供了一个静态方法open()
* 3。jdk1.7中的NIO2的Files工具类的newByteChannel()
* 四、通道之间的数据传输
* transferFrom()
* transferTo()
* 五、分散和聚集
* 分散度区：将通道中的数据分散到多个缓冲区中
* 聚集写入：将多个缓冲区中的数据聚集到通道中
*
* 六、字符集：Charset
* 编码：字符串->字节数组
* 解码：字节数组->字符串
*/
public class TestChannel {
@Test
public void test6() throws CharacterCodingException {
Charset cs1 = Charset.forName("GBK");
//获取编码器和解码器
CharsetEncoder ce = cs1.newEncoder();
//获取解码器
CharsetDecoder cd = cs1.newDecoder(); CharBuffer charBuffer = CharBuffer.allocate(1024);
charBuffer.put("桑丽平加油!!");
charBuffer.flip(); //编码
ByteBuffer byteBuffer = ce.encode(charBuffer);
for (int i=0;i<12;i++){
System.out.println(byteBuffer.get(i));
} //解码
byteBuffer.flip();
CharBuffer charBuffer1 = cd.decode(byteBuffer);
System.out.println(charBuffer1.toString()); System.out.println("------------------------"); Charset cs2 = Charset.forName("UTF-8");
byteBuffer.flip();
CharBuffer cBuf3 =cs2.decode(byteBuffer);
System.out.println(cBuf3.toString());
} @Test
public void test5(){
Map<String,Charset> map=Charset.availableCharsets();
Set<Map.Entry<String,Charset>> set = map.entrySet();
for (Map.Entry<String,Charset> entry :set ){
System.out.println(entry.getKey()+"="+entry.getValue());
}
}
@Test
public void test4() throws IOException {
RandomAccessFile randomAccessFile = new RandomAccessFile("1.txt","rw");
//获取通道
FileChannel channel = randomAccessFile.getChannel();
//分配指定大小的缓冲区
ByteBuffer buffer1 = ByteBuffer.allocate(100);
ByteBuffer buffer2 = ByteBuffer.allocate(1024);
//分散读取
ByteBuffer [] bufs = {buffer1,buffer2};
channel.read(bufs);
for (ByteBuffer byteBuffer:bufs){
byteBuffer.flip();
} System.out.println(new String(bufs[0].array(),0,bufs[0].limit()));
System.out.println("---------------");
System.out.println(new String(bufs[1].array(),0,bufs[1].limit())); //聚集写入
RandomAccessFile randomAccessFile1 = new RandomAccessFile("2.txt","rw");
FileChannel channel1 = randomAccessFile1.getChannel();
channel1.write(bufs); } //通道之间的数据传输(直接缓冲区)
@Test
public void test3() throws IOException {
FileChannel fileChannel = FileChannel.open(Paths.get("pipe.bmp"), StandardOpenOption.READ);
FileChannel outChannel =FileChannel.open(Paths.get("4.bmp"),StandardOpenOption.WRITE,StandardOpenOption.READ,StandardOpenOption.CREATE_NEW); fileChannel.transferTo(0,fileChannel.size(),outChannel);
//outChannel.transferFrom(fileChannel,0,fileChannel.size());或者
fileChannel.close();
outChannel.close();
} //2、利用直接缓冲区完成文件的复制(内存映射文件)
@Test
public void test2() throws IOException {
FileChannel fileChannel = FileChannel.open(Paths.get("pipe.bmp"), StandardOpenOption.READ);
FileChannel outChannel =FileChannel.open(Paths.get("3.bmp"),StandardOpenOption.WRITE,StandardOpenOption.READ,StandardOpenOption.CREATE_NEW);
//内存映射文件
MappedByteBuffer imMappedBuf = fileChannel.map(FileChannel.MapMode.READ_ONLY,0,fileChannel.size());
MappedByteBuffer outMappedBuf = outChannel.map(FileChannel.MapMode.READ_WRITE,0,fileChannel.size());
//直接对缓冲区进行数据的读写操作
byte [] dst = new byte[imMappedBuf.limit()];
imMappedBuf.get(dst);
outMappedBuf.put(dst); fileChannel.close();
outChannel.close(); } //1、利用通道完成文件的复制(费直接缓冲区)
@org.junit.Test
public void test1(){
FileInputStream fis =null;
FileOutputStream fos =null;
FileChannel inChanne=null;
FileChannel outChannel=null;
try{
fis = new FileInputStream("pipe.bmp");
fos = new FileOutputStream("2.jpg");
//获取通道
inChanne =fis.getChannel();
outChannel = fos.getChannel();
//分配指定大小的缓冲区
ByteBuffer buffer = ByteBuffer.allocate(1024);
//将通道中的数据存入缓冲区中
while (inChanne.read(buffer)!=-1) {
buffer.flip();//切换为读取数据的模式
//将缓冲区中的数据写入通道
outChannel.write(buffer);
buffer.clear();//清空缓冲区
}
}catch (IOException e){
e.printStackTrace();
}finally {
if(outChannel!=null){
try {
outChannel.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(inChanne!=null){
try {
inChanne.close();
} catch (IOException e) {
e.printStackTrace();
}
} if(fis!=null){
try {
fis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(fos!=null){
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
} }
}