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Spring和Websocket相结合实现消息的推送

2019年07月22日  | 移动技术网IT编程  | 我要评论

本文主要有三个步骤

1、用户登录后建立websocket连接，默认选择websocket连接，如果浏览器不支持，则使用sockjs进行模拟连接
2、建立连接后，服务端返回该用户的未读消息
3、服务端进行相关操作后，推送给某一个用户或者所有用户新消息 相关环境 spring4.0.6(要选择4.0+),tomcat7.0.55

websocet服务端实现

websocketconfig.java

@configuration
@enablewebmvc
@enablewebsocket
public class websocketconfig extends webmvcconfigureradapter implements websocketconfigurer {
@override
public void registerwebsockethandlers(websockethandlerregistry registry) {
registry.addhandler(systemwebsockethandler(),"/websocketserver").addinterceptors(new websockethandshakeinterceptor());
registry.addhandler(systemwebsockethandler(), "/sockjs/websocketserver").addinterceptors(new websockethandshakeinterceptor())
.withsockjs();
}
@bean
public websockethandler systemwebsockethandler(){
return new systemwebsockethandler();
}
}

不要忘记在springmvc的配置文件中配置对此类的自动扫描

<context:component-scan base-package="com.ldl.origami.websocket" />

@configuration
@enablewebmvc
@enablewebsocket

这三个大致意思是使这个类支持以@bean的方式加载bean，并且支持springmvc和websocket，不是很准确大致这样，试了一下@enablewebmvc不加也没什么影响，@configuration本来就支持springmvc的自动扫描

registry.addhandler(systemwebsockethandler(),"/websocketserver").addinterceptors(new websockethandshakeinterceptor())

用来注册websocket server实现类，第二个参数是访问websocket的地址

registry.addhandler(systemwebsockethandler(), "/sockjs/websocketserver").addinterceptors(new websockethandshakeinterceptor())
.withsockjs();
}

这个是使用sockjs的注册方法

首先systemwebsockethandler.java

public class systemwebsockethandler implements websockethandler {
private static final logger logger;
private static final arraylist<websocketsession> users;
static {
users = new arraylist<>();
logger = loggerfactory.getlogger(systemwebsockethandler.class);
}
@autowired
private websocketservice websocketservice;
@override
public void afterconnectionestablished(websocketsession session) throws exception {
logger.debug("connect to the websocket success......");
users.add(session);
string username = (string) session.getattributes().get(constants.websocket_username);
if(username!= null){
//查询未读消息
int count = websocketservice.getunreadnews((string) session.getattributes().get(constants.websocket_username));
session.sendmessage(new textmessage(count + ""));
}
}
@override
public void handlemessage(websocketsession session, websocketmessage<?> message) throws exception {
//sendmessagetousers();
}
@override
public void handletransporterror(websocketsession session, throwable exception) throws exception {
if(session.isopen()){
session.close();
}
logger.debug("websocket connection closed......");
users.remove(session);
}
@override
public void afterconnectionclosed(websocketsession session, closestatus closestatus) throws exception {
logger.debug("websocket connection closed......");
users.remove(session);
}
@override
public boolean supportspartialmessages() {
return false;
}
/**
* 给所有在线用户发送消息
*
* @param message
*/
public void sendmessagetousers(textmessage message) {
for (websocketsession user : users) {
try {
if (user.isopen()) {
user.sendmessage(message);
}
} catch (ioexception e) {
e.printstacktrace();
}
}
}
/**
* 给某个用户发送消息
*
* @param username
* @param message
*/
public void sendmessagetouser(string username, textmessage message) {
for (websocketsession user : users) {
if (user.getattributes().get(constants.websocket_username).equals(username)) {
try {
if (user.isopen()) {
user.sendmessage(message);
}
} catch (ioexception e) {
e.printstacktrace();
}
break;
}
}
}
}

相关内容大家一看就能明白，就不多解释了

然后websockethandshakeinterceptor.java

public class websockethandshakeinterceptor implements handshakeinterceptor {
private static logger logger = loggerfactory.getlogger(handshakeinterceptor.class);
@override
public boolean beforehandshake(serverhttprequest request, serverhttpresponse response, websockethandler wshandler, map<string, object
> attributes) throws exception {
if (request instanceof servletserverhttprequest) {
servletserverhttprequest servletrequest = (servletserverhttprequest) request;
httpsession session = servletrequest.getservletrequest().getsession(false);
if (session != null) {
//使用username区分websockethandler，以便定向发送消息
string username = (string) session.getattribute(constants.session_username);
attributes.put(constants.websocket_username,username);
}
}
return true;
}
@override
public void afterhandshake(serverhttprequest request, serverhttpresponse response, websockethandler wshandler, exception exception) {
}
}

这个的主要作用是取得当前请求中的用户名，并且保存到当前的websockethandler中，以便确定websockethandler所对应的用户，具体可参考httpsessionhandshakeinterceptor

用户登录建立websocket连接

index.jsp

<script type="text/javascript" src="http://localhost:8080/origami/websocket/sockjs-0.3.min.js"></script>
<script>
var websocket;
if ('websocket' in window) {
websocket = new websocket("ws://localhost:8080/origami/websocketserver");
} else if ('mozwebsocket' in window) {
websocket = new mozwebsocket("ws://localhost:8080/origami/websocketserver");
} else {
websocket = new sockjs("http://localhost:8080/origami/sockjs/websocketserver");
}
websocket.onopen = function (evnt) {
};
websocket.onmessage = function (evnt) {
$("#msgcount").html("(<font color='red'>"+evnt.data+"</font>)")
};
websocket.onerror = function (evnt) {
};
websocket.onclose = function (evnt) {
}
</script>

使用sockjs时要注意

1、这两个的写法

<script type="text/javascript" src="http://localhost:8080/origami/websocket/sockjs-0.3.min.js"></script>
websocket = new sockjs(http://localhost:8080/origami/sockjs/websocketserver);

2、web.xml中

<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_1.xsd">

version

web-app_3_1.xsd

这两个的版本都要是3.0+

然后在这个servlet中加入

<async-supported>true</async-supported>
<servlet>
<servlet-name>appservlet</servlet-name>
<servlet-class>org.springframework.web.servlet.dispatcherservlet</servlet-class>
<init-param>
<param-name>contextconfiglocation</param-name>
<param-value>classpath*:servlet-context.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
<async-supported>true</async-supported>
</servlet>

然后所有的filter中也加入

<async-supported>true</async-supported>

3、添加相关依赖

<dependency>
<groupid>com.fasterxml.jackson.core</groupid>
<artifactid>jackson-annotations</artifactid>
<version>2.3.0</version>
</dependency>
<dependency>
<groupid>com.fasterxml.jackson.core</groupid>
<artifactid>jackson-core</artifactid>
<version>2.3.1</version>
</dependency>
<dependency>
<groupid>com.fasterxml.jackson.core</groupid>
<artifactid>jackson-databind</artifactid>
<version>2.3.3</version>
</dependency>

好了，现在websocket可以正常建立起来了

返回用户未读的消息

当连接建立后，会进入systemwebsockethandler的afterconnectionestablished方法，代码看上边，取出websockethandshakeinterceptor中保存的用户名

查询信息后使用session.sendmessage(new textmessage(count + ""));返回给用户，从哪来回哪去

服务端推送消息给用户

@controller
public class admincontroller {
static logger logger = loggerfactory.getlogger(admincontroller.class);
@autowired(required = false)
private adminservice adminservice;
@bean
public systemwebsockethandler systemwebsockethandler() {
return new systemwebsockethandler();
}
@requestmapping("/auditing")
@responsebody
public string auditing(httpservletrequest request){
//无关代码都省略了
int unreadnewscount = adminservice.getunreadnews(username);
systemwebsockethandler().sendmessagetouser(username, new textmessage(unreadnewscount + ""));
return result;
}
}

在这里可以使用sendmessagetouser给某个用户推送信息，也可以使用sendmessagetousers给所有用户推送信息

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