目录
- Java 调用http接口（基于OkHttp的Http工具类方法示例）
- OkHttp3
- MAVEN依赖
- Http get操作示例
- Http Post操作示例
- Http 超时控制
- 工具类示例
Java 调用http接口（基于OkHttp的Http工具类方法示例）
现在的互联网项目中，自己单撸所有功能的时代已经过去了，有些功能往往有第三方或者公司其他团队提供服务，你要做得仅仅就是和它们进行对接。对接一些大公司提供的服务时，它们往往会提供对应语言的SDK和说明文档；而团队与团队之间的项目对接往往通过接口进行数据交互，往往都是HTTP JSON交互的形式。
本文介绍如何使用这些API，然后给出博主自己写的一个工具列demo，需要的可以在此基础上修改。
OkHttp3
一般来说，Java 直接调用HTTP接口常见的有三种方式，第一种是JDK原生的方式，第二种是apache 提供的HTTP工具，还有一种是本文着重介绍的OkHttp3工具
OkHttp3官方文档介绍了它的4点优势：
- HTTP/2支持允许对同一主机的所有请求共享一个socket。
- 连接池减少了请求延迟(如果HTTP/2不可用)。
- 透明GZIP压缩下载大小。
- 响应缓存完全避免了网络重复请求。
使用OkHttp很容易。它的请求/响应API设计为流畅的构建器和不变性。它同时支持同步阻塞调用和带回调的异步调用。
下面介绍一下常见的GET方法和POST方法官方示例，首先添加依赖：
MAVEN依赖
com.squareup.okhttp3
okhttp
4.0.0
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 超时控制
当调用的对等方不可用时，超时使调用失败。网络可能是由于客户机连接问题、服务器可用性问题或两者之间的任何问题造成的。OkHttp支持连接、读取和写入超时。
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);
}
}工具类示例
提供同步的GET和POST调用工具方法示例，提供了异步调用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请求
* 对于小文档，响应体上的string()方法非常方便和高效。
* 但是，如果响应主体很大(大于1 MB)，则应避免string()，
* 因为它会将整个文档加载到内存中。在这种情况下，将主体处理为流。
*
* @param url
* @return
*/
public static String httpGet(String url) {
if (url == null || "".equals(url)) {
log.error("url为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 请求成功; [url={}]", url);
return response.body().string();
} else {
log.warn("Http GET 请求失败; [errorCode = {} , url={}]", response.code(), url);
}
} catch (IOException e) {
throw new RuntimeException("同步http GET 请求失败,url:" + url, e);
}
return null;
}
public static String httpGet(String url, Map 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 请求成功; [url={}]", url);
return response.body().string();
} else {
log.warn("Http GET 请求失败; [errorxxCode = {} , url={}]", response.code(), url);
}
} catch (IOException e) {
throw new RuntimeException("同步http GET 请求失败,url:" + url, e);
}
return null;
}
/**
* 同步 POST调用 无Header
*
* @param url
* @param json
* @return
*/
public static String httpPostJson(String url, String json) {
if (url == null || "".equals(url)) {
log.error("url为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 请求成功; [url={}, requestContent={}]", url, json);
return response.body().string();
} else {
log.warn("Http POST 请求失败; [ errorCode = {}, url={}, param={}]", response.code(), url, json);
}
} catch (IOException e) {
throw new RuntimeException("同步http请求失败,url:" + url, e);
}
return null;
}
/**
* 同步 POST调用 有Header
*
* @param url
* @param headers
* @param json
* @return
*/
public static String httpPostJson(String url, Map 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 请求成功; [url={}, requestContent={}]", url, json);
return response.body().string();
} else {
log.warn("Http POST 请求失败; [ errorCode = {}, url={}, param={}]", response.code(), url, json);
}
} catch (IOException e) {
throw new RuntimeException("同步http请求失败,url:" + url, e);
}
return null;
}
/**
* 提交表单
* @param url
* @param content
* @param headers
* @return
*/
public static String postDataByForm(String url, String content, Map 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请求失败,[url={}, param={}]", url, content);
}
} catch (IOException e) {
log.error("Http Post Form请求失败,[url={}, param={}]", url, content, e);
throw new RuntimeException("Http Post Form请求失败,url:" + url);
}
return null;
}
/**
* 异步Http调用参考模板：Get、Post、Put
* 需要异步调用的接口一般情况下你需要定制一个专门的Http方法
*
* @param httpMethod
* @param url
* @param content
* @return
*/
@Deprecated
public static Future asyncHttpByJson(HttpMethod httpMethod, String url, Map 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("异步http {} 请求失败,[url={}, param={}]", httpMethod.name(), url, content);
throw new RuntimeException("异步http请求失败,url:" + url);
}
@Override
public void onResponse(Call call, final Response response) throws IOException {
if (response.code() == 200) {
System.out.println("需要加入异步回调操作");
} else {
log.error("异步http {} 请求失败,错误码为{},请求参数为[url={}, param={}]", httpMethod.name(), response.code(), url, content);
}
}
});
return new AsyncResult(true);
}
/**
* lambda表达式异步调用http模板,不建议使用
*
* @param request
* @param failure
* @param respConsumer
*/
public static void asyncCall(Request request, Consumer failure, Consumer 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));
}
} 综上，本文介绍了Okhttp3的使用，并给出了工具类的demo，要注意的是，对于异步调用http方法需要根据你们项目的具体业务进行改造，增加回调失败与成功的业务逻辑。
文档链接：OkHttp官网