Talk about dubbo’s CommandExecutor

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Order

This article mainly studies dubbo’s CommandExecutor

CommandExecutor

dubbo-2.7.2/dubbo-plugin/dubbo-qos/src/main/java/org/apache/dubbo/qos/command/CommandExecutor.java

public interface CommandExecutor {
    /**
     * Execute one command and return the execution result
     *
     * @param commandContext command context
     * @return command execution result
     * @throws NoSuchCommandException
     */
    String execute(CommandContext commandContext) throws NoSuchCommandException;
}
  • CommandExecutor defines the execute method, which passes in the CommandContext parameter.

CommandContext

dubbo-2.7.2/dubbo-plugin/dubbo-qos/src/main/java/org/apache/dubbo/qos/command/CommandContext.java

public class CommandContext {

    private String commandName;
    private String[] args;
    private Channel remote;
    private boolean isHttp;
    private Object originRequest;

    public CommandContext(String commandName) {
        this.commandName = commandName;
    }

    public CommandContext(String commandName, String[] args, boolean isHttp) {
        this.commandName = commandName;
        this.args = args;
        this.isHttp = isHttp;
    }

    public String getCommandName() {
        return commandName;
    }

    public void setCommandName(String commandName) {
        this.commandName = commandName;
    }

    public String[] getArgs() {
        return args;
    }

    public void setArgs(String[] args) {
        this.args = args;
    }

    public Channel getRemote() {
        return remote;
    }

    public void setRemote(Channel remote) {
        this.remote = remote;
    }

    public boolean isHttp() {
        return isHttp;
    }

    public void setHttp(boolean http) {
        isHttp = http;
    }

    public Object getOriginRequest() {
        return originRequest;
    }

    public void setOriginRequest(Object originRequest) {
        this.originRequest = originRequest;
    }
}
  • CommandContext defines commandName, args, remote, isHttp, originRequest parameters.

DefaultCommandExecutor

dubbo-2.7.2/dubbo-plugin/dubbo-qos/src/main/java/org/apache/dubbo/qos/command/DefaultCommandExecutor.java

public class DefaultCommandExecutor implements CommandExecutor {
    @Override
    public String execute(CommandContext commandContext) throws NoSuchCommandException {
        BaseCommand command = null;
        try {
            command = ExtensionLoader.getExtensionLoader(BaseCommand.class).getExtension(commandContext.getCommandName());
        } catch (Throwable throwable) {
                //can't find command
        }
        if (command == null) {
            throw new NoSuchCommandException(commandContext.getCommandName());
        }
        return command.execute(commandContext, commandContext.getArgs());
    }
}
  • DefaultCommandExecutor implements the CommandExecutor interface, and its execute method will load the corresponding comamnd through the ExtensionLoader according to commandName, and then execute the command’s EXECUTE method.

Summary

CommandExecutor defines the execute method, which passes in the CommandContext parameter; CommandContext defines commandName, args, remote, isHttp, originRequest parameters; DefaultCommandExecutor implements the CommandExecutor interface, and its execute method will load the corresponding comamnd through the ExtensionLoader according to commandName, and then execute the command’s EXECUTE method.

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