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我正在計算頁面上查看用戶的數量。基本上，當用戶查看URL localhost:8080/itemDetail.do?itemId=1時，該頁面將顯示有多少用戶同時在該頁面上查看。計數當前用戶查看頁面
解決辦法
當用戶在瀏覽特定網頁，該網頁會繼續發送Ajax請求每隔1秒回服務器，然後服務器將使用Map<String, Map<String, Integer>>（都使用ConcurrentHashMap用於初始化）至包含itemId（要知道哪個頁面被查看）和IP和timeout數（在Map的內部）。每次獲取請求時，計數將增加1.在請求過程中會有一個線程觸發，以每2秒減少超時計數。如果最後，超時計數等於0，則應用程序將認爲用戶停止查看該頁面，然後線程將刪除該條目，從而減少用戶數量。1.此方法的一個小問題是自超時如果用戶打開頁面足夠長時間並關閉頁面，則應用程序需要一段時間才能知道該用戶已經離開該頁面，因爲此刻的超時數量相當大
實施
// Controller
@RequestMapping(value = AppConstants.ACTION_NUMBER_VIEWING, method = GET)
@ResponseBody
public int userItemViewing(HttpServletRequest request, @RequestParam(value = "itemId") String itemId) {
try {
return eventService.countUserOnline(request, itemId);
} catch (CAServiceException e) {
e.printStackTrace();
LOG.error("========== Error when counting number of online user ==========" + e.getMessage());
}
return 0;
}
// Service
private static Map<String, Map<String, Integer>> numberOfCurrentViews;
private Thread countDownOnlineThread;
class OnlineCountingDownRunnable implements Runnable {
private List<String> timeoutList = new ArrayList<String>();
private void cleanTimeoutIps() {
for (String itemId : numberOfCurrentViews.keySet()) {
Map<String, Integer> currentIps = numberOfCurrentViews.get(itemId);
for(String ip : timeoutList){
currentIps.remove(ip);
}
}
}
@Override
public void run() {
try {
for (String itemId : numberOfCurrentViews.keySet()) {
Map<String, Integer> currentIps = numberOfCurrentViews.get(itemId);
for(String ip : currentIps.keySet()){
Integer timeout = new Integer(currentIps.get(ip).intValue() - 1);
if (timeout == 0) {
timeoutList.add(ip);
}
currentIps.put(ip, timeout);
}
}
cleanTimeoutIps();
// counting down time must be double increasing time
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
LOG.error("---------------- Thread error in counting down online user: " + e.getMessage());
}
}
}
public int countUserOnline(HttpServletRequest request, String itemId) throws CAServiceException {
// create a count down timer to detect if the user does not view the page anymore
String ip = request.getRemoteAddr();
// init counting down online user map
if (numberOfCurrentViews == null) {
numberOfCurrentViews = new ConcurrentHashMap<String, Map<String, Integer>>();
}
// start thread to check user online
if (countDownOnlineThread == null) {
countDownOnlineThread = new Thread(new OnlineCountingDownRunnable());
countDownOnlineThread.start();
}
LOG.debug("---------------- Requested IP: " + ip);
if (ip == null || ip.isEmpty()) {
throw new CAServiceException("======= Cannot detect Ip of the client =======");
}
if (numberOfCurrentViews.get(itemId) != null) {
Map<String, Integer> userView = numberOfCurrentViews.get(itemId);
if (userView.get(ip) != null) {
userView.put(ip, userView.get(ip).intValue() + 1);
} else {
userView.put(ip, 1);
}
numberOfCurrentViews.put(itemId, userView);
} else {
Map<String, Integer> ips = new ConcurrentHashMap<String, Integer>();
ips.put(ip, 1);
numberOfCurrentViews.put(itemId, ips);
}
LOG.debug(String.format(
"============= %s is seeing there is %s users viewing item %s =============",
ip, numberOfCurrentViews.get(itemId).size(), itemId
));
return numberOfCurrentViews.get(itemId).size();
}
問題
我不知道如何測試這個功能，因爲它需要多個IP地址來查看頁面。我曾試圖建立的JMeter並設置IP欺騙這樣link，但沒有成功，所以我做了一個小的模擬測試像這樣
@Test
public void testCountUserOnline() throws Exception {
List<HttpServletRequest> requests = new ArrayList<HttpServletRequest>();
for (int i = 0; i < 10; i ++) {
HttpServletRequest request = Mockito.mock(HttpServletRequest.class);
Mockito.when(request.getRemoteAddr()).thenReturn(String.format("192.168.1.%s", i));
requests.add(request);
}
List<Thread> threads = new ArrayList<Thread>();
for (int i = 0; i < 10; i ++) {
Thread thread = new Thread(new RequestRunnable(requests.get(i)));
threads.add(thread);
thread.start();
}
for (Thread thread : threads) {
thread.join();
}
}
class RequestRunnable implements Runnable {
private HttpServletRequest request;
public RequestRunnable(HttpServletRequest request) {
this.request = request;
}
public void run() {
try {
int i = 0;
while (i < 10) {
eventService.countUserOnline(request, "1");
i++;
System.out.println(i);
Thread.sleep(1000);
}
} catch (CAServiceException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
但再次查看日誌，我沒有那麼自信了實施
此外，這是人類用來計算頁面上查看用戶數量的正常方式嗎？我只是想確保我不會錯過任何事情，以防這部分有任何捷徑。我正在使用Spring MVC 3.x。我需要支持IE 9以及：（（（，所以Web Socket不能被廣泛使用
這應該是一個評論，而不是答案... – 2014-11-01 14:13:16