java - ProcessBuilder 或 Runtime 类从哪里获取环境变量？

Question

此链接:Understanding Java Process and Java ProcessBuilder有一句话说exec方法创建的进程不拥有控制台。

如果我从 java 调用 python 脚本，进程从哪里获取环境变量？

如何操作/添加/删除 Java Process 类使用的环境变量？

Answer 1

您可以使用ProcessBuilder.environment()方法来获取环境变量的Map。

<强> ProcessBuilder 文档指出:

Returns a string map view of this process builder's environment. Whenever a process builder is created, the environment is initialized to a copy of the current process environment (see System.getenv()). Subprocesses subsequently started by this object's start() method will use this map as their environment.

使用返回的映射，您可以设置自己的自定义环境变量，该变量将由您启动的进程使用。

下面的示例片段演示了使用 ProcessBuilder API 设置环境变量:

public static void main(String[] args) throws Exception {
     ProcessBuilder pb =
                new ProcessBuilder("cmd.exe", "/C", "echo", "%JAVA_HOME%");
     Map<String, String> env = pb.environment();
     env.put("JAVA_HOME", "c/User/Programs/JDK...");
     Process p = pb.start();
     BufferedReader br  = new BufferedReader(new InputStreamReader(p.getInputStream()));
     String line = "";
     while((line=br.readLine()) != null){
         System.out.println(line);
     }
     try {
         int exitValue = p.waitFor();
         System.out.println("\n\nExit Value is " + exitValue);
     } catch (InterruptedException e) {
            e.printStackTrace();
     }
}