channel代码示例

channel代码示例

package cn.com.github.immortals;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.RandomAccessFile;import java.nio.ByteBuffer;import java.nio.MappedByteBuffer;import java.nio.channels.FileChannel;import java.nio.channels.FileChannel.MapMode;import java.nio.file.Paths;import java.nio.file.StandardOpenOption;import org.junit.Test;/** *  * @author 潘琢文 * */public class TestChannel {    // 分散和聚集    @Test    public void test4() throws IOException {        RandomAccessFile raf1 = new RandomAccessFile("1.txt", "rw");        // 1. 获取通道        FileChannel channel1 = raf1.getChannel();        // 2. 分配指定大小的缓冲区        ByteBuffer buf1 = ByteBuffer.allocate(100);        ByteBuffer buf2 = ByteBuffer.allocate(1024);        // 3. 分散读取        ByteBuffer[] bufs = { buf1, buf2 };        channel1.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()));        // 4. 聚集写入        RandomAccessFile raf2 = new RandomAccessFile("2.txt", "rw");        FileChannel channel2 = raf2.getChannel();        channel2.write(bufs);    }    /**     * 利用channel复制文件     *      * @throws IOException     */    @Test    public void testChannel() throws IOException {        FileInputStream ins = new FileInputStream(new File("D:/大话西游之大圣娶亲[国语版]_bd.mp4"));        FileOutputStream fos = new FileOutputStream(new File("D:/大话西游之大圣娶亲[国语版]_bd_copy.mp4"));        FileChannel in = ins.getChannel();        FileChannel out = fos.getChannel();        ByteBuffer buf = ByteBuffer.allocate(1024);        while (in.read(buf) != -1) {            buf.flip();            out.write(buf);            buf.clear();        }        ins.close();        fos.close();        in.close();        out.close();    }    /**     * channel的直接缓冲区复制文件     *      * @throws IOException     */    @Test    public void testChannel2() throws IOException {        FileChannel in = FileChannel.open(Paths.get("D:/大话西游之大圣娶亲[国语版]_bd.mp4"), StandardOpenOption.READ);        FileChannel out = FileChannel.open(Paths.get("D:/大话西游之大圣娶亲[国语版]_bd_copy.mp4"), StandardOpenOption.CREATE,                StandardOpenOption.WRITE);        in.transferTo(0, in.size(), out);        in.close();        out.close();    }    @Test    public void testChannel3() throws IOException {        FileChannel in = FileChannel.open(Paths.get("D:/大话西游之大圣娶亲[国语版]_bd.mp4"), StandardOpenOption.READ);        FileChannel out = FileChannel.open(Paths.get("D:/大话西游之大圣娶亲[国语版]_bd_copy.mp4"), StandardOpenOption.CREATE,                StandardOpenOption.WRITE, StandardOpenOption.READ);        MappedByteBuffer inBuffer = in.map(MapMode.READ_ONLY, 0, in.size());        MappedByteBuffer outBUffer = out.map(MapMode.READ_WRITE, 0, in.size());        byte[] dst = new byte[inBuffer.limit()];        inBuffer.get(dst);        outBUffer.put(dst);        in.close();        out.close();    }}