springboot websocket 配置超时关闭连接

客户端与服务器在用websocket通信的时候，如果客户端突然关闭网络或者直接关机，此时路由与服务器之间的链接还存在

在服务器端输入查看
netstat -anp | grep 5007
tcp6       0      0 192.168.0.121:5007      119.119.0.0:60944    ESTABLISHED 23585/java

若不给该客户端发信息，除非路由器重启，否则这个链接会一直存在，服务器会一直认为该链接存在，后果就是随着大连无用的tcp连接积累，服务器会报socket too many open files错误导致服务挂掉。

解决方法：

要求websocket客户端定期发送PING，服务器返回PONG，客户端意外断开的时候服务器发现在一段时间内没交互信息关闭该session。

通过读spring-websocket\5.3.24的源码并参考

源码 springframework\spring-websocket\5.3.24\spring-websocket-5.3.24-sources\org\springframework\web\socket\server\standard\ServletServerContainerFactoryBean.java

/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.socket.server.standard;

import javax.servlet.ServletContext;
import javax.websocket.WebSocketContainer;
import javax.websocket.server.ServerContainer;

import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.context.ServletContextAware;

/**
 * A {@link FactoryBean} for configuring {@link javax.websocket.server.ServerContainer}.
 * Since there is usually only one {@code ServerContainer} instance accessible under a
 * well-known {@code javax.servlet.ServletContext} attribute, simply declaring this
 * FactoryBean and using its setters allows for configuring the {@code ServerContainer}
 * through Spring configuration.
 *
 * <p>This is useful even if the {@code ServerContainer} is not injected into any other
 * bean within the Spring application context. For example, an application can configure
 * a {@link org.springframework.web.socket.server.support.DefaultHandshakeHandler},
 * a {@link org.springframework.web.socket.sockjs.SockJsService}, or
 * {@link ServerEndpointExporter}, and separately declare this FactoryBean in order
 * to customize the properties of the (one and only) {@code ServerContainer} instance.
 *
 * @author Rossen Stoyanchev
 * @author Sam Brannen
 * @since 4.0
 */
public class ServletServerContainerFactoryBean
        implements FactoryBean<WebSocketContainer>, ServletContextAware, InitializingBean {

    @Nullable
    private Long asyncSendTimeout;

    @Nullable
    private Long maxSessionIdleTimeout;

    @Nullable
    private Integer maxTextMessageBufferSize;

    @Nullable
    private Integer maxBinaryMessageBufferSize;

    @Nullable
    private ServletContext servletContext;

    @Nullable
    private ServerContainer serverContainer;

    public void setAsyncSendTimeout(Long timeoutInMillis) {
        this.asyncSendTimeout = timeoutInMillis;
    }

    @Nullable
    public Long getAsyncSendTimeout() {
        return this.asyncSendTimeout;
    }

    public void setMaxSessionIdleTimeout(Long timeoutInMillis) {
        this.maxSessionIdleTimeout = timeoutInMillis;
    }

    @Nullable
    public Long getMaxSessionIdleTimeout() {
        return this.maxSessionIdleTimeout;
    }

    public void setMaxTextMessageBufferSize(Integer bufferSize) {
        this.maxTextMessageBufferSize = bufferSize;
    }

    @Nullable
    public Integer getMaxTextMessageBufferSize() {
        return this.maxTextMessageBufferSize;
    }

    public void setMaxBinaryMessageBufferSize(Integer bufferSize) {
        this.maxBinaryMessageBufferSize = bufferSize;
    }

    @Nullable
    public Integer getMaxBinaryMessageBufferSize() {
        return this.maxBinaryMessageBufferSize;
    }

    @Override
    public void setServletContext(ServletContext servletContext) {
        this.servletContext = servletContext;
    }

    @Override
    public void afterPropertiesSet() {
        Assert.state(this.servletContext != null,
                "A ServletContext is required to access the javax.websocket.server.ServerContainer instance");
        this.serverContainer = (ServerContainer) this.servletContext.getAttribute(
                "javax.websocket.server.ServerContainer");
        Assert.state(this.serverContainer != null,
                "Attribute 'javax.websocket.server.ServerContainer' not found in ServletContext");

        if (this.asyncSendTimeout != null) {
            this.serverContainer.setAsyncSendTimeout(this.asyncSendTimeout);
        }
        if (this.maxSessionIdleTimeout != null) {
            this.serverContainer.setDefaultMaxSessionIdleTimeout(this.maxSessionIdleTimeout);
        }
        if (this.maxTextMessageBufferSize != null) {
            this.serverContainer.setDefaultMaxTextMessageBufferSize(this.maxTextMessageBufferSize);
        }
        if (this.maxBinaryMessageBufferSize != null) {
            this.serverContainer.setDefaultMaxBinaryMessageBufferSize(this.maxBinaryMessageBufferSize);
        }
    }

    @Override
    @Nullable
    public ServerContainer getObject() {
        return this.serverContainer;
    }

    @Override
    public Class<?> getObjectType() {
        return (this.serverContainer != null ? this.serverContainer.getClass() : ServerContainer.class);
    }

    @Override
    public boolean isSingleton() {
        return true;
    }

}

https://docs.spring.io/spring-framework/docs/5.3.24/reference/html/web.html#websocket-intro-architecture

方法setMaxSessionIdleTimeout设置session超时时间。

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
import org.springframework.web.socket.server.HandshakeInterceptor;
import org.springframework.web.socket.server.standard.ServletServerContainerFactoryBean;
import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor;

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {

   
    @Bean
    public ServletServerContainerFactoryBean createWebSocketContainer() {
        ServletServerContainerFactoryBean container = new ServletServerContainerFactoryBean();
      
        container.setMaxTextMessageBufferSize(512000);
        container.setMaxBinaryMessageBufferSize(512000);
        container.setMaxSessionIdleTimeout(5 * 1000L);
        return container;
    }
}