开篇
从 2.0.5 版本开始，dubbo 开始支持通过 telnet 命令来进行服务治理。通过telnet ip port连接上server端进行调试，具体的命令可以参考Telnet 命令参考手册。
HeaderExchangeHandler
- 在Dubbo协议export()过程中会对handler进行封装，HeaderExchangeHandler内部封装ExchangeHandlerAdapter对象。
public abstract class ExchangeHandlerAdapter extends TelnetHandlerAdapter implements ExchangeHandler {
@Override
public CompletableFuture<Object> reply(ExchangeChannel channel, Object msg) throws RemotingException {
return null;
}
}- ExchangeHandlerAdapter继承了TelnetHandlerAdapter，TelnetHandlerAdapter包含telnet()方法。
public class HeaderExchangeHandler implements ChannelHandlerDelegate {
public void received(Channel channel, Object message) throws RemotingException {
channel.setAttribute(KEY_READ_TIMESTAMP, System.currentTimeMillis());
final ExchangeChannel exchangeChannel = HeaderExchangeChannel.getOrAddChannel(channel);
try {
if (message instanceof Request) {
// 省略相关代码
} else if (message instanceof Response) {
// 省略相关代码
} else if (message instanceof String) {
if (isClientSide(channel)) {
// 省略相关代码
} else {
String echo = handler.telnet(channel, (String) message);
if (echo != null && echo.length() > 0) {
channel.send(echo);
}
}
} else {
handler.received(exchangeChannel, message);
}
} finally {
HeaderExchangeChannel.removeChannelIfDisconnected(channel);
}
}
}- HeaderExchangeHandler的received()方法针对String类型的参数执行handler.telnet()方法。
public class TelnetHandlerAdapter extends ChannelHandlerAdapter implements TelnetHandler {
private final ExtensionLoader<TelnetHandler> extensionLoader =
ExtensionLoader.getExtensionLoader(TelnetHandler.class);
@Override
public String telnet(Channel channel, String message) throws RemotingException {
String prompt = channel.getUrl().getParameterAndDecoded(Constants.PROMPT_KEY, Constants.DEFAULT_PROMPT);
boolean noprompt = message.contains("--no-prompt");
message = message.replace("--no-prompt", "");
StringBuilder buf = new StringBuilder();
message = message.trim();
String command;
if (message.length() > 0) {
int i = message.indexOf(' ');
if (i > 0) {
command = message.substring(0, i).trim();
message = message.substring(i + 1).trim();
} else {
command = message;
message = "";
}
} else {
command = "";
}
// 解析命令行
if (command.length() > 0) {
if (extensionLoader.hasExtension(command)) {
if (commandEnabled(channel.getUrl(), command)) {
try {
String result = extensionLoader.getExtension(command).telnet(channel, message);
if (result == null) {
return null;
}
buf.append(result);
} catch (Throwable t) {
buf.append(t.getMessage());
}
} else {
buf.append("Command: ");
buf.append(command);
buf.append(" disabled");
}
} else {
buf.append("Unsupported command: ");
buf.append(command);
}
}
if (buf.length() > 0) {
buf.append("\r\n");
}
if (StringUtils.isNotEmpty(prompt) && !noprompt) {
buf.append(prompt);
}
return buf.toString();
}
}com.alibaba.dubbo.remoting.telnet.TelnetHandler文件
clear=com.alibaba.dubbo.remoting.telnet.support.command.ClearTelnetHandler
exit=com.alibaba.dubbo.remoting.telnet.support.command.ExitTelnetHandler
help=com.alibaba.dubbo.remoting.telnet.support.command.HelpTelnetHandler
status=com.alibaba.dubbo.remoting.telnet.support.command.StatusTelnetHandler
log=com.alibaba.dubbo.remoting.telnet.support.command.LogTelnetHandler
ls=com.alibaba.dubbo.rpc.protocol.dubbo.telnet.ListTelnetHandler
ps=com.alibaba.dubbo.rpc.protocol.dubbo.telnet.PortTelnetHandler
cd=com.alibaba.dubbo.rpc.protocol.dubbo.telnet.ChangeTelnetHandler
pwd=com.alibaba.dubbo.rpc.protocol.dubbo.telnet.CurrentTelnetHandler
invoke=com.alibaba.dubbo.rpc.protocol.dubbo.telnet.InvokeTelnetHandler
trace=com.alibaba.dubbo.rpc.protocol.dubbo.telnet.TraceTelnetHandler
count=com.alibaba.dubbo.rpc.protocol.dubbo.telnet.CountTelnetHandler- TelnetHandlerAdapter的telnet()方法会解析除命令字符串command。
- extensionLoader = ExtensionLoader.getExtensionLoader(TelnetHandler.class)获取TelnetHandler的ExtensionLoader。
- extensionLoader.getExtension(command)获取TelnetHandler的扩展类实例，在com.alibaba.dubbo.remoting.telnet.TelnetHandler文件中定义。
InvokeTelnetHandler
@Activate
@Help(parameter = "[service.]method(args) ", summary = "Invoke the service method.",
detail = "Invoke the service method.")
public class InvokeTelnetHandler implements TelnetHandler {
public static final String INVOKE_MESSAGE_KEY = "telnet.invoke.method.message";
public static final String INVOKE_METHOD_LIST_KEY = "telnet.invoke.method.list";
public static final String INVOKE_METHOD_PROVIDER_KEY = "telnet.invoke.method.provider";
@Override
@SuppressWarnings("unchecked")
public String telnet(Channel channel, String message) {
String service = (String) channel.getAttribute(ChangeTelnetHandler.SERVICE_KEY);
// 解析消息的命令，包括服务、方法、参数等。
int i = message.indexOf("(");
String method = message.substring(0, i).trim();
String args = message.substring(i + 1, message.length() - 1).trim();
i = method.lastIndexOf(".");
if (i >= 0) {
service = method.substring(0, i).trim();
method = method.substring(i + 1).trim();
}
List<Object> list;
try {
list = JSON.parseArray("[" + args + "]", Object.class);
} catch (Throwable t) {
return "Invalid json argument, cause: " + t.getMessage();
}
StringBuilder buf = new StringBuilder();
Method invokeMethod = null;
ProviderModel selectedProvider = null;
if (isInvokedSelectCommand(channel)) {
selectedProvider = (ProviderModel) channel.getAttribute(INVOKE_METHOD_PROVIDER_KEY);
invokeMethod = (Method) channel.getAttribute(SelectTelnetHandler.SELECT_METHOD_KEY);
} else {
// 遍历服务service和method
for (ProviderModel provider : ApplicationModel.allProviderModels()) {
if (isServiceMatch(service, provider)) {
selectedProvider = provider;
List<Method> methodList = findSameSignatureMethod(provider.getAllMethods(), method, list);
if (CollectionUtils.isNotEmpty(methodList)) {
if (methodList.size() == 1) {
invokeMethod = methodList.get(0);
} else {
List<Method> matchMethods = findMatchMethods(methodList, list);
if (CollectionUtils.isNotEmpty(matchMethods)) {
if (matchMethods.size() == 1) {
invokeMethod = matchMethods.get(0);
} else { //exist overridden method
channel.setAttribute(INVOKE_METHOD_PROVIDER_KEY, provider);
channel.setAttribute(INVOKE_METHOD_LIST_KEY, matchMethods);
channel.setAttribute(INVOKE_MESSAGE_KEY, message);
printSelectMessage(buf, matchMethods);
return buf.toString();
}
}
}
}
break;
}
}
}
if (!StringUtils.isEmpty(service)) {
buf.append("Use default service ").append(service).append(".");
}
if (selectedProvider != null) {
if (invokeMethod != null) {
try {
Object[] array = realize(list.toArray(), invokeMethod.getParameterTypes(),
invokeMethod.getGenericParameterTypes());
long start = System.currentTimeMillis();
AppResponse result = new AppResponse();
try {
// 找对应方法执行invoke()命令
Object o = invokeMethod.invoke(selectedProvider.getServiceInstance(), array);
result.setValue(o);
} catch (Throwable t) {
result.setException(t);
}
long end = System.currentTimeMillis();
buf.append("\r\nresult: ");
buf.append(JSON.toJSONString(result.recreate()));
buf.append("\r\nelapsed: ");
buf.append(end - start);
buf.append(" ms.");
} catch (Throwable t) {
return "Failed to invoke method " + invokeMethod.getName() + ", cause: " + StringUtils.toString(t);
}
} else {
buf.append("\r\nNo such method ").append(method).append(" in service ").append(service);
}
} else {
buf.append("\r\nNo such service ").append(service);
}
return buf.toString();
}
}- 根据service 和 method 获取对应的provider对象。
- 通过method.invoke()通过反射调用实现方法调用。