如何使用 ProcessBuilder 在 Java 代码中运行 NPM 命令

Question

My environment is mac. I'm trying to run "npm ls" from my java code but it throws error messages.

My java code:

String npm = isWindows() ? "npm.cmd" : "npm";

System.out.println(rootStr);
Process process = new ProcessBuilder(npm, "ls").directory(new File(rootStr)).start();

Error Message:

Users/youngeun/Downloads/zenbot_unstable
java.io.IOException: Cannot run program "npm" (in directory "/Users/youngeun/Downloads/zenbot_unstable"): error=2, No such file or directory
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
    at com.iotcube.scanner.nodejs.npm.NpmService.npmInfo(NpmService.java:26)
    at com.iotcube.scanner.IotcubescannerApplication.main(IotcubescannerApplication.java:174)
Caused by: java.io.IOException: error=2, No such file or directory
    at java.lang.UNIXProcess.forkAndExec(Native Method)
    at java.lang.UNIXProcess.<init>(UNIXProcess.java:247)
    at java.lang.ProcessImpl.start(ProcessImpl.java:134)
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)
    ... 2 more

But it seems to work perfectly in my terminal:

| ~/Downloads/zenbot_unstable @ Youngeunui-MacBook-Pro (youngeun) 
| => npm ls
zenbot4@4.1.0 /Users/youngeun/Downloads/zenbot_unstable
├─┬ @babel/core@7.2.2
│ ├─┬ @babel/code-frame@7.0.0
│ │ └─┬ @babel/highlight@7.0.0
│ │   ├── chalk@2.4.2 deduped
│ │   ├── esutils@2.0.2 deduped
│ │   └── js-tokens@4.0.0
│ ├─┬ @babel/generator@7.3.0
│ │ ├── @babel/types@7.3.0 deduped
│ │ ├── jsesc@2.5.2
│ │ ├── lodash@4.17.11 deduped
...

I've tried solutions from other stackoverflow pages but none of them seems to work... I am so lost.. I would appreciate your help. thanks

Answer 1

Try providing full path to the npm executable:

String dir = "/Users/youngeun/Downloads/zenbot_unstable";
String npm = dir + "/npm";
Process p = new ProcessBuilder(npm, "ls")
                .director(new File(dir))
                .start();
p.waitFor();

Answer 2

如果您正在从 NPM 中寻找一些简单的东西，比如下载包并在本地提取它，或者搜索包或类似的东西：有替代方法 - 使用 Java 本机库来处理 NPM 注册表： https : //github.com/OrienteerBAP /JNPM