springboot websocket简单入门示例

之前做的需求都是客户端请求服务器响应,新需求是服务器主动推送信息到客户端.百度之后有流、长轮询、websoket等方式进行.但是目前更加推崇且合理的显然是websocket.

从springboot官网翻译了一些资料,再加上百度简单实现了springboot使用websocekt与客户端的双工通信.

1.首先搭建一个简单的springboot环境

<!-- Inherit defaults from Spring Boot -->
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.4.RELEASE</version>
  </parent>

  <!-- Add typical dependencies for a web application -->
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
  </dependencies>

2.引入springboot整合websocket依赖

<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-websocket -->
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-websocket</artifactId>
  <version>2.0.4.RELEASE</version>
</dependency>

3.创建启动springboot的核心类

package com;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class GlobalConfig {
  public static void main(String[] args) {
    SpringApplication.run(GlobalConfig.class, args);
  }
}

4.创建websocket服务器

正如springboot 官网推荐的websocket案例,需要实现WebSocketHandler或者继承TextWebSocketHandler/BinaryWebSocketHandler当中的任意一个.

package com.xiaoer.handler;

import com.alibaba.fastjson.JSONObject;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import java.util.HashMap;
import java.util.Map;

/**
 * 相当于controller的处理器
 */
public class MyHandler extends TextWebSocketHandler {
  @Override
  protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
    String payload = message.getPayload();
    Map<String, String> map = JSONObject.parseObject(payload, HashMap.class);
    System.out.println("=====接受到的数据"+map);
    session.sendMessage(new TextMessage("服务器返回收到的信息," + payload));
  }
}

5.注册处理器

package com.xiaoer.config;

import com.xiaoer.handler.MyHandler;
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;

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
  @Override
  public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
    registry.addHandler(myHandler(), "myHandler/{ID}");
  }
  public WebSocketHandler myHandler() {
    return new MyHandler();
  }

}

6.运行访问

出现如上图是因为不能直接通过http协议访问,需要通过html5的ws://协议进行访问.

7.创建Html5 客户端

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <title></title>
  </head>
  <body>
    <input id="text" type="text" />
    <button onclick="send()">Send</button>  
    <button onclick="closeWebSocket()">Close</button>
    <div id="message">
    </div>
    <script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
    <script>
      
      var userID="888";
      var websocket=null;

      $(function(){
        connectWebSocket();
      })
      
      //建立WebSocket连接
      function connectWebSocket(){

        console.log("开始...");
       
       //建立webSocket连接
        websocket = new WebSocket("ws://127.0.0.1:8080/myHandler/ID="+userID);
       
       //打开webSokcet连接时，回调该函数
        websocket.onopen = function () {   
          console.log("onpen"); 
        }
        
        //关闭webSocket连接时，回调该函数
        websocket.onclose = function () {
        //关闭连接  
          console.log("onclose");
        }

        //接收信息
        websocket.onmessage = function (msg) {
          console.log(msg.data);
        }

      }
      //发送消息
      function send(){
        var postValue={};
        postValue.id=userID;
        postValue.message=$("#text").val();     
        websocket.send(JSON.stringify(postValue));
      }
      //关闭连接
      function closeWebSocket(){
        if(websocket != null) {
          websocket.close();
        }
      }
    </script>
  </body>
</html>

8.运行

利用客户端运行之后仍然会出现上图中的一连接就中断了websocket连接.

这是因为spring默认不接受跨域访问:

As of Spring Framework 4.1.5, the default behavior for WebSocket and SockJS is to accept only same origin requests.

需要在WebSocketConfig中设置setAllowedOrigins.

package com.xiaoer.config;

import com.xiaoer.handler.MyHandler;
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;

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
  @Override
  public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
    registry.addHandler(myHandler(), "myHandler/{ID}")
      .setAllowedOrigins("*");
  }
  public WebSocketHandler myHandler() {
    return new MyHandler();
  }

}

如下图,并未输出中断,说明连接成功.

9.服务器和客户端的相互通信

服务器端收到消息

客户端收到服务器主动推送消息

以上就是一个最基础的springboot简单应用.还可以通过拦截器、重写WebSocketConfigurer中的方法进行更为复杂的属性操作.具体可以参考SpringBoot集成WebSocket【基于纯H5】进行点对点[一对一]和广播[一对多]实时推送

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