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RespCommand的使用方法
本篇内容主要讲解“RespCommand的使用方法”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“RespCommand的使用方法”吧!
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序
本文主要研究一下RespCommand
RespCommand
resp-server-0.16.0/src/main/java/com/github/tonivade/resp/command/RespCommand.java
@FunctionalInterface
public interface RespCommand {
redisToken execute(Request request);
}RespCommand定义了execute方法，接收Request参数，返回RedisToken
Request
resp-server-0.16.0/src/main/java/com/github/tonivade/resp/command/Request.java
public interface Request {
String getCommand();
ImmutableArray getParams();
SafeString getParam(int i);
Option getOptionalParam(int i);
int getLength();
boolean isEmpty();
Session getSession();
ServerContext getServerContext();
boolean isExit();
} Request接口定义了getCommand、getParams、getParam、getOptionalParam、getLength、isEmpty、getSession、getServerContext、isExit方法
DefaultRequest
resp-server-0.16.0/src/main/java/com/github/tonivade/resp/command/DefaultRequest.java
public class DefaultRequest implements Request {
private final SafeString command;
private final ImmutableArray params;
private final Session session;
private final ServerContext server;
public DefaultRequest(ServerContext server, Session session, SafeString command, ImmutableArray params) {
this.server = server;
this.session = session;
this.command = requireNonNull(command);
this.params = requireNonNull(params);
}
@Override
public String getCommand() {
return command.toString();
}
@Override
public ImmutableArray getParams() {
return params;
}
@Override
public SafeString getParam(int i) {
if (i < params.size()) {
return params.get(i);
}
return null;
}
@Override
public Option getOptionalParam(int i) {
return Option.of(() -> getParam(i));
}
@Override
public int getLength() {
return params.size();
}
@Override
public boolean isEmpty() {
return params.isEmpty();
}
@Override
public boolean isExit() {
return command.toString().equalsIgnoreCase("quit");
}
@Override
public Session getSession() {
return session;
}
@Override
public ServerContext getServerContext() {
return server;
}
@Override
public String toString() {
return command + "[" + params.size() + "]: " + params;
}
} DefaultRequest实现了Request接口，它定义了command、params、session、server属性，均在构造器中传入
CommandSuite
resp-server-0.16.0/src/main/java/com/github/tonivade/resp/command/CommandSuite.java
public class CommandSuite {
private static final Logger LOGGER = LoggerFactory.getLogger(CommandSuite.class);
private final Map> metadata = new HashMap<>();
private final Map commands = new HashMap<>();
private final NullCommand nullCommand = new NullCommand();
private final CommandWrapperFactory factory;
public CommandSuite() {
this(new DefaultCommandWrapperFactory());
}
public CommandSuite(CommandWrapperFactory factory) {
this.factory = factory;
addCommand(PingCommand.class);
addCommand(EchoCommand.class);
addCommand(QuitCommand.class);
addCommand(TimeCommand.class);
}
public RespCommand getCommand(String name) {
return commands.getOrDefault(name.toLowerCase(), nullCommand);
}
public boolean isPresent(String name, Class annotationClass) {
return getMetadata(name).isAnnotationPresent(annotationClass);
}
public boolean contains(String name) {
return commands.get(name) != null;
}
protected void addCommand(Class clazz) {
Try.of(clazz::newInstance)
.onSuccess(this::processCommand)
.onFailure(e -> LOGGER.error("error loading command: " + clazz.getName(), e));
}
protected void addCommand(String name, RespCommand command) {
commands.put(name.toLowerCase(), factory.wrap(command));
}
private void processCommand(Object command) {
Class clazz = command.getClass();
Command annotation = clazz.getAnnotation(Command.class);
if (annotation != null) {
commands.put(annotation.value(), factory.wrap(command));
metadata.put(annotation.value(), clazz);
} else {
LOGGER.warn("annotation not present at {}", clazz.getName());
}
}
private Class getMetadata(String name) {
return metadata.getOrDefault(name.toLowerCase(), Void.class);
}
} CommandSuite的构造器添加了PingCommand、EchoCommand、QuitCommand、TimeCommand四个command；addCommand方法将factory.wrap(command)的命令放入commands中
CommandWrapperFactory
resp-server-0.16.0/src/main/java/com/github/tonivade/resp/command/CommandWrapperFactory.java
public interface CommandWrapperFactory {
RespCommand wrap(Object command);
}CommandWrapperFactory定义了wrap方法，将command包装为RespCommand
DefaultCommandWrapperFactory
resp-server-0.16.0/src/main/java/com/github/tonivade/resp/command/DefaultCommandWrapperFactory.java
public class DefaultCommandWrapperFactory implements CommandWrapperFactory {
@Override
public RespCommand wrap(Object command) {
if (command instanceof RespCommand) {
return new CommandWrapper((RespCommand) command);
}
throw new IllegalArgumentException("must implements command interface");
}
}DefaultCommandWrapperFactory实现了CommandWrapperFactory接口，其wrap方法使用CommandWrapper包装RespCommand
CommandWrapper
resp-server-0.16.0/src/main/java/com/github/tonivade/resp/command/CommandWrapper.java
public class CommandWrapper implements RespCommand {
private int params;
private final RespCommand command;
public CommandWrapper(RespCommand command) {
this.command = command;
ParamLength length = command.getClass().getAnnotation(ParamLength.class);
if (length != null) {
this.params = length.value();
}
}
@Override
public RedisToken execute(Request request) {
if (request.getLength() < params) {
return error("ERR wrong number of arguments for '" + request.getCommand() + "' command");
}
return command.execute(request);
}
}CommandWrapper会读取ParamLength注解，若读的到则将注解的value值赋值给params，用于execute方法对request的参数长度进行校验
小结
RespCommand定义了execute方法，接收Request参数，返回RedisToken；CommandSuite的构造器添加了PingCommand、EchoCommand、QuitCommand、TimeCommand四个command；addCommand方法将factory.wrap(command)的命令放入commands中；DefaultCommandWrapperFactory实现了CommandWrapperFactory接口，其wrap方法使用CommandWrapper包装RespCommand；CommandWrapper会读取ParamLength注解，若读的到则将注解的value值赋值给params，用于execute方法对request的参数长度进行校验
到此，相信大家对“RespCommand的使用方法”有了更深的了解，不妨来实际操作一番吧！这里是创新互联网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！
新闻标题：RespCommand的使用方法
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