使用示例
例子来自于官网
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| @Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
@Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
registry.addHandler(myHandler(), "/myHandler");
}
@Bean
public WebSocketHandler myHandler() {
return new MyHandler();
}
}
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说明：
WebSocketConfigurer 配置 websocket。
WebSocketHandler 处理 websocket 的连接。
WebSocketServletAutoConfiguration
添加了 tomcat 对 websocket 的支持，也就是 WsSci。
源码位置: org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration
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| @ConditionalOnWebApplication(type = Type.SERVLET)
@AutoConfigureBefore(ServletWebServerFactoryAutoConfiguration.class)
public class WebSocketServletAutoConfiguration {
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ Tomcat.class, WsSci.class })
static class TomcatWebSocketConfiguration {
@Bean
@ConditionalOnMissingBean(name = "websocketServletWebServerCustomizer")
TomcatWebSocketServletWebServerCustomizer websocketServletWebServerCustomizer() {
return new TomcatWebSocketServletWebServerCustomizer();
}
}
...
}
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@EnableWebSocket
最关键的配置入口。
源码位置: org.springframework.web.socket.config.annotation.EnableWebSocket
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| // 导入 websocket 配置类, 父类为 WebSocketConfigurationSupport
@Import(DelegatingWebSocketConfiguration.class)
public @interface EnableWebSocket {
}
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源码位置: org.springframework.web.socket.config.annotation.WebSocketConfigurationSupport
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| public class WebSocketConfigurationSupport {
// 注册 WebSocketHandlerMapping
@Bean
public HandlerMapping webSocketHandlerMapping(@Nullable TaskScheduler defaultSockJsTaskScheduler) {
// 初始化 registry
ServletWebSocketHandlerRegistry registry = initHandlerRegistry();
...
// 很重要, 后面继续解析
return registry.getHandlerMapping();
}
private ServletWebSocketHandlerRegistry initHandlerRegistry() {
if (this.handlerRegistry == null) {
this.handlerRegistry = new ServletWebSocketHandlerRegistry();
// 由子类 DelegatingWebSocketConfiguration 来实现
registerWebSocketHandlers(this.handlerRegistry);
}
return this.handlerRegistry;
}
}
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源码位置: org.springframework.web.socket.config.annotation.ServletWebSocketHandlerRegistry#getHandlerMapping
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| public AbstractHandlerMapping getHandlerMapping() {
Map<String, Object> urlMap = new LinkedHashMap<>();
// 遍历所有的 websocket 的配置
for (ServletWebSocketHandlerRegistration registration : this.registrations) {
// HttpRequestHandler 实现类为 WebSocketHttpRequestHandler，负责处理 websocket 请求, 很重要
MultiValueMap<HttpRequestHandler, String> mappings = registration.getMappings();
mappings.forEach((httpHandler, patterns) -> {
for (String pattern : patterns) {
urlMap.put(pattern, httpHandler);
}
});
}
// WebSocketHandlerMapping 负责拦截 websocket 的 url，然后由 WebSocketHttpRequestHandler 处理请求
WebSocketHandlerMapping hm = new WebSocketHandlerMapping();
hm.setUrlMap(urlMap);
hm.setOrder(this.order);
if (this.urlPathHelper != null) {
hm.setUrlPathHelper(this.urlPathHelper);
}
return hm;
}
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WebSocketHttpRequestHandler 处理 websocket 请求
源码位置: org.springframework.web.socket.server.support.WebSocketHttpRequestHandler#handleRequest
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| @Override
public void handleRequest(HttpServletRequest servletRequest, HttpServletResponse servletResponse)
throws ServletException, IOException {
...
try {
...
// 执行 HandshakeInterceptor#beforeHandshake 方法
if (!chain.applyBeforeHandshake(request, response, attributes)) {
return;
}
// 执行 websocket 握手, 最终会调用 TomcatRequestUpgradeStrategy#upgradeInternal
this.handshakeHandler.doHandshake(request, response, this.wsHandler, attributes);
// 执行 HandshakeInterceptor#afterHandshake 方法
chain.applyAfterHandshake(request, response, null);
}
catch (HandshakeFailureException ex) {
failure = ex;
}
catch (Exception ex) {
failure = new HandshakeFailureException("Uncaught failure for request " + request.getURI(), ex);
}
finally {
...
}
}
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