Question

我有一个简单的JMS设置。请参阅以下代码：

class ProcessingService{
    def jmsService
    def theMethod(){
        jmsService.send(service:'listening', value);
    }
}


 @Transactional
 static scope = "session"
 class ListeningService {
     static expose = ['jms']
     private int value;
     def onMessage(message) {
         value = message;
         println "Completed ${message}"
     }
     int getValue(){
         return value;
     }
}

我的问题是如何使用从控制器发送的消息？

目前我有以下代码，但我不确定这是否正确，因为服务设计为无状态：

class ConsumingController{
    def listeningService
    def method(){
        while(notTimeout){
            log.info(listeningService.getValue())
        }
    }
}

这是我的第一个jms应用程序，如果答案看起来很明显，请原谅我

Answer 1

在这种情况下我更喜欢使用websockets。查看http://grails.org/plugin/atmosphere

否则我建议您将数据推送到数据库并从控制器检查数据库，而不是检查服务。

既然你在工作氛围方面遇到了问题，我会试着解释一下我是如何运作的。

安装了grails氛围插件以获取依赖项。
将jquery.atmosphere.js添加到前端。

添加了AtmosphereService类（查看sendData方法）

类AtmosphereService实现了AtmosphereHandler {

static exposes = ['jms']

static transactional = false
static atmosphere = [mapping: '/atmosphere']

public void sendData(int value, long userId){
    Map result = [value: value];

    String broadcastChannel = "/$userId/value";

    Broadcaster broadcaster = BroadcasterFactory.default.lookup(broadcastChannel, true);
    broadcaster.broadcast((result as JSON) as String);
}

public void onRequest(AtmosphereResource resource) throws IOException {
    try {
        AtmosphereRequest req = resource.request
        if (req.method.equalsIgnoreCase("GET")) {
            resource.broadcaster = BroadcasterFactory.default.lookup(req.pathInfo, true);
            resource.suspend();
        } else if (req.method.equalsIgnoreCase("POST")) {
            String stuff = req.reader.readLine().trim()
            resource.broadcaster = BroadcasterFactory.default.lookup(req.pathInfo, true);
            resource.broadcaster.broadcast(stuff);
        }
    } catch (Exception e) {
        log.error("Error in Atmosphere.onRequest", e);
    }
}

public void onStateChange(AtmosphereResourceEvent event) throws IOException {
    AtmosphereResource r = event.resource
    AtmosphereResponse res = r.response

    try {
        if (event.isSuspended()) {
            String body = (event.message) as String;
            res.writer.write( body );

            switch (r.transport()) {
                case TRANSPORT.JSONP:
                case TRANSPORT.LONG_POLLING:
                    event.resource.resume()
                    break
                default:
                    res.writer.flush()
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
        log.error("ERROR in onStateChange", e);
    }
}

@Override
public void destroy() {
    // TODO Auto-generated method stub

}

}

添加以下js代码以侦听频道“/ $ userId / value”（查看request.onMessage处理程序）

var contentType = "application/json";
var userId = 12312;
var logLevel = 'debug';
var shared = 'true';
var transport = 'websocket';
var fallbackTransport = 'long-polling';
var socket = $.atmosphere;
var partialUpdateRequest=null;
var atmosphereUrl = BASE_HREF+'/atmosphere';
var request = { url: atmosphereUrl +"/"+userId+"/value",
            contentType : contentType,
            logLevel : logLevel,
            shared : shared,
            transport : transport,
            fallbackTransport: fallbackTransport
};

request.onMessage = function (response) {
    var message = response.responseBody;
    try {
        var json = jQuery.parseJSON(message);
        // do your stuff here.
    }catch (e) {
        //return;
    }
};
socket.subscribe(request);

Answer 2

我为我工作的一个替代方案是使用事件api使用grails-platform-core插件。

http://grailsrocks.github.io/grails-platform-core/

和

http://grails.org/plugin/platform-core

以下是我目前正在做的事情：

class ExcelService{
    def processMethod(){
         while(not done){
             //do some processing
             event("excelUpdates", completed)
         }

    }
}

//the controller
class ExcelProcessorService {
    @grails.events.Listener
    def excelUpdates(Float completed){
        println "${completed}% of excel processing task completed"
    }
}

我不确定如何将更新推送到浏览器或刷新页面（如何取消任务），但在完成后会发布更新。

在grails控制器中使用JMS消息

2 个答案: