技術文章 » 用Java寫一個分散式快取——RESP伺服器端

用Java寫一個分散式快取——RESP伺服器端

2023-02-08 18:01:05

前言

本篇我們將完成一個RESP的socket的伺服器端，初步完成一個單機版快取。

另外在其中我們還需要完成命令的動態路由

原始碼：https://github.com/weloe/Java-Distributed-Cache

本篇程式碼：

https://github.com/weloe/Java-Distributed-Cache/tree/master/src/main/java/com/weloe/cache/server

上篇：快取管理 https://www.cnblogs.com/weloe/p/17068891.html

RESP協定

RESP協定支援5種資料型別：字串，異常，整數，多行字串，陣列

資料型別由第一個位元組進行區分，不同部分使用\r\n來分開

  • '+' : 簡單字串
  • '-' : 異常
  • ':' : 整數
  • '$': 多行字串
  • '*': 陣列

簡單字串一般用來返回該操作無誤，操作成功，例如返回+ok\r\n

異常： -error msg\r\n

整數：: 1\r\n

多行字串：

$4\r\n
test

這裡的4是實際資料的長度

實際資訊為 test

陣列：

*2\r\n
$2\r\n
ab\r\n
$3\r\n
cde\r\n

資訊為字串陣列[ab][cde]

實現

https://github.com/weloe/Java-Distributed-Cache/blob/master/src/main/java/com/weloe/cache/util/RESPUtil.java

根據協定我們就能編寫出對請求資訊的解析類了，我們把它抽象為一個工具類

對返回內容解析的程式碼

	/**
     * 讀取RESP協定的位元組，轉為String
     *
     * @return String
     */
    public static String parseRESPBytes(InputStream inputStream) {
        byte[] bytes;

        String result = null;
        try {
            while (inputStream.available() == 0) {
            }
            bytes = new byte[inputStream.available()];
            inputStream.read(bytes);
            result = new String(bytes);

        } catch (IOException e) {
            e.printStackTrace();
        }

        return result;
    }

    /**
     * 解析RESP協定的String
     *
     * @param raw
     * @return
     */
    public static Object parseRESPString(String raw) {
        byte type = raw.getBytes()[0];
        String result = raw.substring(1);
        switch (type) {
            case '+':
                // +ok\r\n
                // 讀單行
                return result.replace("\r\n", "");
            case '-':
                // 異常
                // -Error msg\r\n
                throw new RuntimeException(result.replace("\r\n", ""));
            case ':':
                // 數位
                return result.replace("\r\n", "");
            case '$':
                return result.split("\r\n")[1];
            case '*':
                // 多行字串
                String[] strList = result.substring(result.indexOf("$")).split("\r\n");
                System.out.print("多條批次請求：");
                List<String> list = new LinkedList<>();
                for (int i = 1; i < strList.length; i += 2) {
                    System.out.print(strList[i] + " ");
                    list.add(strList[i]);
                }
                System.out.println();
                return list;
            default:
                throw new RuntimeException("錯誤的資料格式");
        }
    }

傳送請求的程式碼

    /**
     * 傳送RESP請求
     * @param host
     * @param port
     * @param args
     * @return
     * @throws IOException
     */
    public static byte[] sendRequest(String host,Integer port, String ... args) throws IOException {
        Socket socket = new Socket(host,port);
        RESPRequest request = new RESPRequest(socket);
        PrintWriter writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream(), StandardCharsets.UTF_8));
        sendRequest(writer,args);

        byte[] param = request.getBytes();

        request.close();
        writer.close();
        socket.close();
        return param;
    }

    /**
     * 傳送RESP請求
     * @param writer
     * @param args
     * @throws IOException
     */
    public static void sendRequest(PrintWriter writer, String ... args) throws IOException {
        writer.println("*"+args.length);
        for (String arg : args) {
            writer.println("$"+arg.getBytes(StandardCharsets.UTF_8).length);
            writer.println(arg);
        }
        writer.flush();
    }

命令的解析

通過RESP協定的實現，我們就能做到對我們的快取傳送命令，那麼我們又該怎麼對命令進行解析，然後做出對應的操作呢？

這裡我們使用字首樹結構來進行動態路由

Node

https://github.com/weloe/Java-Distributed-Cache/blob/master/src/main/java/com/weloe/cache/server/parser/Node.java

首先要構建樹的節點

需要注意的是隻有葉子節點才有pattern

isWild來判斷是否有萬用字元則是為了來匹配使用者輸入的引數，我們設定路由的時候用:作為萬用字元

例如設定路由set :group :k :v

命令為：set g1 k1 v1

把 :group和g1匹配，:k和k1匹配，:v和v1匹配

最後我們要解析出 group = g1 , k = k1, v = v1

/**
 * @author weloe
 */
public class Node {
    /**
     * 待匹配的命令引數，只有最後一層才有 例如 set :group :key :value
     */
    private String pattern;

    /**
     * 命令引數的一部分例如 set :group :key :value 中的 :group
     */
    private String part;

    /**
     * 子節點
     */
    private List<Node> children;

    /**
     * 是否是萬用字元節點
     */
    private boolean isWild;

    public Node() {
        this.children = new LinkedList<>();
        this.part = "";
        this.pattern = "";
    }

    public Node(String part, boolean isWild) {
        this.part = part;
        this.isWild = isWild;
        this.children = new LinkedList<>();
    }
}

註冊節點的方法

	/**
     * 註冊節點
     *
     * @param pattern
     * @param parts
     * @param height
     */
    public void insert(String pattern, String[] parts, int height) {
        // 終止條件,height匹配完，到了最下層
        if (parts.length == height) {
            this.pattern = pattern;
            return;
        }

        String part = parts[height];
        // 匹配出一個子節點
        Node child = matchChild(part);
        if (child == null) {
            // 如果當前part的第一個字元是":"或者"*"就為模糊匹配
            child = new Node(part, part.startsWith(":") || part.startsWith("*"));
            // 增加當前節點的子節點
            children.add(child);
        }
        child.insert(pattern, parts, height + 1);
    }

註冊節點方法中呼叫的machChild()為 根據part部分匹配子節點的方法

	/**
     * 根據part匹配子節點
     *
     * @param part
     * @return 第一個匹配節點
     */
    public Node matchChild(String part) {
        for (Node child : children) {
            if (child.part.equals(part) || child.isWild) {
                return child;
            }
        }
        return null;
    }

根據字串陣列(輸入命令)來遞迴匹配出對應葉子節點的方法

	/**
     * 根據parts[]匹配出節點
     * @param parts
     * @param height
     * @return
     */
    public Node search(String[] parts, int height) {
        // 匹配到末端
        if(parts.length == height || part.startsWith("*")){
            if(pattern == null){
                return null;
            }
            // 匹配到節點
            return this;
        }

        String part = parts[height];
        // 根據part找到匹配的子節點
        List<Node> children = matchChildren(part);

        for (Node child : children) {
            Node node = child.search(parts, height + 1);
            if(node != null){
                return node;
            }
        }

        return null;
    }

search方法中呼叫的matchChildren為 根據part來匹配出所有符合的子節點的方法

    /**
     * 根據part匹配子節點
     * @param part
     * @return 所有匹配的節點
     */
    public List<Node> matchChildren(String part) {
        ArrayList<Node> nodes = new ArrayList<>();
        for (Node child : children) {
            if (child.part.equals(part) || child.isWild) {
                nodes.add(child);
            }
        }
        return nodes;
    }

Router

https://github.com/weloe/Java-Distributed-Cache/blob/master/src/main/java/com/weloe/cache/server/parser/Router.java

Router提供了新增路由和根據使用者命令匹配路由的方法

這裡的HandlerFunc是需要我們在新增路由addRoute時進行設定的命令對應的處理常式

這裡的Router類是我們在getRoute時返回的，node就是匹配到的樹的葉子節點，map為匹配到的萬用字元引數

例如設定路由set :group :k :v

命令為：set g1 k1 v1

把 :group和g1匹配，:k和k1匹配，:v和v1匹配

map即為 group = g1 , k = k1, v = v1

/**
 * @author weloe
 */
public class Router {

    @FunctionalInterface
    public interface HandlerFunc {
        Object handle(RESPContext context);
    }

    public class Route{
        private Node node;
        private Map<String,String> map;

        public Route(Node node, Map<String, String> map) {
            this.node = node;
            this.map = map;
        }

        public Object handle(RESPContext context){
            context.setParamMap(map);
            String key = "command"+"-"+node.getPattern();
            return handlers.get(key).handle(context);
        }

        public Map<String, String> getMap() {
            return map;
        }

        public Node getNode() {
            return node;
        }
    }

    /**
     * 根節點
     */
    private Map<String,Node> roots;

    private Map<String,HandlerFunc> handlers;


    public Router() {
        this.roots = new LinkedHashMap<>();
        this.handlers = new LinkedHashMap<>();
    }

    /**
     * 解析pattern
     * @param pattern
     * @return
     */
    public String[] parsePattern(String pattern){
        String[] patterns = pattern.split(" ");

        String[] parts = new String[patterns.length];
        for (int i = 0; i < patterns.length; i++) {
            parts[i] = patterns[i];
            if(patterns[i].charAt(0) == '*'){
                break;
            }
        }

        return parts;
    }

    public void addRoute(String method,String pattern,HandlerFunc handler){
        String[] parts = parsePattern(pattern);

        String key = method + "-" + pattern;
        Node node = roots.get(method);
        // 判斷有沒有該method對應的根節點，沒有就建一個
        if (node == null) {
            roots.put(method,new Node());
        }
        roots.get(method).insert(pattern,parts,0);
        handlers.put(key,handler);
    }

    public Route getRoute(String path){
        return getRoute("command",path);
    }

    public Route getRoute(String method,String path){

        String[] patterns = parsePattern(path);
        Map<String, String> params = new LinkedHashMap<>();

        Node root = roots.get(method);
        if(root == null){
            return null;
        }
        Node res = root.search(patterns, 0);

        if (res == null) {
            return null;
        }
        String[] parts = parsePattern(res.getPattern());
        for (int i = 0; i < parts.length; i++) {
            String part = parts[i];
            if (part.charAt(0) == ':') {
                params.put(part.substring(1),patterns[i]);
            }
            if(part.charAt(0) == '*' && part.length() > 1){
                String collect = Arrays.stream(patterns).skip(i).collect(Collectors.joining(" "));
                params.put(part.substring(1),collect);
                break;
            }

        }

        return new Route(res,params);
    }

}

測試

這裡相當於我們輸入delete g1 k1 v1

匹配到命令為 delete

匹配到的引數為key:k1

@Test
    void getRoute() {
        Router router = new Router();

        router.addRoute("command","set :group :key :v",null);
        router.addRoute("command","delete :group :key :v",null);
        router.addRoute("command","expire :group :key :v",null);
        router.addRoute("command","get :group :key :v",null);
        router.addRoute("command","hget :key :field",null);
        router.addRoute("command","config set maxsize :size",null);
        router.addRoute("command","config set maxnum :num",null);
        router.addRoute("command","config set cachestrategy :strategy",null);

        Router.Route route = router.getRoute("command", "delete g1 k1 v1");
        Assertions.assertEquals(route.getNode().getPattern(),"delete :group :key :v");
        Assertions.assertEquals(route.getMap().get("key"),"k1");
    }

伺服器端

根據以上內容我們可以封裝出RESPContext，RESPRqeuest，以及RESPReqspnse類

RESPContext

https://github.com/weloe/Java-Distributed-Cache/blob/master/src/main/java/com/weloe/cache/server/resp/RESPContext.java

作為一個伺服器端自然有上下文資訊，我們將它封裝為一個Context類

/**
 * @author weloe
 */
public class RESPContext {

    private LocalDateTime startTime;

    private Socket socket;

    private RESPRequest request;

    private RESPResponse response;

    private Router.Route route;

    private Map<String,String> paramMap;

    private Group group;


    public void initServer(Socket socket, RESPRequest request, RESPResponse response) throws IOException {

        this.socket = socket;
        this.request = request;
        this.response = response;
        this.startTime = LocalDateTime.now();
    }


    /**
     * 解析RESP協定的位元組
     *
     * @return
     */
    public String parseRESPBytes() {
        String result = request.parseRESPBytes();

        return result;
    }

    /**
     * 解析RESP協定的String
     *
     * @param raw
     * @return
     */
    public Object parseRESPString(String raw) {
        Object obj = request.parseRESPString(raw);
        return obj;
    }

    public void ok() {
        response.ok();
    }

    public void ok(byte[] bytes){
        response.ok(String.valueOf(bytes));
    }

    public void ok(String arg) {
        response.ok(arg);
    }

    public void ok(String... args) {
        response.ok(args);
    }

    public void error(String msg) {
        response.error(msg);
    }

    public void close() {
        if (request != null) {
            try {
                request.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        if (response != null) {
            response.close();
        }

        if (socket != null) {
            try {
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

    public Socket getSocket() {
        return socket;
    }

    public RESPRequest getRequest() {
        return request;
    }

    public RESPResponse getResponse() {
        return response;
    }

    public LocalDateTime getStartTime() {
        return startTime;
    }

    public void setStartTime(LocalDateTime startTime) {
        this.startTime = startTime;
    }

    public void setParamMap(Map<String, String> paramMap) {
        this.paramMap = paramMap;
    }

    public Map<String, String> getParamMap() {
        return paramMap;
    }

    public void setRoute(Router.Route route) {
        this.route = route;
    }

    public Router.Route getRoute() {
        return route;
    }

    public void setGroup(Group group) {
        this.group = group;
    }

    public Group getGroup() {
        return group;
    }

    public String getParam(String key){
        return paramMap.get(key);
    }
}

RESPRequest

https://github.com/weloe/Java-Distributed-Cache/blob/master/src/main/java/com/weloe/cache/server/resp/RESPRequest.java

/**
 * @author weloe
 */
public class RESPRequest {
    private InputStream inputStream;

    private Map<String,String> params;

    public RESPRequest(Socket socket) throws IOException {
        this.inputStream = socket.getInputStream();
    }

    public String getParam(String key) {
        return params.get(key);
    }

    /**
     * 解析RESP協定的位元組
     *
     * @return
     */
    public byte[] getBytes() {
        byte[] bytes = null;

        try {
            while (inputStream.available() == 0) {
            }
            bytes = new byte[inputStream.available()];
            inputStream.read(bytes);

        } catch (IOException e) {
            e.printStackTrace();
        }

        return bytes;
    }

    /**
     * 解析RESP協定的位元組
     *
     * @return
     */
    public String parseRESPBytes() {
        byte[] bytes;
        byte[] buf = new byte[1];
        String result = null;
        try {
            System.out.println("等待資料傳輸");
//            try {
//                // 讀不到阻塞
//                inputStream.read(buf);
//            } catch (IOException e) {
//                return null;
//            }
//            result = new String(buf) + new String(bytes);
            while (inputStream.available() == 0) {
            }
            bytes = new byte[inputStream.available()];
            inputStream.read(bytes);
            result = new String(bytes);

        } catch (IOException e) {
            e.printStackTrace();
        }

        return result;
    }

    /**
     * 解析RESP協定的String
     *
     * @param raw
     * @return
     */
    public Object parseRESPString(String raw) {
        byte type = raw.getBytes()[0];
        String result = raw.substring(1);
        switch (type) {
            case '+':
                // +ok\r\n
                // 讀單行
                return result.replace("\r\n", "");
            case '-':
                // 異常
                // -Error msg\r\n
                throw new RuntimeException(result.replace("\r\n", ""));
            case ':':
                // 數位
                return result.replace("\r\n", "");
            case '$':
                return result.substring(1).replace("\r\n", "");
            case '*':
                // 多行字串
                String[] strList = result.substring(result.indexOf("$")).split("\r\n");
                System.out.print("多條批次請求：");
                List<String> list = new LinkedList<>();
                for (int i = 1; i < strList.length; i += 2) {
                    System.out.print(strList[i] + " ");
                    list.add(strList[i]);
                }
                System.out.println();
                return list;
            default:
                throw new RuntimeException("錯誤的資料格式");
        }
    }

    public void close() throws IOException {
        if (inputStream != null) {
            inputStream.close();
        }
    }


    public InputStream getInputStream() {
        return inputStream;
    }
}

RESPResponse

https://github.com/weloe/Java-Distributed-Cache/blob/master/src/main/java/com/weloe/cache/server/resp/RESPResponse.java

/**
 * @author weloe
 */
public class RESPResponse {
    private PrintWriter writer;

    public RESPResponse(Socket socket) throws IOException {
        // 字元輸出流，可以直接按行輸出
        writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream(), StandardCharsets.UTF_8));
    }

    public void ok() {
        writer.println(RESPStatus.OK.getMsg());
        writer.flush();
    }

    public void ok(Integer arg) {
        writer.println(":" + arg);
        writer.flush();
    }

    public void ok(String arg) {
        writer.println("$" + arg.getBytes(StandardCharsets.UTF_8).length);
        writer.println(arg);
        writer.flush();
    }

    public void ok(String... args) {
        writer.println("*" + args.length);
        for (String arg : args) {
            writer.println("$" + arg.getBytes(StandardCharsets.UTF_8).length);
            writer.println(arg);
        }
        writer.flush();
    }

    public void error(String msg) {
        writer.println(RESPStatus.ERROR.getMsg() + " " + msg);
        writer.flush();
    }

    public void close() {
        if (writer != null) {
            writer.close();
        }
    }

    public PrintWriter getWriter() {
        return writer;
    }


}

Service

https://github.com/weloe/Java-Distributed-Cache/tree/master/src/main/java/com/weloe/cache/server/command

命令有對應的HandlerFunc函數，我們就需要在函數中呼叫我們的相應的service，因此需要抽象出對應的service

這裡的service為對前篇快取管理中的類的簡單呼叫，就不再一一贅述

ConfigService

/**
 * config操作
 * @author weloe
 */
public class ConfigService {

    public Object getNormalSize(Group group){
        return group.getNormalSize();
    }

    public Object getMaxSize(Group group){
        return group.getMaxSize();
    }

    public Object setMaxSize(Group group,String size) {
        group.setMaxSize(Integer.parseInt(size));
        return "";
    }

    public Object setMaxNum(Group group,String num) {
        return null;
    }

}

DeleteService

/**
 * 刪除key相關操作
 * @author weloe
 */
public class DeleteService {

    public Object delete(Group group,String key) {
        CacheObj delete = group.delete(key);
        if(delete == null){
            return null;
        }
        return "";
    }


    public Object clear(Group group) {
        group.clear();
        return "";
    }
}

ExpireService

/**
 * 設定,獲取key的過期時間，單位秒
 * @author weloe
 */
public class ExpireService {

    public Object expire(Group group,String key,String value) {
        LocalDateTime time = group.expire(key, Long.parseLong(value), ChronoUnit.SECONDS);
        return time;
    }

    public Object ttl(Group group,String key) {
        long ttl = group.ttl(key);
        return ttl;
    }
}

GroupService

/**
 * group操作
 * @author weloe
 */
public class GroupService {

    private GroupManager groupManager = GroupManager.getInstance();

    public Object add(String groupName) {

        Group group = new Group();
        group.setName(groupName);
        group.setCache(new Cache());
        group.setGetter(k -> null);
        groupManager.put(group);

        return "";
    }


}

StringService

/**
 * 快取set，get操作
 * @author weloe
 */
public class StringService {

    public String get(Group group,String key) {
        CacheObj cacheObj = group.get(key);
        if(cacheObj != null){
            return new String(cacheObj.getData());
        }
        return null;
    }


    public Object set(Group group,String key,String value) {
        group.putCacheObj(key, new CacheObj(value.getBytes(StandardCharsets.UTF_8)));
        return "";
    }
}

ServiceFactory

為了方便管理，另外寫了管理service的類

public class ServiceFactory {

    Map<String,Object> map;

    public ServiceFactory() {
        map = new LinkedHashMap<>();
        map.put("str",new StringService());
        map.put("group",new GroupService());
        map.put("config",new ConfigService());
        map.put("delete",new DeleteService());
        map.put("expire",new ExpireService());
    }


    public<T> T getBean(String name){
        return (T) map.get(name);
    }
}

CommandQueue

https://github.com/weloe/Java-Distributed-Cache/blob/master/src/main/java/com/weloe/cache/server/parser/CommandQueue.java

這裡我們使用多執行緒io解析命令，單執行緒執行命令的模型，多執行緒解析完命令得到Route後把Context加入到阻塞佇列中，再消費阻塞佇列的Context執行命令

public class CommandQueue {

    private static PriorityBlockingQueue<RESPContext> commandQueue = new PriorityBlockingQueue<>(5, (o1, o2) -> {
        if (o1.getStartTime().isBefore(o2.getStartTime())) {
            return -1;
        }
        return 1;
    });

    public boolean add(RESPContext context){
        return commandQueue.add(context);
    }


    public void consume() {
        new Thread(() -> {
            System.out.println("伺服器端等待接收命令...");
            while (true) {
                RESPContext respContext = null;
                try {
                    respContext = commandQueue.take();
                } catch (InterruptedException e) {
                    respContext.error(e.getMessage());
                    e.printStackTrace();
                    continue;
                }

                System.out.println("執行命令"+respContext.getRoute().getNode().getPattern());
                // 執行命令
                Object handle = respContext.getRoute().handle(respContext);
                System.out.println(handle);
                if(handle == null){
                    respContext.ok("nil");
                }else if(handle.equals("")){
                    respContext.ok();
                }else {
                    respContext.ok(handle.toString());
                }
            }
        }).start();


    }

    public PriorityBlockingQueue<RESPContext> getCommandQueue() {
        return commandQueue;
    }
}

Launch伺服器端啟動類

https://github.com/weloe/Java-Distributed-Cache/blob/master/src/main/java/com/weloe/cache/Launch.java

public class Launch {
    private static final ExecutorService poolExecutor = new ThreadPoolExecutor(2, 5,
            30L, TimeUnit.SECONDS,
            new ArrayBlockingQueue(10));

    private static final GroupManager groupManager = GroupManager.getInstance();

    private static final ServiceFactory factory = new ServiceFactory();

    private static final Router router = new Router();

    static {
        // 註冊路由資訊
        ConfigService config = factory.getBean("config");
        StringService str = factory.getBean("str");
        DeleteService delete = factory.getBean("delete");
        ExpireService expire = factory.getBean("expire");
        GroupService groupService = factory.getBean("group");

        router.addRoute("group add :name", c -> groupService.add(c.getParam("name")));

        router.addRoute("config set maxByteSize :group :size", c -> config.setMaxSize(c.getGroup(),c.getParam("size")))
              .addRoute("config get maxByteSize :group", c -> config.getMaxSize(c.getGroup()))
              .addRoute("config get normalSize :group", c -> config.getNormalSize(c.getGroup()))
              .addRoute("config set maxNum :group :num", c -> config.setMaxNum(c.getGroup(),c.getParam("num")));


        router.addRoute("expire :group :k :n", c -> expire.expire(c.getGroup(),c.getParam("k"),c.getParam("n")))
              .addRoute("ttl :group :k", c -> expire.ttl(c.getGroup(),c.getParam("k")));

        router.addRoute("delete :group :k", c -> delete.delete(c.getGroup(),c.getParam("size")))
              .addRoute("clear :group", c -> delete.clear(c.getGroup()));

        router.addRoute("set :group :k :v", c -> str.set(c.getGroup(),c.getParam("k"),c.getParam("v")))
              .addRoute("get :group :k", c -> str.get(c.getGroup(),c.getParam("k")));


    }


    public static void main(String[] args) throws IOException {

        CommandQueue commandQueue = new CommandQueue();
        commandQueue.consume();

        ServerSocket serverSocket = new ServerSocket(8081);

        while (true) {
            // 初始化server
            Socket socket = serverSocket.accept();
            System.out.println(socket.getInetAddress() + ":" + socket.getPort() + "連線");
            poolExecutor.submit(() -> task(commandQueue, socket));

        }


    }

    private static void task(CommandQueue commandQueue, Socket socket) {
        RESPContext context = null;

        System.out.println("執行緒"+Thread.currentThread().getId()+" 執行");
        try {
            while (true) {
                context = new RESPContext();
                context.initServer(socket,new RESPRequest(socket),new RESPResponse(socket));

                Object requestData = null;
                try {
                    // 處理請求
                    String res = context.parseRESPBytes();
                    if(res == null){
                        return;
                    }
                    System.out.printf("%s => %s%n", "原始格式", res.replace("\r\n", "\\r\\n"));
                    requestData = context.parseRESPString(res);

                } catch (Exception e) {
                    System.out.println(e.getMessage());
                    context.error(e.getMessage());
                    continue;
                }

                List<String> commandStr = (List<String>) requestData;

                System.out.println("接收到" + socket.getInetAddress() + ":" + socket.getPort() +"的命令");

                // 解析命令
                Router.Route route = router.getRoute(String.join(" ",commandStr));
                if (route == null) {
                    context.ok("請檢查你的命令引數");
                    continue;
                }

                Map<String, String> paramMap = route.getMap();
                String name = paramMap.get("group");
                if(name != null){
                    if(groupManager.getGroup(name) == null){
                        context.ok("該group不存在");
                        continue;
                    }
                    context.setGroup(groupManager.getGroup(name));
                }
                context.setRoute(route);


                // 命令加入阻塞佇列
                commandQueue.add(context);
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            context.close();
        }
    }

}

Client

https://github.com/weloe/Java-Distributed-Cache/blob/master/src/main/java/com/weloe/cache/client/Client.java

public class ClientLaunch {
    static Socket socket;
    static PrintWriter writer;
    static BufferedReader reader;
    static InputStream inputStream;

    static String host = "127.0.0.1";
    static int port = 8081;

    public static void main(String[] args) {

        try {
            // 建立連線
            socket = new Socket(host,port);
            // 獲取輸出輸入流
            // 字元輸出流，可以直接按行輸出
            writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream(), StandardCharsets.UTF_8));
            inputStream = socket.getInputStream();

            while (true) {
                Scanner reader = new Scanner(System.in);
                if (reader.hasNextLine()) {
                    String s = reader.nextLine();
                    if("exit".equals(s)){
                        System.out.println("exit cli");
                        return;
                    }
                    if (!s.isEmpty()) {
                        Object obj;
                        // 操作命令
                        sendRequest(s.split(" "));
                        // 響應
                        obj = inputStreamHandleByteResponse();
                        System.out.println(obj);
                    }
                }
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 釋放連線
            try {
                if(reader != null) {
                    reader.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if(inputStream != null) {
                    inputStream.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if(writer != null) {
                    writer.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            try {
                if(socket != null) {
                    socket.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

    private static void sendRequest(String ... args) {

        writer.println("*"+args.length);
        for (String arg : args) {
            writer.println("$"+arg.getBytes(StandardCharsets.UTF_8).length);
            writer.println(arg);
        }

        writer.flush();

    }


    public static Object inputStreamHandleByteResponse() {
        String result = RESPUtil.parseRESPBytes(inputStream);
        return RESPUtil.parseRESPString(result);
    }


}

測試

最後我們就可以啟動Launch和Client來進行一下使用了

伺服器端啟動

伺服器端等待接收命令...
/127.0.0.1:53779連線
執行緒13 執行
等待資料傳輸

使用者端傳送請求group add test

伺服器端返回

ok

伺服器端輸出

原始格式 => *3\r\n$5\r\ngroup\r\n$3\r\nadd\r\n$4\r\ntest\r\n
多條批次請求：group add test 
接收到/127.0.0.1:53779的命令
執行命令group add :name

使用者端設定快取set test testKey testV

伺服器端返回

ok

伺服器端輸出

原始格式 => *4\r\n$3\r\nset\r\n$4\r\ntest\r\n$7\r\ntestKey\r\n$5\r\ntestV\r\n
多條批次請求：set test testKey testV 
接收到/127.0.0.1:53779的命令
執行命令set :group :k :v

使用者端get操作get test testKey

伺服器端返回

testV

至此，單機的快取就基本完成~