背景：

         市面上很多公司都有人脸识别技术的解决方案，比如腾讯、百度、旷世、科大讯飞。我调用的旷世Face++的人脸识别API。

原理：

        Face++API-通过url设置参数请求，Face++返回参数，然后自己对参数解析，最后呈现出来，没有什么难度，主要是学会对API的使用。

申请账号:

1.         旷世Face++(https://www.faceplusplus.com.cn/)注册账号
2.         进入应用管理，申请API Key API Secret

API的使用：

        URL:https://api-cn.faceplusplus.com/facepp/v3/detect

private static String httpRequest(String apiUrl, String picUrl) {
		StringBuffer strBuffer = new StringBuffer();
		try {
			URL url = new URL(apiUrl);
			HttpURLConnection httpURLConn = (HttpURLConnection) url.openConnection();
			httpURLConn.setDoOutput(true);
			httpURLConn.setDoInput(true);
			httpURLConn.setRequestMethod("POST");
			httpURLConn.connect();
			//
			DataOutputStream out = new DataOutputStream(
					httpURLConn.getOutputStream());
			String data = "image_url=" + java.net.URLEncoder.encode(picUrl,"UTF-8") +
					"&api_key=你的api_key"&api_secret=你的&api_secret";
			out.writeBytes(data);
            out.flush();
            out.close();

			
			//将返回的输入流转化成字符串
			InputStream inputStream = httpURLConn.getInputStream();
			InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "UTF-8");
			BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
			//
			String str = null;
			while((str = bufferedReader.readLine()) != null) {
				strBuffer.append(str);
			}
			//读取完毕，释放资源
			bufferedReader.close();
			inputStreamReader.close();
			inputStream.close();
			inputStream = null;
			httpURLConn.disconnect();	
		} catch (Exception e) {
			// TODO: handle exception
		}
		return strBuffer.toString();	
	}

//api请求网址
String apiUrl = "https://api-cn.faceplusplus.com/facepp/v3/detect?return_attributes=gender,age,eyestatus,emotion,ethnicity,skinstatus";
//调用Http请求
String json = httpRequest(apiUrl, picUrl);

请求方法：POST

        必填参数：api_key，api_secret，image_url / image_file / mage_base64 （三选一）

        可选参数：return_landmark，return_attributes

   返回实例：

{
	"image_id": "Dd2xUw9S/7yjr0oDHHSL/Q==",
	"request_id": "1470472868,dacf2ff1-ea45-4842-9c07-6e8418cea78b",
	"time_used": 752,
	"faces": [{
		"landmark": {
			"mouth_upper_lip_left_contour2": {
				"y": 185,
				"x": 146
			},
			"contour_chin": {
				"y": 231,
				"x": 137
			},
			.............省略关键点信息 
			"right_eye_pupil": {
				"y": 146,
				"x": 205
			},
			"mouth_upper_lip_bottom": {
				"y": 195,
				"x": 159
			}
		},
		"attributes": {
			"gender": {
				"value": "Female"
			},
			"age": {
				"value": 21
			},
			"glass": {
				"value": "None"
			},
			"headpose": {
				"yaw_angle": -26.625063,
				"pitch_angle": 12.921974,
				"roll_angle": 22.814377
			},
			"smile": {
				"threshold": 30.1,
				"value": 2.566890001296997
			}
		},
		"face_rectangle": {
			"width": 140,
			"top": 89,
			"left": 104,
			"height": 141
		},
		"face_token": "ed319e807e039ae669a4d1af0922a0c8"
	}]
}