如何在Java项目中执行python代码 - 好文

最近在做一个项目，需要在java里调用python代码，网上找了一些资料，想简单总结一下。可是我对java运行机制并不是很了解，所以只能说说怎么做。

1. 安装Jython (什么是Jython <https://baike.so.com/doc/5458872-5697261.html>)

下载安装jython_installer-2.5.0.jar
<http://download.csdn.net/download/radhot/1572368>,
安装完毕后需要把其中的jython.jar复制到项目中的lib中（引入jar包）；

2. 编写简易python代码

import java.io.IOException; import org.python.util.PythonInterpreter; public
class test { public static void main(String args[]) throws IOException {
PythonInterpreter interpreter = new PythonInterpreter(); // 运行python语句
interpreter.exec("a = \"hello, Jython\""); interpreter.exec("print a"); } }
结果报错：console: Failed to install '':
java.nio.charset.UnsupportedCharsetException: cp0.

把上述代码改成下面形式即可

import java.io.IOException; import org.python.util.PythonInterpreter; public
class test { public static void main(String args[]) throws IOException { 



Properties props = new Properties();
props.put("python.console.encoding", "UTF-8"); // Used to prevent: console:
Failed to install '': java.nio.charset.UnsupportedCharsetException: cp0.
props.put("python.security.respectJavaAccessibility", "false"); //don't respect
java accessibility, so that we can access protected members on subclasses
props.put("python.import.site","false"); Properties preprops =
System.getProperties(); PythonInterpreter.initialize(preprops, props, args);
PythonInterpreter interpreter = new PythonInterpreter(); // 运行python语句
interpreter.exec("a = \"hello, Jython\""); interpreter.exec("print a"); } }3.
执行python文件

把上述执行python语句的代码改为

interpreter.execfile("C:/Users/JingYi/Desktop/hello.py"); ///执行python py文件
4. 执行python文件并传参

package jp; import java.util.Properties; import org.python.core.Py; import
org.python.core.PyException; import org.python.core.PyObject; import
org.python.core.PyString; import org.python.util.PythonInterpreter; public
class main { public static void main(String args[]) { Properties props = new
Properties(); props.put("python.console.encoding", "UTF-8"); // Used to
prevent: console: Failed to install '':
java.nio.charset.UnsupportedCharsetException: cp0.
props.put("python.security.respectJavaAccessibility", "false"); //don't respect
java accessibility, so that we can access protected members on subclasses
props.put("python.import.site","false"); Properties preprops =
System.getProperties(); String[] arguments ={ "string1", "string2","string3"};
PythonInterpreter.initialize(preprops, props, arguments); PythonInterpreter
interpreter = new PythonInterpreter(); interpreter.exec("import sys");
interpreter.exec("sys.path.append('E:/Python27/Lib')"); // 加载第三方包的路径
interpreter.exec("sys.path.append('E:/Python27/Lib/site-packages')"); //
加载第三方包的路径
interpreter.exec("sys.path.append('E:/Python27/Lib/site-packages/numpy/lib')");
// 加载第三方包的路径 interpreter.execfile("C:/Users/JingYi/Desktop/hello.py");
//执行python文件 String funcName ="myFunction"; PyObject someFunc
=interpreter.get(funcName); // 调用python的猴哥函数 if (someFunc == null) { //throw
new Exception("Could notfind Python function: " + funcName); } else {
someFunc.__call__(new PyString(arguments[0]), new PyString(arguments[1]), new
PyString(arguments[2])); // 把参数传过去 } }// main }其中hello.py文件内容如下：

def myFunction(str1, str2, str3): print 'print parameters from java' print
str1 print str2 print str3
5. 引入第三方库

根据上述方法，暂时不清楚如何在jython中引用类似numpy pandas这样的第三方库，这里给出一种实现方法（与jython无关）。
package jp; import java.io.BufferedReader; import java.io.InputStreamReader;
public class test { public static void main(String[] args){ try{
System.out.println("start"); Process pr =
Runtime.getRuntime().exec("E:\\Python27\\python.exe
C:/Users/JingYi/Desktop/hello.py"); // 本机的python运行环境 & 即将要调用的py文件
BufferedReader in = new BufferedReader(new
InputStreamReader(pr.getInputStream())); String line; while ((line =
in.readLine()) != null) { System.out.println(line); } in.close(); pr.waitFor();
System.out.println("end"); } catch (Exception e){ e.printStackTrace(); } } }
参考：

1. Jython：java调用python文件之第三方包路径问题 java调用python总出现python第三方库没有定义
<http://blog.csdn.net/ztf312/article/details/51338060>

2. java调用python总出现python第三方库没有定义
<http://blog.csdn.net/johline/article/details/65633466>

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