摘要：的這幾天看了看的請求處理流程，因為之前一直用的和，一開始對的處理流程有點懵逼，找不到入口，后來跟了代碼，在網上找了點資料，發現的入口在的方法該方法的作用就是把接收到的或者最終需要返回的，包裝轉換為和。
spring-cloud-gateway 的ReactorHttpHandlerAdapter
這幾天看了看spring-cloud-gateway的請求處理流程，因為之前一直用的springboot1.x和spring4，一開始對spring-cloud-gateway的處理流程有點懵逼，找不到入口，后來跟了代碼，在網上找了點資料，發現spring-cloud-gateway的入口在ReactorHttpHandlerAdapter的apply方法
public class ReactorHttpHandlerAdapter implements BiFunction> {
private static final Log logger = HttpLogging.forLogName(ReactorHttpHandlerAdapter.class);
private final HttpHandler httpHandler;
public ReactorHttpHandlerAdapter(HttpHandler httpHandler) {
Assert.notNull(httpHandler, "HttpHandler must not be null");
this.httpHandler = httpHandler;
}
@Override
public Mono apply(HttpServerRequest reactorRequest, HttpServerResponse reactorResponse) {
NettyDataBufferFactory bufferFactory = new NettyDataBufferFactory(reactorResponse.alloc());
try {
ReactorServerHttpRequest request = new ReactorServerHttpRequest(reactorRequest, bufferFactory);
ServerHttpResponse response = new ReactorServerHttpResponse(reactorResponse, bufferFactory);
if (request.getMethod() == HttpMethod.HEAD) {
response = new HttpHeadResponseDecorator(response);
}
return this.httpHandler.handle(request, response)
.doOnError(ex -> logger.trace(request.getLogPrefix() + "Failed to complete: " + ex.getMessage()))
.doOnSuccess(aVoid -> logger.trace(request.getLogPrefix() + "Handling completed"));
}
catch (URISyntaxException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Failed to get request URI: " + ex.getMessage());
}
reactorResponse.status(HttpResponseStatus.BAD_REQUEST);
return Mono.empty();
}
}
}
該方法的作用就是把接收到的HttpServerRequest或者最終需要返回的HttpServerResponse，包裝轉換為ReactorServerHttpRequest和ReactorServerHttpResponse。
spring-webflux
當然，這篇文章的主要內容不是談論spring-cloud-gateway了，因為之前一直用的spring4，所以對spring5當中的反應式編程范式和webflux不太了解，所以先寫個demo了解一下
第一步：引入相關pom,測試的相關pom根據自己的需要引入
org.springframework.boot
spring-boot-starter-parent
2.1.4.RELEASE
org.springframework.boot
spring-boot-starter-webflux
org.springframework.boot
spring-boot-starter-test
test
io.projectreactor
reactor-test
test
第二步：創建一個HandlerFunction
public class TestFunction implements HandlerFunction {
@Override
public Mono handle(ServerRequest serverRequest) {
return ServerResponse.ok().body(
Mono.just(parse(serverRequest, "args1") + parse(serverRequest, "args2"))
, Integer.class);
}
private int parse(final ServerRequest request, final String param) {
return Integer.parseInt(request.queryParam(param).orElse("0"));
}
}
第三步：注入一個RouterFunction
@Configuration
public class TestRouteFunction {
@Bean
public RouterFunction routerFunction() {
return RouterFunctions.route(RequestPredicates.GET("/add"), new TestFunction());
}
}
第四步：在webflux中，也可以使用之前的java注解的編程方式，我們也創建一個controller
@RestController
@RequestMapping("/api/test")
public class HelloController {
@RequestMapping("/hello")
public Mono hello() {
return Mono.just("hello world");
}
}
第五步：創建啟動類
@SpringBootApplication
public class Spring5DemoApplication {
public static void main(String[] args) {
SpringApplication.run(Spring5DemoApplication.class, args);
}
}
第六步：啟動項目，訪問如下兩個接口都可以
http://localhost:8080/api/test/hello
http://localhost:8080/add?args1=2&args2=3
和spring-boot結合
通過上面的例子，我們看到基本的兩個類：HandlerFunction和RouterFunction，同時webflux有如下特性：
異步非阻塞
響應式(reactive)函數編程，純lambda表達式
不僅僅是在Servlet容器中tomcat/jetty中運行，同時支持NIO的Netty和Undertow中，實際項目中，我們往往與spring-boot項目結合，我們跟進代碼可以看看spring-boot是在什么時候創建的server
一、SpringApplication
public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
Collection exceptionReporters = new ArrayList<>();
configureHeadlessProperty();
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(
args);
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
configureIgnoreBeanInfo(environment);
Banner printedBanner = printBanner(environment);
context = createApplicationContext();
exceptionReporters = getSpringFactoriesInstances(
SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
prepareContext(context, environment, listeners, applicationArguments,
printedBanner);
refreshContext(context);
afterRefresh(context, applicationArguments);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
.logStarted(getApplicationLog(), stopWatch);
}
listeners.started(context);
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}
try {
listeners.running(context);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}
我們只分析入口，其它代碼暫時不管，找到refreshContext(context);這一行進去
二、ReactiveWebServerApplicationContext的refresh()
@Override
public final void refresh() throws BeansException, IllegalStateException {
try {
super.refresh();
}
catch (RuntimeException ex) {
stopAndReleaseReactiveWebServer();
throw ex;
}
}
三、ReactiveWebServerApplicationContext的onRefresh()
@Override
protected void onRefresh() {
super.onRefresh();
try {
createWebServer();
}
catch (Throwable ex) {
throw new ApplicationContextException("Unable to start reactive web server",
ex);
}
}
四、看到這里我們就找到入口方法了：createWebServer(),跟進去，找到NettyReactiveWebServerFactory中創建webserver
@Override
public WebServer getWebServer(HttpHandler httpHandler) {
HttpServer httpServer = createHttpServer();
ReactorHttpHandlerAdapter handlerAdapter = new ReactorHttpHandlerAdapter(
httpHandler);
return new NettyWebServer(httpServer, handlerAdapter, this.lifecycleTimeout);
}
看到ReactorHttpHandlerAdapter這個類想必特別親切，在開篇說過是spring-cloud-gateway的入口，createHttpServer方法的細節暫時沒有去學習了，后續有時間去深入了解下
結語
spring5的相關新特性也是在學習中，這一篇文章算是和springboot結合的入門吧，后續有時間再深入學習
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