目錄

• Java 調用http接口（基于OkHttp的Http工具類方法示例）
  • OkHttp3
  • MAVEN依賴
  • Http get操作示例
  • Http Post操作示例
  • Http 超時控制
  • 工具類示例

Java 調用http接口（基于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，然后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，還有一種是本文著重介紹的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復請求。

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。網絡可能是由于客戶機連接問題、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* 對于小文檔，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(大于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制一個專門的Http方法** @param httpMethod* @param url* @param content* @return*/@Deprecatedpublic 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() {@Overridepublic 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);}@Overridepublic 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() {@Overridepublic void onFailure(Call call, IOException e) {failure.accept(e);}@Overridepublic void onResponse(Call call, Response response) throws IOException {respConsumer.accept(response);}});}//testpublic 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，并給出了工具類的demo，要注意的是，對于異步調用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

轉載于:https://www.cnblogs.com/keeya/p/11368791.html

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