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_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 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）调用其他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)

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_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)

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。

2.3 Linux服务器启动python服务

      nohup python restapi.py &