如何设计一个注册中心？（2）实现注册接口

柔光的暖阳◎ 2023-10-13 19:03 13阅读 0赞

### 1. 创建SpringBoot工程 ###

创建父工程及三个子模块，其中一个模块作为注册中心，另外两个作为服务提供者。  
![在这里插入图片描述][19b9aa09e28f4f4cace1fc72ff2c1122.png]  
pom

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>org.example</groupId>
        <artifactId>registerTest</artifactId>
        <packaging>pom</packaging>
        <version>1.0-SNAPSHOT</version>
        <modules>
            <module>server</module>
            <module>provider1</module>
            <module>provider2</module>
        </modules>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.2.1.RELEASE</version>
            <relativePath/> 
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.apache.httpcomponents</groupId>
                <artifactId>httpclient</artifactId>
            </dependency>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>fastjson</artifactId>
                <version>1.1.23</version>
            </dependency>
        </dependencies>
    
    </project>

### 2. 实现http访问 ###

注意：这里目前用的是同步请求，实际用异步才是合适的

package http.client;
    
    import com.alibaba.fastjson.JSONObject;
    import org.apache.http.HttpEntity;
    import org.apache.http.HttpResponse;
    import org.apache.http.client.methods.HttpGet;
    import org.apache.http.client.methods.HttpPost;
    import org.apache.http.entity.StringEntity;
    import org.apache.http.impl.client.CloseableHttpClient;
    import org.apache.http.impl.client.HttpClientBuilder;
    import org.apache.http.util.EntityUtils;
    
    public class HttpClient {
        
        private String url;
        private String contentType;
        private String encoding;
        private JSONObject data;
    
        public HttpClient(String url, String encoding, String contentType, JSONObject data) {
        
            this.url = url;
            this.data = data;
            this.encoding = encoding == null ? "UTF-8" : encoding;
            this.contentType = contentType == null ? "application/json" : contentType;
        }
    
        public JSONObject httpGet() throws Exception {
        
            try (CloseableHttpClient httpClient = HttpClientBuilder.create().build()) {
        
                HttpGet httpGet = new HttpGet(url);
                HttpResponse response = httpClient.execute(httpGet);
                if (response.getStatusLine().getStatusCode() != 200) {
        
    //            throw new Exception("调用服务端异常.");
                    return getResult(false, "调用服务端异常.");
                }
                HttpEntity res = response.getEntity();
                String resultData = EntityUtils.toString(res);
                System.out.println("从服务端返回结果: " + resultData);
                return JSONObject.parseObject(resultData);
            } catch (Exception e) {
        
                e.printStackTrace();
            }
            return getResult(false, "");
        }
    
        public JSONObject httpPost() throws Exception {
        
            try (CloseableHttpClient httpClient = HttpClientBuilder.create().build()) {
        
                String json = JSONObject.toJSONString(data);
                StringEntity entity = new StringEntity(json);
                entity.setContentEncoding(encoding);
                entity.setContentType(contentType);
                HttpPost httpPost = new HttpPost(url);
                httpPost.setEntity(entity);
                HttpResponse response = httpClient.execute(httpPost);
                if (response.getStatusLine().getStatusCode() != 200) {
        
                    return getResult(false, "调用服务端异常.");
                }
                HttpEntity res = response.getEntity();
                String resultData = EntityUtils.toString(res);
                System.out.println("从服务端返回结果: " + resultData);
            } catch (Exception e) {
        
                e.printStackTrace();
            }
            return getResult(false, "");
        }
    
        public static JSONObject getResult(boolean res, String msg) {
        
            return new JSONObject(){
        {
        
                put("res", res);
                put("msg", msg);
            }};
        }
    }

实现一个简单的注册表结构，代表模块的名称和ip

package common;
    
    public class RegisterTable {
        
        private String name;
        private String ip;
    
        public RegisterTable(String name, String ip) {
        
            this.name = name;
            this.ip = ip;
        }
    
        public String getIp() {
        
            return ip;
        }
    }

### 3. 注册中心实现 ###

实现注册表管理，增加，删除，查询

package register.list;
    
    import com.alibaba.fastjson.JSONObject;
    import common.RegisterTable;
    import http.client.HttpClient;
    import org.springframework.stereotype.Component;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    
    @Component
    public class RegisterList {
        
        HashMap<String, ArrayList<RegisterTable>> hashMap = new HashMap<>();
    
        public JSONObject add(String name, String ip) {
        
            ArrayList<RegisterTable> list = hashMap.get(name);
            if (list == null) {
        
                list = new ArrayList<RegisterTable>();
            } else {
        
                for (RegisterTable table : list) {
        
                    if (table.getIp().equals(ip)) {
        
                        return HttpClient.getResult(false, "repeat");
                    }
                }
            }
            RegisterTable registerTable = new RegisterTable(name,ip);
            list.add(registerTable);
            hashMap.put(name, list);
            return HttpClient.getResult(true, "success");
        }
    
        public HashMap<String, ArrayList<RegisterTable>> getAll() {
        
            return hashMap;
        }
    
        public ArrayList<RegisterTable> getByName(String name) {
        
            return hashMap.get(name);
        }
    }

提供注册接口：

package register.control;
    
    import com.alibaba.fastjson.JSONObject;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.*;
    import register.list.RegisterList;
    
    @RestController
    @RequestMapping("/register")
    public class Register {
        
    
        @Autowired
        RegisterList registerList;
    
        @PostMapping("/register")
        public JSONObject register(@RequestBody JSONObject data) {
        
            //处理注册逻辑
            return registerList.add(data.getString("name"), data.getString("ip"));
        }
    
        @GetMapping("/list/{name}")
        public Object getList(@PathVariable(value = "name", required = true) String name) {
        
            //获取注册列表
            return registerList.getByName(name);
        }
    
        @GetMapping("/list/all")
        public Object getList() {
        
            return registerList.getAll();
        }
    }

### 4. provider模块 ###

功能：项目启动后发送注册信息到注册中心模块。

package common.register;
    
    import com.alibaba.fastjson.JSONObject;
    import http.client.HttpClient;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.boot.ApplicationArguments;
    import org.springframework.boot.ApplicationRunner;
    import org.springframework.stereotype.Component;
    
    @Component
    public class Register implements ApplicationRunner {
        
    
        @Value("${model.name}")
        String name;
    
        @Value("${model.host}")
        String host;
    
        @Value("${model.port}")
        String port;
    
        @Value("${register.url}")
        String url;
    
        //发送注册消息
        @Override
        public void run(ApplicationArguments args) throws Exception {
        
            register();
        }
    
        private void register() throws Exception {
        
            JSONObject data = new JSONObject() {
        {
        
                put("name", name);
                put("ip", "http://" + host + ":" + port);
            }};
            HttpClient client = new HttpClient(url, null, null, data);
            client.httpPost();
        }
    }

application.yml

server:
      port: 8001
    
    model:
      name: "provider"
      port: "8001"
      host: "127.0.0.1"
    
    register:
      url: "http://localhost:8080/register/register"

另外一个provider也是一样，不过端口不同

### 5. 测试 ###

启动后：  
![在这里插入图片描述][64e9a421e5ea47e7919319896a4d7f43.png]  
查询注册表：两个模块都已经注册。  
![在这里插入图片描述][b9a139eae30241b490c07da06a8abc4c.png]

### 缺点 ###

这种做法有非常大的缺点，就是如果先启动客户端再启动服务器，则无法完成注册，会报错链接服务器失败。因此客户端需要不断的重新注册，直到成功。

[19b9aa09e28f4f4cace1fc72ff2c1122.png]: https://img-blog.csdnimg.cn/19b9aa09e28f4f4cace1fc72ff2c1122.png
[64e9a421e5ea47e7919319896a4d7f43.png]: https://img-blog.csdnimg.cn/64e9a421e5ea47e7919319896a4d7f43.png
[b9a139eae30241b490c07da06a8abc4c.png]: https://img-blog.csdnimg.cn/b9a139eae30241b490c07da06a8abc4c.png