TCP粘包拆包问题
- LineBasedFrameDecoder+StringDecoder 换行符为结束标志
- DelimiterBasedFrameDecoder + StringDecoder 分隔符作为结束标志
- FixedLengthFrameDecoder + StringDecoder 定长
代码示例(netty权威指南修改的例子，不多解释)
EchoServerHandler.class
public class EchoServerHandler extends ChannelInboundHandlerAdapter{
int counter = 0;
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// String body = (String) msg;
// System.out.println("This is " + ++counter + " times received client:[" + body + "]");
// body += "$_";
// ByteBuf echo = Unpooled.copiedBuffer(body.getBytes());
// ctx.writeAndFlush(echo);
System.out.println("Received client : [" + msg + "]");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
EchoServer.class
public class EchoServer {
public void bind(int port) throws InterruptedException {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.group(bossGroup,workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG,100)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
ByteBuf delimiter = Unpooled.copiedBuffer("$_".getBytes());
// socketChannel.pipeline().addLast(new DelimiterBasedFrameDecoder(1024,delimiter));
socketChannel.pipeline().addLast(new FixedLengthFrameDecoder(20));
socketChannel.pipeline().addLast(new StringDecoder());
socketChannel.pipeline().addLast(new EchoServerHandler());
}
});
ChannelFuture future = bootstrap.bind(port).sync();
future.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws InterruptedException {
int port = 8080;
if(args != null && args.length > 0){
try {
port = Integer.parseInt(args[0]);
} catch (NumberFormatException e) {
// e.printStackTrace();
}
}
new EchoServer().bind(port);
}
}
EchoClientHandler.class
public class EchoClientHandler extends ChannelInboundHandlerAdapter {
private int counter;
static final String ECHO_REQ = "Hi,welcome to netty.$_";
public EchoClientHandler() {
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
for( int i = 0 ; i < 10 ; i++){
ctx.writeAndFlush(Unpooled.copiedBuffer(ECHO_REQ.getBytes()));
}
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("This is " + ++counter + " times received client:[" + msg + "]");
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
super.exceptionCaught(ctx, cause);
}
}
EchoClient.class
public class EchoClient {
public void connect(int port,String host) throws InterruptedException {
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
try {
b.group(group).channel(NioSocketChannel.class)
.option(ChannelOption.TCP_NODELAY,true)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
ByteBuf delimiter = Unpooled.copiedBuffer("$_".getBytes());
socketChannel.pipeline().addLast(new DelimiterBasedFrameDecoder(1024,delimiter));
socketChannel.pipeline().addLast(new StringDecoder());
socketChannel.pipeline().addLast(new EchoClientHandler());
}
});
ChannelFuture future = b.connect(host,port).sync();
future.channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws InterruptedException {
int port = 8080;
if(args != null && args.length > 0){
try {
port = Integer.parseInt(args[0]);
} catch (NumberFormatException e) {
// e.printStackTrace();
}
}
new EchoClient().connect(port,"127.0.0.1");
}
}
编解码技术
Java序列化
- 无法跨语言
- 序列化后流太大
- 序列化性能太低
Google的Protobuf
- 语言无关
- 高效
- 结构化数据存储格式（XML JSON等）
- 官方支持Java C++ Python
Facebook的Thrift
- 优缺点
- 适用于静态的数据交换，需要首先确定好它的数据结构；当数据结构发生变化时，必须重新编辑IDL文件，生成代码和编译
- 支持多种程序语言
- 组成
- 语言系统以及IDL编译器
- TProtocal:RPC协议层，可以选择多种不同的对象序列化方式
- TTransport:RPC的传输层
- TProcesser:协议层和用户服务之间的纽带，负责调用服务实现的接口
- TServer:聚合TProtocal、TTransport、TProcesser等对象
netty使用不同解码方式
在netty中使用java序列化
public class SubscribeReq implements Serializable {
private static final long serialVersionUID = 2394470753940199464L;
private int subReqId;
private String userName;
private String productName;
private String phoneNumber;
private String address;
public int getSubReqId() {
return subReqId;
}
public void setSubReqId(int subReqId) {
this.subReqId = subReqId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getProductName() {
return productName;
}
public void setProductName(String productName) {
this.productName = productName;
}
public String getPhoneNumber() {
return phoneNumber;
}
public void setPhoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
SubscribeReq that = (SubscribeReq) o;
if (subReqId != that.subReqId) return false;
if (userName != null ? !userName.equals(that.userName) : that.userName != null) return false;
if (productName != null ? !productName.equals(that.productName) : that.productName != null) return false;
if (phoneNumber != null ? !phoneNumber.equals(that.phoneNumber) : that.phoneNumber != null) return false;
return address != null ? address.equals(that.address) : that.address == null;
}
@Override
public int hashCode() {
int result = subReqId;
result = 31 * result + (userName != null ? userName.hashCode() : 0);
result = 31 * result + (productName != null ? productName.hashCode() : 0);
result = 31 * result + (phoneNumber != null ? phoneNumber.hashCode() : 0);
result = 31 * result + (address != null ? address.hashCode() : 0);
return result;
}
@Override
public String toString() {
return "SubscribeReq{" +
"subReqId=" + subReqId +
", userName='" + userName + '\'' +
", productName='" + productName + '\'' +
", phoneNumber='" + phoneNumber + '\'' +
", address='" + address + '\'' +
'}';
}
}
public class SubscribeResp implements Serializable {
private static final long serialVersionUID = 1L;
private int subReqId;
private int respCode;
private String desc;
public int getSubReqId() {
return subReqId;
}
public void setSubReqId(int subReqId) {
this.subReqId = subReqId;
}
public int getRespCode() {
return respCode;
}
public void setRespCode(int respCode) {
this.respCode = respCode;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
SubscribeResp that = (SubscribeResp) o;
if (subReqId != that.subReqId) return false;
if (respCode != that.respCode) return false;
return desc != null ? desc.equals(that.desc) : that.desc == null;
}
@Override
public int hashCode() {
int result = subReqId;
result = 31 * result + respCode;
result = 31 * result + (desc != null ? desc.hashCode() : 0);
return result;
}
@Override
public String toString() {
return "SubscribeResp{" +
"subReqId=" + subReqId +
", respCode=" + respCode +
", desc='" + desc + '\'' +
'}';
}
}
在netty中使用protobuf
- 安装protobuf
下载解压编译 make && make check && sudo make install && sudo ldconfig
-
编写proto文件
syntax="proto3"; option java_package = "com.oneapm.netty.opendecode.protobuf"; option java_outer_classname = "SubscribeReqProto"; message SubscribeReq { int32 subReqId = 1; string userName = 2; string productName = 3; repeated string address = 4; }syntax="proto3"; option java_package = "com.oneapm.netty.opendecode.protobuf"; option java_outer_classname = "SubscribeRespProto"; message SubscribeResp { int32 subReqId = 1; int32 respCode = 2; string desc = 3; } 自动生成class文件
proto文件放在与/src/main/java平齐的/src/main/protobuf下
cd src/main/protobuf
/usr/local/bin/protoc --java_out=../java/ SubscribeReq.proto
/usr/local/bin/protoc --java_out=../java/ SubscribeResp.proto
- 在server和client增加编码解码
通用代码
server端
public class SubReqServerHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// SubscribeReq req = (SubscribeReq) msg;
SubscribeReqProto.SubscribeReq req = (SubscribeReqProto.SubscribeReq) msg;
if ("oneapm".equalsIgnoreCase(req.getUserName())) {
System.out.println("Service accept client subscribe req:[" + req.toString() + "]");
ctx.writeAndFlush(resp(req.getSubReqId()));
}
}
/**
* java serializable
* @param subReqId
* @return
*/
// private SubscribeResp resp(int subReqId) {
// SubscribeResp resp = new SubscribeResp();
// resp.setSubReqId(subReqId);
// resp.setRespCode(0);
// resp.setDesc("Welcome to China");
// return resp;
// }
/**
* protobuf
* @param subReqId
* @return
*/
private SubscribeRespProto.SubscribeResp resp(int subReqId) {
SubscribeRespProto.SubscribeResp.Builder resp = SubscribeRespProto.SubscribeResp.newBuilder();
resp.setSubReqId(subReqId);
resp.setRespCode(0);
resp.setDesc("Welcome to China");
return resp.build();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
public class SubReqServer {
public void bind(int port) throws InterruptedException {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.group(bossGroup,workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG,100)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
//java Serializable
// socketChannel.pipeline().addLast(new ObjectDecoder(1024*1024, ClassResolvers.weakCachingConcurrentResolver(this.getClass().getClassLoader())));
// socketChannel.pipeline().addLast(new ObjectEncoder());
// socketChannel.pipeline().addLast(new SubReqServerHandler());
//protobuf
socketChannel.pipeline().addLast(new ProtobufVarint32FrameDecoder());
socketChannel.pipeline().addLast(new ProtobufDecoder(SubscribeReqProto.SubscribeReq.getDefaultInstance()));
socketChannel.pipeline().addLast(new ProtobufVarint32LengthFieldPrepender());
socketChannel.pipeline().addLast(new ProtobufEncoder());
socketChannel.pipeline().addLast(new SubReqServerHandler());
}
});
ChannelFuture future = bootstrap.bind(port).sync();
future.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws InterruptedException {
int port = 8080;
if(args != null && args.length > 0){
try {
port = Integer.parseInt(args[0]);
} catch (NumberFormatException e) {
// e.printStackTrace();
}
}
new SubReqServer().bind(port);
}
}
client端
public class SubReqClientHandler extends ChannelInboundHandlerAdapter {
public SubReqClientHandler() {
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
for( int i = 0 ; i < 10 ; i++){
ctx.write(subReq(i));
}
ctx.flush();
}
// private SubscribeReq subReq(int i){
// SubscribeReq req = new SubscribeReq();
// req.setAddress("宜昌市三峡大坝");
// req.setProductName("netty深入学习");
// req.setPhoneNumber("185********");
// req.setSubReqId(i);
// req.setUserName("oneapm");
// return req;
// }
/**
* protobuf
* @param i
* @return
*/
private SubscribeReqProto.SubscribeReq subReq(int i){
SubscribeReqProto.SubscribeReq.Builder req = SubscribeReqProto.SubscribeReq.newBuilder();
List<String> address = new ArrayList<>();
address.add("NanJing");
address.add("BeiJing");
req.addAllAddress(address);
req.setProductName("netty study");
req.setSubReqId(i);
req.setUserName("oneapm");
return req.build();
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("Receive server response: [" + msg + "]");
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
public class SubReqClient {
public void connect(int port,String host) throws InterruptedException {
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
try {
b.group(group).channel(NioSocketChannel.class)
.option(ChannelOption.TCP_NODELAY,true)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
// socketChannel.pipeline().addLast(new ObjectDecoder(1024, ClassResolvers.cacheDisabled(this.getClass().getClassLoader())));
// socketChannel.pipeline().addLast(new ObjectEncoder());
// socketChannel.pipeline().addLast(new SubReqClientHandler());
socketChannel.pipeline().addLast(new ProtobufVarint32FrameDecoder());
socketChannel.pipeline().addLast(new ProtobufDecoder(SubscribeRespProto.SubscribeResp.getDefaultInstance()));
socketChannel.pipeline().addLast(new ProtobufVarint32LengthFieldPrepender());
socketChannel.pipeline().addLast(new ProtobufEncoder());
socketChannel.pipeline().addLast(new SubReqClientHandler());
}
});
ChannelFuture future = b.connect(host,port).sync();
future.channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws InterruptedException {
int port = 8080;
if(args != null && args.length > 0){
try {
port = Integer.parseInt(args[0]);
} catch (NumberFormatException e) {
// e.printStackTrace();
}
}
new SubReqClient().connect(port,"127.0.0.1");
}
}
facebook/nifty:Thrift on Netty
facebook提供的构建在Thrift和Netty之上的封装https://github.com/facebook/nifty，简单来说，就是让我们的编码更加简单（脑残）
项目github地址
https://github.com/engimatic/effectivejava/tree/master/netty/src/main/java/com/oneapm/netty
