我试图以json的形式向我的websocket发送一条消息，但在运行web应用程序时，我在开发人员控制台中遇到了这个错误。我知道这个错误发生在找不到元素的时候。然而，"send"不是websocket的默认成员吗？为什么找不到它？错误发生在我的最后一行代码中。js文件的代码如下：
// to keep the session id
var sessionId = '';
// name of the client
var name = '';
$(document).ready(function() {
$("#form_submit, #form_send_message").submit(function(e) {
e.preventDefault();
join();
});
});
var webSocket;
/**
* Connecting to socket
*/
function join() {
// Checking person name
if ($('#input_name').val().trim().length <= 0) {
alert('Enter your name');
} else {
name = $('#input_name').val().trim();
$('#prompt_name_container').fadeOut(1000, function() {
// opening socket connection
openSocket();
});
}
return false;
}
/**
* Will open the socket connection
*/
function openSocket() {
// Ensures only one connection is open at a time
if (webSocket !== undefined && webSocket.readyState !== WebSocket.CLOSED) {
return;
}
var wsUrl;
if (window.location.protocol == 'http:') {
wsUrl = 'ws://' + window.location.host + ':8000/chat'+'?name='+name;
} else {
wsUrl = 'wss://' + window.location.host + ':8443/chat'+'?name='+name;
}
console.log('WebSockets Url : ' + wsUrl);
var webSocket = new WebSocket(wsUrl);
// Create a new instance of the websocket
//webSocket = new WebSocket("ws://jbosslew-weihao.rhcloud.com:8000/" );
/**
* Binds functions to the listeners for the websocket.
*/
webSocket.onopen = function(event) {
$('#message_container').fadeIn();
if (event.data === undefined)
return;
};
webSocket.onmessage = function(event) {
// parsing the json data
parseMessage(event.data);
};
webSocket.onclose = function(event) {
};
}
/**
* Sending the chat message to server
*/
function send() {
var message = $('#input_message').val();
if (message.trim().length > 0) {
sendMessageToServer('message', message);
} else {
alert('Please enter message to send!');
}
}
/**
* Closing the socket connection
*/
function closeSocket() {
webSocket.close();
$('#message_container').fadeOut(600, function() {
$('#prompt_name_container').fadeIn();
// clearing the name and session id
sessionId = '';
name = '';
// clear the ul li messages
$('#messages').html('');
$('p.online_count').hide();
});
}
/**
* Parsing the json message. The type of message is identified by 'flag' node
* value flag can be self, new, message, exit
*/
function parseMessage(message) {
var jObj = $.parseJSON(message);
// if the flag is 'self' message contains the session id
if (jObj.flag == 'self') {
sessionId = jObj.sessionId;
} else if (jObj.flag == 'new') {
// if the flag is 'new', a client joined the chat room
var new_name = 'You';
// number of people online
var online_count = jObj.onlineCount;
$('p.online_count').html(
'Hello, <span class="green">' + name + '</span>. <b>'
+ online_count + '</b> people online right now')
.fadeIn();
if (jObj.sessionId != sessionId) {
new_name = jObj.name;
}
var li = '<li class="new"><span class="name">' + new_name + '</span> '
+ jObj.message + '</li>';
$('#messages').append(li);
$('#input_message').val('');
} else if (jObj.flag == 'message') {
// if the json flag is 'message', it means somebody sent the chat
// message
var from_name = 'You';
if (jObj.sessionId != sessionId) {
from_name = jObj.name;
}
var li = '<li><span class="name">' + from_name + '</span> '
+ jObj.message + '</li>';
// appending the chat message to list
appendChatMessage(li);
$('#input_message').val('');
} else if (jObj.flag == 'exit') {
// if the json flag is 'exit', it means somebody left the chat room
var li = '<li class="exit"><span class="name red">' + jObj.name
+ '</span> ' + jObj.message + '</li>';
var online_count = jObj.onlineCount;
$('p.online_count').html(
'Hello, <span class="green">' + name + '</span>. <b>'
+ online_count + '</b> people online right now');
appendChatMessage(li);
}
}
/**
* Appending the chat message to list
*/
function appendChatMessage(li) {
$('#messages').append(li);
// scrolling the list to bottom so that new message will be visible
$('#messages').scrollTop($('#messages').height());
}
/**
* Sending message to socket server message will be in json format
*/
function sendMessageToServer(flag, message) {
var json = '{""}';
// preparing json object
var myObject = new Object();
myObject.sessionId = sessionId;
myObject.message = message;
myObject.flag = flag;
// converting json object to json string
json = JSON.stringify(myObject);
// sending message to server
webSocket.send(json); // Uncaught type error occurs here
}
如果它也是相关的，我的服务器套接字的java代码如下：
package info.androidhive.webmobilegroupchat;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import javax.websocket.OnClose;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
import org.json.JSONException;
import org.json.JSONObject;
import com.google.common.collect.Maps;
@ServerEndpoint("/chat")
public class SocketServer {
// set to store all the live sessions
private static final Set<Session> sessions = Collections
.synchronizedSet(new HashSet<Session>());
// Mapping between session and person name
private static final HashMap<String, String> nameSessionPair = new HashMap<String, String>();
private JSONUtils jsonUtils = new JSONUtils();
// Getting query params
public static Map<String, String> getQueryMap(String query) {
Map<String, String> map = Maps.newHashMap();
if (query != null) {
String[] params = query.split("&");
for (String param : params) {
String[] nameval = param.split("=");
map.put(nameval[0], nameval[1]);
}
}
return map;
}
/**
* Called when a socket connection opened
* */
@OnOpen
public void onOpen(Session session) {
System.out.println(session.getId() + " has opened a connection");
Map<String, String> queryParams = getQueryMap(session.getQueryString());
String name = "";
if (queryParams.containsKey("name")) {
// Getting client name via query param
name = queryParams.get("name");
try {
name = URLDecoder.decode(name, "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
// Mapping client name and session id
nameSessionPair.put(session.getId(), name);
}
// Adding session to session list
sessions.add(session);
try {
// Sending session id to the client that just connected
session.getBasicRemote().sendText(
jsonUtils.getClientDetailsJson(session.getId(),
"Your session details"));
} catch (IOException e) {
e.printStackTrace();
}
// Notifying all the clients about new person joined
sendMessageToAll(session.getId(), name, " joined conversation!", true,
false);
}
/**
* method called when new message received from any client
*
* @param message
* JSON message from client
* */
@OnMessage
public void onMessage(String message, Session session) {
System.out.println("Message from " + session.getId() + ": " + message);
String msg = null;
// Parsing the json and getting message
try {
JSONObject jObj = new JSONObject(message);
msg = jObj.getString("message");
} catch (JSONException e) {
e.printStackTrace();
}
// Sending the message to all clients
sendMessageToAll(session.getId(), nameSessionPair.get(session.getId()),
msg, false, false);
}
/**
* Method called when a connection is closed
* */
@OnClose
public void onClose(Session session) {
System.out.println("Session " + session.getId() + " has ended");
// Getting the client name that exited
String name = nameSessionPair.get(session.getId());
// removing the session from sessions list
sessions.remove(session);
// Notifying all the clients about person exit
sendMessageToAll(session.getId(), name, " left conversation!", false,
true);
}
/**
* Method to send message to all clients
*
* @param sessionId
* @param message
* message to be sent to clients
* @param isNewClient
* flag to identify that message is about new person
* @param isExit
* flag to identify that a person left the conversation
* */
private void sendMessageToAll(String sessionId, String name,
String message, boolean isNewClient, boolean isExit) {
// Looping through all the sessions and sending the message individually
for (Session s : sessions) {
String json = null;
// Checking if the message is about new client joined
if (isNewClient) {
json = jsonUtils.getNewClientJson(sessionId, name, message,
sessions.size());
} else if (isExit) {
// Checking if the person left the conversation
json = jsonUtils.getClientExitJson(sessionId, name, message,
sessions.size());
} else {
// Normal chat conversation message
json = jsonUtils
.getSendAllMessageJson(sessionId, name, message);
}
try {
System.out.println("Sending Message To: " + sessionId + ", "
+ json);
s.getBasicRemote().sendText(json);
} catch (IOException e) {
System.out.println("error in sending. " + s.getId() + ", "
+ e.getMessage());
e.printStackTrace();
}
}
}
}
根据Tiny Giant的说法，我不小心重新声明了我的变量webSocket，而不是使用它的全局版本，导致我的webSocket在那一刻没有定义。