java - Runtime.exec() 无输出

Question

运行 4 个“街道”进程的代码:

for (int i=0; i < NUM_STREETS; i++) {
        Process process = runtime.exec("java -classpath \\bin trafficcircle.Street 1 2");

        InputStream is = process.getInputStream();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader br = new BufferedReader(isr);
        String line;

        while ((line = br.readLine()) != null && !line.isEmpty()) {
            System.out.println(line);
            System.out.flush();
        }

        InputStream es = process.getErrorStream();
        InputStreamReader esr = new InputStreamReader(es);
        BufferedReader br2 = new BufferedReader(esr);

        while ((line = br2.readLine()) != null && !line.isEmpty()) {
            System.out.println(line);
            System.out.flush();
        }

        int exitVal = process.waitFor();
        System.out.println("Process exitValue: " + exitVal);
    }

“街道”在哪里:

public class Street {

/**
 * @param args
 * 0 - Simulation run time
 * 1 - Flow time interval
 */
public static void main(String[] args) {
    System.out.println(args[0]);
    System.out.println(args[1]);
    System.out.flush();
}

打印出来:

Error: Could not find or load main class trafficcircle.Street
Process exitValue: 1
Error: Could not find or load main class trafficcircle.Street
Process exitValue: 1
Error: Could not find or load main class trafficcircle.Street
Process exitValue: 1
Error: Could not find or load main class trafficcircle.Street
Process exitValue: 1

我的 Eclipse 项目中的“Street.class”位于包 trafficcircle 中的\bin 下。我以为如果找不到 Runtime.exec 会首先提示...这是怎么回事？

Answer 1

我假设您遇到了一个您正在丢弃的错误。尝试使用 ProcessBuilder.redirectErrorStream(true);

当您尝试运行一个命令时，它不是在 shell 中运行的，并且可能会收到您在命令行中看不到的错误。我会明确地使用

"java","-classpath","bin","trafficcircle.Street","1","2"`

并确保您收到任何错误消息。

另一种选择是使用像这样的外壳

"/bin/bash", "-c", "java -classpath bin trafficcircle.Street 1 2"