Java调用Python传list(多个list，不同类型list)参数

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## 1、通过Runtime进行调用 #### 1.1 传一个字符串 * java文件 
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public class CoalType {
    public static String coalType_list(String data) {
        String arr = null;
        try {
            String[] arg = new String[] { "E:\\Program Files\\Python36\\python.exe", "E:\\Test\\test\\qiting.py",data};
            Process proc = Runtime.getRuntime().exec(arg);// 执行py文件

            BufferedReader in = new BufferedReader(new InputStreamReader(proc.getInputStream()));
            String line = null;
            while ((line = in.readLine()) != null) {
                arr = line;
            }
            in.close();
            proc.waitFor();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return arr;
    }

    public static void main(String[] args) {
        String data = "Lisa";
        String test_name = CoalType.coalType_list(data);
        System.out.println(test_name);
    }
}
  • py文件
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import numpy as np
import sys as ss
        
def main():
	print (ss.argv[1])

if __name__ == '__main__':
    main()
  • 结果
1
Lisa

如下图：

   在Java中通过Runtime调用Python程序与直接执行Python程序的效果是一样的，可以在Python中读取传递的参数，也可以在Java中读取到Python的执行结果。
   如上图所示，这样是获取不到数据的，需要输出语句print，StartStopOpt方法在java中也调用不了，需要在.py文件里初始化调用，然后输出，java才能获取到数据
   需要注意的是，不能在Python中通过return语句返回结果，只能将返回值写入到标准输出流中，然后在Java中通过标准输入流读取Python的输出值。

1.1 传一个list集合

  • java文件

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    public class Mogun {
        public static String coalType_list(List<Double> list_one) {
            String arr = null;
            try {
                String sysPython = "E:\\Program Files\\Python36\\python.exe ";
                String filePython = "E:\\Test\\test\\qiting.py ";
                Process proc = Runtime.getRuntime().exec(sysPython + filePython + list_one);// 执行py文件
                BufferedReader in = new BufferedReader(new InputStreamReader(proc.getInputStream()));
                String line = null;
                while ((line = in.readLine()) != null) {
                    arr = line;
                }
                in.close();
                proc.waitFor();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return arr;
        }

        public static void main(String[] args) throws Exception {
            List<Double> list_one = new ArrayList<>();
            list_one.add(1.222);
            list_one.add(2.888);
            list_one.add(3.888);
            list_one.add(4.888);
            list_one.add(5.888);
            String flag = Mogun.coalType_list(list_one);
            System.out.println(flag);

        }
    }

  • py文件

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    import numpy as np
    import sys as ss

    def StartStopOpt(list_str,list_float):
    	............
    	...........
    	return result
            
    def main():
    	list_str = []
        list_float = []
        for i in range(1, len(ss.argv)):
            list_str.append(ss.argv[i].replace(",", ""))
        list_str[0] = list_str[0].replace("[", "")
        list_str[len(ss.argv) - 2] = list_str[len(ss.argv) - 2].replace("]", "")
        # 字符串数组
        # print(list_str)
        # 浮点数数组
        list_int = list(map(float, list_str))
        # print(list_int)
    	# 调用函数传参得到返回值输出
    	test = StartStopOpt(list_str,list_float)
    	print(test)
    	
    if __name__ == '__main__':
        main()

  • 结果

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    字符串数组
    ['1.222', '2.888', '3.888', '4.888', '5.888']
    浮点数数组
    [1.222, 2.888, 3.888, 4.888, 5.888]
    调用函数传参得到返回值输出
    ...省略

注意：一定要记得空格，不然会报错

1.1 传两个list集合

  • java文件

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    public class Mogun {
        public static String coalType_list(List<Double> list_one, List<Integer> list_two) {
            String arr = null;
            try {
                String sysPython = "E:\\Program Files\\Python36\\python.exe ";
                String filePython = "E:\\Test\\test\\qiting.py ";
                Process proc = Runtime.getRuntime().exec(sysPython + filePython + list_one + list_two);// 执行py文件
                BufferedReader in = new BufferedReader(new InputStreamReader(proc.getInputStream()));
                String line = null;
                while ((line = in.readLine()) != null) {
                    arr = line;
                }
                in.close();
                proc.waitFor();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return arr;
        }

        public static void main(String[] args) throws Exception {
            List<Double> list_one = new ArrayList<>();
            list_one.add(1.222);
            list_one.add(2.888);
            list_one.add(3.888);
            list_one.add(4.888);
            list_one.add(5.888);
            List<Integer> list_two = new ArrayList<>();
            list_two.add(1);
            list_two.add(2);
            list_two.add(3);
            list_two.add(4);
            list_two.add(5);
            String flag = Mogun.coalType_list(list_one, list_two);
            System.out.println(flag);

        }
    }

  • py文件

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    import numpy as np
    import sys as ss

    def StartStopOpt(turn,current):
    	............
    	...........
    	return result
            
    def main():
    	#初始数据
        # print (ss.argv[1:])
        list_str = []
        turn = []
        current = []
        for i in range(1, len(ss.argv)):
            list_str.append(ss.argv[i].replace(",", ""))
        list_str[0] = list_str[0].replace("[", "")
        list_str[len(ss.argv) - 2] = list_str[len(ss.argv) - 2].replace("]", "")
        str = ','.join(list_str)
        arr = str.split("][")
        turn = arr[0].split(",")
        turn = list(map(float, turn))#转换成浮点数数组
        #输出第一个数组
        # print (turn)
        current = arr[1].split(",")
        current = list(map(int, current))#转换成整数数组
        #输出第二个数组
        # print (current)
    	
    	# 调用函数传参得到返回值输出
    	test = StartStopOpt(turn,current)
    	print(test)
    	

    if __name__ == '__main__':
        main()

  • 结果

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    初始数据
    ['[1.222,', '2.888,', '3.888,', '4.888,', '5.888][1,', '2,', '3,', '4,', '5]']
    输出第一个数组
    [1, 2, 3, 4, 5]
    输出第二个数组
    [1.222, 2.888, 3.888, 4.888, 5.888]
    调用函数传参得到返回值输出
    ...省略

问题：数组的长度也是有限制的，我试着添加了8000元素的double类型的集合，就报错了
解决：https://www.cnblogs.com/downmoon/archive/2012/11/18/2775587.html

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