序
本文主要研究一下Java11的HttpClient的基本使用。
變化從java9的jdk.incubator.httpclient模塊遷移到j(luò)ava.net.http模塊,包名由jdk.incubator.http改為java.net.http
原來的諸如HttpResponse.BodyHandler.asString()方法變更為HttpResponse.BodyHandlers.ofString(),變化一為BodyHandler改為BodyHandlers,變化二為asXXX()之類的方法改為ofXXX(),由as改為of
實例 設(shè)置超時時間@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(); HttpResponseresponse = client.send(request, HttpResponse.BodyHandlers.ofString()); System.out.println(response.body()); }
HttpConnectTimeoutException實例
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實例
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)設(shè)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(); HttpResponseresponse = client.send(request, HttpResponse.BodyHandlers.ofString()); System.out.println(response.statusCode()); System.out.println(response.body()); }
authenticator可以用來設(shè)置HTTP authentication,比如Basic authentication
雖然Basic authentication也可以自己設(shè)置header,不過通過authenticator省得自己去構(gòu)造header
設(shè)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(); HttpResponseresponse = client.send(request, HttpResponse.BodyHandlers.ofString()); System.out.println(response.statusCode()); System.out.println(response.body()); }
通過request可以自己設(shè)置header
GET同步
@Test public void testSyncGet() throws IOException, InterruptedException { HttpClient client = HttpClient.newHttpClient(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("https://www.baidu.com")) .build(); HttpResponseresponse = client.send(request, HttpResponse.BodyHandlers.ofString()); System.out.println(response.body()); }
異步
@Test public void testAsyncGet() throws ExecutionException, InterruptedException { HttpClient client = HttpClient.newHttpClient(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("https://www.baidu.com")) .build(); CompletableFuturePOST表單result = client.sendAsync(request, HttpResponse.BodyHandlers.ofString()) .thenApply(HttpResponse::body); System.out.println(result.get()); }
@Test public void testPostForm() throws IOException, InterruptedException { HttpClient client = HttpClient.newBuilder().build(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("http://www.w3school.com.cn/demo/demo_form.asp")) .header("Content-Type","application/x-www-form-urlencoded") .POST(HttpRequest.BodyPublishers.ofString("name1=value1&name2=value2")) .build(); HttpResponseresponse = client.send(request, HttpResponse.BodyHandlers.ofString()); System.out.println(response.statusCode()); }
header指定內(nèi)容是表單類型,然后通過BodyPublishers.ofString傳遞表單數(shù)據(jù),需要自己構(gòu)建表單參數(shù)
POST JSON@Test public void testPostJsonGetJson() throws ExecutionException, InterruptedException, JsonProcessingException { ObjectMapper objectMapper = new ObjectMapper(); StockDto dto = new StockDto(); dto.setName("hj"); dto.setSymbol("hj"); dto.setType(StockDto.StockType.SH); String requestBody = objectMapper .writerWithDefaultPrettyPrinter() .writeValueAsString(dto); HttpRequest request = HttpRequest.newBuilder(URI.create("http://localhost:8080/json/demo")) .header("Content-Type", "application/json") .POST(HttpRequest.BodyPublishers.ofString(requestBody)) .build(); CompletableFutureresult = HttpClient.newHttpClient() .sendAsync(request, HttpResponse.BodyHandlers.ofString()) .thenApply(HttpResponse::body) .thenApply(body -> { try { return objectMapper.readValue(body,StockDto.class); } catch (IOException e) { return new StockDto(); } }); System.out.println(result.get()); }
post json的話,body自己json化為string,然后header指定是json格式
文件上傳@Test public void testUploadFile() throws IOException, InterruptedException, URISyntaxException { HttpClient client = HttpClient.newHttpClient(); Path path = Path.of(getClass().getClassLoader().getResource("body.txt").toURI()); File file = path.toFile(); String multipartFormDataBoundary = "Java11HttpClientFormBoundary"; org.apache.http.HttpEntity multipartEntity = MultipartEntityBuilder.create() .addPart("file", new FileBody(file, ContentType.DEFAULT_BINARY)) .setBoundary(multipartFormDataBoundary) //要設(shè)置,否則阻塞 .build(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("http://localhost:8080/file/upload")) .header("Content-Type", "multipart/form-data; boundary=" + multipartFormDataBoundary) .POST(HttpRequest.BodyPublishers.ofInputStream(() -> { try { return multipartEntity.getContent(); } catch (IOException e) { e.printStackTrace(); throw new RuntimeException(e); } })) .build(); HttpResponseresponse = client.send(request, HttpResponse.BodyHandlers.ofString()); System.out.println(response.body()); }
官方的HttpClient并沒有提供類似WebClient那種現(xiàn)成的BodyInserters.fromMultipartData方法,因此這里需要自己轉(zhuǎn)換
這里使用org.apache.httpcomponents(httpclient及httpmime)的MultipartEntityBuilder構(gòu)建multipartEntity,最后通過HttpRequest.BodyPublishers.ofInputStream來傳遞內(nèi)容
這里header要指定Content-Type值為multipart/form-data以及boundary的值,否則服務(wù)端可能無法解析
文件下載@Test public void testAsyncDownload() throws ExecutionException, InterruptedException { HttpClient client = HttpClient.newHttpClient(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("http://localhost:8080/file/download")) .build(); CompletableFutureresult = client.sendAsync(request, HttpResponse.BodyHandlers.ofFile(Paths.get("/tmp/body.txt"))) .thenApply(HttpResponse::body); System.out.println(result.get()); }
使用HttpResponse.BodyHandlers.ofFile來接收文件
并發(fā)請求@Test public void testConcurrentRequests(){ HttpClient client = HttpClient.newHttpClient(); Listurls = List.of("http://www.baidu.com","http://www.alibaba.com/","http://www.tencent.com"); List requests = urls.stream() .map(url -> HttpRequest.newBuilder(URI.create(url))) .map(reqBuilder -> reqBuilder.build()) .collect(Collectors.toList()); List >> futures = requests.stream() .map(request -> client.sendAsync(request, HttpResponse.BodyHandlers.ofString())) .collect(Collectors.toList()); futures.stream() .forEach(e -> e.whenComplete((resp,err) -> { if(err != null){ err.printStackTrace(); }else{ System.out.println(resp.body()); System.out.println(resp.statusCode()); } })); CompletableFuture.allOf(futures .toArray(CompletableFuture>[]::new)) .join(); }
sendAsync方法返回的是CompletableFuture,可以方便地進(jìn)行轉(zhuǎn)換、組合等操作
這里使用CompletableFuture.allOf組合在一起,最后調(diào)用join等待所有future完成
錯誤處理@Test public void testHandleException() throws ExecutionException, InterruptedException { HttpClient client = HttpClient.newBuilder() .connectTimeout(Duration.ofMillis(5000)) .build(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("https://twitter.com")) .build(); CompletableFutureresult = client.sendAsync(request, HttpResponse.BodyHandlers.ofString()) // .whenComplete((resp,err) -> { // if(err != null){ // err.printStackTrace(); // }else{ // System.out.println(resp.body()); // System.out.println(resp.statusCode()); // } // }) .thenApply(HttpResponse::body) .exceptionally(err -> { err.printStackTrace(); return "fallback"; }); System.out.println(result.get()); }
HttpClient異步請求返回的是CompletableFuture
另外值得注意的是HttpClient不像WebClient那樣,它沒有對4xx或5xx的狀態(tài)碼拋出異常,需要自己根據(jù)情況來處理,手動檢測狀態(tài)碼拋出異?;蛘叻祷仄渌麅?nèi)容
HTTP2@Test public void testHttp2() throws URISyntaxException { HttpClient.newBuilder() .followRedirects(HttpClient.Redirect.NEVER) .version(HttpClient.Version.HTTP_2) .build() .sendAsync(HttpRequest.newBuilder() .uri(new URI("https://http2.akamai.com/demo")) .GET() .build(), HttpResponse.BodyHandlers.ofString()) .whenComplete((resp,t) -> { if(t != null){ t.printStackTrace(); }else{ System.out.println(resp.version()); System.out.println(resp.statusCode()); } }).join(); }
執(zhí)行之后可以看到返回的response的version為HTTP_2
WebSocket@Test public void testWebSocket() throws InterruptedException { HttpClient client = HttpClient.newHttpClient(); WebSocket webSocket = client.newWebSocketBuilder() .buildAsync(URI.create("ws://localhost:8080/echo"), new WebSocket.Listener() { @Override public CompletionStage> onText(WebSocket webSocket, CharSequence data, boolean last) { // request one more webSocket.request(1); // Print the message when it"s available return CompletableFuture.completedFuture(data) .thenAccept(System.out::println); } }).join(); webSocket.sendText("hello ", false); webSocket.sendText("world ",true); TimeUnit.SECONDS.sleep(10); webSocket.sendClose(WebSocket.NORMAL_CLOSURE, "ok").join(); }
HttpClient支持HTTP2,也包含了WebSocket,通過newWebSocketBuilder去構(gòu)造WebSocket
傳入listener進(jìn)行接收消息,要發(fā)消息的話,使用WebSocket來發(fā)送,關(guān)閉使用sendClose方法
reactive streamsHttpClient本身就是reactive的,支持reactive streams,這里舉ResponseSubscribers.ByteArraySubscriber的源碼看看:
java.net.http/jdk/internal/net/http/ResponseSubscribers.java
public static class ByteArraySubscriberimplements BodySubscriber { private final Function finisher; private final CompletableFuture result = new MinimalFuture<>(); private final List received = new ArrayList<>(); private volatile Flow.Subscription subscription; public ByteArraySubscriber(Function finisher) { this.finisher = finisher; } @Override public void onSubscribe(Flow.Subscription subscription) { if (this.subscription != null) { subscription.cancel(); return; } this.subscription = subscription; // We can handle whatever you"ve got subscription.request(Long.MAX_VALUE); } @Override public void onNext(List items) { // incoming buffers are allocated by http client internally, // and won"t be used anywhere except this place. // So it"s free simply to store them for further processing. assert Utils.hasRemaining(items); received.addAll(items); } @Override public void onError(Throwable throwable) { received.clear(); result.completeExceptionally(throwable); } static private byte[] join(List bytes) { int size = Utils.remaining(bytes, Integer.MAX_VALUE); byte[] res = new byte[size]; int from = 0; for (ByteBuffer b : bytes) { int l = b.remaining(); b.get(res, from, l); from += l; } return res; } @Override public void onComplete() { try { result.complete(finisher.apply(join(received))); received.clear(); } catch (IllegalArgumentException e) { result.completeExceptionally(e); } } @Override public CompletionStage getBody() { return result; } }
BodySubscriber接口繼承了Flow.Subscriber>接口
這里的Subscription來自Flow類,該類是java9引入的,里頭包含了支持Reactive Streams的實現(xiàn)
小結(jié)HttpClient在Java11從incubator變?yōu)檎桨妫鄬τ趥鹘y(tǒng)的HttpUrlConnection其提升可不是一點半點,不僅支持異步,也支持reactive streams,同時也支持了HTTP2以及WebSocket,非常值得大家使用。
docjava.net.http javadoc
Examples and Recipes
Java 11: Standardized HTTP Client API
Exploring the New HTTP Client in Java 9
Introduction to the New HTTP Client in Java 9
Getting Started With Java 9"s New HTTP Client
java9系列(六)HTTP/2 Client (Incubator)
Java 9 HttpClient send a multipart/form-data request
Java 9: High level HTTP and WebSocket API
WebSocket Client API in Java 9 with Example
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