如何测试FileChannel结合MappedByteBuffer往文件中写入数据

本篇内容主要讲解"如何测试FileChannel结合MappedByteBuffer往文件中写入数据"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"如何测试FileChannel结合MappedByteBuffer往文件中写入数据"吧!

FileChannel结合ByteBuffer测试

package com;import java.io.RandomAccessFile;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;/** * FileChannel Test * * @author Dale * @date 2019/10/23 */public class FileChannelTest{    static ByteBuffer writeBuffer = ByteBuffer.allocate(9);    static Integer wrotePosition = 0;    static Integer committedPosition = 0;    static FileChannel fileChannel = null;    static {        try {            RandomAccessFile randomAccessFile = new RandomAccessFile("d://test.log", "rw");            fileChannel = randomAccessFile.getChannel();        }catch (Exception e){            e.printStackTrace();        }    }    public static void main(String[] args) throws Exception{        appendData("1234");        commit();        appendData("567");        commit();        appendData("89");        commit();        //fileChannel.force(false);    }    public static void appendData(String msg) throws Exception{        int msgLen = msg.length();        ByteBuffer byteBuffer = writeBuffer.slice();        byteBuffer.position(wrotePosition);        ByteBuffer msgStoreItemMemory = ByteBuffer.allocate(msgLen);        msgStoreItemMemory.put(msg.getBytes("UTF-8"));        byteBuffer.put(msgStoreItemMemory.array(), 0, msgLen);        wrotePosition = wrotePosition + msgLen;    }    public static void commit() throws Exception{        ByteBuffer byteBuffer = writeBuffer.slice();        byteBuffer.position(committedPosition);        byteBuffer.limit(wrotePosition);        fileChannel.position(committedPosition);        fileChannel.write(byteBuffer);        committedPosition = wrotePosition;    }}

MappedByteBuffer结合ByteBuffer测试

package com;import java.io.RandomAccessFile;import java.nio.ByteBuffer;import java.nio.MappedByteBuffer;import java.nio.channels.FileChannel;/** * MappedByteBuffer Test * * @author Dale * @date 2019/10/23 */public class MappedByteBufferTest {    static ByteBuffer writeBuffer = ByteBuffer.allocate(9);    static Integer wrotePosition = 0;    static Integer committedPosition = 0;    static FileChannel fileChannel = null;    static MappedByteBuffer mappedByteBuffer;    static {        try {            RandomAccessFile randomAccessFile = new RandomAccessFile("d://test.log", "rw");            fileChannel = randomAccessFile.getChannel();            mappedByteBuffer = fileChannel.map(FileChannel.MapMode.READ_WRITE, 0, 9);        }catch (Exception e){            e.printStackTrace();        }    }    public static void main(String[] args) throws Exception{        appendData("1234");        appendData("567");        appendData("89");        //mappedByteBuffer.force();    }    public static void appendData(String msg) throws Exception{        int msgLen = msg.length();        ByteBuffer byteBuffer = mappedByteBuffer.slice();        byteBuffer.position(wrotePosition);        ByteBuffer msgStoreItemMemory = ByteBuffer.allocate(msgLen);        msgStoreItemMemory.put(msg.getBytes("UTF-8"));        byteBuffer.put(msgStoreItemMemory.array(), 0, msgLen);        wrotePosition = wrotePosition + msgLen;    }}

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