1. 問題描述

Java平臺要調用Pyhon平臺已有的算法，為了減少耦合度，采用Pyhon平臺提供Restful 接口，Java平臺負責來調用，采用Http+Json格式交互。

2. 解決方案

2.1 JAVA平臺側

2.1.1 項目代碼

  public static String invokeAlgorithm(String url, HashMap params) throws Exception {

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.parseMediaType("application/json; charset=UTF-8"));
        headers.add("Accept", MediaType.APPLICATION_JSON.toString());
        HttpEntity<String> httpEntity = new HttpEntity<>(JSONObject.toJSONString(params), headers);
        RestTemplate rst = new RestTemplate();

        ResponseEntity<String> stringResponseEntity = rst.postForEntity(url, httpEntity, String.class);

        return stringResponseEntity.getBody();
    }

2.1.2 代碼解析

兩個入參：url為Python提供restful調用方法；params參數，項目中參數使用了map，然后將map轉成了Json，與Python服務器約定Json格式傳輸。

2.2 python平臺側

經過反復調研與深思熟慮的考慮后，決定采用flask提供Rest接口， flask 是一款非常流行的python web框架，微框架、簡潔，社區活躍等。（其實是因為安裝的Anaconda自帶了flask，一配置一啟動好了，就是這么巧）

2.2.1 項目代碼

# -*- coding: utf-8 -*-
from flask import Flask, request, send_from_directory
from k_means import exec
app = Flask(__name__)
import logging

@app.route('/')
def index():
    return "Hello, World!"

# k-means算法
@app.route('/getKmeansInfoByPost', methods=['POST'])
def getKmeansInfoByPost():
    try:
         result = exec(request.get_json())
    except IndexError as e:
        logging.error(str(e))
        return 'exception:' + str(e)
    except KeyError as e:
        logging.error(str(e))
        return 'exception:' + str(e)
    except ValueError as e:
        logging.error(str(e))
        return 'exception:' + str(e)
    except Exception as e:
        logging.error(str(e))
        return 'exception:' + str(e)
    else:
        return result

@app.route("/<path:filename>")
def getImages(filename):
    return send_from_directory(dirpath, filename, as_attachment=True)

if __name__ == '__main__':
    app.run(host="0.0.0.0", port=5000, debug=True)

2.2.2 代碼解析

代碼為真實項目示例，去掉了一些配置而已，示例中包含三個方法，分別說一下

（1）最基本Rest接口：helloword

# -*- coding: utf-8 -*-
from flask import Flask
app = Flask(__name__)

@app.route('/')
def index():
    return "Hello, World!"

if __name__ == '__main__':
    app.run(host="0.0.0.0", port=5000, debug=True)

（2）調用其他python文件的Rest接口

# -*- coding: utf-8 -*-
from flask import Flask, request
from k_means import exec
app = Flask(__name__)
import logging

# k-means算法
@app.route('/getKmeansInfoByPost', methods=['POST'])
def getKmeansInfoByPost():
    try:
         result = exec(request.get_json())
    except IndexError as e:
        logging.error(str(e))
        return 'exception:' + str(e)
    except KeyError as e:
        logging.error(str(e))
        return 'exception:' + str(e)
    except ValueError as e:
        logging.error(str(e))
        return 'exception:' + str(e)
    except Exception as e:
        logging.error(str(e))
        return 'exception:' + str(e)
    else:
        return result

if __name__ == '__main__':
    app.run(host="0.0.0.0", port=5000, debug=True)

說明：1.接收POST方法；2. 從request獲取java傳過來的參數，對應上面的java調用代碼

（3） 文件下載Rest接口

# -*- coding: utf-8 -*-
from flask import Flask, send_from_directory

app = Flask(__name__)

@app.route("/<path:filename>")
def getImages(filename):
    return send_from_directory(dirpath, filename, as_attachment=True)

if __name__ == '__main__':
    app.run(host="0.0.0.0", port=5000, debug=True)

說明：1.還是flask框架提供的：send_from_directory

2.dirpath目錄，一般可以給個固定存放目錄，調用的時候只用給文件名稱就可以直接下載對應文件。

2.3 Linux服務器啟動python服務

      nohup python restapi.py &