Java 調用http接口（基於OkHttp的Http工具類方法示例）
- 2019 年 10 月 3 日
- 筆記
Java 調用http接口（基於OkHttp的Http工具類方法示例）
現在的互聯網項目中，自己單擼所有功能的時代已經過去了，有些功能往往有第三方或者公司其他團隊提供服務，你要做得僅僅就是和它們進行對接。對接一些大公司提供的服務時，它們往往會提供對應語言的SDK和說明文檔；而團隊與團隊之間的項目對接往往通過接口進行數據交互，往往都是HTTP JSON交互的形式。
本文介紹如何使用這些API，然後給出博主自己寫的一個工具列demo，需要的可以在此基礎上修改。
OkHttp3
一般來說，Java 直接調用HTTP接口常見的有三種方式，第一種是JDK原生的方式，第二種是apache 提供的HTTP工具，還有一種是本文着重介紹的OkHttp3工具
OkHttp3官方文檔介紹了它的4點優勢：
- HTTP/2支持允許對同一主機的所有請求共享一個socket。
- 連接池減少了請求延遲(如果HTTP/2不可用)。
- 透明GZIP壓縮下載大小。
- 響應緩存完全避免了網絡重複請求。
使用OkHttp很容易。它的請求/響應API設計為流暢的構建器和不變性。它同時支持同步阻塞調用和帶回調的異步調用。
下面介紹一下常見的GET方法和POST方法官方示例，首先添加依賴：
MAVEN依賴
<!--okhttp依賴--> <dependency> <groupId>com.squareup.okhttp3</groupId> <artifactId>okhttp</artifactId> <version>4.0.0</version> </dependency>Http get操作示例
OkHttpClient client = new OkHttpClient(); String run(String url) throws IOException { Request request = new Request.Builder() .url(url) .build(); try (Response response = client.newCall(request).execute()) { return response.body().string(); } }Http Post操作示例
public static final MediaType JSON = MediaType.get("application/json; charset=utf-8"); OkHttpClient client = new OkHttpClient(); String post(String url, String json) throws IOException { RequestBody body = RequestBody.create(JSON, json); Request request = new Request.Builder() .url(url) .post(body) .build(); try (Response response = client.newCall(request).execute()) { return response.body().string(); } }Http 超時控制
當調用的對等方不可用時，超時使調用失敗。網絡可能是由於客戶機連接問題、服務器可用性問題或兩者之間的任何問題造成的。OkHttp支持連接、讀取和寫入超時。
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); } }工具類示例
提供同步的GET和POST調用工具方法示例，提供了異步調用HTTP接口的demo
import okhttp3.*; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.http.HttpMethod; import org.springframework.scheduling.annotation.AsyncResult; import org.springframework.util.CollectionUtils; import java.io.IOException; import java.util.Map; import java.util.concurrent.Future; import java.util.concurrent.TimeUnit; import java.util.function.Consumer; /** * @author axin * @since 2019-08-14 */ public class OkHttpUtils { private static final Logger log = LoggerFactory.getLogger(OkHttpUtils.class); private static final String HTTP_JSON = "application/json; charset=utf-8"; private static final String HTTP_FORM = "application/x-www-form-urlencoded; charset=utf-8"; private static final OkHttpClient okHttpClient = new OkHttpClient.Builder() .connectTimeout(120, TimeUnit.SECONDS) .readTimeout(120, TimeUnit.SECONDS) .writeTimeout(120, TimeUnit.SECONDS) .build(); /** * get請求 * 對於小文檔，響應體上的string()方法非常方便和高效。 * 但是，如果響應主體很大(大於1 MB)，則應避免string()， * 因為它會將整個文檔加載到內存中。在這種情況下，將主體處理為流。 * * @param url * @return */ public static String httpGet(String url) { if (url == null || "".equals(url)) { log.error("url為null!"); return ""; } Request.Builder builder = new Request.Builder(); Request request = builder.get().url(url).build(); try { Response response = okHttpClient.newCall(request).execute(); if (response.code() == 200) { log.info("http GET 請求成功; [url={}]", url); return response.body().string(); } else { log.warn("Http GET 請求失敗; [errorCode = {} , url={}]", response.code(), url); } } catch (IOException e) { throw new RuntimeException("同步http GET 請求失敗,url:" + url, e); } return null; } public static String httpGet(String url, Map<String, String> headers) { if (CollectionUtils.isEmpty(headers)) { return httpGet(url); } Request.Builder builder = new Request.Builder(); headers.forEach((String key, String value) -> builder.header(key, value)); Request request = builder.get().url(url).build(); try { Response response = okHttpClient.newCall(request).execute(); if (response.code() == 200) { log.info("http GET 請求成功; [url={}]", url); return response.body().string(); } else { log.warn("Http GET 請求失敗; [errorxxCode = {} , url={}]", response.code(), url); } } catch (IOException e) { throw new RuntimeException("同步http GET 請求失敗,url:" + url, e); } return null; } /** * 同步 POST調用 無Header * * @param url * @param json * @return */ public static String httpPostJson(String url, String json) { if (url == null || "".equals(url)) { log.error("url為null!"); return ""; } MediaType JSON = MediaType.parse(HTTP_JSON); RequestBody body = RequestBody.create(JSON, json); Request.Builder requestBuilder = new Request.Builder().url(url); Request request = requestBuilder.post(body).build(); try { Response response = okHttpClient.newCall(request).execute(); if (response.code() == 200) { log.info("http Post 請求成功; [url={}, requestContent={}]", url, json); return response.body().string(); } else { log.warn("Http POST 請求失敗; [ errorCode = {}, url={}, param={}]", response.code(), url, json); } } catch (IOException e) { throw new RuntimeException("同步http請求失敗,url:" + url, e); } return null; } /** * 同步 POST調用 有Header * * @param url * @param headers * @param json * @return */ public static String httpPostJson(String url, Map<String, String> headers, String json) { if (CollectionUtils.isEmpty(headers)) { httpPostJson(url, json); } MediaType JSON = MediaType.parse(HTTP_JSON); RequestBody body = RequestBody.create(JSON, json); Request.Builder requestBuilder = new Request.Builder().url(url); headers.forEach((k, v) -> requestBuilder.addHeader(k, v)); Request request = requestBuilder.post(body).build(); try { Response response = okHttpClient.newCall(request).execute(); if (response.code() == 200) { log.info("http Post 請求成功; [url={}, requestContent={}]", url, json); return response.body().string(); } else { log.warn("Http POST 請求失敗; [ errorCode = {}, url={}, param={}]", response.code(), url, json); } } catch (IOException e) { throw new RuntimeException("同步http請求失敗,url:" + url, e); } return null; } /** * 提交表單 * @param url * @param content * @param headers * @return */ public static String postDataByForm(String url, String content, Map<String, String> headers) { MediaType JSON = MediaType.parse(HTTP_FORM); RequestBody body = RequestBody.create(JSON, content); Request.Builder requestBuilder = new Request.Builder().url(url); if (headers != null && headers.size() > 0) { headers.forEach((k, v) -> requestBuilder.addHeader(k, v)); } Request request = requestBuilder .post(body) .build(); Response response = null; try { response = okHttpClient.newCall(request).execute(); if (response.code() == 200) { log.info("postDataByForm; [postUrl={}, requestContent={}, responseCode={}]", url, content, response.code()); return response.body().string(); } else { log.warn("Http Post Form請求失敗,[url={}, param={}]", url, content); } } catch (IOException e) { log.error("Http Post Form請求失敗,[url={}, param={}]", url, content, e); throw new RuntimeException("Http Post Form請求失敗,url:" + url); } return null; } /** * 異步Http調用參考模板：Get、Post、Put * 需要異步調用的接口一般情況下你需要定製一個專門的Http方法 * * @param httpMethod * @param url * @param content * @return */ @Deprecated public static Future<Boolean> asyncHttpByJson(HttpMethod httpMethod, String url, Map<String, String> headers, String content) { MediaType JSON = MediaType.parse(HTTP_JSON); RequestBody body = RequestBody.create(JSON, content); Request.Builder requestBuilder = new Request.Builder() .url(url); if (!CollectionUtils.isEmpty(headers)) { headers.forEach((key, value) -> requestBuilder.header(key, value)); } switch (httpMethod) { case GET: requestBuilder.get(); break; case POST: requestBuilder.post(body); break; default: } Request request = requestBuilder.build(); Call call = okHttpClient.newCall(request); call.enqueue(new Callback() { @Override public void onFailure(Call call, IOException e) { log.error("異步http {} 請求失敗,[url={}, param={}]", httpMethod.name(), url, content); throw new RuntimeException("異步http請求失敗,url:" + url); } @Override public void onResponse(Call call, final Response response) throws IOException { if (response.code() == 200) { System.out.println("需要加入異步回調操作"); } else { log.error("異步http {} 請求失敗,錯誤碼為{},請求參數為[url={}, param={}]", httpMethod.name(), response.code(), url, content); } } }); return new AsyncResult(true); } /** * lambda表達式異步調用http模板,不建議使用 * * @param request * @param failure * @param respConsumer */ public static void asyncCall(Request request, Consumer<Exception> failure, Consumer<Response> respConsumer) { okHttpClient.newCall(request).enqueue(new Callback() { @Override public void onFailure(Call call, IOException e) { failure.accept(e); } @Override public void onResponse(Call call, Response response) throws IOException { respConsumer.accept(response); } }); } //test public static void main(String[] args) { String url = "http://www.baidu.com"; System.out.println(httpGet(url)); } }綜上，本文介紹了Okhttp3的使用，並給出了工具類的demo，要注意的是，對於異步調用http方法需要根據你們項目的具體業務進行改造，增加回調失敗與成功的業務邏輯。
文檔鏈接：OkHttp官網
