23、Netty 基础 之 Protobuf1、
一、Protobuf基本介绍
1、 Protobuf是Google发布的开源项目，全称GoogleProtobufBuffers，是一种轻便高效的结构化数据存储格式，可以用于结构化数据串行化，或者说序列化它很适合做数据存储或RPC数据交换格式；
2、 参考文档；
https://developers.google.cn/protocol-buffers/docs/proto
3、 Protobuf是以message的方式来管理数据的；
4、支持跨平台、跨语言，即【客户端和服务端可以是不同的语言编写的】（支持目前绝大多数语言，例如C++、C#、Java、Python等）
5、 目前很多公司从http+json->tcp+protobuf；
6、 高性能，高可靠性；
7、 使用protobuf编译器能自动生成代码；
Protobuf是将类的定义使用.proto文件进行描述。
说明，在idea中编写.proto文件时，会自动提示是否下载.ptotot编写插件，可以让语法高亮。
8、 然后通过protoc.exe编译器根据.proto自动生成.java文件；
9、 protobuf使用示意图；
二、Protobuf入门案例—生成类
1、 客户端可以发送一个StudentPOJO对象到服务器（通过Protobuf编码）；
2、 服务端能接收StudentPOJO对象，并显示信息（通过Protobuf解码）；
3、 代码；
三、netty中使用Protobuf的步骤
1、 pom文件添加依赖；
<dependency>
<groupId>com.google.protobuf</groupId>
<artifactId>protobuf-java</artifactId>
<version>3.21.12</version>
</dependency>
2、 建立Student.proto文件；
syntax = "proto3"; //协议版本
option java_outer_classname = "StudentPOJO"; //生成的外部类名，同时也是生成的xx.java名称
//protobuf使用message的形式来管理数据的
message Student { //会在StudentPOJO外部类，生成一个内部类Student，它是真正发送的POJO对象
int32 id = 1; //Student类中有一个属性，名字为id，类型为int32(protobuf类型)
//1不代表值，而是代表属性的序号
string name = 2; //第二个属性
}
3、 编译proto文件；
C:\Users\user\Downloads\protoc-21.12-win32\bin>protoc.exe --java_out=. Student.proto
生成文件StudentPOJO.java
// Generated by the protocol buffer compiler. DO NOT EDIT!
// source: Student.proto
public final class StudentPOJO {
private StudentPOJO() {}
public static void registerAllExtensions(
com.google.protobuf.ExtensionRegistryLite registry) {
}
public static void registerAllExtensions(
com.google.protobuf.ExtensionRegistry registry) {
registerAllExtensions(
(com.google.protobuf.ExtensionRegistryLite) registry);
}
public interface StudentOrBuilder extends
// @@protoc_insertion_point(interface_extends:Student)
com.google.protobuf.MessageOrBuilder {
/**
* <pre>
*Student类中有一个属性，名字为id，类型为int32(protobuf类型)
* </pre>
*
* <code>int32 id = 1;</code>
* @return The id.
*/
int getId();
/**
* <pre>
*第二个属性
* </pre>
*
* <code>string name = 2;</code>
* @return The name.
*/
java.lang.String getName();
/**
* <pre>
*第二个属性
* </pre>
*
* <code>string name = 2;</code>
* @return The bytes for name.
*/
com.google.protobuf.ByteString
getNameBytes();
}
/**
* <pre>
*protobuf使用message的形式来管理数据的
* </pre>
*
* Protobuf type {@code Student}
*/
public static final class Student extends
com.google.protobuf.GeneratedMessageV3 implements
// @@protoc_insertion_point(message_implements:Student)
StudentOrBuilder {
private static final long serialVersionUID = 0L;
// Use Student.newBuilder() to construct.
private Student(com.google.protobuf.GeneratedMessageV3.Builder<?> builder) {
super(builder);
}
private Student() {
name_ = "";
}
@java.lang.Override
@SuppressWarnings({"unused"})
protected java.lang.Object newInstance(
UnusedPrivateParameter unused) {
return new Student();
}
@java.lang.Override
public final com.google.protobuf.UnknownFieldSet
getUnknownFields() {
return this.unknownFields;
}
public static final com.google.protobuf.Descriptors.Descriptor
getDescriptor() {
return StudentPOJO.internal_static_Student_descriptor;
}
@java.lang.Override
protected com.google.protobuf.GeneratedMessageV3.FieldAccessorTable
internalGetFieldAccessorTable() {
return StudentPOJO.internal_static_Student_fieldAccessorTable
.ensureFieldAccessorsInitialized(
StudentPOJO.Student.class, StudentPOJO.Student.Builder.class);
}
public static final int ID_FIELD_NUMBER = 1;
private int id_ = 0;
/**
* <pre>
*Student类中有一个属性，名字为id，类型为int32(protobuf类型)
* </pre>
*
* <code>int32 id = 1;</code>
* @return The id.
*/
@java.lang.Override
public int getId() {
return id_;
}
public static final int NAME_FIELD_NUMBER = 2;
@SuppressWarnings("serial")
private volatile java.lang.Object name_ = "";
/**
* <pre>
*第二个属性
* </pre>
*
* <code>string name = 2;</code>
* @return The name.
*/
@java.lang.Override
public java.lang.String getName() {
java.lang.Object ref = name_;
if (ref instanceof java.lang.String) {
return (java.lang.String) ref;
} else {
com.google.protobuf.ByteString bs =
(com.google.protobuf.ByteString) ref;
java.lang.String s = bs.toStringUtf8();
name_ = s;
return s;
}
}
/**
* <pre>
*第二个属性
* </pre>
*
* <code>string name = 2;</code>
* @return The bytes for name.
*/
@java.lang.Override
public com.google.protobuf.ByteString
getNameBytes() {
java.lang.Object ref = name_;
if (ref instanceof java.lang.String) {
com.google.protobuf.ByteString b =
com.google.protobuf.ByteString.copyFromUtf8(
(java.lang.String) ref);
name_ = b;
return b;
} else {
return (com.google.protobuf.ByteString) ref;
}
}
private byte memoizedIsInitialized = -1;
@java.lang.Override
public final boolean isInitialized() {
byte isInitialized = memoizedIsInitialized;
if (isInitialized == 1) return true;
if (isInitialized == 0) return false;
memoizedIsInitialized = 1;
return true;
}
@java.lang.Override
public void writeTo(com.google.protobuf.CodedOutputStream output)
throws java.io.IOException {
if (id_ != 0) {
output.writeInt32(1, id_);
}
if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(name_)) {
com.google.protobuf.GeneratedMessageV3.writeString(output, 2, name_);
}
getUnknownFields().writeTo(output);
}
@java.lang.Override
public int getSerializedSize() {
int size = memoizedSize;
if (size != -1) return size;
size = 0;
if (id_ != 0) {
size += com.google.protobuf.CodedOutputStream
.computeInt32Size(1, id_);
}
if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(name_)) {
size += com.google.protobuf.GeneratedMessageV3.computeStringSize(2, name_);
}
size += getUnknownFields().getSerializedSize();
memoizedSize = size;
return size;
}
@java.lang.Override
public boolean equals(final java.lang.Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof StudentPOJO.Student)) {
return super.equals(obj);
}
StudentPOJO.Student other = (StudentPOJO.Student) obj;
if (getId()
!= other.getId()) return false;
if (!getName()
.equals(other.getName())) return false;
if (!getUnknownFields().equals(other.getUnknownFields())) return false;
return true;
}
@java.lang.Override
public int hashCode() {
if (memoizedHashCode != 0) {
return memoizedHashCode;
}
int hash = 41;
hash = (19 * hash) + getDescriptor().hashCode();
hash = (37 * hash) + ID_FIELD_NUMBER;
hash = (53 * hash) + getId();
hash = (37 * hash) + NAME_FIELD_NUMBER;
hash = (53 * hash) + getName().hashCode();
hash = (29 * hash) + getUnknownFields().hashCode();
memoizedHashCode = hash;
return hash;
}
public static StudentPOJO.Student parseFrom(
java.nio.ByteBuffer data)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data);
}
public static StudentPOJO.Student parseFrom(
java.nio.ByteBuffer data,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data, extensionRegistry);
}
public static StudentPOJO.Student parseFrom(
com.google.protobuf.ByteString data)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data);
}
public static StudentPOJO.Student parseFrom(
com.google.protobuf.ByteString data,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data, extensionRegistry);
}
public static StudentPOJO.Student parseFrom(byte[] data)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data);
}
public static StudentPOJO.Student parseFrom(
byte[] data,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws com.google.protobuf.InvalidProtocolBufferException {
return PARSER.parseFrom(data, extensionRegistry);
}
public static StudentPOJO.Student parseFrom(java.io.InputStream input)
throws java.io.IOException {
return com.google.protobuf.GeneratedMessageV3
.parseWithIOException(PARSER, input);
}
public static StudentPOJO.Student parseFrom(
java.io.InputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws java.io.IOException {
return com.google.protobuf.GeneratedMessageV3
.parseWithIOException(PARSER, input, extensionRegistry);
}
public static StudentPOJO.Student parseDelimitedFrom(java.io.InputStream input)
throws java.io.IOException {
return com.google.protobuf.GeneratedMessageV3
.parseDelimitedWithIOException(PARSER, input);
}
public static StudentPOJO.Student parseDelimitedFrom(
java.io.InputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws java.io.IOException {
return com.google.protobuf.GeneratedMessageV3
.parseDelimitedWithIOException(PARSER, input, extensionRegistry);
}
public static StudentPOJO.Student parseFrom(
com.google.protobuf.CodedInputStream input)
throws java.io.IOException {
return com.google.protobuf.GeneratedMessageV3
.parseWithIOException(PARSER, input);
}
public static StudentPOJO.Student parseFrom(
com.google.protobuf.CodedInputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws java.io.IOException {
return com.google.protobuf.GeneratedMessageV3
.parseWithIOException(PARSER, input, extensionRegistry);
}
@java.lang.Override
public Builder newBuilderForType() { return newBuilder(); }
public static Builder newBuilder() {
return DEFAULT_INSTANCE.toBuilder();
}
public static Builder newBuilder(StudentPOJO.Student prototype) {
return DEFAULT_INSTANCE.toBuilder().mergeFrom(prototype);
}
@java.lang.Override
public Builder toBuilder() {
return this == DEFAULT_INSTANCE
? new Builder() : new Builder().mergeFrom(this);
}
@java.lang.Override
protected Builder newBuilderForType(
com.google.protobuf.GeneratedMessageV3.BuilderParent parent) {
Builder builder = new Builder(parent);
return builder;
}
/**
* <pre>
*protobuf使用message的形式来管理数据的
* </pre>
*
* Protobuf type {@code Student}
*/
public static final class Builder extends
com.google.protobuf.GeneratedMessageV3.Builder<Builder> implements
// @@protoc_insertion_point(builder_implements:Student)
StudentPOJO.StudentOrBuilder {
public static final com.google.protobuf.Descriptors.Descriptor
getDescriptor() {
return StudentPOJO.internal_static_Student_descriptor;
}
@java.lang.Override
protected com.google.protobuf.GeneratedMessageV3.FieldAccessorTable
internalGetFieldAccessorTable() {
return StudentPOJO.internal_static_Student_fieldAccessorTable
.ensureFieldAccessorsInitialized(
StudentPOJO.Student.class, StudentPOJO.Student.Builder.class);
}
// Construct using StudentPOJO.Student.newBuilder()
private Builder() {
}
private Builder(
com.google.protobuf.GeneratedMessageV3.BuilderParent parent) {
super(parent);
}
@java.lang.Override
public Builder clear() {
super.clear();
bitField0_ = 0;
id_ = 0;
name_ = "";
return this;
}
@java.lang.Override
public com.google.protobuf.Descriptors.Descriptor
getDescriptorForType() {
return StudentPOJO.internal_static_Student_descriptor;
}
@java.lang.Override
public StudentPOJO.Student getDefaultInstanceForType() {
return StudentPOJO.Student.getDefaultInstance();
}
@java.lang.Override
public StudentPOJO.Student build() {
StudentPOJO.Student result = buildPartial();
if (!result.isInitialized()) {
throw newUninitializedMessageException(result);
}
return result;
}
@java.lang.Override
public StudentPOJO.Student buildPartial() {
StudentPOJO.Student result = new StudentPOJO.Student(this);
if (bitField0_ != 0) { buildPartial0(result); }
onBuilt();
return result;
}
private void buildPartial0(StudentPOJO.Student result) {
int from_bitField0_ = bitField0_;
if (((from_bitField0_ & 0x00000001) != 0)) {
result.id_ = id_;
}
if (((from_bitField0_ & 0x00000002) != 0)) {
result.name_ = name_;
}
}
@java.lang.Override
public Builder clone() {
return super.clone();
}
@java.lang.Override
public Builder setField(
com.google.protobuf.Descriptors.FieldDescriptor field,
java.lang.Object value) {
return super.setField(field, value);
}
@java.lang.Override
public Builder clearField(
com.google.protobuf.Descriptors.FieldDescriptor field) {
return super.clearField(field);
}
@java.lang.Override
public Builder clearOneof(
com.google.protobuf.Descriptors.OneofDescriptor oneof) {
return super.clearOneof(oneof);
}
@java.lang.Override
public Builder setRepeatedField(
com.google.protobuf.Descriptors.FieldDescriptor field,
int index, java.lang.Object value) {
return super.setRepeatedField(field, index, value);
}
@java.lang.Override
public Builder addRepeatedField(
com.google.protobuf.Descriptors.FieldDescriptor field,
java.lang.Object value) {
return super.addRepeatedField(field, value);
}
@java.lang.Override
public Builder mergeFrom(com.google.protobuf.Message other) {
if (other instanceof StudentPOJO.Student) {
return mergeFrom((StudentPOJO.Student)other);
} else {
super.mergeFrom(other);
return this;
}
}
public Builder mergeFrom(StudentPOJO.Student other) {
if (other == StudentPOJO.Student.getDefaultInstance()) return this;
if (other.getId() != 0) {
setId(other.getId());
}
if (!other.getName().isEmpty()) {
name_ = other.name_;
bitField0_ |= 0x00000002;
onChanged();
}
this.mergeUnknownFields(other.getUnknownFields());
onChanged();
return this;
}
@java.lang.Override
public final boolean isInitialized() {
return true;
}
@java.lang.Override
public Builder mergeFrom(
com.google.protobuf.CodedInputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws java.io.IOException {
if (extensionRegistry == null) {
throw new java.lang.NullPointerException();
}
try {
boolean done = false;
while (!done) {
int tag = input.readTag();
switch (tag) {
case 0:
done = true;
break;
case 8: {
id_ = input.readInt32();
bitField0_ |= 0x00000001;
break;
} // case 8
case 18: {
name_ = input.readStringRequireUtf8();
bitField0_ |= 0x00000002;
break;
} // case 18
default: {
if (!super.parseUnknownField(input, extensionRegistry, tag)) {
done = true; // was an endgroup tag
}
break;
} // default:
} // switch (tag)
} // while (!done)
} catch (com.google.protobuf.InvalidProtocolBufferException e) {
throw e.unwrapIOException();
} finally {
onChanged();
} // finally
return this;
}
private int bitField0_;
private int id_ ;
/**
* <pre>
*Student类中有一个属性，名字为id，类型为int32(protobuf类型)
* </pre>
*
* <code>int32 id = 1;</code>
* @return The id.
*/
@java.lang.Override
public int getId() {
return id_;
}
/**
* <pre>
*Student类中有一个属性，名字为id，类型为int32(protobuf类型)
* </pre>
*
* <code>int32 id = 1;</code>
* @param value The id to set.
* @return This builder for chaining.
*/
public Builder setId(int value) {
id_ = value;
bitField0_ |= 0x00000001;
onChanged();
return this;
}
/**
* <pre>
*Student类中有一个属性，名字为id，类型为int32(protobuf类型)
* </pre>
*
* <code>int32 id = 1;</code>
* @return This builder for chaining.
*/
public Builder clearId() {
bitField0_ = (bitField0_ & ~0x00000001);
id_ = 0;
onChanged();
return this;
}
private java.lang.Object name_ = "";
/**
* <pre>
*第二个属性
* </pre>
*
* <code>string name = 2;</code>
* @return The name.
*/
public java.lang.String getName() {
java.lang.Object ref = name_;
if (!(ref instanceof java.lang.String)) {
com.google.protobuf.ByteString bs =
(com.google.protobuf.ByteString) ref;
java.lang.String s = bs.toStringUtf8();
name_ = s;
return s;
} else {
return (java.lang.String) ref;
}
}
/**
* <pre>
*第二个属性
* </pre>
*
* <code>string name = 2;</code>
* @return The bytes for name.
*/
public com.google.protobuf.ByteString
getNameBytes() {
java.lang.Object ref = name_;
if (ref instanceof String) {
com.google.protobuf.ByteString b =
com.google.protobuf.ByteString.copyFromUtf8(
(java.lang.String) ref);
name_ = b;
return b;
} else {
return (com.google.protobuf.ByteString) ref;
}
}
/**
* <pre>
*第二个属性
* </pre>
*
* <code>string name = 2;</code>
* @param value The name to set.
* @return This builder for chaining.
*/
public Builder setName(
java.lang.String value) {
if (value == null) { throw new NullPointerException(); }
name_ = value;
bitField0_ |= 0x00000002;
onChanged();
return this;
}
/**
* <pre>
*第二个属性
* </pre>
*
* <code>string name = 2;</code>
* @return This builder for chaining.
*/
public Builder clearName() {
name_ = getDefaultInstance().getName();
bitField0_ = (bitField0_ & ~0x00000002);
onChanged();
return this;
}
/**
* <pre>
*第二个属性
* </pre>
*
* <code>string name = 2;</code>
* @param value The bytes for name to set.
* @return This builder for chaining.
*/
public Builder setNameBytes(
com.google.protobuf.ByteString value) {
if (value == null) { throw new NullPointerException(); }
checkByteStringIsUtf8(value);
name_ = value;
bitField0_ |= 0x00000002;
onChanged();
return this;
}
@java.lang.Override
public final Builder setUnknownFields(
final com.google.protobuf.UnknownFieldSet unknownFields) {
return super.setUnknownFields(unknownFields);
}
@java.lang.Override
public final Builder mergeUnknownFields(
final com.google.protobuf.UnknownFieldSet unknownFields) {
return super.mergeUnknownFields(unknownFields);
}
// @@protoc_insertion_point(builder_scope:Student)
}
// @@protoc_insertion_point(class_scope:Student)
private static final StudentPOJO.Student DEFAULT_INSTANCE;
static {
DEFAULT_INSTANCE = new StudentPOJO.Student();
}
public static StudentPOJO.Student getDefaultInstance() {
return DEFAULT_INSTANCE;
}
private static final com.google.protobuf.Parser<Student>
PARSER = new com.google.protobuf.AbstractParser<Student>() {
@java.lang.Override
public Student parsePartialFrom(
com.google.protobuf.CodedInputStream input,
com.google.protobuf.ExtensionRegistryLite extensionRegistry)
throws com.google.protobuf.InvalidProtocolBufferException {
Builder builder = newBuilder();
try {
builder.mergeFrom(input, extensionRegistry);
} catch (com.google.protobuf.InvalidProtocolBufferException e) {
throw e.setUnfinishedMessage(builder.buildPartial());
} catch (com.google.protobuf.UninitializedMessageException e) {
throw e.asInvalidProtocolBufferException().setUnfinishedMessage(builder.buildPartial());
} catch (java.io.IOException e) {
throw new com.google.protobuf.InvalidProtocolBufferException(e)
.setUnfinishedMessage(builder.buildPartial());
}
return builder.buildPartial();
}
};
public static com.google.protobuf.Parser<Student> parser() {
return PARSER;
}
@java.lang.Override
public com.google.protobuf.Parser<Student> getParserForType() {
return PARSER;
}
@java.lang.Override
public StudentPOJO.Student getDefaultInstanceForType() {
return DEFAULT_INSTANCE;
}
}
private static final com.google.protobuf.Descriptors.Descriptor
internal_static_Student_descriptor;
private static final
com.google.protobuf.GeneratedMessageV3.FieldAccessorTable
internal_static_Student_fieldAccessorTable;
public static com.google.protobuf.Descriptors.FileDescriptor
getDescriptor() {
return descriptor;
}
private static com.google.protobuf.Descriptors.FileDescriptor
descriptor;
static {
java.lang.String[] descriptorData = {
"\n\rStudent.proto\"#\n\007Student\022\n\n\002id\030\001 \001(\005\022\014" +
"\n\004name\030\002 \001(\tB\rB\013StudentPOJOb\006proto3"
};
descriptor = com.google.protobuf.Descriptors.FileDescriptor
.internalBuildGeneratedFileFrom(descriptorData,
new com.google.protobuf.Descriptors.FileDescriptor[] {
});
internal_static_Student_descriptor =
getDescriptor().getMessageTypes().get(0);
internal_static_Student_fieldAccessorTable = new
com.google.protobuf.GeneratedMessageV3.FieldAccessorTable(
internal_static_Student_descriptor,
new java.lang.String[] { "Id", "Name", });
}
// @@protoc_insertion_point(outer_class_scope)
}
四、从客户端发送一个Student对象给服务端
1、 NettyClient.java添加ProtobufEncoder；
package netty.protobuf;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.protobuf.ProtobufEncoder;
public class NettyClient {
public static void main(String[] args) throws Exception {
//客户端需要一个事件循环组
EventLoopGroup group = new NioEventLoopGroup();
try {
//创建客户端的启动对象
//注意客户端使用的是Bootstrap
Bootstrap bootstrap = new Bootstrap();
//设置相关参数
bootstrap.group(group) //设置线程组
.channel(NioSocketChannel.class) //设置客户端通道的实现类
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
//在pipeline中加入ProtobufEncoder
pipeline.addLast("encoder", new ProtobufEncoder());
//加入自己的处理器
pipeline.addLast(new NettyClientHandler());
}
});
System.out.println("...客户端 is ready...");
//启动客户端去连接服务器端
//ChannelFuture涉及到netty的异步模型
ChannelFuture cf = bootstrap.connect("127.0.0.1", 6668).sync();
//对关闭通道进行监听
cf.channel().closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
} finally {
//优雅的关闭
group.shutdownGracefully();
}
}
}
2、 NettyClientHandler.java添加发送student对象；
package netty.protobuf;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
public class NettyClientHandler extends ChannelInboundHandlerAdapter {
//当通道就绪时，就会触发该方法
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
//发送一个Student对象到服务器
StudentPOJO.Student student = StudentPOJO.Student.newBuilder().setId(10).setName("张三").build();
ctx.writeAndFlush(student);
}
//当通道有读取事件时会触发
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
ByteBuf buf = (ByteBuf) msg;
System.out.println("服务器回复的消息：" + buf.toString(CharsetUtil.UTF_8));
System.out.println("服务器的地址：" + ctx.channel().remoteAddress());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
3、 NettyServer.java添加ProtobufDecoder；
package netty.protobuf;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.protobuf.ProtobufDecoder;
public class NettyServer {
public static void main(String[] args) throws Exception {
//创建BossGroup和WorkerGroup
//说明
//1. 创建两个线程组bossGroup和workerGroup
//2. bossGroup它只是处理连接请求，真正的与客户端业务处理会交给workerGroup去完成
//3. 两个都是无限循环
EventLoopGroup bossGroup = new NioEventLoopGroup(1);
EventLoopGroup workerGroup = new NioEventLoopGroup(8);
try {
//创建服务器端的启动对象，配置启动参数
ServerBootstrap bootstrap = new ServerBootstrap();
//使用链式编程来进行设置
bootstrap.group(bossGroup, workerGroup) //设置两个线程组
.channel(NioServerSocketChannel.class) //使用NioServerSocketChannel作为服务器的通道实现
.childHandler(new ChannelInitializer<SocketChannel>() { //创建一个通道初始化对象
//给pipeline设置处理器
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
//在pipeline加入ProtobufDecoder
//指定对哪种对象进行解码
pipeline.addLast("decoder", new ProtobufDecoder(StudentPOJO.Student.getDefaultInstance()));
//向管道的最后增加一个处理器
pipeline.addLast(new NettyChannelHandler());
};
}); //给我们的workerGroup的EventLoop对应的管道设置处理器
//bossGroup参数
bootstrap.option(ChannelOption.SO_BACKLOG, 1024); //设置线程队列等待连接的个数
//workerGroup参数
bootstrap.childOption(ChannelOption.SO_KEEPALIVE, true); //设置保持活动连接状态
System.out.println("...服务器 is ready...");
//绑定一个端口并且同步，生成了一个ChannelFuture对象
//启动服务器并绑定端口
ChannelFuture cf = bootstrap.bind(6668).sync();
//对关闭通道进行监听
cf.channel().closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
} finally {
System.out.println("Shutdown Netty Server...");
//优雅的关闭
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
System.out.println("Shutdown Netty Server Success!");
}
}
}
4、 NettyChannelHandler.java添加读取student对象；
package netty.protobuf;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
/**
* 说明
* 1. 我们自定义一个Handler，需要继承netty规定好的某个HandlerAdapter（规范）
* 2. 这时我们自定义一个Handler，才能称之为Handler
*
*/
public class NettyChannelHandler extends ChannelInboundHandlerAdapter {
//读取数据的事件（这里我们可以读取客户端发送的消息）
/*
* 1. ChannelHandlerContext ctx：上下文对象，含有管道pipeline，通道channel，地址
* 2. Object msg：就是客户端发送的数据，默认是Object
* 3. 通道读写数据，管道处理数据
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
//读取从客户端发送的StudentPOJO.Student
StudentPOJO.Student student = (StudentPOJO.Student)msg;
System.out.println("客户端发送的数据 id=" + student.getId() + " name=" + student.getName());
}
//数据读取完毕
//这个方法会在channelRead读完后触发
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
//把数据写到缓冲区，并且刷新缓冲区，是write + flush
//一般来讲，我们对这个发送的数据进行编码
ctx.channel().writeAndFlush(Unpooled.copiedBuffer("hello，客户端~", CharsetUtil.UTF_8));
}
//处理异常，一般是需要关闭通道
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.channel().close();
}
}
五、执行
1、 服务端日志；
...服务器 is ready...
客户端发送的数据 id=10 name=张三
2、 客户端日志；
...客户端 is ready...
服务器回复的消息：hello，客户端~
服务器的地址：/127.0.0.1:6668