首先Spring Boot 3必须使用最新版本的Dubbo 3.2

使用zookeeper可以修改依赖

<dependency>
   <groupId>org.apache.dubbo</groupId>
   <artifactId>dubbo-dependencies-zookeeper-curator5</artifactId>
   <type>pom</type>
 </dependency>

Dubbo默认使用了fastjson 2序列化，可能会出现一些小问题，可以修改配置文件，在provider中使用hessian2

dubbo:
  registry:
    protocol: zookeeper
    address: localhost:2181
  config-center:
    timeout: 100000
  protocol:
    name: dubbo
    port: 20801
    telnet: help
    payload: 104857600
    serialization: hessian2
  provider:
    timeout: 100000
    filter: -exception,dubboExceptionFilter

  consumer:
    timeout: 100000
    check: false

如何使用了基于apache httpclient的RestTemplate，可以修改依赖

 <dependency>
   <groupId>org.apache.httpcomponents.client5</groupId>
   <artifactId>httpclient5</artifactId>
</dependency>

如果需要自定义RestTemplate，可以参考以下内容

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

import org.apache.hc.client5.http.classic.HttpClient;
import org.apache.hc.client5.http.config.RequestConfig;
import org.apache.hc.client5.http.impl.classic.HttpClientBuilder;
import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManager;
import org.apache.hc.client5.http.socket.ConnectionSocketFactory;
import org.apache.hc.client5.http.socket.PlainConnectionSocketFactory;
import org.apache.hc.client5.http.ssl.SSLConnectionSocketFactory;
import org.apache.hc.core5.http.config.Registry;
import org.apache.hc.core5.http.config.RegistryBuilder;
import org.apache.hc.core5.util.Timeout;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.client.RestTemplate;

import com.fasterxml.jackson.databind.MapperFeature;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;

@Configuration
public class RestTemplateConfig {
    @Value("${spring.jackson.date-format}")
    private String dateFormat;

    @Bean
    public RestTemplate restTemplate(ClientHttpRequestFactory factory) {
        var restTemplate = new RestTemplate(factory);
        var converters = restTemplate.getMessageConverters();
        var iterator = converters.iterator();

        while (iterator.hasNext()) {
            var converter = iterator.next();

            if (converter instanceof MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter) {
                var objectMapper = mappingJackson2HttpMessageConverter.getObjectMapper();
                var javaTimeModule = new JavaTimeModule();

                javaTimeModule.addSerializer(LocalDateTime.class,
                        new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(dateFormat)));
                javaTimeModule.addDeserializer(LocalDateTime.class,
                        new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(dateFormat)));

                objectMapper.disable(MapperFeature.IGNORE_DUPLICATE_MODULE_REGISTRATIONS);

                objectMapper.registerModule(javaTimeModule);

                objectMapper.enable(MapperFeature.IGNORE_DUPLICATE_MODULE_REGISTRATIONS);
            }
        }

        return restTemplate;
    }

    @Bean
    public ClientHttpRequestFactory httpRequestFactory() {
        return new HttpComponentsClientHttpRequestFactory(httpClient());
    }

    public HttpClient httpClient() {
        Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory>create()
                .register("http", PlainConnectionSocketFactory.getSocketFactory())
                .register("https", SSLConnectionSocketFactory.getSocketFactory()).build();

        PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(registry);
        // 设置最大连接池的数量
        connectionManager.setMaxTotal(1000);
        // 每个主机的最大并发量，route是指域名。--对MaxTotal的细化
        connectionManager.setDefaultMaxPerRoute(300);

        RequestConfig requestConfig = RequestConfig.custom()
                // 数据返回超时时间
                .setResponseTimeout(Timeout.ofMilliseconds(60000))
                // 连接超时时间
                .setConnectTimeout(Timeout.ofMilliseconds(60000))
                // 从连接池中获取连接的超时时间
                .setConnectionRequestTimeout(Timeout.ofMilliseconds(10000)).build();

        return HttpClientBuilder.create().setDefaultRequestConfig(requestConfig).setConnectionManager(connectionManager)
                .build();
    }

}