Introduction
The so-called WebSocket, similar to Socket, its function is to allow the client and server in the Web application to establish full-duplex communication. There are generally three ways to use WebSocket in Spring-based applications:
• Use the @ServerEndpoint annotation provided by Java to implement
• Use the low-level WebSocket API provided by Spring to implement
• Use STOMP message implementation
Use the @ServerEndpoint annotation provided by Java to achieve
(1) Use the @ServerEndpoint annotation to monitor a WebSocket request path:
here, the client's connection port/reverse is monitored, and how to handle the message sent by the client is defined
import javax.websocket.OnMessage;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
/**
* ReverseWebSocketEndpoint
*
* @author zifangsky
* @date 2018/9/30
* @since 1.0.0
*/
@ServerEndpoint("/reverse")
public class ReverseWebSocketEndpoint {
@OnMessage
public void handleMessage(Session session, String message) throws IOException {
session.getBasicRemote().sendText("Reversed: " + new StringBuilder(message).reverse());
}
}
(2)WebSocket相关配置:
package cn.zifangsky.samplewebsocket.config;
import cn.zifangsky.samplewebsocket.websocket.ReverseWebSocketEndpoint;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;
/**
* WebSocket相关配置
*
* @author zifangsky
* @date 2018/9/30
* @since 1.0.0
*/
@Configuration
@EnableWebSocket
public class WebSocketConfig{
@Bean
public ReverseWebSocketEndpoint reverseWebSocketEndpoint() {
return new ReverseWebSocketEndpoint();
}
@Bean
public ServerEndpointExporter serverEndpointExporter() {
return new ServerEndpointExporter();
}
}
(3) Sample page:
<head>
<meta content="text/html;charset=UTF-8"/>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=edge"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>WebSocket Examples: Reverse</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script th:src="@{/layui/layui.js}"></script>
<link th:href="@{/layui/css/layui.css}" rel="stylesheet">
<style type="text/css">
#connect-container {
margin: 0 auto;
width: 400px;
}
#connect-container div {
padding: 5px;
margin: 0 7px 10px 0;
}
.layui-btn {
display: inline-block;
}
</style>
<script type="text/javascript">
var ws = null;
$(function () {
var target = $("#target");
if (window.location.protocol === 'http:') {
target.val('ws://' + window.location.host + target.val());
} else {
target.val('wss://' + window.location.host + target.val());
}
});
function setConnected(connected) {
var connect = $("#connect");
var disconnect = $("#disconnect");
var reverse = $("#reverse");
if (connected) {
connect.addClass("layui-btn-disabled");
disconnect.removeClass("layui-btn-disabled");
reverse.removeClass("layui-btn-disabled");
} else {
connect.removeClass("layui-btn-disabled");
disconnect.addClass("layui-btn-disabled");
reverse.addClass("layui-btn-disabled");
}
connect.attr("disabled", connected);
disconnect.attr("disabled", !connected);
reverse.attr("disabled", !connected);
}
//连接
function connect() {
var target = $("#target").val();
ws = new WebSocket(target);
ws.onopen = function () {
setConnected(true);
log('Info: WebSocket connection opened.');
};
ws.onmessage = function (event) {
log('Received: ' + event.data);
};
ws.onclose = function () {
setConnected(false);
log('Info: WebSocket connection closed.');
};
}
//断开连接
function disconnect() {
if (ws != null) {
ws.close();
ws = null;
}
setConnected(false);
}
//文字反转
function reverse() {
if (ws != null) {
var message = $("#message").val();
log('Sent: ' + message);
ws.send(message);
} else {
alert('WebSocket connection not established, please connect.');
}
}
//日志输出
function log(message) {
console.debug(message);
}
</script>
</head>
<body>
<noscript><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websockets rely on Javascript being
enabled. Please enable
Javascript and reload this page!</h2></noscript>
<div>
<div id="connect-container" class="layui-elem-field">
<legend>Reverse</legend>
<div>
<input id="target" type="text" class="layui-input" size="40" style="width: 350px" value="/reverse"/>
</div>
<div>
<button id="connect" class="layui-btn layui-btn-normal" onclick="connect();">Connect</button>
<button id="disconnect" class="layui-btn layui-btn-normal layui-btn-disabled" disabled="disabled"
onclick="disconnect();">Disconnect
</button>
</div>
<div>
<textarea id="message" class="layui-textarea" placeholder="请输入需要反转的内容" style="width: 350px"></textarea>
</div>
<div>
<button id="reverse" class="layui-btn layui-btn-normal layui-btn-disabled" disabled="disabled"
onclick="reverse();">Reverse message
</button>
</div>
</div>
</div>
</body>
</html>
Visit the page after starting the project, the effect is as follows:
Use the low-level WebSocket API implementation provided by Spring
Spring 4.0 provides support for WebSocket communication, including:
• Low-level API
for sending and receiving messages;
• High -level API for sending and receiving messages; • Templates for sending messages;
• Support for SockJS to solve browser and server And the problem that the proxy does not support WebSocket.
Using the low-level API provided by Spring to implement WebSocket requires the following steps:
(1) Add a WebSocketHandler:
define a message processing class that inherits the AbstractWebSocketHandler class, and then customize the "connection establishment" and "receive/send messages" , "Abnormal situation" and other situations to deal with
package cn.zifangsky.samplewebsocket.websocket;
import cn.zifangsky.samplewebsocket.service.EchoService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;
import javax.annotation.Resource;
import java.text.MessageFormat;
/**
* 通过继承 {@link org.springframework.web.socket.handler.AbstractWebSocketHandler} 的示例
*
* @author zifangsky
* @date 2018/10/9
* @since 1.0.0
*/
public class EchoWebSocketHandler extends TextWebSocketHandler{
private final Logger logger = LoggerFactory.getLogger(getClass());
@Resource(name = "echoServiceImpl")
private EchoService echoService;
@Override
public void afterConnectionEstablished(WebSocketSession session) throws Exception {
logger.debug("Opened new session in instance " + this);
}
@Override
protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
//组装返回的Echo信息
String echoMessage = this.echoService.echo(message.getPayload());
logger.debug(MessageFormat.format("Echo message \"{0}\"", echoMessage));
session.sendMessage(new TextMessage(echoMessage));
}
@Override
public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
session.close(CloseStatus.SERVER_ERROR);
logger.debug("Info: WebSocket connection closed.");
}
}
(2) WebSocket related configuration:
import cn.zifangsky.samplewebsocket.websocket.EchoWebSocketHandler;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
/**
* WebSocket相关配置
*
* @author zifangsky
* @date 2018/9/30
* @since 1.0.0
*/
@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer{
@Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
registry.addHandler(echoWebSocketHandler(), "/echoMessage");
registry.addHandler(echoWebSocketHandler(), "/echoMessage_SockJS").withSockJS();
}
/**
* 通过继承 {@link org.springframework.web.socket.handler.AbstractWebSocketHandler} 的示例
*/
@Bean
public WebSocketHandler echoWebSocketHandler(){
return new EchoWebSocketHandler();
}
}
As can be seen from the above code, in addition to configuring the basic WebSocket (that is, the connection address of /echoMessage), SockJS is also used to configure an alternative when the browser does not support WebSocket technology (that is, the connection address of /echoMessage_SockJS).
(3) Two sample pages:
i) echo.html:
<head>
<meta content="text/html;charset=UTF-8"/>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=edge"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>WebSocket Examples: Reverse</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script th:src="@{/layui/layui.js}"></script>
<link th:href="@{/layui/css/layui.css}" rel="stylesheet">
<style type="text/css">
#connect-container {
margin: 0 auto;
width: 400px;
}
#connect-container div {
padding: 5px;
margin: 0 7px 10px 0;
}
.layui-btn {
display: inline-block;
}
</style>
<script type="text/javascript">
var ws = null;
$(function () {
var target = $("#target");
if (window.location.protocol === 'http:') {
target.val('ws://' + window.location.host + target.val());
} else {
target.val('wss://' + window.location.host + target.val());
}
});
function setConnected(connected) {
var connect = $("#connect");
var disconnect = $("#disconnect");
var echo = $("#echo");
if (connected) {
connect.addClass("layui-btn-disabled");
disconnect.removeClass("layui-btn-disabled");
echo.removeClass("layui-btn-disabled");
} else {
connect.removeClass("layui-btn-disabled");
disconnect.addClass("layui-btn-disabled");
echo.addClass("layui-btn-disabled");
}
connect.attr("disabled", connected);
disconnect.attr("disabled", !connected);
echo.attr("disabled", !connected);
}
//连接
function connect() {
var target = $("#target").val();
ws = new WebSocket(target);
ws.onopen = function () {
setConnected(true);
log('Info: WebSocket connection opened.');
};
ws.onmessage = function (event) {
log('Received: ' + event.data);
};
ws.onclose = function () {
setConnected(false);
log('Info: WebSocket connection closed.');
};
}
//断开连接
function disconnect() {
if (ws != null) {
ws.close();
ws = null;
}
setConnected(false);
}
//Echo
function echo() {
if (ws != null) {
var message = $("#message").val();
log('Sent: ' + message);
ws.send(message);
} else {
alert('WebSocket connection not established, please connect.');
}
}
//日志输出
function log(message) {
console.debug(message);
}
</script>
</head>
<body>
<noscript><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websockets rely on Javascript being
enabled. Please enable
Javascript and reload this page!</h2></noscript>
<div>
<div id="connect-container" class="layui-elem-field">
<legend>Echo</legend>
<div>
<input id="target" type="text" class="layui-input" size="40" style="width: 350px" value="/echoMessage"/>
</div>
<div>
<button id="connect" class="layui-btn layui-btn-normal" onclick="connect();">Connect</button>
<button id="disconnect" class="layui-btn layui-btn-normal layui-btn-disabled" disabled="disabled"
onclick="disconnect();">Disconnect
</button>
</div>
<div>
<textarea id="message" class="layui-textarea" placeholder="请输入请求的内容" style="width: 350px"></textarea>
</div>
<div>
<button id="echo" class="layui-btn layui-btn-normal layui-btn-disabled" disabled="disabled"
onclick="echo();">Echo message
</button>
</div>
</div>
</div>
</body>
</html>
ii)echo_sockjs.html:
<head>
<meta content="text/html;charset=UTF-8"/>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=edge"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>WebSocket Examples: Reverse</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/sockjs-client/1.1.4/sockjs.min.js"></script>
<script th:src="@{/layui/layui.js}"></script>
<link th:href="@{/layui/css/layui.css}" rel="stylesheet">
<style type="text/css">
#connect-container {
margin: 0 auto;
width: 400px;
}
#connect-container div {
padding: 5px;
margin: 0 7px 10px 0;
}
.layui-btn {
display: inline-block;
}
</style>
<script type="text/javascript">
var ws = null;
$(function () {
var target = $("#target");
if (window.location.protocol === 'http:') {
target.val('http://' + window.location.host + target.val());
} else {
target.val('https://' + window.location.host + target.val());
}
});
function setConnected(connected) {
var connect = $("#connect");
var disconnect = $("#disconnect");
var echo = $("#echo");
if (connected) {
connect.addClass("layui-btn-disabled");
disconnect.removeClass("layui-btn-disabled");
echo.removeClass("layui-btn-disabled");
} else {
connect.removeClass("layui-btn-disabled");
disconnect.addClass("layui-btn-disabled");
echo.addClass("layui-btn-disabled");
}
connect.attr("disabled", connected);
disconnect.attr("disabled", !connected);
echo.attr("disabled", !connected);
}
//连接
function connect() {
var target = $("#target").val();
ws = new SockJS(target);
ws.onopen = function () {
setConnected(true);
log('Info: WebSocket connection opened.');
};
ws.onmessage = function (event) {
log('Received: ' + event.data);
};
ws.onclose = function () {
setConnected(false);
log('Info: WebSocket connection closed.');
};
}
//断开连接
function disconnect() {
if (ws != null) {
ws.close();
ws = null;
}
setConnected(false);
}
//Echo
function echo() {
if (ws != null) {
var message = $("#message").val();
log('Sent: ' + message);
ws.send(message);
} else {
alert('WebSocket connection not established, please connect.');
}
}
//日志输出
function log(message) {
console.debug(message);
}
</script>
</head>
<body>
<noscript><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websockets rely on Javascript being
enabled. Please enable
Javascript and reload this page!</h2></noscript>
<div>
<div id="connect-container" class="layui-elem-field">
<legend>Echo With SockJS</legend>
<div>
<input id="target" type="text" class="layui-input" size="40" style="width: 350px" value="/echoMessage_SockJS"/>
</div>
<div>
<button id="connect" class="layui-btn layui-btn-normal" onclick="connect();">Connect</button>
<button id="disconnect" class="layui-btn layui-btn-normal layui-btn-disabled" disabled="disabled"
onclick="disconnect();">Disconnect
</button>
</div>
<div>
<textarea id="message" class="layui-textarea" placeholder="请输入请求的内容" style="width: 350px"></textarea>
</div>
<div>
<button id="echo" class="layui-btn layui-btn-normal layui-btn-disabled" disabled="disabled"
onclick="echo();">Echo message
</button>
</div>
</div>
</div>
</body>
</html>
The specific effect is omitted, and you can run the source code to view it by yourself.
Use STOMP message to achieve
The so-called STOMP (Simple Text Oriented Messaging Protocol) is to provide a frame-based wire format layer on the basis of WebSocket. It defines a set of standardized formats for sending simple text messages (STOMP messages are based on Text, and of course also supports the transmission of binary data). At present, many server-side message queues already support STOMP, such as RabbitMQ, ActiveMQ, etc.
(1) WebSocket related configuration:
import cn.zifangsky.stompwebsocket.interceptor.websocket.MyChannelInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.simp.config.ChannelRegistration;
import org.springframework.messaging.simp.config.MessageBrokerRegistry;
import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;
/**
* WebSocket相关配置
*
* @author zifangsky
* @date 2018/9/30
* @since 1.0.0
*/
@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer{
@Autowired
private MyChannelInterceptor myChannelInterceptor;
@Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
registry.addEndpoint("/stomp-websocket").withSockJS();
}
@Override
public void configureMessageBroker(MessageBrokerRegistry registry) {
//客户端需要把消息发送到/message/xxx地址
registry.setApplicationDestinationPrefixes("/message");
//服务端广播消息的路径前缀,客户端需要相应订阅/topic/yyy这个地址的消息
registry.enableSimpleBroker("/topic");
}
@Override
public void configureClientInboundChannel(ChannelRegistration registration) {
registration.interceptors(myChannelInterceptor);
}
}
As can be seen from the above code, there are several addresses set up here. A brief explanation is as follows:
• First, an endpoint named /stomp-websocket is registered, which is the address where the STOMP client connects.
• In addition, it is defined that the server-side processing WebSocket message prefix is /message, this address is used by the client to send messages to the server (for example, the client sends a message to the address /message/hello, then the server uses @MessageMapping("/ hello”) This annotation is used to receive and process messages)
• Finally, a simple message agent is defined, which is the path prefix of the server broadcast message (for example, the client listens to the address /topic/greeting, then the server can use @SendTo ("/Topic/greeting") This annotation sends a STOMP message to the client).
It should be noted that an interceptor named MyChannelInterceptor is also added to the above code, the purpose is to print a log after the client disconnects. The relevant code is as follows:
As can be seen from the above code, there are several addresses set here, and a brief explanation is as follows:
• First, an endpoint named /stomp-websocket is registered, which is the address where the STOMP client connects.
• In addition, it is defined that the server-side processing WebSocket message prefix is /message, this address is used by the client to send messages to the server (for example, the client sends a message to the address /message/hello, then the server uses @MessageMapping("/ hello”) This annotation is used to receive and process messages)
• Finally, a simple message agent is defined, which is the path prefix of the server broadcast message (for example, the client listens to the address /topic/greeting, then the server can use @SendTo ("/Topic/greeting") This annotation sends a STOMP message to the client).
package cn.zifangsky.stompwebsocket.interceptor.websocket;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.simp.stomp.StompCommand;
import org.springframework.messaging.simp.stomp.StompHeaderAccessor;
import org.springframework.messaging.support.ChannelInterceptor;
import org.springframework.stereotype.Component;
import java.security.Principal;
import java.text.MessageFormat;
/**
* 自定义{@link org.springframework.messaging.support.ChannelInterceptor},实现断开连接的处理
*
* @author zifangsky
* @date 2018/10/10
* @since 1.0.0
*/
@Component
public class MyChannelInterceptor implements ChannelInterceptor{
private final Logger logger = LoggerFactory.getLogger(getClass());
@Override
public void afterSendCompletion(Message<?> message, MessageChannel channel, boolean sent, Exception ex) {
StompHeaderAccessor accessor = StompHeaderAccessor.wrap(message);
StompCommand command = accessor.getCommand();
//用户已经断开连接
if(StompCommand.DISCONNECT.equals(command)){
String user = "";
Principal principal = accessor.getUser();
if(principal != null && StringUtils.isNoneBlank(principal.getName())){
user = principal.getName();
}else{
user = accessor.getSessionId();
}
logger.debug(MessageFormat.format("用户{0}的WebSocket连接已经断开", user));
}
}
}
(2) Use @MessageMapping and @SendTo annotations to process messages:
@MessageMapping annotations are used to monitor client messages of a specified path, while @SendTo annotations are used to send messages from the server to the client that monitors the path.
package cn.zifangsky.stompwebsocket.controller;
import cn.zifangsky.stompwebsocket.model.websocket.Greeting;
import cn.zifangsky.stompwebsocket.model.websocket.HelloMessage;
import org.springframework.messaging.handler.annotation.MessageMapping;
import org.springframework.messaging.handler.annotation.SendTo;
import org.springframework.stereotype.Controller;
/**
* Greeting
* @author zifangsky
* @date 2018/9/30
* @since 1.0.0
*/
@Controller
public class GreetingController {
@MessageMapping("/hello")
@SendTo("/topic/greeting")
public HelloMessage greeting(Greeting greeting) {
return new HelloMessage("Hello," + greeting.getName() + "!");
}
}
(3) Sample page:
<head>
<meta content="text/html;charset=UTF-8"/>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=edge"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>WebSocket Examples: Reverse</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/sockjs-client/1.1.4/sockjs.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/stomp.js/2.3.3/stomp.min.js"></script>
<script th:src="@{/layui/layui.js}"></script>
<link th:href="@{/layui/css/layui.css}" rel="stylesheet">
<style type="text/css">
#connect-container {
margin: 0 auto;
width: 400px;
}
#connect-container div {
padding: 5px;
margin: 0 7px 10px 0;
}
.layui-btn {
display: inline-block;
}
</style>
<script type="text/javascript">
var stompClient = null;
$(function () {
var target = $("#target");
if (window.location.protocol === 'http:') {
target.val('http://' + window.location.host + target.val());
} else {
target.val('https://' + window.location.host + target.val());
}
});
function setConnected(connected) {
var connect = $("#connect");
var disconnect = $("#disconnect");
var echo = $("#echo");
if (connected) {
connect.addClass("layui-btn-disabled");
disconnect.removeClass("layui-btn-disabled");
echo.removeClass("layui-btn-disabled");
} else {
connect.removeClass("layui-btn-disabled");
disconnect.addClass("layui-btn-disabled");
echo.addClass("layui-btn-disabled");
}
connect.attr("disabled", connected);
disconnect.attr("disabled", !connected);
echo.attr("disabled", !connected);
}
//连接
function connect() {
var target = $("#target").val();
var ws = new SockJS(target);
stompClient = Stomp.over(ws);
stompClient.connect({}, function () {
setConnected(true);
log('Info: STOMP connection opened.');
//订阅服务端的/topic/greeting地址
stompClient.subscribe("/topic/greeting", function (greeting) {
log('Received: ' + JSON.parse(greeting.body).content);
})
},function () {
//断开处理
setConnected(false);
log('Info: STOMP connection closed.');
});
}
//断开连接
function disconnect() {
if (stompClient != null) {
stompClient.disconnect();
stompClient = null;
}
setConnected(false);
log('Info: STOMP connection closed.');
}
//向服务端发送姓名
function sendName() {
if (stompClient != null) {
var username = $("#username").val();
log('Sent: ' + username);
stompClient.send("/message/hello", {}, JSON.stringify({'name': username}));
} else {
alert('STOMP connection not established, please connect.');
}
}
//日志输出
function log(message) {
console.debug(message);
}
</script>
</head>
<body>
<noscript><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websockets rely on Javascript being
enabled. Please enable
Javascript and reload this page!</h2></noscript>
<div>
<div id="connect-container" class="layui-elem-field">
<legend>STOMP Message With SockJS</legend>
<div>
<input id="target" type="text" class="layui-input" size="40" style="width: 350px" value="/stomp-websocket"/>
</div>
<div>
<button id="connect" class="layui-btn layui-btn-normal" onclick="connect();">Connect</button>
<button id="disconnect" class="layui-btn layui-btn-normal layui-btn-disabled" disabled="disabled"
onclick="disconnect();">Disconnect
</button>
</div>
<div>
<input id="username" type="text" class="layui-input" size="40" style="width: 350px" placeholder="请输入你的姓名" value=""/>
</div>
<div>
<button id="echo" class="layui-btn layui-btn-normal layui-btn-disabled" disabled="disabled"
onclick="sendName();">Say hello
</button>
</div>
</div>
</div>
</body>
</html>