spring4新特性Websocket(一)

1.構建開發環境

在pom.xml添加依賴包：

<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>

同時，要注意tomcat的版本，必須在版本7.45以上。

2.詳細介紹

    2.1 建立並配置一個WebSocketHandler

    建立一個webSocket服務器就像實現一個WebsocketHandler，或者繼續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) {
	        // ...
	    }
}

同時須要進行配置，下面採用兩種方式，一是註解，二是xml的方式。

第一種：

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();
    }

}

須要注意的是:@Configuration和@EnableWebSocket兩個註解。

第二種方式 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>

同時須要注意的是：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. 意思就是說：以上是用於Spring MVC的應用中使用，應包括在DispatcherServlet的配置。然而，Spring的WebSocket的支持，不依賴於Spring MVC的。這句話很重要，知道配置在哪裏。

2.2 自定義Websocket Handshake

Java類：

@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）提供了兩種部署機制。第一個涉及在啓動Servlet容器的classpath掃描（3 Servlet的功能）;另外一種是一個登記的API在Servlet容器初始化使用。這些都不機制，使其可以用於全部HTTP處理一個單一的「前端控制器」 - 包括WebSocket的握手和全部其餘HTTP請求 - 好比Spring MVC中的DispatcherServlet。

在web.xml進行配置：

<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>

而後，您能夠選擇性地啓用按名稱web片斷，如Spring本身SpringServletContainerInitializer提供支持Servlet的3 Java的API初始化，若是須要的話：

<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

每一個底層的WebSocket引擎公開的控制運行特徵，例如消息緩衝區大小，空閒超時，和其餘人的大小配置屬性。在tomcat中：

註解：

@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>