WebSocket整合SpringBoot并传输JSON数据进行操作_springboot websocket json

WebSocket整合SpringBoot并传输JSON数据进行操作

1、引入依赖

	<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <springboot.version>2.2.1.RELEASE</springboot.version>
        <java.version>1.8</java.version>
        <swagger.version>2.7.0</swagger.version>
        <lombok.version>1.18.10</lombok.version>
    </properties>

<dependencies>
        <!--Springboot-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <!--swagger-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>${swagger.version}</version>
        </dependency>
        <!--swagger ui-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>${swagger.version}</version>
        </dependency>
        <!--lombok用来简化实体类：需要安装lombok插件-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${lombok.version}</version>
            <scope>provided</scope>
        </dependency>
        <!-- webSocket 集成 springboot-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.75</version>
        </dependency>

    </dependencies>
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2、创建Configuration配置类注入WebSocket

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

@Configuration
public class WebSocketConfig {

    /**
     * 向spring容器中注入这个ServerEndpointExporter对象
     * @return
     */
    @Bean
    public ServerEndpointExporter serverEndpointExporter(){
        return new ServerEndpointExporter();
    }
}
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3、编写WebSocketServer服务类

decoders = {OperatorDecoder.class},
encoders = {OperatorEncoder.class}
是进行webSocketMessage和实体类之间映射关系的类

import com.camera.entity.LoginCamera;
import com.camera.entity.Operator;
import com.camera.entity.OperatorDecoder;
import com.camera.entity.OperatorEncoder;
import com.camera.service.CloudService;
import com.camera.service.LoginService;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.atomic.AtomicInteger;

@ServerEndpoint(value = "/ptzControl",decoders = {OperatorDecoder.class},encoders = {OperatorEncoder.class})
@Component
public class WebSocketServer {

    //在WebSocket也是这样注入，因 SpringBoot+WebSocket 对每个客户端连接都会创建一个 WebSocketServer（@ServerEndpoint 注解对应的）对象，
    // Bean 注入操作会被直接略过，因而手动注入一个全局变量

    private static final AtomicInteger OnlineCount = new AtomicInteger(0);
    // concurrent包的线程安全Set，用来存放每个客户端对应的Session对象。
    private static CopyOnWriteArraySet<Session> SessionSet = new CopyOnWriteArraySet<Session>();

    private static CloudService cloudService = new CloudServiceImpl();

    @PostConstruct
    public void init(){
        System.out.println("websocket loading");
    }

    /**
     * 连接建立成功调用方法
     * @param session
     */
    @OnOpen
    public void onOpen(Session session){
        SessionSet.add(session);
        OnlineCount.incrementAndGet();  // 在线数+1
        SendMessage(session,"连接成功");    // 告知客户端连接成功
    }

    /**
     * 连接关闭调用方法
     */
    @OnClose
    public void onClose(Session session){
        loginService.logOutAndCleanUp();
        SessionSet.remove(session);
        OnlineCount.decrementAndGet();
    }

    /**
     * 收到客户端消息后调用的方法
     * (这一部分有些丑啊 别骂 别骂)
     */
    @OnMessage
    public void onMessage(Operator operator, Session session){
        SendMessage(session,"接收到消息，消息内容："+ operator);
        System.out.println(operator.toString());
        if ("moveLeft".equals(operator.getOperate()))
            cloudService.moveLeft(operator.getNChannelID(), operator.getIparam2());
        if ("moveRight".equals(operator.getOperate()))
            cloudService.moveRight(operator.getNChannelID(), operator.getIparam2());
        if ("moveUp".equals(operator.getOperate()))
            cloudService.moveUp(operator.getNChannelID(), operator.getIparam2());
        if ("moveDown".equals(operator.getOperate()))
            cloudService.moveDown(operator.getNChannelID(), operator.getIparam2());
    }

    /**
     * 出现错误
     */
    @OnError
    public void onError(Session session,Throwable error){
        error.printStackTrace();
    }

    /**
     * 发送消息 实践表明 每次浏览器刷新 session会发生变化
     */
    public static void SendMessage(Session session,String message){
        try {
            session.getBasicRemote().sendText(String.format("%s (From Server,Session ID=%s)",message,session.getId()));
            session.getBasicRemote().sendText(message);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 群发消息
     */
    public static void BroadCastInfo(String message) throws IOException {
        for (Session session : SessionSet) {
            if (session.isOpen())
                SendMessage(session,message);
        }
    }

    /**
     * 指定Session发送消息
     * @param sessionId
     * @param message
     * @throws IOException
     */
    public static void SendMessage(String message,String sessionId) throws IOException {
        Session session = null;
        for (Session s : SessionSet) {
            if(s.getId().equals(sessionId)){
                session = s;
                break;
            }
        }
        if(session!=null)
            SendMessage(session, message);
    }

}
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4、编写entity->json的编码类

import com.alibaba.fastjson.JSON;

import javax.websocket.EncodeException;
import javax.websocket.Encoder;
import javax.websocket.EndpointConfig;

/**
 * 将JSON编码为entity
 */
public class OperatorEncoder implements Encoder.Text<Operator> {

    /**
     * 发送编码 entity->json
     * @param object
     * @return
     * @throws EncodeException
     */
    @Override
    public String encode(Operator object) throws EncodeException {
        return JSON.toJSONString(object);
    }

    @Override
    public void init(EndpointConfig endpointConfig) {

    }

    @Override
    public void destroy() {

    }
}

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5、编写json->entity的解码类

import com.alibaba.fastjson.JSON;

import javax.websocket.Decoder;
import javax.websocket.EndpointConfig;

/**
 * 解码 json-> entity映射
 */
public class OperatorDecoder implements Decoder.Text<Operator> {

    /**
     * 转换json->entity
     * @param move
     * @return
     */
    @Override
    public Operator decode(String move) {
        return JSON.parseObject(move, Operator.class);
    }

    /**
     * 是否进行转换
     * @param s
     * @return
     */
    @Override
    public boolean willDecode(String s) {
        return true;
    }

    @Override
    public void init(EndpointConfig endpointConfig) {

    }

    @Override
    public void destroy() {

    }
}
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至此，即可使用

6、可能出现的疑问或错误

1、空指针

在WebSocket也是这样注入，因 SpringBoot+WebSocket
对每个客户端连接都会创建一个WebSocketServer对象，Bean
注入操作会被直接略过，因而手动注入一个全局变量

2、主动发送消息时如果需要发送entity类型的数据使用

session.getBasicRemote().sendObject();

3、解码时报错无法解析

willDecode()会在decode()之前执行，查看是否被拦截导致无法转换