Java调用Python脚本实现HelloWorld的示例详解

# 检查Java
java -version
# 检查Python
python --version  # 或python3 --version（根据系统配置）

# 接收Java传递的参数
import sys

if __name__ == "__main__":
    # 获取Java传入的参数（第0个参数是脚本名）
    name = sys.argv[1] if len(sys.argv) > 1 else "World"
    # 输出结果（会被Java捕获）
    print(f"Hello, {name}! From Python")

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class JavaCallPythonByRuntime {
    public static void main(String[] args) {
        // 1. 定义Python脚本路径和参数
        String pythonScriptPath = "hello.py";
        String param = "Java";  // 要传递给Python的参数

        // 2. 构建命令数组（推荐用数组形式，避免空格问题）
        String[] cmd = new String[]{"python", pythonScriptPath, param};

        try {
            // 3. 启动Python进程
            Process process = Runtime.getRuntime().exec(cmd);

            // 4. 读取Python的输出（必须读取，否则可能导致进程阻塞）
            InputStream inputStream = process.getInputStream();
            BufferedReader reader = new BufferedReader(
                new InputStreamReader(inputStream, "UTF-8")  // 指定编码，避免中文乱码
            );
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println("Python输出：" + line);
            }

            // 5. 等待进程执行完成并获取退出码（0表示成功）
            int exitCode = process.waitFor();
            System.out.println("进程退出码：" + exitCode);

        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

import sys
import os

if __name__ == "__main__":
    name = sys.argv[1] if len(sys.argv) > 1 else "World"
    # 读取Java设置的环境变量
    app_name = os.getenv("APP_NAME", "UnknownApp")
    print(f"[{app_name}] Hello, {name}! From Python")

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Map;

public class JavaCallPythonByProcessBuilder {
    public static void main(String[] args) {
        try {
            // 1. 创建ProcessBuilder，指定命令和参数
            ProcessBuilder pb = new ProcessBuilder(
                "python", "hello.py", "JavaDeveloper"
            );

            // 2. 设置工作目录（脚本所在目录，不设置则默认当前目录）
            pb.directory(new java.io.File("./scripts"));  // 假设脚本放在scripts子目录

            // 3. 设置环境变量（给Python脚本传递配置）
            Map<String, String> env = pb.environment();
            env.put("APP_NAME", "JavaCallPythonDemo");

            // 4. 重定向错误流到输入流（方便统一处理输出和错误）
            pb.redirectErrorStream(true);

            // 5. 启动进程
            Process process = pb.start();

            // 6. 读取输出
            try (BufferedReader reader = new BufferedReader(
                new InputStreamReader(process.getInputStream(), "UTF-8")
            )) {
                String line;
                while ((line = reader.readLine()) != null) {
                    System.out.println("Python输出：" + line);
                }
            }

            // 7. 等待进程完成
            int exitCode = process.waitFor();
            System.out.println("进程退出码：" + exitCode);

        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

pip install flask

from flask import Flask, request

app = Flask(__name__)

@app.route('/hello', methods=['GET'])
def hello():
    # 从请求参数获取name
    name = request.args.get('name', 'World')
    return f"Hello, {name}! From Python Service"

if __name__ == '__main__':
    # 启动服务，允许外部访问
    app.run(host='0.0.0.0', port=5000, debug=True)

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Duration;

public class JavaCallPythonByHttp {
    public static void main(String[] args) {
        // 1. 创建HttpClient
        HttpClient client = HttpClient.newBuilder()
                .connectTimeout(Duration.ofSeconds(5))
                .build();

        // 2. 构建请求（Python服务地址）
        String name = "JavaHttpClient";
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create("http://localhost:5000/hello?name=" + name))
                .timeout(Duration.ofSeconds(3))
                .GET()
                .build();

        try {
            // 3. 发送请求并获取响应
            HttpResponse<String> response = client.send(
                request, HttpResponse.BodyHandlers.ofString()
            );

            // 4. 处理响应
            if (response.statusCode() == 200) {
                System.out.println("Python服务响应：" + response.body());
            } else {
                System.err.println("请求失败，状态码：" + response.statusCode());
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}