关于Undertow启动时的警告日志

错误提示：

当使用 Undertow 作为 Spring Boot 嵌入式服务器时，启动应用。会看到有一条 WARN 日志，如下：

UT026010: Buffer pool was not set on WebSocketDeploymentInfo, the default pool will be used

大致意思是“没有给 WebSocketDeploymentInfo 设置 Buffer pool，将会使用默认值”。

解决方法如下：

1.排除 undertow-websockets-jsr 依赖

如果未使用到 WebSocket 技术，那么可以直接从 spring-boot-starter-undertow 中排除 undertow-websockets-jsr 依赖即可。

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-undertow</artifactId>
    <exclusions>
        <!-- 排除 undertow-websockets-jsr 依赖 -->
        <exclusion>
            <groupId>io.undertow</groupId>
            <artifactId>undertow-websockets-jsr</artifactId>
        </exclusion>
    </exclusions>
</dependency>

2.为 WebSocketDeploymentInfo 设置合理的参数

也可以通过上述的 “编程式” 配置方式，为 WebSocketDeploymentInfo 设置一个合理的参数。如下：

import org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory;
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.context.annotation.Configuration;

import io.undertow.server.DefaultByteBufferPool;
import io.undertow.websockets.jsr.WebSocketDeploymentInfo;

@Configuration
public class UndertowConfiguration implements WebServerFactoryCustomizer<UndertowServletWebServerFactory>{

    @Override
    public void customize(UndertowServletWebServerFactory factory) {
        factory.addDeploymentInfoCustomizers(deploymentInfo -> {
            
            WebSocketDeploymentInfo webSocketDeploymentInfo = new WebSocketDeploymentInfo();
            
            // 设置合理的参数
            webSocketDeploymentInfo.setBuffers(new DefaultByteBufferPool(true, 8192));
            
            deploymentInfo.addServletContextAttribute("io.undertow.websockets.jsr.WebSocketDeploymentInfo", webSocketDeploymentInfo);
        });
    }
}