在java代码中执行带有参数的外部程序

Question

Process p;
String line;
String path;
String[] params = new String [3];

params[0] = "D:\\prog.exe";
params[1] = picA+".jpg";
params[2] = picB+".jpg";

try
{
    p = Runtime.getRuntime().exec(params);

    BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));

    while ((line = input.readLine()) != null)
        System.out.println(line);

    input.close();
}
catch (IOException e)
{
    System.out.println(" procccess not read"+e);
}

我没有收到任何错误，只是什么都没有。在 cmd.exe prog.exe 中工作正常。

为了使这段代码正常工作，需要改进什么？

Answer 1

使用 p = new ProcessBuilder(params).start(); 而不是

p = Runtime.getRuntime().exec(params);

除此之外看起来不错。

Answer 2

也许您应该使用 waitFor() 来获取结果代码。这意味着标准输出的转储必须在另一个线程中完成：

String path;
String[] params = new String [3];

                    params[0] = "D:\\prog.exe";
        params[1] = picA+".jpg";
        params[2] = picB+".jpg";

        try {
            final Process p = Runtime.getRuntime().exec(params);
            Thread thread = new Thread() {
                public void run() {
                    String line;
                    BufferedReader input =
                       new BufferedReader
                         (new InputStreamReader(p.getInputStream()));

                     while ((line = input.readLine()) != null)
                         System.out.println(line);


                     input.close();
               } catch (IOException e) {System.out.println(" procccess not read"+e);}
            };
            thread.start();
            int result = p.waitFor();
            thread.join();
            if (result != 0) {
                System.out.println("Process failed with status: " + result);
            }

Answer 3

我刚刚在我的系统上尝试过：

public static void main(String[] args) throws IOException {
        String[] params = { "svn", "help" };
        Process p = Runtime.getRuntime().exec(params);

        BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));

        String line;
        while ((line = input.readLine()) != null) {
            System.out.println(line);
        }

        input.close();
    }

效果很好。
您确定您使用的程序确实在控制台上打印了一些内容吗？我看到它接受 jpeg 作为输入，也许它写入文件，而不是标准输出。

Answer 4

就像从进程的输入流中读取一样，您也可以像这样从错误流中读取：

    Process p;
    String line;
    String path;
    String[] params = new String [3];

    params[0] = "D:\\prog.exe";
    params[1] = picA+".jpg";
    params[2] = picB+".jpg";

    try {
        p = Runtime.getRuntime().exec(params);

        BufferedReader input =
            new BufferedReader
              (new InputStreamReader(p.getInputStream()));

        BufferedReader error =
            new BufferedReader
              (new InputStreamReader(p.getErrorStream()));

          while ((line = input.readLine()) != null)
              System.out.println(line);


          while ((line = error.readLine()) != null)
              System.out.println(line);

          input.close();
          error.close();

    } catch (IOException e) {
            System.out.println(" procccess not read"+e);
    }