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本文主要研究一下Java11的HttpClient的基本使用。

变化

从java9的jdk.incubator.httpclient模块迁移到java.net.http模块，包名由jdk.incubator.http改为java.net.http

原来的诸如HttpResponse.BodyHandler.asString()方法变更为HttpResponse.BodyHandlers.ofString()，变化一为BodyHandler改为BodyHandlers，变化二为asXXX()之类的方法改为ofXXX()，由as改为of

实例

设置超时时间

@Test public void testTimeout() throws IOException, InterruptedException { //1.set connect timeout HttpClient client = HttpClient.newBuilder() .connectTimeout(Duration.ofMillis(5000)) .followRedirects(HttpClient.Redirect.NORMAL) .build(); //2.set read timeout HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("http://openjdk.java.net/")) .timeout(Duration.ofMillis(5009)) .build(); HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString()); System.out.println(response.body()); }

HttpConnectTimeoutException实例

Caused by: java.net.http.HttpConnectTimeoutException: HTTP connect timed out at java.net.http/jdk.internal.net.http.ResponseTimerEvent.handle(ResponseTimerEvent.java:68) at java.net.http/jdk.internal.net.http.HttpClientImpl.purgeTimeoutsAndReturnNextDeadline(HttpClientImpl.java:1248) at java.net.http/jdk.internal.net.http.HttpClientImpl$SelectorManager.run(HttpClientImpl.java:877)Caused by: java.net.ConnectException: HTTP connect timed out at java.net.http/jdk.internal.net.http.ResponseTimerEvent.handle(ResponseTimerEvent.java:69) ... 2 more

HttpTimeoutException实例

java.net.http.HttpTimeoutException: request timed out at java.net.http/jdk.internal.net.http.HttpClientImpl.send(HttpClientImpl.java:559) at java.net.http/jdk.internal.net.http.HttpClientFacade.send(HttpClientFacade.java:119) at com.example.HttpClientTest.testTimeout(HttpClientTest.java:40)

设置authenticator

@Test public void testBasicAuth() throws IOException, InterruptedException { HttpClient client = HttpClient.newBuilder() .connectTimeout(Duration.ofMillis(5000)) .authenticator(new Authenticator() { @Override protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication("admin","password".toCharArray()); } }) .build(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("http://localhost:8080/json/info")) .timeout(Duration.ofMillis(5009)) .build(); HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString()); System.out.println(response.statusCode()); System.out.println(response.body()); }

authenticator可以用来设置HTTP authentication，比如Basic authentication

虽然Basic authentication也可以自己设置header，不过通过authenticator省得自己去构造header

设置header

@Test public void testCookies() throws IOException, InterruptedException { HttpClient client = HttpClient.newBuilder() .connectTimeout(Duration.ofMillis(5000)) .build(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("http://localhost:8080/json/cookie")) .header("Cookie","JSESSIONID=4f994730-32d7-4e22-a18b-25667ddeb636; userId=java11") .timeout(Duration.ofMillis(5009)) .build(); HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString()); System.out.println(response.statusCode()); System.out.println(response.body()); }

通过request可以自己设置header

GET

同步

@Test public void testSyncGet() throws IOException, InterruptedException { HttpClient client = HttpClient.newHttpClient(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("https://pletionStage<T> getBody() { return result; } }

BodySubscriber接口继承了Flow.Subscriber<List<ByteBuffer>>接口

这里的Subscription来自Flow类，该类是java9引入的，里头包含了支持Reactive Streams的实现

小结

HttpClient在Java11从incubator变为正式版，相对于传统的HttpUrlConnection其提升可不是一点半点，不仅支持异步，也支持reactive streams，同时也支持了HTTP2以及WebSocket，非常值得大家使用。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。