[Python] py4j的使用

py4j简介：

官网
Py4J enables Python programs running in a Python interpreter to dynamically access Java objects in a Java Virtual Machine. Methods are called as if the Java objects resided in the Python interpreter and Java collections can be accessed through standard Python collection methods. Py4J also enables Java programs to call back Python objects.

Mac安装：

• pip 安装

pip install py4j

py4j.jar包路径：/usr/share/py4j/py4j0.x.jar or /usr/local/share/py4j/py4j0.x.jar

• conda 安装（或者使用Anaconda-Navigator安装）

conda install py4j

py4j.jar包路径：/anaconda3/share/py4j/py4j0.x.jar

使用：

1.java代码

// 需要导入py4j.jar包
import py4j.GatewayServer;
import java.util.Random;


public class EntryPoint {
    private static final Random random = new Random();

    public int randInt() {
        return random.nextInt();
    }

    public static void main(String[] args) {

        EntryPoint app = new EntryPoint();
        // py4j服务
        GatewayServer gatewayServer = new GatewayServer(app);
        gatewayServer.start();
        System.out.println("Gateway Server Started");
    }
}

2.Python代码

from py4j.java_gateway import JavaGateway

# 初始化
gateway = JavaGateway()

def main():
    # 调用Java-EntryPoint中的randInt函数
    a = gateway.entry_point.randInt()
    print(a)

if __name__ == '__main__':
    main()

注意：
1.导入py4j.jar包
2.运行Java代码
3.运行Python代码（必须在2之后）

python调用Java的其他方式：

感谢ayuLiao的这篇文章python调用Java的多种方法

• Pyjnius
• JCC
• Javabridge
• Jpype