spring4新特性Websocket(一)

1.构建开发环境

在pom.xml添加依赖包：

<dependency>  
    <groupId>javax.servlet</groupId>  
    <artifactId>javax.servlet-api</artifactId>  
    <version>3.1.0</version>  
</dependency>  
<dependency>  
    <groupId>com.fasterxml.jackson.core</groupId>  
    <artifactId>jackson-core</artifactId>  
    <version>2.3.0</version>  
</dependency>  
<dependency>  
    <groupId>com.fasterxml.jackson.core</groupId>  
    <artifactId>jackson-databind</artifactId>  
    <version>2.3.0</version>  
</dependency>  
<dependency>  
   <groupId>org.springframework</groupId>  
   <artifactId>spring-websocket</artifactId>  
   <version>4.0.1.RELEASE</version>  
</dependency>  
<dependency>  
   <groupId>org.springframework</groupId>  
   <artifactId>spring-messaging</artifactId>  
   <version>4.0.1.RELEASE</version>  
</dependency>

同时，要注意tomcat的版本，必须在版本7.45以上。

2.详细介绍

    2.1 建立并配置一个WebSocketHandler

    建立一个webSocket服务器就像实现一个WebsocketHandler，或者继续TextWebSocket。

package com.test.spring;

import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

public class MyHlader extends TextWebSocketHandler{
	 @Override
	    public void handleTextMessage(WebSocketSession session, TextMessage message) {
	        // ...
	    }
}

同时须要进行配置，下面采用两种方式，一是注解，二是xml的方式。

第一种：

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;

@Configuration
@EnableWebSocket
public class WebSocketConnfig implements WebSocketConfigurer{

	@Override
	public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
		 registry.addHandler(myHandler(), "/myHandler");
    }

    @Bean
    public WebSocketHandler myHandler() {
        return new MyHlader();
    }

}

须要注意的是:@Configuration和@EnableWebSocket两个注解。

第二种方式 xml：

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:websocket="http://www.springframework.org/schema/websocket"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/websocket
        http://www.springframework.org/schema/websocket/spring-websocket.xsd">

    <websocket:handlers>
        <websocket:mapping path="/myHandler" handler="myHandler"/>
    </websocket:handlers>

    <bean id="myHandler" class="org.springframework.samples.MyHandler"/>

</beans>

同时须要注意的是：The above is for use in Spring MVC applications and should be included in the configuration of a DispatcherServlet. However, Spring’s WebSocket support does not depend on Spring MVC. 意思就是说：以上是用于Spring MVC的应用中使用，应包括在DispatcherServlet的配置。然而，Spring的WebSocket的支持，不依赖于Spring MVC的。这句话很重要，知道配置在哪里。

2.2 自定义Websocket Handshake

Java类：

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(new MyHandler(), "/myHandler")
            .addInterceptors(new HttpSessionHandshakeInterceptor());
    }

}

xml配置：

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:websocket="http://www.springframework.org/schema/websocket"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/websocket
        http://www.springframework.org/schema/websocket/spring-websocket.xsd">

    <websocket:handlers>
        <websocket:mapping path="/myHandler" handler="myHandler"/>
        <websocket:handshake-interceptors>
            <bean class="org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor"/>
        </websocket:handshake-interceptors>
    </websocket:handlers>

    <bean id="myHandler" class="com.test.spring.MyHlader"/>

</beans>

2.3部署方式

在Java的WebSocket API（JSR-356）提供了两种部署机制。第一个涉及在启动Servlet容器的classpath扫描（3 Servlet的功能）;另外一种是一个登记的API在Servlet容器初始化使用。这些都不机制，使其可以用于全部HTTP处理一个单一的“前端控制器” - 包括WebSocket的握手和全部其余HTTP请求 - 好比Spring MVC中的DispatcherServlet。

在web.xml进行配置：

<web-app 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_0.xsd"
    version="3.0">

    <absolute-ordering/>

</web-app>

而后，您能够选择性地启用按名称web片断，如Spring本身SpringServletContainerInitializer提供支持Servlet的3 Java的API初始化，若是须要的话：

<web-app 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_0.xsd"
    version="3.0">

    <absolute-ordering>
        <name>spring_web</name>
    </absolute-ordering>

</web-app>

2.4配置引擎

每一个底层的WebSocket引擎公开的控制运行特征，例如消息缓冲区大小，空闲超时，和其余人的大小配置属性。在tomcat中：

注解：

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {

    @Bean
    public ServletServerContainerFactoryBean createWebSocketContainer() {
        ServletServerContainerFactoryBean container = new ServletServerContainerFactoryBean();
        container.setMaxTextMessageBufferSize(8192);
        container.setMaxBinaryMessageBufferSize(8192);
        return container;
    }

}

xml配置：

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:websocket="http://www.springframework.org/schema/websocket"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/websocket
        http://www.springframework.org/schema/websocket/spring-websocket.xsd">

    <bean class="org.springframework...ServletServerContainerFactoryBean">
        <property name="maxTextMessageBufferSize" value="8192"/>
        <property name="maxBinaryMessageBufferSize" value="8192"/>
    </bean>

</beans>