这篇文章给大家介绍如何从零搭建dubbogo和dubbo，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。
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最近开始参与 dubbogo 的一些开发测试，之前都是直接拿 samples 的例子验证功能，而这次为了复现一个功能问题，打算从零开始搭建一个 dubbo-go 和 dubbo 调用的工程，踩到了一些新人使用 dubbogo 的坑，把这个过程记录下供大家参考。
定义 DemoService 接口：
public interface DemoService {
String sayHello(String name);
String sayHello(User user);
String sayHello(User user, String name);
}定义 User 对象：
public class User implements Serializable {
private String name;
private int age;
......
}用的 dubbo 官方示例代码：
public static void main(String[] args) throws IOException {
// 服务实现
DemoService demoService = new DemoServiceImpl();
// 当前应用配置
ApplicationConfig application = new ApplicationConfig();
application.setName("demoProvider");
// 连接注册中心配置
RegistryConfig registry = new RegistryConfig();
registry.setAddress("127.0.0.1:2181");
registry.setProtocol("zookeeper");
registry.setUsername("");
registry.setPassword("");
// 服务提供者协议配置
ProtocolConfig protocol = new ProtocolConfig();
protocol.setName("dubbo");
protocol.setPort(12345);
protocol.setThreads(200);
// 注意：ServiceConfig为重对象，内部封装了与注册中心的连接，以及开启服务端口
// 服务提供者暴露服务配置
ServiceConfig service = new ServiceConfig<>(); // 此实例很重，封装了与注册中心的连接，请自行缓存，否则可能造成内存和连接泄漏
service.setApplication(application);
service.setRegistry(registry); // 多个注册中心可以用setRegistries()
service.setProtocol(protocol); // 多个协议可以用setProtocols()
service.setInterface(DemoService.class);
service.setRef(demoService);
service.setVersion("1.0.0");
service.setGroup("tc");
service.setTimeout(60 * 1000);
// 暴露及注册服务
service.export();
System.in.read();
} 查看 zookeeper 看是否注册成功：
$ls /dubbo/com.funnycode.DemoService/providers [dubbo%3A%2F%2F127.0.0.1%3A12345%2Fcom.funnycode.DemoService%3Fanyhost%3Dtrue%26application%3DdemoProvider%26deprecated%3Dfalse%26dubbo%3D2.0.2%26dynamic%3Dtrue%26generic%3Dfalse%26group%3Dtc%26interface%3Dcom.funnycode.DemoService%26methods%3DsayHello%26pid%3D18167%26release%3D2.7.7%26revision%3D1.0.0%26side%3Dprovider%26threads%3D200%26timestamp%3D1606896020691%26version%3D1.0.0]
如上的输出表示服务提供方已经启动。
定义 User 对象：
type User struct {
Name string
Age int
}
func (User) JavaClassName() string {
return "com.funnycode.User"
}定义 DemoProvider 接口：
type DemoProvider struct {
SayHello func(ctx context.Context, name string) (string, error) `dubbo:"sayHello"`
SayHello2 func(ctx context.Context, user User) (string, error) `dubbo:"sayHello"`
SayHello3 func(ctx context.Context, user User, name string) (string, error) `dubbo:"sayHello"`
}
func (p *DemoProvider) Reference() string {
return "DemoProvider"
}func main() {
config.Load()
gxlog.CInfo("\n\n\nstart to test dubbo")
res, err := demoProvider.SayHello(context.TODO(), "tc")
if err != nil {
panic(err)
}
gxlog.CInfo("response result: %v\n", res)
user := User{
Name: "tc",
Age: 18,
}
res, err = demoProvider.SayHello2(context.TODO(), user)
if err != nil {
panic(err)
}
gxlog.CInfo("response result: %v\n", res)
res, err = demoProvider.SayHello3(context.TODO(), user, "tc")
if err != nil {
panic(err)
}
gxlog.CInfo("response result: %v\n", res)
initSignal()
}确认问题的存在。
第一个接口的参数是字符串，可以正常返回 [2020-12-03/18:59:12 main.main: client.go: 29] response result: Hello tc。
第二、三两个接口存在 User 对象，无法调用成功。错误信息如下：
2020-12-02T17:10:47.739+0800 INFO getty/listener.go:87 session{session session-closed, Read Bytes: 924, Write Bytes: 199, Read Pkgs: 0, Write Pkgs: 1} got error{java exception:Fail to decode request due to: java.lang.IllegalArgumentException: Service not found:com.funnycode.DemoService, sayHello
at org.apache.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation.decode(DecodeableRpcInvocation.java:134)
at org.apache.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation.decode(DecodeableRpcInvocation.java:80)
at org.apache.dubbo.remoting.transport.DecodeHandler.decode(DecodeHandler.java:57)
at org.apache.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:44)
at org.apache.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:57)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
}, will be closed.错误正如 issue 中描述的一模一样，因为错误信息返回到了消费端，可以看到 Java 那边的错误堆栈信息，所以直接去看 DecodeableRpcInvocation.decode#134。
代码如下：
// 反序列化
public class DecodeableRpcInvocation extends RpcInvocation implements Codec, Decodeable {
public Object decode(Channel channel, InputStream input) throws IOException {
......
if (serviceDescriptor != null) {
// 方法描述里面根据方法名查找
MethodDescriptor methodDescriptor = serviceDescriptor.getMethod(getMethodName(), desc);
if (methodDescriptor != null) {
pts = methodDescriptor.getParameterClasses();
this.setReturnTypes(methodDescriptor.getReturnTypes());
}
}
// 表示没有找到方法
if (pts == DubboCodec.EMPTY_CLASS_ARRAY) {
if (!RpcUtils.isGenericCall(path, getMethodName()) && !RpcUtils.isEcho(path, getMethodName())) {
throw new IllegalArgumentException("Service not found:" + path + ", " + getMethodName());
}
pts = ReflectUtils.desc2classArray(desc);
}
......
}
}查看 MethodDescriptor，即找方法是否存在，存在的话就会设置好 ParameterClasses。
如果上面没找到，pts == DubboCodec.EMPTY_CLASS_ARRAY 就会满足条件，进而判断是否是泛化调用或者是 echo 调用，如果都不是则报服务找不到方法错误。
desc 是 Ljava/lang/Object ，很明显并没有参数是 Object 的方法，所以必然是会报错的。
补充说明：方法查询。** 代码如下:
public MethodDescriptor getMethod(String methodName, String params) {
Map methods = descToMethods.get(methodName);
if (CollectionUtils.isNotEmptyMap(methods)) {
return methods.get(params);
}
return null;
} 优点：比之前的版本加了方法的元信息缓存起来，不使用反射可以提高效率，可以理解用空间换时间。
因为直接撸代码并 hold 不住，所以通过比较来查看问题所在。
通过 api 模式启动，参考官方例子。启动这个是为了查看 Java 版本的传输内容。
public static void main(String[] args) throws InterruptedException {
// 当前应用配置
ApplicationConfig application = new ApplicationConfig();
application.setName("demoProvider2");
// 连接注册中心配置
RegistryConfig registry = new RegistryConfig();
registry.setAddress("127.0.0.1:2181");
registry.setProtocol("zookeeper");
registry.setUsername("");
registry.setPassword("");
// 注意：ReferenceConfig为重对象，内部封装了与注册中心的连接，以及与服务提供方的连接
// 引用远程服务
ReferenceConfig reference
= new ReferenceConfig<>(); // 此实例很重，封装了与注册中心的连接以及与提供者的连接，请自行缓存，否则可能造成内存和连接泄漏
reference.setApplication(application);
reference.setRegistry(registry); // 多个注册中心可以用setRegistries()
reference.setInterface(DemoService.class);
reference.setVersion("1.0.0");
reference.setGroup("tc");
reference.setCheck(true);
reference.setTimeout(1000 * 60);
// 和本地bean一样使用xxxService
DemoService demoService = reference.get(); // 注意：此代理对象内部封装了所有通讯细节，对象较重，请缓存复用
System.out.println(demoService.sayHello(new User("tc", 18)));
TimeUnit.MINUTES.sleep(10);
} 
desc 肉眼可见的是 Lcom/funnycode/User，这个就是正确的对象了。
代码位置： protocol/dubbo/impl/hessian.go:120#marshalRequest
代码实现：
func marshalRequest(encoder *hessian.Encoder, p DubboPackage) ([]byte, error) {
service := p.Service
request := EnsureRequestPayload(p.Body)
encoder.Encode(DEFAULT_DUBBO_PROTOCOL_VERSION)
encoder.Encode(service.Path)
encoder.Encode(service.Version)
encoder.Encode(service.Method)
args, ok := request.Params.([]interface{})
if !ok {
logger.Infof("request args are: %+v", request.Params)
return nil, perrors.Errorf("@params is not of type: []interface{}")
}
types, err := getArgsTypeList(args)
if err != nil {
return nil, perrors.Wrapf(err, " PackRequest(args:%+v)", args)
}
encoder.Encode(types)
for _, v := range args {
encoder.Encode(v)
}
......
}断点可以发现，types 返回的时候就已经是 Object 了，没有返回 User，那么继续跟进去查看代码。
protocol/dubbo/impl/hessian.go:394#getArgsTypeList
protocol/dubbo/impl/hessian.go:418#getArgType
func getArgType(v interface{}) string {
// 常见的类型处理
......
default:
t := reflect.TypeOf(v)
if reflect.Ptr == t.Kind() {
t = reflect.TypeOf(reflect.ValueOf(v).Elem())
}
switch t.Kind() {
case reflect.Struct:
return "java.lang.Object"
}
......
}很明显当发现是 reflect.Struct 的时候就返回了 java.lang.Object，所以参数就变成了 Object，那么因为 Java 代码那边依赖这个类型所以就调用失败了。
因为反馈是 2.7.7 出错，所以先考虑到在之前的版本是否功能正常，于是把服务提供者切换到 dubbo 2.7.3，发现调用仍然有错误，如下：
2020-12-02T21:52:25.945+0800 INFO getty/listener.go:85 session{session session-closed, Read Bytes: 4586, Write Bytes: 232, Read Pkgs: 0, Write Pkgs: 1} got error{java exception:org.apache.dubbo.rpc.RpcException: Failed to invoke remote proxy method sayHello to registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=demoProvider&dubbo=2.0.2&export=dubbo%3A%2F%2F192.168.0.113%3A12345%2Fcom.funnycode.DemoService%3Fanyhost%3Dtrue%26application%3DdemoProvider%26bind.ip%3D192.168.0.113%26bind.port%3D12345%26deprecated%3Dfalse%26dubbo%3D2.0.2%26dynamic%3Dtrue%26generic%3Dfalse%26group%3Dtc%26interface%3Dcom.funnycode.DemoService%26methods%3DsayHello%26pid%3D23889%26register%3Dtrue%26release%3D2.7.3%26revision%3D1.0.0%26side%3Dprovider%26threads%3D200%26timeout%3D60000%26timestamp%3D1606916702204%26version%3D1.0.0&pid=23889®istry=zookeeper&release=2.7.3×tamp=1606916702193, cause: Not found method "sayHello" in class com.funnycode.DemoServiceImpl.
org.apache.dubbo.rpc.RpcException: Failed to invoke remote proxy method sayHello to registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=demoProvider&dubbo=2.0.2&export=dubbo%3A%2F%2F192.168.0.113%3A12345%2Fcom.funnycode.DemoService%3Fanyhost%3Dtrue%26application%3DdemoProvider%26bind.ip%3D192.168.0.113%26bind.port%3D12345%26deprecated%3Dfalse%26dubbo%3D2.0.2%26dynamic%3Dtrue%26generic%3Dfalse%26group%3Dtc%26interface%3Dcom.funnycode.DemoService%26methods%3DsayHello%26pid%3D23889%26register%3Dtrue%26release%3D2.7.3%26revision%3D1.0.0%26side%3Dprovider%26threads%3D200%26timeout%3D60000%26timestamp%3D1606916702204%26version%3D1.0.0&pid=23889®istry=zookeeper&release=2.7.3×tamp=1606916702193, cause: Not found method "sayHello" in class com.funnycode.DemoServiceImpl.
at org.apache.dubbo.rpc.proxy.AbstractProxyInvoker.invoke(AbstractProxyInvoker.java:107)
at org.apache.dubbo.config.invoker.DelegateProviderMetaDataInvoker.invoke(DelegateProviderMetaDataInvoker.java:56)
at org.apache.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:56)
at org.apache.dubbo.rpc.filter.ExceptionFilter.invoke(ExceptionFilter.java:55)
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:82)
at org.apache.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:92)
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:82)
at org.apache.dubbo.rpc.filter.TimeoutFilter.invoke(TimeoutFilter.java:48)
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:82)
at org.apache.dubbo.rpc.protocol.dubbo.filter.TraceFilter.invoke(TraceFilter.java:81)
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:82)
at org.apache.dubbo.rpc.filter.ContextFilter.invoke(ContextFilter.java:96)
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:82)
at org.apache.dubbo.rpc.filter.GenericFilter.invoke(GenericFilter.java:148)
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:82)
at org.apache.dubbo.rpc.filter.ClassLoaderFilter.invoke(ClassLoaderFilter.java:38)
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:82)
at org.apache.dubbo.rpc.filter.EchoFilter.invoke(EchoFilter.java:41)
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:82)
at org.apache.dubbo.rpc.protocol.ProtocolFilterWrapper$CallbackRegistrationInvoker.invoke(ProtocolFilterWrapper.java:157)
at org.apache.dubbo.rpc.protocol.dubbo.DubboProtocol$1.reply(DubboProtocol.java:152)
at org.apache.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.handleRequest(HeaderExchangeHandler.java:102)
at org.apache.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.received(HeaderExchangeHandler.java:193)
at org.apache.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:51)
at org.apache.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:57)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.dubbo.common.bytecode.NoSuchMethodException: Not found method "sayHello" in class com.funnycode.DemoServiceImpl.
at org.apache.dubbo.common.bytecode.Wrapper1.invokeMethod(Wrapper1.java)
at org.apache.dubbo.rpc.proxy.javassist.JavassistProxyFactory$1.doInvoke(JavassistProxyFactory.java:47)
at org.apache.dubbo.rpc.proxy.AbstractProxyInvoker.invoke(AbstractProxyInvoker.java:84)
... 27 more
}, will be closed.虽然和 2.7.7 的代码是不一样的，但是通过错误也能看出来是在代理增强类里面方法找不到，大概率是反射找不到方法，所以归根结底也是参数的问题。
修复相对简单，就是拿到 struct 定义的 JavaClassName。
case reflect.Struct:
v, ok := v.(hessian.POJO)
if ok {
return v.JavaClassName()
}
return "java.lang.Object"再次执行消费者，运行（提供方 2.7.7 和 2.7.3）正常，输出如下：
[2020-12-03/20:04:06 main.main: client.go: 29] response result: Hello tc ... [2020-12-03/20:04:09 main.main: client.go: 41] response result: Hello tc You are 18 ... [2020-12-03/20:04:09 main.main: client.go: 48] response result: Hello tc You are 18
细心的你是否已经发现，在我 dubbogo 的消费端接口叫 DemoProvider，然后发现提供者叫 DemoService，这个又是如何正常运行的？
实际上和 client.yml 中配置项 references 有关，在配置文件详细说明了 interface，version，group 等，你还可以通过 methods 配置方法的超时时间等信息。
references: "DemoProvider": # 可以指定多个registry，使用逗号隔开;不指定默认向所有注册中心注册 registry: "zk1" protocol: "dubbo" interface: "com.funnycode.DemoService" cluster: "failover" version: "1.0.0" group: "tc" methods: - name: "SayHello" retries: 3 ......
配置文件如下：
# application config application: organization: "dubbogoproxy.com" name: "Demo Micro Service" module: "dubbogoproxy tc client" version: "1.0.0" group: "tc" owner: "ZX" environment: "dev" references: "DemoProvider": # 可以指定多个registry，使用逗号隔开;不指定默认向所有注册中心注册 registry: "zk1" protocol: "dubbo" interface: "com.funnycode.DemoService" cluster: "failover" # version: "1.0.0" # group: "tc" methods: - name: "SayHello" retries: 3
从使用的习惯来讲，肯定是 application 表示了全局的配置，但是我发现启动的时候在 application 配置的 version 和 group 并不会赋值给接口，启动会报服务提供方找不到，如下：
2020-12-03T20:15:42.208+0800 DEBUG zookeeper/registry.go:237 Create a zookeeper node:/dubbo/com.funnycode.DemoService/consumers/consumer%3A%2F%2F30.11.176.107%2FDemoProvider%3Fapp.version%3D1.0.0%26application%3DDemo+Micro+Service%26async%3Dfalse%26bean.name%3DDemoProvider%26cluster%3Dfailover%26environment%3Ddev%26generic%3Dfalse%26group%3D%26interface%3Dcom.funnycode.DemoService%26ip%3D30.11.176.107%26loadbalance%3D%26methods.SayHello.loadbalance%3D%26methods.SayHello.retries%3D3%26methods.SayHello.sticky%3Dfalse%26module%3Ddubbogoproxy+tc+client%26name%3DDemo+Micro+Service%26organization%3Ddubbogoproxy.com%26owner%3DZX%26pid%3D38692%26protocol%3Ddubbo%26provided-by%3D%26reference.filter%3Dcshutdown%26registry.role%3D0%26release%3Ddubbo-golang-1.3.0%26retries%3D%26side%3Dconsumer%26sticky%3Dfalse%26timestamp%3D1606997742%26version%3D
version 和 group 都是空。必须把 DemoProvider 下的 version 和 group 注释打开。
dubbogo 调用 dubbo，因为 go 是大写的方法名，java 里面是小写的方法名，所以会出现如下错误：
2020-12-02T17:10:47.739+0800 INFO getty/listener.go:87 session{session session-closed, Read Bytes: 924, Write Bytes: 199, Read Pkgs: 0, Write Pkgs: 1} got error{java exception:Fail to decode request due to: java.lang.IllegalArgumentException: Service not found:com.funnycode.DemoService, SayHello
java.lang.IllegalArgumentException: Service not found:com.funnycode.DemoService, SayHello
at org.apache.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation.decode(DecodeableRpcInvocation.java:134)
at org.apache.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation.decode(DecodeableRpcInvocation.java:80)
at org.apache.dubbo.remoting.transport.DecodeHandler.decode(DecodeHandler.java:57)
at org.apache.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:44)
at org.apache.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:57)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
}, will be closed.细心的读者可能已经注意到了，我在消费端的接口声明是有个 dubbo:"sayHello" 的，表示方法名是 sayHello，这样在服务提供方就可以得到 sayHello 这个方法名。
还有我声明的三个方法都指明它们的方法名叫 dubbo:"sayHello"，这是因为 Java 可以方法名字一样进行重载，而 go 是不能方法名重复的。
直接贴能跑通的代码。
我的提供者接口：
type DemoProvider struct{}
func (p *DemoProvider) SayHello(ctx context.Context, name string) (string, error) {
return "Hello " + name, nil
}
func (p *DemoProvider) SayHello4(ctx context.Context, user *User) (string, error) {
return "Hello " + user.Name + " You are " + strconv.Itoa(user.Age), nil
}
func (p *DemoProvider) SayHello5(ctx context.Context, user *User, name string) (string, error) {
return "Hello " + name + " You are " + strconv.Itoa(user.Age), nil
}
func (p *DemoProvider) Reference() string {
return "DemoProvider"
}
func (p *DemoProvider) MethodMapper() map[string]string {
return map[string]string{
"SayHello": "sayHello",
}
}我的消费者接口：
type DemoProvider struct {
// 调用 java 和 go
SayHello func(ctx context.Context, name string) (string, error) `dubbo:"sayHello"`
// 只调用 java
SayHello2 func(ctx context.Context, user *User) (string, error) `dubbo:"sayHello"`
SayHello3 func(ctx context.Context, user *User, name string) (string, error) `dubbo:"sayHello"`
// 只调用 go
SayHello4 func(ctx context.Context, user *User) (string, error)
SayHello5 func(ctx context.Context, user *User, name string) (string, error)
}启动服务消费者：
func main() {
config.Load()
gxlog.CInfo("\n\n\nstart to test dubbo")
res, err := demoProvider.SayHello(context.TODO(), "tc")
if err != nil {
panic(err)
}
gxlog.CInfo("response result: %v\n", res)
user := &User{
Name: "tc",
Age: 18,
}
res, err = demoProvider.SayHello4(context.TODO(), user)
if err != nil {
panic(err)
}
gxlog.CInfo("response result: %v\n", res)
res, err = demoProvider.SayHello5(context.TODO(), user, "tc")
if err != nil {
panic(err)
}
gxlog.CInfo("response result: %v\n", res)
initSignal()
}这里需要注意 MethodMapper 方法，有时候需要在这个方法中配置方法名的映射关系，否则还是会出现找不到方法的错误。
比如因为配置 dubbo:"sayHello"，所以在 go 里面请求 SayHello 变成了 sayHello，那么服务提供方通过 MethodMapper 方法配置后使得提供方也是 sayHello，这样 go 和 java 下暴露的都是小写的 sayHello。
老司机都懂，在 dubbo 中 SPI 机制的默认值就是 hessian2
@SPI("hessian2")
public interface Serialization {
}而在 dubbo-go 中：
func NewDubboCodec(reader *bufio.Reader) *ProtocolCodec {
s, _ := GetSerializerById(constant.S_Hessian2)
return &ProtocolCodec{
reader: reader,
pkgType: 0,
bodyLen: 0,
headerRead: false,
serializer: s.(Serializer),
}
}可以自行断点查看，两边基本上一样，我也是通过两边比出来的，RpcInvocation.getParameterTypesDesc() 就是方法的参数.
go 代码 protocol/dubbo/impl/hessian.go:120#marshalRequest
java 代码 org.apache.dubbo.rpc.protocol.dubbo.DubboCodec#encodeRequestData(org.apache.dubbo.remoting.Channel, org.apache.dubbo.common.serialize.ObjectOutput, java.lang.Object, java.lang.String)
之前的例子都是 copy 的，这次是纯手打的，才发现了这个问题。 如果你的提供类似：func (p *DemoProvider) SayHello4(ctx context.Context, user User) (string, error)，那么会出现如下错误：
2020-12-03T12:42:32.834+0800 ERROR getty/listener.go:280 OnMessage panic: reflect: Call using *main.User as type main.User github.com/apache/dubbo-go/remoting/getty.(*RpcServerHandler).OnMessage.func1
参数里面的 User 需要改成 *User。
SayHello4 func(ctx context.Context, user *User) (string, error) // or SayHello4 func(ctx context.Context, user User) (string, error)
因为在参数序列化的时候会对指针做操作：
t := reflect.TypeOf(v)
if reflect.Ptr == t.Kind() {
t = reflect.TypeOf(reflect.ValueOf(v).Elem())
}完整代码
dubbogo 主要有三个配置文件：
server.yaml 服务提供方的配置文件
client.yaml 服务消费方的配置文件
log.yaml 日志文件
如果你什么都不配置，会出现：
2021/01/11 15:31:41 [InitLog] warn: log configure file name is nil 2021/01/11 15:31:41 [consumerInit] application configure(consumer) file name is nil 2021/01/11 15:31:41 [providerInit] application configure(provider) file name is nil
这样是没法正常使用的。如果你是服务提供方，必须要配置 server.yaml 文件，如果你是服务消费方，必须要配置 client.yaml，实际我们的应用应该既是消费者又是提供者，所以往往两个文件都是需要配置的。
服务提供方正常启动是会有如下输出的：
2021-01-11T15:36:55.003+0800 INFO protocol/protocol.go:205 The cached exporter keys is dubbo://:20000/DemoProvider?accesslog=&app.version=1.0.0&application=Demo+Micro+Service&auth=&bean.name=DemoProvider&cluster=failover&environment=dev&execute.limit=&execute.limit.rejected.handler=&group=tc&interface=com.funnycode.DemoService&loadbalance=random&methods.SayHello.loadbalance=random&methods.SayHello.retries=3&methods.SayHello.tps.limit.interval=&methods.SayHello.tps.limit.rate=&methods.SayHello.tps.limit.strategy=&methods.SayHello.weight=0&methods.SayHello4.loadbalance=random&methods.SayHello4.retries=3&methods.SayHello4.tps.limit.interval=&methods.SayHello4.tps.limit.rate=&methods.SayHello4.tps.limit.strategy=&methods.SayHello4.weight=0&methods.SayHello5.loadbalance=random&methods.SayHello5.retries=3&methods.SayHello5.tps.limit.interval=&methods.SayHello5.tps.limit.rate=&methods.SayHello5.tps.limit.strategy=&methods.SayHello5.weight=0&module=dubbogoproxy+tc+client&name=Demo+Micro+Service&organization=dubbogoproxy.com&owner=ZX¶m.sign=®istry.role=3&release=dubbo-golang-1.3.0&retries=&serialization=&service.filter=echo%2Ctoken%2Caccesslog%2Ctps%2Cgeneric_service%2Cexecute%2Cpshutdown&side=provider&ssl-enabled=false×tamp=1610350614&tps.limit.interval=&tps.limit.rate=&tps.limit.rejected.handler=&tps.limit.strategy=&tps.limiter=&version=1.0.0&warmup=100! 2021-01-11T15:36:55.003+0800 INFO dubbo/dubbo_protocol.go:86 Export service: dubbo://:20000/DemoProvider?accesslog=&app.version=1.0.0&application=Demo+Micro+Service&auth=&bean.name=DemoProvider&cluster=failover&environment=dev&execute.limit=&execute.limit.rejected.handler=&group=tc&interface=com.funnycode.DemoService&loadbalance=random&methods.SayHello.loadbalance=random&methods.SayHello.retries=3&methods.SayHello.tps.limit.interval=&methods.SayHello.tps.limit.rate=&methods.SayHello.tps.limit.strategy=&methods.SayHello.weight=0&methods.SayHello4.loadbalance=random&methods.SayHello4.retries=3&methods.SayHello4.tps.limit.interval=&methods.SayHello4.tps.limit.rate=&methods.SayHello4.tps.limit.strategy=&methods.SayHello4.weight=0&methods.SayHello5.loadbalance=random&methods.SayHello5.retries=3&methods.SayHello5.tps.limit.interval=&methods.SayHello5.tps.limit.rate=&methods.SayHello5.tps.limit.strategy=&methods.SayHello5.weight=0&module=dubbogoproxy+tc+client&name=Demo+Micro+Service&organization=dubbogoproxy.com&owner=ZX¶m.sign=®istry.role=3&release=dubbo-golang-1.3.0&retries=&serialization=&service.filter=echo%2Ctoken%2Caccesslog%2Ctps%2Cgeneric_service%2Cexecute%2Cpshutdown&side=provider&ssl-enabled=false×tamp=1610350614&tps.limit.interval=&tps.limit.rate=&tps.limit.rejected.handler=&tps.limit.strategy=&tps.limiter=&version=1.0.0&warmup=100
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