java - 从 exec 运行 java -jar

Question

我尝试运行:java -jar/home/user/workspace/maltparser-1.8/maltparser-1.8.jar这是工作。并返回:

-----------------------------------------------------------------------------
                          MaltParser 1.8                             
-----------------------------------------------------------------------------
         MALT (Models and Algorithms for Language Technology) Group          
             Vaxjo University and Uppsala University                         
                             Sweden                                          
-----------------------------------------------------------------------------

Usage:     java -jar maltparser-1.8.jar -f <path to option file> <options>    java -jar maltparser-1.8.jar -h for more help and options

help                  (  -h) : Show options                           

----------------------------------------------------------------------------- option_file           (  -f) : Path to option file                    

----------------------------------------------------------------------------- verbosity            *(  -v) : Verbosity level                         debug      - Logging of debugging messages   error      - Logging of error events   fatal      - Logging of very severe error events   info
- Logging of informational messages   off        - Logging turned off     warn       - Logging of harmful situations
-----------------------------------------------------------------------------

Documentation: docs/index.html

现在，我尝试从我的类(class)运行这个 .jar:

public class Main {

        public static void main(String[] args) throws IOException, InterruptedException {

                    Process ps = Runtime.getRuntime().exec(new String[]{"java","-jar","/home/user/workspace/maltparser-1.8/maltparser-1.8.jar"});
                    ps.waitFor();
                    java.io.InputStream is=ps.getInputStream();
                    byte b[]=new byte[is.available()];
                    is.read(b,0,b.length);
                    System.out.println(new String(b));
        }
}

它什么也没返回给我...我想拦截输出流。我该怎么做？

Answer 1

恕我直言，您读取InputStream的方法有点奇怪，您可能不想等到流填满后再打印某些内容，而且您忽略了错误流。 ..

我更喜欢使用 ProcessBuilder 因为...

1. 您可以将错误流重定向到 InputStream，这使得管理更加容易
2. 您可以更改启动命令的工作目录的上下文...

举个例子...

try {
    ProcessBuilder pb = new ProcessBuilder(new String[]{"java", "-jar", "Your.jar"});
    pb.redirectError();
    //pb.directory(new File("you/path"));
    Process ps = pb.start();
    try (java.io.InputStream is = ps.getInputStream()) {
        int read = -1;
        while ((read = is.read()) != -1) {
            System.out.print((char) read);
        }
    }
    System.out.println("Command exited with: " + ps.waitFor());
} catch (IOException | InterruptedException exp) {
    exp.printStackTrace();
}

已更新

由于我不知道的原因，通过 log4j 的 ConsoleAppender 发送的输出似乎没有到达 Process 的 InputStream.. .

要解决此问题，您可以使用 ProcessBuilder 的 inheritIO...

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

public class TestRunJar {

    public static void main(String[] args) {
        try {
            ProcessBuilder pb = new ProcessBuilder(new String[]{"java", "-jar", "/../maltparser-1.8.jar"});
            pb.inheritIO();
            pb.redirectError();
            pb.directory(new File("/..")); // Path to where maltparser-1.8.jar resides
            Process ps = pb.start();

            InputStreamConsumer stdout = new InputStreamConsumer(ps.getInputStream());
            InputStreamConsumer stderr = new InputStreamConsumer(ps.getErrorStream());

            stderr.start();
            stdout.start();

            stderr.join();
            stderr.join();

            System.out.println("Command exited with: " + ps.waitFor());
        } catch (IOException | InterruptedException exp) {
            exp.printStackTrace();
        }
    }

    public static class InputStreamConsumer extends Thread {

        private InputStream is;
        private IOException exp;
        private StringBuilder output;

        public InputStreamConsumer(InputStream is) {
            this.is = is;
        }

        @Override
        public void run() {
            int in = -1;
            output = new StringBuilder(64);
            try {
                while ((in = is.read()) != -1) {
                    output.append((char) in);
                }
            } catch (IOException ex) {
                ex.printStackTrace();
                exp = ex;
            }
        }

        public StringBuilder getOutput() {
            return output;
        }

        public IOException getException() {
            return exp;
        }
    }

}

这只是我的测试代码，所以可能有点过头了;)

最终被抛弃了......

-----------------------------------------------------------------------------
                          MaltParser 1.8                             
-----------------------------------------------------------------------------
         MALT (Models and Algorithms for Language Technology) Group          
             Vaxjo University and Uppsala University                         
                             Sweden                                          
-----------------------------------------------------------------------------

Usage: 
   java -jar maltparser-1.8.jar -f <path to option file> <options>
   java -jar maltparser-1.8.jar -h for more help and options

help                  (  -h) : Show options                                 
-----------------------------------------------------------------------------
option_file           (  -f) : Path to option file                          
-----------------------------------------------------------------------------
verbosity            *(  -v) : Verbosity level                              
  debug      - Logging of debugging messages
  error      - Logging of error events
  fatal      - Logging of very severe error events
  info       - Logging of informational messages
  off        - Logging turned off  
  warn       - Logging of harmful situations
-----------------------------------------------------------------------------

Documentation: docs/index.html
Command exited with: 0