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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!
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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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