Java Process Builder - 不能运行一个简单的程序

Question

我有一个名为 darknet 的程序。这是一个由 Darknet.

编写的 C 程序

我想运行文件夹 Darknet 中的 darknet 程序，如下所示：

我打算运行 darknet 使用 Java Process Builder，但是当我运行这段代码时我没有得到任何回应：

    // Arguments
    String darknetNamePath = darknet.getValue().getFilePath().replace("Darknet/", "./");
    String configurationFlag = configuration.getValue().getFilePath().replace("Darknet/", "");
    String weightsFlag = weights.getValue().getFilePath().replace("Darknet/", "");
    String imageFlag = "data/cameraSnap.png";
    String thresholdFlag = "-thresh " + thresholds.getValue();
    
    // Process builder
    ProcessBuilder processBuilder = new ProcessBuilder();
    processBuilder.directory(new File("Darknet")); // We need to stand inside the folder "Darknet"
    String commandString = "detect " + configurationFlag + " " + weightsFlag + " " + imageFlag + " " + thresholdFlag;
    System.out.println("darknetNamePath  = " + darknetNamePath);
    System.out.println("commandString  = " + commandString);
    processBuilder.command(darknetNamePath, commandString);
    Process process = processBuilder.start();
    BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
    String line;
    while ((line = reader.readLine()) != null) {
        System.out.println(line);
    }
    int exitCode = process.waitFor();
    System.out.println("\nExited with error code : " + exitCode);

这是我的输出。为什么它对我不起作用？

darknetNamePath  = ./darknet
commandString  = detect cfg/yolov2-tiny.cfg weights/yolov2-tiny.weights data/cameraSnap.png -thresh 0.8

Exited with error code : 0

但是当我通过终端调用 darknet 文件时，它就可以工作了。

./darknet detect cfg/yolov2-tiny.cfg weights/yolov2-tiny.weights data/cameraSnap.png -thresh 0.6

更新 2：

这是我的更新。

    // Arguments
    String darknetNamePath = darknet.getValue().getFile().getAbsolutePath();
    String configurationFlag = configuration.getValue().getFilePath().replace("Darknet/", "");
    String weightsFlag = weights.getValue().getFilePath().replace("Darknet/", "");
    String imageFlag = "data/cameraSnap.png";
    String thresholdFlag = "-thresh " + thresholds.getValue();

    // Process builder
    ProcessBuilder processBuilder = new ProcessBuilder();
    processBuilder.command(darknetNamePath, "detect", configurationFlag, weightsFlag, imageFlag, thresholdFlag);
    Process process = processBuilder.start();
    if (process.getInputStream().read() == -1) {
        System.out.println(darknetNamePath);
        System.out.println("detect");
        System.out.println(configurationFlag);
        System.out.println(weightsFlag);
        System.out.println(imageFlag);
        System.out.println(thresholdFlag);
        System.out.printf("ERROR!");
    }
    BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
    String line;
    while ((line = reader.readLine()) != null) {
        System.out.println(line);
    }
    int exitCode = process.waitFor();
    System.out.println("\nExited with error code : " + exitCode);

输出：

/home/dell/Dokument/GitHub/Vaadin-DL4J-YOLO-Camera-Mail-Reporter/Vaadin-DL4J-YOLO-Camera-Mail-Reporter/Darknet/darknet
detect
cfg/yolov2-tiny.cfg
weights/yolov2-tiny.weights
data/cameraSnap.png
-thresh 0.3
ERROR!
Exited with error code : 0

更新 3：

这个有效：

            // Arguments
            String darkPath = darknet.getValue().getFilePath().replace("Darknet/", "./"); // We need to call ./darknet, not absolute path
            String configurationFlag = configuration.getValue().getFilePath().replace("Darknet/", "");
            String weightsFlag = weights.getValue().getFilePath().replace("Darknet/", "");
            String imageFlag = "data/camera.png";
            String thresValue = String.valueOf(thresholds.getValue());

            // Process builder
            ProcessBuilder processBuilder = new ProcessBuilder();
            processBuilder.directory(new File("Darknet")); // Important
            processBuilder.command(darkPath, "detect", configurationFlag, weightsFlag, imageFlag, "-thresh", thresValue);
            processBuilder.redirectErrorStream(true); // Important
            Process process = processBuilder.start();
            BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
            int exitCode = process.waitFor();
            System.out.println("\nExited with error code : " + exitCode);

Answer 1

您使用 ProcessBuilder 的方式不对。 command 方法将可执行文件和参数作为单独的字符串，而不是路径，然后是另一个包含实际命令及其所有参数的字符串。没有 shell 涉及对命令进行分词，因此您将所有不同的参数作为一个参数传递。

我没有暗网，所以这是一个使用 Unix echo 命令的简单命令：

import java.io.*;

public class ProcessBuilderTest {
    public static void main(String[] args) throws Exception {
        ProcessBuilder processBuilder = new ProcessBuilder();
        String[] command = {"/bin/echo", "hello", "world"};
        processBuilder.command(command);
        Process process = processBuilder.start();
        BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
        String line;
        while ((line = reader.readLine()) != null) {
            System.out.println(line);
        }
        int exitCode = process.waitFor();
        System.out.println("Exited with error code : " + exitCode);
    }
}

当我运行这个时，我得到：

robert@saaz:~$ java ProcessBuilderTest.java
hello world
Exited with error code : 0

我不清楚为什么你的命令没有产生错误。如果我给出一个错误的命令（例如，“echo”后面的尾随 space），我会得到一个例外：

Exception in thread "main" java.io.IOException: Cannot run program "/bin/echo ": error=2, No such file or directory

这可能是 OS 具体的。或者，也许您有一些其他 darknet 可执行文件被拾取。

Answer 2

您的命令必须将所有参数分成单独的部分 - 包括 thresholdFlag。检查可执行文件是否存在是个好主意。如果没有，您应该检查它的位置或修复您的 Path 变量以确保可以找到它：

File darkpath = new File(darknetNamePath);
String [] cmd = new String[] { darkpath.getAbsolutePath(), "detect", configurationFlag, weightsFlag, imageFlag, "-thresh", String.valueOf(thresholds.getValue()) };

System.out.println("Path: "+darkpath+ " exists="+darkpath.exists());
System.out.println("exec "+Arrays.toString(cmd));

processBuilder.command(cmd);

也值得处理 STDERR，最简单的方法是在调用之前重定向 STDERR=>STDOUT processBuilder.start()

processBuilder.redirectErrorStream(true);

如果您希望 Java 在不添加绝对路径前缀的情况下启动可执行文件，它需要位于以下目录之一：

System.out.println("PATH COMPONENTS FOR JAVA LAUNCH:");
Arrays.asList(System.getenv("PATH").split(File.pathSeparator)).forEach(System.out::println);

Java Process Builder - 不能运行一个简单的程序

Java Process Builder - Cannot run a simple program

java

processbuilder

darknet

Java Process Builder - 不能 运行 一个简单的程序

Java Process Builder - Cannot run a simple program

java

processbuilder

darknet

Java Process Builder - 不能运行一个简单的程序