Apache httpclient okhttp（2）

学习链接

Apache httpclient & okhttp（1）
Apache httpclient & okhttp（2）

okhttp github

okhttp官方使用文档

okhttp官方示例代码

OkHttp使用介绍
OkHttp使用进阶 译自OkHttp Github官方教程

SpringBoot 整合okHttp okhttp3用法

Java中常用的HTTP客户端库：OkHttp和HttpClient（包含请求示例代码）

深入浅出 OkHttp 源码解析及应用实践

okhttp

okhttp概述

HTTP是现代应用程序的网络方式。这是我们交换数据和媒体的方式。高效地使用HTTP可以让您的东西加载更快并节省带宽。

OkHttp使用起来很方便。它的请求/响应API设计具有流式构建和不可变性。它支持同步阻塞调用和带有回调的异步调用。

特点

OkHttp是一个高效的默认HTTP客户端

• HTTP/2支持允许对同一主机的所有请求共享一个套接字。
• 连接池减少了请求延时（如果HTTP/2不可用）。
• 透明GZIP缩小了下载大小。
• 响应缓存完全避免了重复请求的网络。

OkHttp遵循现代HTTP规范，例如

• HTTP语义-RFC 9110
• HTTP缓存-RFC 9111
• HTTP/1.1-RFC 9112
• HTTP/2-RFC 9113
• Websocket-RFC 6455
• SSE-服务器发送的事件

快速入门

pom.xml

注意：okhttp的3.9.0版本用的是java，okhttp4.12.0用的是kotlin。

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.zzhua</groupId><artifactId>demo-okhttp</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><!--<okhttp.version>3.9.0</okhttp.version>--><!--<okhttp.version>3.14.9</okhttp.version>--><!-- OkHttp从4.x版本开始转向Kotlin, Kotlin 代码可以被编译成标准的 JVM 字节码运行，这与 Java 代码的最终执行形式完全兼容。 --><okhttp.version>4.12.0</okhttp.version></properties><dependencies><dependency><groupId>com.squareup.okhttp3</groupId><artifactId>okhttp</artifactId><version>${okhttp.version}</version></dependency></dependencies></project>

get请求

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;import java.io.IOException;public class Test01 {public static void main(String[] args) {OkHttpClient client = new OkHttpClient();Request request = new Request.Builder().url("http://www.baidu.com").build();try (Response response = client.newCall(request).execute()) {System.out.println(response.body().string());} catch (IOException e) {throw new RuntimeException(e);}}}

Post请求

import okhttp3.*;
public class Test02 {public static void main(String[] args) {OkHttpClient client = new OkHttpClient();RequestBody body = RequestBody.create(MediaType.parse("application/json"), "{\"username\":\"zzhua\"}");Request request = new Request.Builder().url("http://localhost:8080/ok01").post(body).build();try (Response response = client.newCall(request).execute()) {System.out.println(response.body().string());} catch (Exception e) {throw new RuntimeException(e);}}}

示例代码

这些示例代码来自：https://square.github.io/okhttp/recipes，

官方也有对应的代码：https://github.com/square/okhttp/blob/okhttp_3.14.x/samples

同步请求

下载文件，打印headers，并将其响应正文打印为字符串。

• 响应正文上的string()方法对于小文档来说既方便又高效。但是如果响应正文很大（大于1 MiB），避免string()，因为它会将整个文档加载到内存中。在这种情况下，更推荐将正文作为流处理。

import okhttp3.Headers;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;import java.io.IOException;public class TestSynchronous {private final static OkHttpClient client = new OkHttpClient();public static void main(String[] args) {Request request = new Request.Builder().url("https://publicobject.com/helloworld.txt").build();try (Response response = client.newCall(request).execute()) {if (!response.isSuccessful())throw new IOException("Unexpected code " + response);// 获取响应头Headers responseHeaders = response.headers();for (int i = 0; i < responseHeaders.size(); i++) {System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));}// 获取响应体System.out.println(response.body().string());} catch (IOException e) {throw new RuntimeException(e);}}}

异步请求

在工作线程中下载文件，并在响应可读取时触发回调。该回调会在响应头准备就绪后触发，但读取响应体仍可能阻塞线程。当前OkHttp未提供异步API以分块接收响应体内容。

@Slf4j
public class Test02Async {public static void main(String[] args) {log.info("main start");OkHttpClient okHttpClient = new OkHttpClient();Request requeset = new Request.Builder().url("http://publicobject.com/helloworld.txt").build();Call call = okHttpClient.newCall(requeset);log.info("call.enqueue");// 执行回调的线程不是main线程call.enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {log.info("=========请求失败=========: {}", e);}@Overridepublic void onResponse(Call call, Response response) throws IOException {log.info("=========获得响应=========");try (ResponseBody responseBody = response.body()) {if (!response.isSuccessful())throw new IOException("Unexpected code " + response);Headers responseHeaders = response.headers();for (int i = 0, size = responseHeaders.size(); i < size; i++) {System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));}System.out.println(responseBody.string());}}});log.info("main end");}}

请求头&响应头

public class TestHeader {public static void main(String[] args) {OkHttpClient okHttpClient = new OkHttpClient();Request request = new Request.Builder().url("https://api.github.com/repos/square/okhttp/issues")// 单个header值.header("User-Agent", "OkHttp Headers.java")// 多个header值.addHeader("Accept", "application/json; q=0.5").addHeader("Accept", "application/vnd.github.v3+json").build();try (Response response = okHttpClient.newCall(request).execute()) {if (!response.isSuccessful())throw new IOException("Unexpected code " + response);System.out.println("Server: " + response.header("Server"));System.out.println("Date: " + response.header("Date"));// 多个响应头使用headers()获取System.out.println("Vary: " + response.headers("Vary"));} catch (IOException e) {throw new RuntimeException(e);}}}

post + 请求体

使用HTTP POST向服务发送请求正文。此示例将markdown文档发布到将markdown渲染为html。由于整个请求正文同时在内存中，因此避免使用此API发布大型（大于1 MiB）文档。

public class TestRequestBody {public static void main(String[] args) {MediaType mediaType = MediaType.parse("text/x-markdown; charset=utf-8");OkHttpClient client = new OkHttpClient();String postBody = ""+ "Releases\n"+ "--------\n"+ "\n"+ " * _1.0_ May 6, 2013\n"+ " * _1.1_ June 15, 2013\n"+ " * _1.2_ August 11, 2013\n";Request request = new Request.Builder().url("https://api.github.com/markdown/raw").post(RequestBody.create(mediaType, postBody)).build();try {Response response = client.newCall(request).execute();if (!response.isSuccessful())throw new IOException("Unexpected code " + response);System.out.println(response.body().string());} catch (Exception e) {throw new RuntimeException(e);}}}

流式传输

我们在这里将请求体以流的形式进行POST提交。该请求体的内容在写入过程中动态生成。此示例直接将数据流式写入Okio的缓冲池(Buffered Sink)。您的程序可能更倾向于使用OutputStream，您可以通过BufferedSink.outputStream()方法获取它。

• 流式传输(Streaming)：区别于一次性加载完整数据到内存，流式传输允许边生成数据边发送，尤其适合：大文件传输（如视频上传）、实时生成数据（如传感器数据流）、内存敏感场景（避免OOM）

public class Test05Stream {public static void main(String[] args) {MediaType MEDIA_TYPE_MARKDOWN = MediaType.parse("text/x-markdown; charset=utf-8");OkHttpClient client = new OkHttpClient();RequestBody requestBody = new RequestBody() {@Override public MediaType contentType() {return MEDIA_TYPE_MARKDOWN;}@Override public void writeTo(BufferedSink sink) throws IOException {sink.writeUtf8("Numbers\n");sink.writeUtf8("-------\n");for (int i = 2; i <= 997; i++) {sink.writeUtf8(String.format(" * %s = %s\n", i, factor(i)));}}private String factor(int n) {for (int i = 2; i < n; i++) {int x = n / i;if (x * i == n) return factor(x) + " × " + i;}return Integer.toString(n);}};Request request = new Request.Builder().url("https://api.github.com/markdown/raw").post(requestBody).build();try (Response response = client.newCall(request).execute()) {if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);System.out.println(response.body().string());} catch (IOException e) {throw new RuntimeException(e);}}}

流式传输扩展示例

通过观察客户端和服务端的日志，可以看到客户端发的同时，服务端也在收。

Test05StreamClient

@Slf4j
public class Test05StreamClient {public static void main(String[] args) {OkHttpClient client = new OkHttpClient.Builder().writeTimeout(30, TimeUnit.SECONDS) // 延长写入超时.build();// 创建流式 RequestBodyRequestBody requestBody = new RequestBody() {@Overridepublic MediaType contentType() {return MediaType.parse("application/octet-stream");}@Overridepublic void writeTo(BufferedSink sink) throws IOException {try (java.io.OutputStream os = sink.outputStream()) {for (int i = 0; i < 50; i++) {// 模拟生成数据块String chunk = "Chunk-" + i + "\n";log.info("发送数据块: {}", chunk);os.write(chunk.getBytes());os.flush(); // 立即刷新缓冲区Thread.sleep(100); // 模拟延迟}} catch (InterruptedException e) {Thread.currentThread().interrupt();}}};Request request = new Request.Builder().url("http://localhost:8080/stream-upload-raw").post(requestBody).header("Content-Type", "application/octet-stream") // 强制覆盖.build();// 异步执行client.newCall(request).enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {log.info("[请求失败]");}@Overridepublic void onResponse(Call call, Response response) throws IOException {log.info("[请求成功]");System.out.println("上传成功: " + response.code());System.out.println("响应内容: " + response.body().string());response.close();}});}
}

StreamController

@Slf4j
@RestController
public class StreamController {// 通过 HttpServletRequest 获取原始流@PostMapping("/stream-upload-raw")public String handleRawStream(HttpServletRequest request) {try (InputStream rawStream = request.getInputStream()) {byte[] buffer = new byte[1024];int bytesRead;while ((bytesRead = rawStream.read(buffer)) != -1) { // 按字节读取String chunk = new String(buffer, 0, bytesRead);log.info("[字节流] {}, {}", chunk.trim(), bytesRead);}return "Raw stream processed";} catch (IOException e) {return "Error: " + e.getMessage();}}
}

文件传输

将文件作为请求体。

public class Test06File {public static void main(String[] args) {OkHttpClient client = new OkHttpClient();Request request = new Request.Builder().url("http://localhost:8080/okFile").post(RequestBody.create(null, new File("C:\\Users\\zzhua195\\Desktop\\test.png"))).build();try (Response response = client.newCall(request).execute()) {if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);System.out.println(response.body().string());} catch (IOException e) {throw new RuntimeException(e);}}}

后端代码

@RequestMapping("okFile")
public Object okFile(HttpServletRequest request) throws Exception {ServletInputStream inputStream = request.getInputStream();org.springframework.util.FileCopyUtils.copy(request.getInputStream(), new FileOutputStream("D:\\Projects\\practice\\demo-boot\\src\\main\\resources\\test.png"));return "ok";
}

表单提交

使用FormBody.Builder构建一个像超文本标记语言<form>标签一样工作的请求正文。名称和值将使用超文本标记语言兼容的表单URL编码进行编码。

public class Test07Form {public static void main(String[] args) {OkHttpClient client = new OkHttpClient();RequestBody formBody = new FormBody.Builder().add("username", "Jurassic Park").build();Request request = new Request.Builder().url("http://localhost:8080/okForm").post(formBody).build();try (Response response = client.newCall(request).execute()) {if (!response.isSuccessful())throw new IOException("Unexpected code " + response);System.out.println(response.body().string());} catch (IOException e) {throw new RuntimeException(e);}}}

对应的后端代码

@RequestMapping("okForm")
public Object okForm(LoginForm loginForm) throws Exception {log.info("[okForm] {}", loginForm);return "ok";}

文件上传

MultipartBody.Builder可以构建与超文本标记语言文件上传表单兼容的复杂请求正文。多部分请求正文的每个部分本身就是一个请求正文，并且可以定义自己的标头。如果存在，这些标头应该描述部分正文，例如它的Content-Disposition。如果可用，Content-Length和Content-Type标头会自动添加

public class Test08MultipartFile {public static void main(String[] args) {OkHttpClient client = new OkHttpClient();RequestBody requestBody = new MultipartBody.Builder().setType(MultipartBody.FORM).addFormDataPart("comment", "Square Logo").addFormDataPart("bin", "logo-square.png", RequestBody.create(null, new File("C:\\Users\\zzhua195\\Desktop\\test.png"))).build();Request request = new Request.Builder().header("Authorization", "Client-ID").url("http://127.0.0.1:8080/multipart02").post(requestBody).build();try (Response response = client.newCall(request).execute()) {if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);System.out.println(response.body().string());} catch (IOException e) {throw new RuntimeException(e);}}}

对应的后端代码

@RequestMapping("multipart01")public Object multipart(@RequestPart("bin") MultipartFile file,@RequestPart("comment") String comment) throws InterruptedException, IOException {System.out.println(file.getBytes().length);System.out.println(comment);return "ojbk";}@RequestMapping("multipart02")public Object multipart(MultipartDTO multipartDTO) throws InterruptedException, IOException {System.out.println(multipartDTO.getBin().getBytes().length);System.out.println(multipartDTO.getComment());return "ojbk";}

响应缓存

1、要缓存响应，您需要一个可以读取和写入的缓存目录，以及对缓存大小的限制。缓存目录应该是私有的，不受信任的应用程序应该无法读取其内容！
2、让多个缓存同时访问同一个缓存目录是错误的。大多数应用程序应该只调用一次new OkHttpClient()，用它们的缓存配置它，并在任何地方使用相同的实例。否则两个缓存实例会互相踩踏，破坏响应缓存，并可能使您的程序崩溃。

3、响应缓存对所有配置都使用HTTP标头。您可以添加请求标头，如Cache-Control: max-stale=3600，OkHttp的缓存将尊重它们。您的网络服务器使用自己的响应标头配置缓存响应的时间，如Cache-Control: max-age=9600。有缓存标头可以强制缓存响应、强制网络响应或强制使用条件GET验证网络响应。
4、要防止响应使用缓存，请使用CacheControl.FORCE_NETWORK。要防止它使用网络，请使用CacheControl.FORCE_CACHE。请注意：如果您使用FORCE_CACHE并且响应需要网络，OkHttp将返回504 Unsatisfiable Request响应。

import okhttp3.Cache;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;import java.io.File;
import java.io.IOException;public class Test09CacheResponse {public static void main(String[] args) {try {Test09CacheResponse test = new Test09CacheResponse(new File("cache"));test.run();} catch (Exception e) {throw new RuntimeException(e);}}private final OkHttpClient client;public Test09CacheResponse(File cacheDirectory) throws Exception {int cacheSize = 10 * 1024 * 1024; // 10 MiBCache cache = new Cache(cacheDirectory, cacheSize);client = new OkHttpClient.Builder().cache(cache).build();}public void run() throws Exception {Request request = new Request.Builder().url("http://publicobject.com/helloworld.txt").build();String response1Body;try (Response response1 = client.newCall(request).execute()) {if (!response1.isSuccessful()) throw new IOException("Unexpected code " + response1);response1Body = response1.body().string();System.out.println("Response 1 response:          " + response1);System.out.println("Response 1 cache response:    " + response1.cacheResponse());System.out.println("Response 1 network response:  " + response1.networkResponse());}String response2Body;try (Response response2 = client.newCall(request).execute()) {if (!response2.isSuccessful()) throw new IOException("Unexpected code " + response2);response2Body = response2.body().string();System.out.println("Response 2 response:          " + response2);System.out.println("Response 2 cache response:    " + response2.cacheResponse());System.out.println("Response 2 network response:  " + response2.networkResponse());}System.out.println("Response 2 equals Response 1? " + response1Body.equals(response2Body));}}
/*
Response 1 response:          Response{protocol=http/1.1, code=200, message=OK, url=https://publicobject.com/helloworld.txt}
Response 1 cache response:    null
Response 1 network response:  Response{protocol=http/1.1, code=200, message=OK, url=https://publicobject.com/helloworld.txt}
Response 2 response:          Response{protocol=http/1.1, code=200, message=OK, url=https://publicobject.com/helloworld.txt}
Response 2 cache response:    Response{protocol=http/1.1, code=200, message=OK, url=https://publicobject.com/helloworld.txt}
Response 2 network response:  null
Response 2 equals Response 1? true
*/

取消调用

使用Call.cancel()立即停止正在进行的调用。如果线程当前正在写入请求或读取响应，它将收到IOException。当不再需要调用时，使用它来节省网络；例如，当您的用户导航离开应用程序时。同步和异步调用都可以取消。

public class Test09CancelCall {public static void main(String[] args) throws Exception {new Test09CancelCall().run();}private final ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);private final OkHttpClient client = new OkHttpClient();public void run() throws Exception {Request request = new Request.Builder().url("http://httpbin.org/delay/2") // This URL is served with a 2 second delay..build();final long startNanos = System.nanoTime();final Call call = client.newCall(request);// Schedule a job to cancel the call in 1 second.executor.schedule(new Runnable() {@Override public void run() {System.out.printf("%.2f Canceling call.%n", (System.nanoTime() - startNanos) / 1e9f);call.cancel();System.out.printf("%.2f Canceled call.%n", (System.nanoTime() - startNanos) / 1e9f);}}, 1, TimeUnit.SECONDS);System.out.printf("%.2f Executing call.%n", (System.nanoTime() - startNanos) / 1e9f);try (Response response = call.execute()) {System.out.printf("%.2f Call was expected to fail, but completed: %s%n",  (System.nanoTime() - startNanos) / 1e9f, response);} catch (IOException e) {System.out.printf("%.2f Call failed as expected: %s%n", (System.nanoTime() - startNanos) / 1e9f, e);}}}

超时

private final OkHttpClient client;public ConfigureTimeouts() throws Exception {client = new OkHttpClient.Builder().connectTimeout(10, TimeUnit.SECONDS).writeTimeout(10, TimeUnit.SECONDS).readTimeout(30, TimeUnit.SECONDS).build();
}public void run() throws Exception {Request request = new Request.Builder().url("http://httpbin.org/delay/2") // This URL is served with a 2 second delay..build();try (Response response = client.newCall(request).execute()) {System.out.println("Response completed: " + response);}
}

每次调用配置

所有HTTP客户端配置都存在OkHttpClient中，包括代理设置、超时和缓存。当您需要更改单个调用的配置时，调用OkHttpClient.newBuilder()。这将返回一个与原始客户端共享相同连接池、调度程序和配置的构建器。在下面的示例中，我们发出一个超时500毫秒的请求，另一个超时3000毫秒。

private final OkHttpClient client = new OkHttpClient();public void run() throws Exception {Request request = new Request.Builder().url("http://httpbin.org/delay/1") // This URL is served with a 1 second delay..build();// 拷贝client的属性，并作出自定义修改OkHttpClient client1 = client.newBuilder().readTimeout(500, TimeUnit.MILLISECONDS).build();try (Response response = client1.newCall(request).execute()) {System.out.println("Response 1 succeeded: " + response);} catch (IOException e) {System.out.println("Response 1 failed: " + e);}// Copy to customize OkHttp for this request.OkHttpClient client2 = client.newBuilder().readTimeout(3000, TimeUnit.MILLISECONDS).build();try (Response response = client2.newCall(request).execute()) {System.out.println("Response 2 succeeded: " + response);} catch (IOException e) {System.out.println("Response 2 failed: " + e);}
}

处理鉴权

OkHttp可以自动重试未经身份验证的请求。当响应为401 Not Authorized时，会要求Authenticator提供凭据。实现应该构建一个包含缺失凭据的新请求。如果没有可用的凭据，则返回null以跳过重试。

private final OkHttpClient client;public Authenticate() {client = new OkHttpClient.Builder().authenticator(new Authenticator() {@Override public Request authenticate(Route route, Response response) throws IOException {if (response.request().header("Authorization") != null) {return null; // Give up, we've already attempted to authenticate.}System.out.println("Authenticating for response: " + response);System.out.println("Challenges: " + response.challenges());String credential = Credentials.basic("jesse", "password1");return response.request().newBuilder().header("Authorization", credential).build();}}).build();
}public void run() throws Exception {Request request = new Request.Builder().url("http://publicobject.com/secrets/hellosecret.txt").build();try (Response response = client.newCall(request).execute()) {if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);System.out.println(response.body().string());}
}

为避免在鉴权不起作用时进行多次重试，您可以返回null以放弃。例如，当已经尝试了这些确切的凭据时，您可能希望跳过重试：

if (credential.equals(response.request().header("Authorization"))) {return null; // If we already failed with these credentials, don't retry.
}

当您达到应用程序定义的尝试限制时，您也可以跳过重试：

if (responseCount(response) >= 3) {return null; // If we've failed 3 times, give up.
}

拦截器

参考：https://square.github.io/okhttp/features/interceptors/

import okhttp3.Interceptor;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;import java.io.IOException;@Slf4j
public class TestInterceptor {public static void main(String[] args) throws IOException {OkHttpClient client = new OkHttpClient.Builder().addInterceptor(new LoggingInterceptor())// .addNetworkInterceptor(new LoggingInterceptor()).build();Request request = new Request.Builder().url("http://www.publicobject.com/helloworld.txt").header("User-Agent", "OkHttp Example").build();Response response = client.newCall(request).execute();response.body().close();}static class LoggingInterceptor implements Interceptor {@Override public Response intercept(Interceptor.Chain chain) throws IOException {Request request = chain.request();long t1 = System.nanoTime();log.info(String.format("Sending request %s on %s%n%s",request.url(), chain.connection(), request.headers()));Response response = chain.proceed(request);long t2 = System.nanoTime();log.info(String.format("Received response for %s in %.1fms%n%s",response.request().url(), (t2 - t1) / 1e6d, response.headers()));return response;}}}

事件监听