maven工程
依赖

<dependencies><dependency><groupId>io.netty</groupId><artifactId>netty-all</artifactId><version>4.1.39.Final</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.16.18</version></dependency><dependency><groupId>com.google.code.gson</groupId><artifactId>gson</artifactId><version>2.8.5</version></dependency><dependency><groupId>com.google.guava</groupId><artifactId>guava</artifactId><version>19.0</version></dependency><dependency><groupId>ch.qos.logback</groupId><artifactId>logback-classic</artifactId><version>1.2.3</version></dependency><dependency><groupId>com.google.protobuf</groupId><artifactId>protobuf-java</artifactId><version>3.11.3</version></dependency></dependencies>

这里写目录标题

  • 一.bytebuffer
    • 1.bytebuffer基本使用
    • 2.bytebuffer-内部结构
    • 3.bytebuffer-方法演示
    • 4.bytebuffer-黏半包解析

一.bytebuffer

1.bytebuffer基本使用

package cn.itcast.netty.c1;import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;public class TestByteBuffer {public static void main(String[] args) {//FileChannel//1.输入输出流try (FileChannel channel = new FileInputStream("data.txt").getChannel()) {//准备缓冲区ByteBuffer byteBuffer=ByteBuffer.allocate(5);//从channel读取数据，向buffer写入while(true){int read = channel.read(byteBuffer);System.out.println("read="+read);if(read==-1){break;}//打印buffer的内容byteBuffer.flip();while(byteBuffer.hasRemaining()){byte b = byteBuffer.get();System.out.println((char)b);}byteBuffer.clear();//切换为写模式}} catch (IOException e) {}}
}
read=5
1
3
5
7
9
read=5
0
q
w
e
r
read=3
t
y
u
read=-1

2.bytebuffer-内部结构



3.bytebuffer-方法演示

工具类ByteBufferUtil

package cn.itcast.netty.c1;import io.netty.util.internal.StringUtil;import java.nio.ByteBuffer;import static io.netty.util.internal.MathUtil.isOutOfBounds;
import static jdk.nashorn.internal.runtime.regexp.joni.encoding.CharacterType.NEWLINE;public class ByteBufferUtil {private static final char[] BYTE2CHAR = new char[256];private static final char[] HEXDUMP_TABLE = new char[256 * 4];private static final String[] HEXPADDING = new String[16];private static final String[] HEXDUMP_ROWPREFIXES = new String[65536 >>> 4];private static final String[] BYTE2HEX = new String[256];private static final String[] BYTEPADDING = new String[16];static {final char[] DIGITS = "0123456789abcdef".toCharArray();for (int i = 0; i < 256; i++) {HEXDUMP_TABLE[i << 1] = DIGITS[i >>> 4 & 0x0F];HEXDUMP_TABLE[(i << 1) + 1] = DIGITS[i & 0x0F];}int i;// Generate the lookup table for hex dump paddingsfor (i = 0; i < HEXPADDING.length; i++) {int padding = HEXPADDING.length - i;StringBuilder buf = new StringBuilder(padding * 3);for (int j = 0; j < padding; j++) {buf.append("   ");}HEXPADDING[i] = buf.toString();}// Generate the lookup table for the start-offset header in each row (up to 64KiB).for (i = 0; i < HEXDUMP_ROWPREFIXES.length; i++) {StringBuilder buf = new StringBuilder(12);buf.append(NEWLINE);buf.append(Long.toHexString(i << 4 & 0xFFFFFFFFL | 0x100000000L));buf.setCharAt(buf.length() - 9, '|');buf.append('|');HEXDUMP_ROWPREFIXES[i] = buf.toString();}// Generate the lookup table for byte-to-hex-dump conversionfor (i = 0; i < BYTE2HEX.length; i++) {BYTE2HEX[i] = ' ' + StringUtil.byteToHexStringPadded(i);}// Generate the lookup table for byte dump paddingsfor (i = 0; i < BYTEPADDING.length; i++) {int padding = BYTEPADDING.length - i;StringBuilder buf = new StringBuilder(padding);for (int j = 0; j < padding; j++) {buf.append(' ');}BYTEPADDING[i] = buf.toString();}// Generate the lookup table for byte-to-char conversionfor (i = 0; i < BYTE2CHAR.length; i++) {if (i <= 0x1f || i >= 0x7f) {BYTE2CHAR[i] = '.';} else {BYTE2CHAR[i] = (char) i;}}}/*** 打印所有内容* @param buffer*/public static void debugAll(ByteBuffer buffer) {int oldlimit = buffer.limit();buffer.limit(buffer.capacity());StringBuilder origin = new StringBuilder(256);appendPrettyHexDump(origin, buffer, 0, buffer.capacity());System.out.println("+--------+-------------------- all ------------------------+----------------+");System.out.printf("position: [%d], limit: [%d]\n", buffer.position(), oldlimit);System.out.println(origin);buffer.limit(oldlimit);}/*** 打印可读取内容* @param buffer*/public static void debugRead(ByteBuffer buffer) {StringBuilder builder = new StringBuilder(256);appendPrettyHexDump(builder, buffer, buffer.position(), buffer.limit() - buffer.position());System.out.println("+--------+-------------------- read -----------------------+----------------+");System.out.printf("position: [%d], limit: [%d]\n", buffer.position(), buffer.limit());System.out.println(builder);}private static void appendPrettyHexDump(StringBuilder dump, ByteBuffer buf, int offset, int length) {if (isOutOfBounds(offset, length, buf.capacity())) {throw new IndexOutOfBoundsException("expected: " + "0 <= offset(" + offset + ") <= offset + length(" + length+ ") <= " + "buf.capacity(" + buf.capacity() + ')');}if (length == 0) {return;}dump.append("         +-------------------------------------------------+" +NEWLINE + "         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |" +NEWLINE + "+--------+-------------------------------------------------+----------------+");final int startIndex = offset;final int fullRows = length >>> 4;final int remainder = length & 0xF;// Dump the rows which have 16 bytes.for (int row = 0; row < fullRows; row++) {int rowStartIndex = (row << 4) + startIndex;// Per-row prefix.appendHexDumpRowPrefix(dump, row, rowStartIndex);// Hex dumpint rowEndIndex = rowStartIndex + 16;for (int j = rowStartIndex; j < rowEndIndex; j++) {dump.append(BYTE2HEX[getUnsignedByte(buf, j)]);}dump.append(" |");// ASCII dumpfor (int j = rowStartIndex; j < rowEndIndex; j++) {dump.append(BYTE2CHAR[getUnsignedByte(buf, j)]);}dump.append('|');}// Dump the last row which has less than 16 bytes.if (remainder != 0) {int rowStartIndex = (fullRows << 4) + startIndex;appendHexDumpRowPrefix(dump, fullRows, rowStartIndex);// Hex dumpint rowEndIndex = rowStartIndex + remainder;for (int j = rowStartIndex; j < rowEndIndex; j++) {dump.append(BYTE2HEX[getUnsignedByte(buf, j)]);}dump.append(HEXPADDING[remainder]);dump.append(" |");// Ascii dumpfor (int j = rowStartIndex; j < rowEndIndex; j++) {dump.append(BYTE2CHAR[getUnsignedByte(buf, j)]);}dump.append(BYTEPADDING[remainder]);dump.append('|');}dump.append(NEWLINE +"+--------+-------------------------------------------------+----------------+");}private static void appendHexDumpRowPrefix(StringBuilder dump, int row, int rowStartIndex) {if (row < HEXDUMP_ROWPREFIXES.length) {dump.append(HEXDUMP_ROWPREFIXES[row]);} else {dump.append(NEWLINE);dump.append(Long.toHexString(rowStartIndex & 0xFFFFFFFFL | 0x100000000L));dump.setCharAt(dump.length() - 9, '|');dump.append('|');}}public static short getUnsignedByte(ByteBuffer buffer, int index) {return (short) (buffer.get(index) & 0xFF);}
}

测试类

package cn.itcast.netty.c1;import java.nio.ByteBuffer;import static cn.itcast.netty.c1.ByteBufferUtil.debugAll;public class TestByteBufferReadWrite {public static void main(String[] args) {ByteBuffer byteBuffer=ByteBuffer.allocate(10);byteBuffer.put((byte)0x61);debugAll(byteBuffer);byteBuffer.put(new byte[]{0x62,0x63,0x64});debugAll(byteBuffer);//System.out.println(byteBuffer.get());byteBuffer.flip();System.out.println(byteBuffer.get());debugAll(byteBuffer);byteBuffer.compact();debugAll(byteBuffer);byteBuffer.put(new byte[]{0x65,0x66,0x67});debugAll(byteBuffer);}
}
15:35:14.029 [main] DEBUG io.netty.util.internal.logging.InternalLoggerFactory - Using SLF4J as the default logging framework
+--------+-------------------- all ------------------------+----------------+
position: [1], limit: [10]+-------------------------------------------------+0         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |0+--------+-------------------------------------------------+----------------+0|00000000| 61 00 00 00 00 00 00 00 00 00                   |a.........      |0+--------+-------------------------------------------------+----------------+
+--------+-------------------- all ------------------------+----------------+
position: [4], limit: [10]+-------------------------------------------------+0         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |0+--------+-------------------------------------------------+----------------+0|00000000| 61 62 63 64 00 00 00 00 00 00                   |abcd......      |0+--------+-------------------------------------------------+----------------+
97
+--------+-------------------- all ------------------------+----------------+
position: [1], limit: [4]+-------------------------------------------------+0         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |0+--------+-------------------------------------------------+----------------+0|00000000| 61 62 63 64 00 00 00 00 00 00                   |abcd......      |0+--------+-------------------------------------------------+----------------+
+--------+-------------------- all ------------------------+----------------+
position: [3], limit: [10]+-------------------------------------------------+0         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |0+--------+-------------------------------------------------+----------------+0|00000000| 62 63 64 64 00 00 00 00 00 00                   |bcdd......      |0+--------+-------------------------------------------------+----------------+
+--------+-------------------- all ------------------------+----------------+
position: [6], limit: [10]+-------------------------------------------------+0         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |0+--------+-------------------------------------------------+----------------+0|00000000| 62 63 64 65 66 67 00 00 00 00                   |bcdefg....      |0+--------+-------------------------------------------------+----------------+Process finished with exit code 0

测试类

package cn.itcast.netty.c1;import java.nio.ByteBuffer;import static cn.itcast.netty.c1.ByteBufferUtil.debugAll;public class TestByteBufferRead {public static void main(String[] args) {ByteBuffer buffer = ByteBuffer.allocate(10);buffer.put(new byte[]{'a', 'b', 'c','d'});buffer.flip();byte[] bytes = new byte[4];buffer.get(bytes);for(int i=0;i<bytes.length;i++){System.out.println(bytes[i]);}debugAll(buffer);buffer.rewind();//rewind 方法将 position 重新置为 0byte b = buffer.get();System.out.println(b);}
}
97
98
99
100
19:50:47.673 [main] DEBUG io.netty.util.internal.logging.InternalLoggerFactory - Using SLF4J as the default logging framework
+--------+-------------------- all ------------------------+----------------+
position: [4], limit: [4]+-------------------------------------------------+0         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |0+--------+-------------------------------------------------+----------------+0|00000000| 61 62 63 64 00 00 00 00 00 00                   |abcd......      |0+--------+-------------------------------------------------+----------------+
97

测试类

public class TestByteBufferRead {public static void main(String[] args) {ByteBuffer buffer = ByteBuffer.allocate(10);buffer.put(new byte[]{'a', 'b', 'c','d'});buffer.flip();/*byte[] bytes = new byte[4];buffer.get(bytes);for(int i=0;i<bytes.length;i++){System.out.println(bytes[i]);}debugAll(buffer);buffer.rewind();byte b = buffer.get();System.out.println(b);*/System.out.println(buffer.get());System.out.println(buffer.get());buffer.mark();//标记System.out.println(buffer.get());System.out.println(buffer.get());buffer.reset();System.out.println(buffer.get());System.out.println(buffer.get());}
}

import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;import static cn.itcast.netty.c1.ByteBufferUtil.debugAll;public class ScatteringReads {public static void main(String[] args) {try (RandomAccessFile file = new RandomAccessFile("parts.txt", "r")) {FileChannel channel = file.getChannel();ByteBuffer a = ByteBuffer.allocate(3);ByteBuffer b = ByteBuffer.allocate(3);ByteBuffer c = ByteBuffer.allocate(5);channel.read(new ByteBuffer[]{a, b, c});a.flip();b.flip();c.flip();debugAll(a);debugAll(b);debugAll(c);} catch (IOException e) {e.printStackTrace();}}}

import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.StandardCharsets;public class GatheringWrites {public static void main(String[] args) {ByteBuffer hello = StandardCharsets.UTF_8.encode("hello");ByteBuffer world = StandardCharsets.UTF_8.encode("world");ByteBuffer nihao = StandardCharsets.UTF_8.encode("你好");try (FileChannel rw = new RandomAccessFile("world.txt", "rw").getChannel()) {rw.write(new ByteBuffer []{hello,world,nihao});//生成world.txt,字符串helloworld你好} catch (IOException e) {}}
}

4.bytebuffer-黏半包解析

import java.nio.ByteBuffer;import static cn.itcast.netty.c1.ByteBufferUtil.debugAll;public class TestByteBufferExam {public static void main(String[] args) {ByteBuffer source = ByteBuffer.allocate(32);//                     11            24source.put("Hello,world\nI'm zhangsan\nHo".getBytes());split(source);source.put("w are you?\n".getBytes());split(source);}private static void split(ByteBuffer source) {source.flip();for(int i=0;i<source.limit();i++){if(source.get(i)=='\n'){int length= i+1-source.position();ByteBuffer allocate = ByteBuffer.allocate(length);for(int j=0;j<length;j++){allocate.put(source.get());}debugAll(allocate);}}source.compact();}}
        +-------------------------------------------------+0         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |0+--------+-------------------------------------------------+----------------+0|00000000| 48 65 6c 6c 6f 2c 77 6f 72 6c 64 0a             |Hello,world.    |0+--------+-------------------------------------------------+----------------+
+--------+-------------------- all ------------------------+----------------+
position: [13], limit: [13]+-------------------------------------------------+0         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |0+--------+-------------------------------------------------+----------------+0|00000000| 49 27 6d 20 7a 68 61 6e 67 73 61 6e 0a          |I'm zhangsan.   |0+--------+-------------------------------------------------+----------------+
+--------+-------------------- all ------------------------+----------------+
position: [13], limit: [13]+-------------------------------------------------+0         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |0+--------+-------------------------------------------------+----------------+0|00000000| 48 6f 77 20 61 72 65 20 79 6f 75 3f 0a          |How are you?.   |0+--------+-------------------------------------------------+----------------+
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
//
public class TestChannel {public static void main(String[] args) {try (FileChannel from = new FileInputStream("data.txt").getChannel();FileChannel to=new FileOutputStream("to.txt").getChannel();){from.transferTo(0,from.size(),to);} catch (IOException e) {e.printStackTrace();}}
}

Server

import lombok.extern.slf4j.Slf4j;import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketOption;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;import static cn.itcast.netty.c1.ByteBufferUtil.debugRead;
@Slf4j
public class Server {public static void main(String[] args) throws IOException {//创建selector，管理多个channel//Selector selector= Selector.open();ByteBuffer buffer = ByteBuffer.allocate(16);//1.创建了服务器ServerSocketChannel ssc = ServerSocketChannel.open();ssc.configureBlocking(false);//非阻塞模式//建立selector和channel的联系////SelectionKey sscKey = ssc.register(selector, 0, null);//2.绑定监听端口ssc.bind(new InetSocketAddress(8080));List<SocketChannel> channel = new ArrayList<>();while (true) {//log.debug("connecting");//3.建立与客户端连接，SocketChannel用来与客户端通信SocketChannel sc = ssc.accept();//阻塞方法，线程停止运行if(sc!=null) {log.debug("connected...{}", sc);sc.configureBlocking(false);channel.add(sc);}for (SocketChannel socketChannel : channel) {//log.debug("before read...{}", channel);int read = socketChannel.read(buffer);//阻塞方法，线程停止运行if(read>0) {buffer.flip();debugRead(buffer);buffer.clear();log.debug("after read...{}", channel);}}}}
}

Client

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.channels.SocketChannel;public class Client {public static void main(String[] args) throws IOException {SocketChannel sc=SocketChannel.open();sc.connect(new InetSocketAddress("localhost",8080));System.out.println("waiting");}
}

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