java 调用python_Java平台如何调用Python平台？

1. 问题描述

Java平台要调用Pyhon平台已有的算法，为了减少耦合度，采用Pyhon平台提供Restful 接口，Java平台负责来调用，采用Http+Json格式交互。

2. 解决方案

2.1 JAVA平台侧

2.1.1 项目代码

  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 httpEntity = new HttpEntity<>(JSONObject.toJSONString(params), headers);        RestTemplate rst = new RestTemplate();        ResponseEntity stringResponseEntity = rst.postForEntity(url, httpEntity, String.class);        return stringResponseEntity.getBody();    }

2.1.2 代码解析

两个入参：url为Python提供restful调用方法；params参数，项目中参数使用了map，然后将map转成了Json，与Python服务器约定Json格式传输。

2.2 python平台侧

经过反复调研与深思熟虑的考虑后，决定采用flask提供Rest接口， flask 是一款非常流行的python web框架，微框架、简洁，社区活跃等。(其实是因为安装的Anaconda自带了flask，一配置一启动好了，就是这么巧)

2.2.1 项目代码

# -*- coding: utf-8 -*-from flask import Flask, request, send_from_directoryfrom k_means import execapp = 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("/")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 代码解析

代码为真实项目示例，去掉了一些配置而已，示例中包含三个方法，分别说一下

(1)最基本Rest接口：helloword

# -*- coding: utf-8 -*-from flask import Flaskapp = Flask(__name__)@app.route('/')def index():    return "Hello, World!"if __name__ == '__main__':    app.run(host="0.0.0.0", port=5000, debug=True)

(2)调用其他python文件的Rest接口

# -*- coding: utf-8 -*-from flask import Flask, requestfrom k_means import execapp = 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 resultif __name__ == '__main__':    app.run(host="0.0.0.0", port=5000, debug=True)

说明：1.接收POST方法；2. 从request获取java传过来的参数，对应上面的java调用代码

(3) 文件下载Rest接口

# -*- coding: utf-8 -*-from flask import Flask, send_from_directoryapp = Flask(__name__)@app.route("/")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)

说明：1.还是flask框架提供的：send_from_directory

2.dirpath目录，一般可以给个固定存放目录，调用的时候只用给文件名称就可以直接下载对应文件。