Java调用python代码的五种方式
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你还在纠结怎么样在Java中调用python吗?我们在实际工程项目问题中,经常会碰到不同语言代码之间互调的问题,比如此处的Java调用python(常见Java调用python写的处理模型来完成数据处理等)。
目录
让我们来看看具体怎么操作吧!
1. 无参数调用
说明: Java调用不带参数的python代码执行
样例代码如下:
try {
String exe = "python解释器所处的绝对路径";
String py = "python代码文件绝对地址";
Process process = Runtime.getRuntime().exec(exe + " " + py);
//获取结果的同时设置输入流编码格式"gb2312"
InputStreamReader isr = new InputStreamReader(process.getInputStream(),"gb2312");
LineNumberReader input = new LineNumberReader(isr);
String result = "";
result = input.readLine();
System.out.println(result);
input.close();
isr.close();
process.waitFor();
} catch (InterruptedException | IOException e) {
System.out.println("调用python脚本并读取结果时出错:" + e.getMessage());
}
2. 带参数调用
带参调用可以将命令和参数写入String数组,然后作为执行参数执行。
基本语句如下:
String exe = "python解释器所处的绝对路径";
String py = "python代码文件绝对地址";
String pram = "单个传递参数,若参数为基本类型,转化为String;若为数组等类型,也是将其转换为String型";
String [] args = new String[] {exe, py, pram...};
Process process = Runtime.getRuntime().exec(args);
2.1. 单行返回值
说明: Java调用不带参数的python代码执行
样例代码如下:
try {
String exe = "python解释器所处的绝对路径";
String py = "python代码文件绝对地址";
String pram = "单个传递参数,若参数为基本类型,转化为String;若为数组等类型,也是将其转换为String型";
String [] args = new String[] {exe, py, pram...};
Process process = Runtime.getRuntime().exec(args);
//获取结果的同时设置输入流编码格式"gb2312"
InputStreamReader isr = new InputStreamReader(process.getInputStream(),"gb2312");
LineNumberReader input = new LineNumberReader(isr);
String result = "";
result = input.readLine();
System.out.println(result);
input.close();
isr.close();
process.waitFor();
} catch (InterruptedException | IOException e) {
System.out.println("调用python脚本并读取结果时出错:" + e.getMessage());
}
2.2. 多行返回值
说明: Java调用不带参数的python代码执行
样例代码如下:
try {
String exe = "python解释器所处的绝对路径";
String py = "python代码文件绝对地址";
String pram = "单个传递参数,若参数为基本类型,转化为String;若为数组等类型,也是将其转换为String型";
String [] args = new String[] {exe, py, pram...};
ProcessBuilder builder = new ProcessBuilder(args);
Process process = builder.start();
BufferedReader success = new BufferedReader(new InputStreamReader(process.getInputStream(), "GB2312"));//获取字符输入流对象
BufferedReader error = new BufferedReader(new InputStreamReader(process.getErrorStream(), "GB2312"));//获取错误信息的字符输入流对象
String line = null;
List<String> success_result = new ArrayList<>();
List<String> error_result = new ArrayList<>();
//记录输出结果
while ((line = success.readLine()) != null) {
success_result.add(line);
}
//记录错误信息
while ((line = error.readLine()) != null) {
error_result.add(line);
}
success.close();
error.close();
process.waitFor();
System.out.println(success_result);
System.out.println(error_result);
} catch (InterruptedException | IOException e) {
System.out.println("调用python脚本并读取结果时出错:" + e.getMessage());
}
3. Java中直接执行python语句
注意: 此方法在使用之前需要导入依赖环境,如在maven中导入如下依赖:
<dependency>
<groupId>org.python</groupId>
<artifactId>jython-standalone</artifactId>
<!--python版本在这里指定(2.x或3.x等)-->
<version>3.7.0</version>
</dependency>
调用语句如下:
import org.python.util.PythonInterpreter
public class JavaRunPython {
public static void main(String[] args) {
//调用python的解释器
PythonInterpreter interpreter = new PythonInterpreter();
//执行Python语句
interpreter.exec("str = 'hello world!'; ");
interpreter.exec("print(str);");
}
}
4. 通过PythonInterpreter直接调用python脚本
注意: 此方法也需要导入1.3中依赖
Java调用代码如下:
import org.python.util.PythonInterpreter;
public class JavaPythonFile {
public static void main(String[] args) {
PythonInterpreter interpreter = new PythonInterpreter();
//我在这里使用相对路径,注意区分
interpreter.execfile("D:/code/test.py");
}
}
test.py举例如下:
a = 1
b = 2
print(a +b)
5. Java通过调用bat文件间接调用python
hello.bat测试代码如下:
echo hello world!
D:
cd D:\code\
start python test.py
pause
Java调用代码如下:
try {
StringBuilder sb = new StringBuilder();
String batPath = "D:/hello.bat";
Process process = Runtime.getRuntime().exec(batPath);
InputStream in = process.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(in));
String line;
while ((line = bufferedReader.readLine()) != null) {
sb.append(line + "\n");
}
in.close();
try {
process.waitFor();
} catch (InterruptedException e) {
System.out.println(e);
}
} catch (IOException e) {
System.out.println(e);
}
如果大家有好的方法,欢迎交流评论!
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