java远程调用python脚本讲解 java执行python代码

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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<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("/<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("/<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)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。

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