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This is a client library for Nadron server https://github.com/menacher/java-game-server/tree/netty4/nadron. Java clients can use this program to connect and interact with nadron server.
package io.nadron.client.util;
import static io.netty.buffer.Unpooled.copiedBuffer;
import io.nadron.client.app.Session;
import io.nadron.client.communication.NettyTCPMessageSender;
import io.nadron.convert.Transform;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelPipeline;
import io.netty.util.CharsetUtil;
import java.net.InetSocketAddress;
import java.nio.charset.Charset;
import java.util.NoSuchElementException;
/**
* This class would be an assortment of netty related utility methods.
*
* @author Abraham Menacherry
*
*/
public class NettyUtils
{
public static final String NETTY_CHANNEL = "NETTY_CHANNEL";
public static ChannelPipeline getPipeLineOfConnection(
NettyTCPMessageSender messageSender)
{
if(null != messageSender){
return messageSender.getChannel().pipeline();
}
return null;
}
public static ChannelPipeline getPipeLineOfSession(
Session playerSession)
{
return getPipeLineOfConnection((NettyTCPMessageSender)playerSession.getTcpMessageSender());
}
/**
* A utility method to clear the netty pipeline of all handlers.
*
* @param pipeline
*/
public static void clearPipeline(ChannelPipeline pipeline)
{
if(null == pipeline){
return;
}
try
{
while (pipeline.first() != null)
{
pipeline.removeFirst();
}
}
catch (NoSuchElementException e)
{
// all elements removed.
}
}
public static ByteBuf createBufferForOpcode(int opcode)
{
ByteBuf buffer = Unpooled.buffer(1);
buffer.writeByte(opcode);
return buffer;
}
/**
* This method will read multiple strings of the buffer and return them as a
* string array. It internally uses the readString(ByteBuf buffer) to
* accomplish this task. The strings are read back in the order they are
* written.
*
* @param buffer
* The buffer containing the strings, with each string being a
* strlength-strbytes combination.
* @param numOfStrings
* The number of strings to be read. Should not be negative or 0
* @return the strings read from the buffer as an array.
*/
public static String[] readStrings(ByteBuf buffer, int numOfStrings)
{
return readStrings(buffer,numOfStrings,CharsetUtil.UTF_8);
}
/**
* This method will read multiple strings of the buffer and return them as a
* string array. It internally uses the readString(ByteBuf buffer) to
* accomplish this task. The strings are read back in the order they are
* written.
*
* @param buffer
* The buffer containing the strings, with each string being a
* strlength-strbytes combination.
* @param numOfStrings
* The number of strings to be read. Should not be negative or 0
* @param charset
* The Charset say 'UTF-8' in which the decoding needs to be
* done.
*
* @return the strings read from the buffer as an array.
*/
public static String[] readStrings(ByteBuf buffer, int numOfStrings,
Charset charset)
{
String[] strings = new String[numOfStrings];
for(int i=0;i 2)
{
int length = buffer.readUnsignedShort();
readString = readString(buffer, length, charset);
}
return readString;
}
/**
* Read a string from a channel buffer with the specified length. It resets
* the reader index of the buffer to the end of the string.
*
* @param buffer
* The Netty buffer containing the String.
* @param length
* The number of bytes in the String.
* @return Returns the read string.
*/
public static String readString(ByteBuf buffer, int length)
{
return readString(buffer, length, CharsetUtil.UTF_8);
}
/**
* Read a string from a channel buffer with the specified length. It resets
* the reader index of the buffer to the end of the string. Defaults to
* UTF-8 encoding in case charset passed in is null
*
* @param buffer
* The Netty buffer containing the String.
* @param length
* The number of bytes in the String.
* @param charset
* The Charset say 'UTF-8' in which the decoding needs to be
* done.
* @return Returns the read string.
*/
public static String readString(ByteBuf buffer, int length,
Charset charset)
{
String str = null;
if (null == charset)
{
charset = CharsetUtil.UTF_8;
}
try
{
ByteBuf stringBuffer = buffer.readSlice(length);
str = stringBuffer.toString(charset);
}
catch (Exception e)
{
throw new RuntimeException(e);
}
return str;
}
/**
* Writes multiple strings to a ByteBuf with the length of the string
* preceding its content. So if there are two string Hello and
* World then the channel buffer returned would contain
*
* @param msgs
* The messages to be written.
* @return {@link ByteBuf} with format
* length-stringbinary-length-stringbinary
*/
public static ByteBuf writeStrings(String... msgs)
{
return writeStrings(CharsetUtil.UTF_8, msgs);
}
/**
* Writes multiple strings to a ByteBuf with the length of the string
* preceding its content. So if there are two string Hello and
* World then the channel buffer returned would contain
*
* @param charset
* The Charset say 'UTF-8' in which the encoding needs to be
* done.
* @param msgs
* The messages to be written.
* @return {@link ByteBuf} with format
* length-stringbinary-length-stringbinary
*/
public static ByteBuf writeStrings(Charset charset, String... msgs)
{
ByteBuf buffer = null;
for (String msg : msgs)
{
if (null == buffer)
{
buffer = writeString(msg, charset);
}
else
{
ByteBuf theBuffer = writeString(msg,charset);
if(null != theBuffer)
{
buffer = Unpooled.wrappedBuffer(buffer,theBuffer);
}
}
}
return buffer;
}
/**
* Creates a channel buffer of which the first 2 bytes contain the length of
* the string in bytes and the remaining is the actual string in binary
* UTF-8 format.
*
* @param msg
* The string to be written.
* @return Returns the ByteBuf instance containing the encoded string
*/
public static ByteBuf writeString(String msg)
{
return writeString(msg, CharsetUtil.UTF_8);
}
/**
* Creates a channel buffer of which the first 2 bytes contain the length of
* the string in bytes and the remaining is the actual string in binary with
* specified format. Defaults to UTF-8 encoding in case charset passed in is
* null
*
* @param msg
* The string to be written.
* @param charset
* The Charset say 'UTF-8' in which the encoding needs to be
* done.
* @return The Netty channel buffer containing the string encoded as bytes
* in the provided charset. It will return null if the
* string parameter is null.
*/
public static ByteBuf writeString(String msg, Charset charset)
{
ByteBuf buffer = null;
try
{
ByteBuf stringBuffer = null;
if (null == charset)
{
charset = CharsetUtil.UTF_8;
}
stringBuffer = copiedBuffer(msg, charset);
int length = stringBuffer.readableBytes();
ByteBuf lengthBuffer = Unpooled.buffer(2);
lengthBuffer.writeShort(length);
buffer = Unpooled.wrappedBuffer(lengthBuffer, stringBuffer);
}
catch (Exception e)
{
throw new RuntimeException(e);
}
return buffer;
}
/**
* Read an object from a channel buffer with the specified length. It sets
* the reader index of the buffer to current reader index + 2(length bytes)
* + actual length.
*
* @param buffer
* The Netty buffer containing the Object.
* @return Returns the read object.
*/
public static V readObject(ByteBuf buffer, Transform decoder)
{
int length = 0;
if(null != buffer && buffer.readableBytes() > 2)
{
length = buffer.readUnsignedShort();
}
else
{
return null;
}
ByteBuf objBuffer = buffer.readSlice(length);
V obj = null;
try{
obj = decoder.convert(objBuffer);
}catch(Exception e){
throw new RuntimeException(e);
}
return obj;
}
public static ByteBuf writeObject(
Transform converter, V object)
{
ByteBuf buffer = null;
try
{
ByteBuf objectBuffer = converter.convert(object);
int length = objectBuffer.readableBytes();
ByteBuf lengthBuffer = Unpooled.buffer(2);
lengthBuffer.writeShort(length);
buffer = Unpooled.wrappedBuffer(lengthBuffer,
objectBuffer);
} catch (Exception e) {
throw new RuntimeException(e);
}
return buffer;
}
/**
* Read a socket address from a buffer. The socket address will be provided
* as two strings containing host and port.
*
* @param buffer
* The buffer containing the host and port as string.
* @return The InetSocketAddress object created from host and port or null
* in case the strings are not there.
*/
public static InetSocketAddress readSocketAddress(ByteBuf buffer)
throws Exception
{
String remoteHost = NettyUtils.readString(buffer);
int remotePort = 0;
if (buffer.readableBytes() >= 4)
{
remotePort = buffer.readInt();
}
else
{
return null;
}
InetSocketAddress remoteAddress = null;
if (null != remoteHost)
{
remoteAddress = new InetSocketAddress(remoteHost, remotePort);
}
return remoteAddress;
}
public static ByteBuf writeSocketAddress(
InetSocketAddress socketAddress)
{
String host = socketAddress.getHostName();
int port = socketAddress.getPort();
ByteBuf hostName = writeString(host);
ByteBuf portNum = Unpooled.buffer(4);
portNum.writeInt(port);
ByteBuf socketAddressBuffer = Unpooled.wrappedBuffer(
hostName, portNum);
return socketAddressBuffer;
}
}