Netty编解码技术和UDP实现
背景
作为网络传输框架，免不了传输对象，对象在传输之前就要序列化，这个序列化的过程就是编码过程。接收到编码后的数据就需要解码，还原传输的数据。
编解码技术就是java序列化技术，序列化的目的有两个，一是进行网络传输，二是对象持久化。
但是Java的序列化缺点很多，如无法跨语言，序列化后码流太大，序列化性能太低
主流的序列化框架：
JBoss的Marshalling包
google的Protobuf
基于Protobuf的Kyro
MessagePack框架
JBoss Marshalling的实现
代码示例：
public class Server {
public static void main(String[] args) throws Exception {
EventLoopGroup pGroup = new NioEventLoopGroup();
EventLoopGroup cGroup = new NioEventLoopGroup();
ServerBootstrap b = new ServerBootstrap();
b.group(pGroup, cGroup).channel(NioServerSocketChannel.class).option(ChannelOption.SO_BACKLOG, 1024)
// 设置日志
.handler(new LoggingHandler(LogLevel.INFO)).childHandler(new ChannelInitializer<SocketChannel>() {
protected void initChannel(SocketChannel sc) throws Exception {
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
sc.pipeline().addLast(new ServerHandler());
}
});
ChannelFuture cf = b.bind(8765).sync();
cf.channel().closeFuture().sync();
pGroup.shutdownGracefully();
cGroup.shutdownGracefully();
}
}
public class ServerHandler extends ChannelHandlerAdapter {
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
Req req = (Req) msg;
System.out.println("Server : " + req.getId() + ", " + req.getName() + ", " + req.getRequestMessage());
byte[] attachment = GzipUtils.ungzip(req.getAttachment());
String path = System.getProperty("user.dir") + File.separatorChar + "receive" + File.separatorChar + "001.jpg";
FileOutputStream fos = new FileOutputStream(path);
fos.write(attachment);
fos.close();
Resp resp = new Resp();
resp.setId(req.getId());
resp.setName("resp" + req.getId());
resp.setResponseMessage("响应内容" + req.getId());
ctx.writeAndFlush(resp);// .addListener(ChannelFutureListener.CLOSE);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}
public class Client {
public static void main(String[] args) throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
b.group(group).channel(NioSocketChannel.class).handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
sc.pipeline().addLast(new ClientHandler());
}
});
ChannelFuture cf = b.connect("127.0.0.1", 8765).sync();
for (int i = 0; i < 5; i++) {
Req req = new Req();
req.setId("" + i);
req.setName("pro" + i);
req.setRequestMessage("数据信息" + i);
String path = System.getProperty("user.dir") + File.separatorChar + "sources" + File.separatorChar
+ "001.jpg";
File file = new File(path);
FileInputStream in = new FileInputStream(file);
byte[] data = new byte[in.available()];
in.read(data);
in.close();
req.setAttachment(GzipUtils.gzip(data));
cf.channel().writeAndFlush(req);
}
cf.channel().closeFuture().sync();
group.shutdownGracefully();
}
}
public class ClientHandler extends ChannelHandlerAdapter {
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
try {
Resp resp = (Resp) msg;
System.out.println("Client : " + resp.getId() + ", " + resp.getName() + ", " + resp.getResponseMessage());
} finally {
ReferenceCountUtil.release(msg);
}
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}
/**
* Marshalling工厂
*
*/
public final class MarshallingCodeCFactory {
/**
* 创建Jboss Marshalling解码器MarshallingDecoder
*
* @return MarshallingDecoder
*/
public static MarshallingDecoder buildMarshallingDecoder() {
// 首先通过Marshalling工具类的精通方法获取Marshalling实例对象 参数serial标识创建的是java序列化工厂对象。
final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
// 创建了MarshallingConfiguration对象，配置了版本号为5
final MarshallingConfiguration configuration = new MarshallingConfiguration();
configuration.setVersion(5);
// 根据marshallerFactory和configuration创建provider
UnmarshallerProvider provider = new DefaultUnmarshallerProvider(marshallerFactory, configuration);
// 构建Netty的MarshallingDecoder对象，俩个参数分别为provider和单个消息序列化后的最大长度
MarshallingDecoder decoder = new MarshallingDecoder(provider, 1024 * 1024 * 1);
return decoder;
}
/**
* 创建Jboss Marshalling编码器MarshallingEncoder
*
* @return MarshallingEncoder
*/
public static MarshallingEncoder buildMarshallingEncoder() {
final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
final MarshallingConfiguration configuration = new MarshallingConfiguration();
configuration.setVersion(5);
MarshallerProvider provider = new DefaultMarshallerProvider(marshallerFactory, configuration);
// 构建Netty的MarshallingEncoder对象，MarshallingEncoder用于实现序列化接口的POJO对象序列化为二进制数组
MarshallingEncoder encoder = new MarshallingEncoder(provider);
return encoder;
}
}
public class Req implements Serializable {
private static final long serialVersionUID = 1L;
private String id;
private String name;
private String requestMessage;
private byte[] attachment;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getRequestMessage() {
return requestMessage;
}
public void setRequestMessage(String requestMessage) {
this.requestMessage = requestMessage;
}
public byte[] getAttachment() {
return attachment;
}
public void setAttachment(byte[] attachment) {
this.attachment = attachment;
}
}
public class Resp implements Serializable {
private static final long serialVersionUID = 1L;
private String id;
private String name;
private String responseMessage;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getResponseMessage() {
return responseMessage;
}
public void setResponseMessage(String responseMessage) {
this.responseMessage = responseMessage;
}
}
工具类：
public class GzipUtils {
public static byte[] gzip(byte[] data) throws Exception {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
GZIPOutputStream gzip = new GZIPOutputStream(bos);
gzip.write(data);
gzip.finish();
gzip.close();
byte[] ret = bos.toByteArray();
bos.close();
return ret;
}
public static byte[] ungzip(byte[] data) throws Exception {
ByteArrayInputStream bis = new ByteArrayInputStream(data);
GZIPInputStream gzip = new GZIPInputStream(bis);
byte[] buf = new byte[1024];
int num = -1;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
while ((num = gzip.read(buf, 0, buf.length)) != -1) {
bos.write(buf, 0, num);
}
gzip.close();
bis.close();
byte[] ret = bos.toByteArray();
bos.flush();
bos.close();
return ret;
}
public static void main(String[] args) throws Exception {
// 读取文件
String readPath = System.getProperty("user.dir") + File.separatorChar + "sources" + File.separatorChar
+ "006.jpg";
File file = new File(readPath);
FileInputStream in = new FileInputStream(file);
byte[] data = new byte[in.available()];
in.read(data);
in.close();
System.out.println("文件原始大小:" + data.length);
// 测试压缩
byte[] ret1 = GzipUtils.gzip(data);
System.out.println("压缩之后大小:" + ret1.length);
byte[] ret2 = GzipUtils.ungzip(ret1);
System.out.println("还原之后大小:" + ret2.length);
// 写出文件
String writePath = System.getProperty("user.dir") + File.separatorChar + "receive" + File.separatorChar
+ "006.jpg";
FileOutputStream fos = new FileOutputStream(writePath);
fos.write(ret2);
fos.close();
}
}
UDP的实现
代码示例：
public class Server {
public void run(int port) throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group).channel(NioDatagramChannel.class).option(ChannelOption.SO_BROADCAST, true)
.handler(new ServerHandler());
b.bind(port).sync().channel().closeFuture().await();
} finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new Server().run(8765);
new Server().run(8764);
}
}
public class ServerHandler extends
SimpleChannelInboundHandler<DatagramPacket> {
// 谚语列表
private static final String[] DICTIONARY = {
"只要功夫深，铁棒磨成针。",
"旧时王谢堂前燕，飞入寻常百姓家。",
"洛阳亲友如相问，一片冰心在玉壶。",
"一寸光阴一寸金，寸金难买寸光阴。",
"老骥伏枥，志在千里。烈士暮年，壮心不已!"
};
private String nextQuote() {
int quoteId = ThreadLocalRandom.current().nextInt(DICTIONARY.length);
return DICTIONARY[quoteId];
}
@Override
public void messageReceived(ChannelHandlerContext ctx, DatagramPacket packet)
throws Exception {
String req = packet.content().toString(CharsetUtil.UTF_8);
System.out.println(req);
if ("谚语字典查询?".equals(req)) {
ctx.writeAndFlush(
new DatagramPacket(Unpooled.copiedBuffer("谚语查询结果: " + nextQuote(),
CharsetUtil.UTF_8), packet.sender()));
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
throws Exception {
ctx.close();
cause.printStackTrace();
}
}
public class Client {
public void run(int port) throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group).channel(NioDatagramChannel.class).option(ChannelOption.SO_BROADCAST, true)
.handler(new ClientHandler());
Channel ch = b.bind(0).sync().channel();
// 向网段内的所有机器广播UDP消息
ch.writeAndFlush(new DatagramPacket(Unpooled.copiedBuffer("谚语字典查询?", CharsetUtil.UTF_8),
new InetSocketAddress("255.255.255.255", port))).sync();
if (!ch.closeFuture().await(15000)) {
System.out.println("查询超时!");
}
} finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
new Client().run(8765);
}
}
public class ClientHandler extends SimpleChannelInboundHandler<DatagramPacket> {
@Override
public void messageReceived(ChannelHandlerContext ctx, DatagramPacket msg) throws Exception {
String response = msg.content().toString(CharsetUtil.UTF_8);
if (response.startsWith("谚语查询结果: ")) {
System.out.println(response);
ctx.close();
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
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